version 3.8

* NEWS: Record release date.

.gitattributes

@@ -1 +1,2 @@
-
+*.at   diff=autotest
+*.texi diff=texinfo

.gitconfig

@@ -0,0 +1,12 @@
+# To use this gitconfig file, run
+#
+# git config --local include.path ../.gitconfig
+#
+# It adds an `[include]` section in .git/config.
+# See <https://git-scm.com/docs/git-config#_includes>.
+
+[diff "autotest"]
+        xfuncname = "^((m4_define|m4_pushdef|AT_SETUP).*)$"
+
+[diff "texinfo"]
+        xfuncname = "^@node .*$"

.prev-version

@@ -1 +1 @@
-3.6.92
+3.7.91

.travis.yml

@@ -44,12 +44,15 @@ jobs:
         - git fetch --unshallow || true
         - git submodule update --init --recursive
 
+        # As of 2021-08, we don't have Autoconf 2.71 on Ubuntu.
+        - sed -i 's/AC_PREREQ(\[2\.71\])/AC_PREREQ([2.69])/g' configure.ac
         - ./bootstrap
         - ./configure --enable-gcc-warnings || { cat config.log && false; }
         - make -j2
         - make -j2 dist-xz
         # Can help understanding why we get "dirty" tarballs.
         - git status
+        - git diff
         - dist=$(echo bison*.xz)
 
         # Unfortunately we cannot deterministically know the name of the tarball without the full
@@ -70,55 +73,57 @@ jobs:
 
     # Start with three completely different environments, to get errors asap.
 
-    - name: "GCC 10 -O3"
+    - name: "GCC 11 -O3"
       stage: check
       os: linux
       dist: bionic
-      addons: &gcc10
+      addons: &gcc11
         apt:
           sources:
             # See https://github.com/travis-ci/apt-source-safelist/issues/410.
             - sourceline: 'ppa:ubuntu-toolchain-r/test'
-          packages: g++-10
+          packages: g++-11
       env:
-        - CC=gcc-10
-        - CXX=g++-10
+        - CC=gcc-11
+        - CXX=g++-11
         - CONFIGUREFLAGS='CPPFLAGS=-DNDEBUG CFLAGS=-O3 CXXFLAGS=-O3'
 
     # ASAN is time consuming, and we timeout the 50min granted by
     # Travis if we run all the tests in one go.  Run in two parts.
-    - name: "Clang 10 libc++ and ASAN part 1"
+    - name: "Clang 11 libc++ and ASAN part 1"
       stage: check
       os: linux
       dist: bionic
-      addons: &clang10
+      addons: &clang11
         apt:
           sources:
             # See https://github.com/travis-ci/apt-source-safelist/issues/410.
             - sourceline: 'ppa:ubuntu-toolchain-r/test'
-            - sourceline: 'deb http://apt.llvm.org/bionic/ llvm-toolchain-bionic-10 main'
+            - sourceline: 'deb http://apt.llvm.org/bionic/ llvm-toolchain-bionic-11 main'
               key_url: 'https://apt.llvm.org/llvm-snapshot.gpg.key'
           packages:
-            - clang-10
-            - libc++-10-dev
-            - libc++abi-10-dev
+            - clang-11
+            - libc++-11-dev
+            - libc++abi-11-dev
       env:
         # Do not use ASAN with ubuntu's libc++: https://bugs.llvm.org/show_bug.cgi?id=17379
-        - CC='clang-10 -fsanitize=address'
-        - CXX='clang++-10 -fsanitize=address -stdlib=libc++'
+        - CC='clang-11 -fsanitize=address'
+        - CXX='clang++-11 -fsanitize=address -stdlib=libc++'
         - PART=1
 
-    - name: "Clang 10 libc++ and ASAN part 2"
+    - name: "Clang 11 libc++ and ASAN part 2"
       stage: check
       os: linux
       dist: bionic
-      addons: *clang10
+      addons: *clang11
       env:
         # Do not use ASAN with ubuntu's libc++: https://bugs.llvm.org/show_bug.cgi?id=17379
-        - CC='clang-10 -fsanitize=address'
-        - CXX='clang++-10 -fsanitize=address -stdlib=libc++'
+        - CC='clang-11 -fsanitize=address'
+        - CXX='clang++-11 -fsanitize=address -stdlib=libc++'
         - PART=2
 
+    # See https://github.com/simd-everywhere/simde/blob/master/.travis.yml
+    # and https://software.intel.com/content/www/us/en/develop/documentation/get-started-with-intel-oneapi-render-linux/top/configure-your-system.html.
     - name: "ICC"
       stage: check
       os: linux
@@ -127,7 +132,7 @@ jobs:
         - CC=icc
         - CXX=icpc
       install:
-        - source /opt/intel/inteloneapi/compiler/latest/env/vars.sh
+        - source /opt/intel/oneapi/compiler/latest/env/vars.sh
       addons:
         apt:
           sources:
@@ -136,19 +141,19 @@ jobs:
           packages:
           - intel-oneapi-icc
 
-    - name: "ARM64: GCC 10 -O2 part 1"
+    - name: "ARM64: GCC 11 -O2 part 1"
       stage: check
       os: linux
       arch: arm64
       dist: bionic
-      addons: *gcc10
+      addons: *gcc11
       env:
-        - CC=gcc-10
-        - CXX=g++-10
+        - CC=gcc-11
+        - CXX=g++-11
         - CONFIGUREFLAGS='CPPFLAGS=-DNDEBUG CFLAGS=-O2 CXXFLAGS=-O2'
         - PART=1
 
-    - name: "PPC64le: GCC 10 -O2 part 1"
+    - name: "PPC64le: GCC 11 -O2 part 1"
       stage: check
       os: linux
       arch: ppc64le
@@ -158,22 +163,22 @@ jobs:
           sources:
             # See https://github.com/travis-ci/apt-source-safelist/issues/410.
             - sourceline: 'ppa:ubuntu-toolchain-r/test'
-          packages: g++-10
+          packages: g++-11
       env:
-        - CC=gcc-10
-        - CXX=g++-10
+        - CC=gcc-11
+        - CXX=g++-11
         - CONFIGUREFLAGS='CFLAGS=-O2 CXXFLAGS=-O2'
         - PART=1
 
-    - name: "s390x: GCC 10 -O2 part 1"
+    - name: "s390x: GCC 11 -O2 part 1"
       stage: check
       os: linux
       arch: s390x
       dist: bionic
-      addons: *gcc10
+      addons: *gcc11
       env:
-        - CC=gcc-10
-        - CXX=g++-10
+        - CC=gcc-11
+        - CXX=g++-11
         - CONFIGUREFLAGS='CFLAGS=-O2 CXXFLAGS=-O2'
         - PART=1
 
@@ -181,7 +186,24 @@ jobs:
     ## GCC.  ##
     ## ----- ##
 
-    - name: "GCC 9 with sanitizers part 1"
+    - name: "GCC 10 with sanitizers part 1"
+      stage: check
+      os: linux
+      dist: bionic
+      addons:
+        apt:
+          sources:
+            # See https://github.com/travis-ci/apt-source-safelist/issues/410.
+            - sourceline: 'ppa:ubuntu-toolchain-r/test'
+          packages: g++-10
+      env:
+        - CC='gcc-10 -fsanitize=undefined,address -fno-omit-frame-pointer'
+        - CXX='g++-10 -fsanitize=undefined,address -fno-omit-frame-pointer'
+        - CONFIGUREFLAGS='CFLAGS=-O1 CXXFLAGS=-O1'
+        - PART=1
+
+    # With glr2.cc, we run out of time with the full test suite.
+    - name: "GCC 9 part 1"
       stage: check
       os: linux
       dist: bionic
@@ -192,12 +214,12 @@ jobs:
             - sourceline: 'ppa:ubuntu-toolchain-r/test'
           packages: g++-9
       env:
-        - CC='gcc-9 -fsanitize=undefined,address -fno-omit-frame-pointer'
-        - CXX='g++-9 -fsanitize=undefined,address -fno-omit-frame-pointer'
-        - CONFIGUREFLAGS='CFLAGS=-O1 CXXFLAGS=-O1'
+        - CC=gcc-9
+        - CXX=g++-9
         - PART=1
 
-    - name: "GCC 8"
+    # With glr2.cc, we run out of time with the full test suite.
+    - name: "GCC 8 part 1"
       stage: check
       os: linux
       dist: bionic
@@ -207,6 +229,7 @@ jobs:
       env:
         - CC=gcc-8
         - CXX=g++-8
+        - PART=1
 
     - name: "GCC 7"
       stage: check
@@ -295,7 +318,28 @@ jobs:
     ## Clang.  ##
     ## ------- ##
 
-    - name: "Clang 9 -O3"
+    - name: "Clang 10 -O3, libc++, part 1"
+      stage: check
+      os: linux
+      dist: bionic
+      addons:
+        apt:
+          sources:
+            # See https://github.com/travis-ci/apt-source-safelist/issues/410.
+            - sourceline: 'ppa:ubuntu-toolchain-r/test'
+            - sourceline: 'deb http://apt.llvm.org/bionic/ llvm-toolchain-bionic-10 main'
+              key_url: 'https://apt.llvm.org/llvm-snapshot.gpg.key'
+          packages:
+            - clang-10
+            - libc++-10-dev
+            - libc++abi-10-dev
+      env:
+        - CC='clang-10'
+        - CXX='clang++-10 -stdlib=libc++'
+        - CONFIGUREFLAGS='CPPFLAGS=-DNDEBUG CFLAGS=-O3 CXXFLAGS=-O3'
+        - PART=1
+
+    - name: "Clang 9 and libc++"
       stage: check
       os: linux
       dist: bionic
@@ -313,9 +357,8 @@ jobs:
       env:
         - CC='clang-9'
         - CXX='clang++-9 -stdlib=libc++'
-        - CONFIGUREFLAGS='CPPFLAGS=-DNDEBUG CFLAGS=-O3 CXXFLAGS=-O3'
 
-    - name: "Clang 8"
+    - name: "Clang 8 and libc++"
       stage: check
       os: linux
       dist: bionic
@@ -329,7 +372,7 @@ jobs:
         - CC=clang-8
         - CXX='clang++-8 -stdlib=libc++'
 
-    - name: "Clang 7"
+    - name: "Clang 7 and libc++"
       stage: check
       os: linux
       dist: bionic

AUTHORS

@@ -24,7 +24,7 @@ and nasty bugs.
 
 -----
 
-Copyright (C) 1998-2015, 2018-2020 Free Software Foundation, Inc.
+Copyright (C) 1998-2015, 2018-2021 Free Software Foundation, Inc.
 
 This file is part of Bison, the GNU Compiler Compiler.
 
@@ -39,4 +39,4 @@ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.
 
 You should have received a copy of the GNU General Public License
-along with this program.  If not, see <http://www.gnu.org/licenses/>.
+along with this program.  If not, see <https://www.gnu.org/licenses/>.

COPYING

@@ -1,7 +1,7 @@
                     GNU GENERAL PUBLIC LICENSE
                        Version 3, 29 June 2007
 
- Copyright (C) 2007 Free Software Foundation, Inc. <http://fsf.org/>
+ Copyright (C) 2007 Free Software Foundation, Inc. <https://fsf.org/>
  Everyone is permitted to copy and distribute verbatim copies
  of this license document, but changing it is not allowed.
 
@@ -645,7 +645,7 @@ the "copyright" line and a pointer to where the full notice is found.
     GNU General Public License for more details.
 
     You should have received a copy of the GNU General Public License
-    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 Also add information on how to contact you by electronic and paper mail.
 
@@ -664,11 +664,11 @@ might be different; for a GUI interface, you would use an "about box".
   You should also get your employer (if you work as a programmer) or school,
 if any, to sign a "copyright disclaimer" for the program, if necessary.
 For more information on this, and how to apply and follow the GNU GPL, see
-<http://www.gnu.org/licenses/>.
+<https://www.gnu.org/licenses/>.
 
   The GNU General Public License does not permit incorporating your program
 into proprietary programs.  If your program is a subroutine library, you
 may consider it more useful to permit linking proprietary applications with
 the library.  If this is what you want to do, use the GNU Lesser General
 Public License instead of this License.  But first, please read
-<http://www.gnu.org/philosophy/why-not-lgpl.html>.
+<https://www.gnu.org/licenses/why-not-lgpl.html>.

Makefile.am

@@ -1,6 +1,6 @@
 ## Process this file with automake to produce Makefile.in.
 
-# Copyright (C) 2001-2015, 2018-2020 Free Software Foundation, Inc.
+# Copyright (C) 2001-2015, 2018-2021 Free Software Foundation, Inc.
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -13,7 +13,7 @@
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 AUTOMAKE_OPTIONS = subdir-objects
 ACLOCAL_AMFLAGS = -I m4
@@ -76,6 +76,13 @@ include tests/local.mk
 clean-local:
 	rm -rf $(CLEANDIRS)
 
+.PHONY: gitsort
+gitsort:
+	cd $(srcdir)							\
+	&& for i in $$(git ls-files '*.gitignore' | grep -v doc); do	\
+	  LC_ALL=C sort $$i -o $$i;					\
+	done
+
 # See comments in build-aux/git-version-gen.  However, we make .version depend
 # on configure so that .version and VERSION/PACKAGE_VERSION stay in sync in the
 # working copy (for example, when you run autoreconf && make).  Allowing these
@@ -133,9 +140,10 @@ gen-ChangeLog:
 	$(CC) $(AM_CPPFLAGS) $(CPPFLAGS) $(AM_CFLAGS) $(CFLAGS) -o $@ -E $<
 
 .PHONY: codespell
+CODESPELL = codespell
 codespell:
 	$(AM_V_GEN) cd $(srcdir) \
-	&& codespell \
+	&& $(CODESPELL) \
 	     --regex "[\\w\\-'’\`]+\+*" \
 	     --ignore-words-list "ba,circularly,cloneable,copyable,define'd,dout,froms,iff,ifset,od,ois" \
 	     $$(git ls-files data doc lib src tests)

NEWS

@@ -1,36 +1,245 @@
 GNU Bison NEWS
 
-* Noteworthy changes in release 3.6.93 (2020-07-20) [beta]
+* Noteworthy changes in release 3.8 (2021-09-07) [stable]
+
+** Backward incompatible changes
+
+  In conformance with the recommendations of the Graphviz team
+  (https://marc.info/?l=graphviz-devel&m=129418103126092), `-g`/`--graph`
+  now generates a *.gv file by default, instead of *.dot.  A transition
+  started in Bison 3.4.
+
+  To comply with the latest POSIX standard, in Yacc compatibility mode
+  (options `-y`/`--yacc`) Bison now generates prototypes for yyerror and
+  yylex.  In some situations, this is breaking compatibility: if the user
+  has already declared these functions but with some differences (e.g., to
+  declare them as static, or to use specific attributes), the generated
+  parser will fail to compile.  To disable these prototypes, #define yyerror
+  (to `yyerror`), and likewise for yylex.
+
+** Deprecated features
+
+  Support for the YYPRINT macro is removed. It worked only with yacc.c and
+  only for tokens.  It was obsoleted by %printer, introduced in Bison 1.50
+  (November 2002).
+
+  It has always been recommended to prefer `%define api.value.type foo` to
+  `#define YYSTYPE foo`.  The latter is supported in C for compatibility
+  with Yacc, but not in C++.  Warnings are now issued if `#define YYSTYPE`
+  is used in C++, and eventually support will be removed.
+
+  In C++ code, prefer value_type to semantic_type to denote the semantic
+  value type, which is specified by the `api.value.type` %define variable.
+
+** New features
+
+*** A skeleton for the D programming language
+
+  The "lalr1.d" skeleton is now officially part of Bison.
+
+  It was originally contributed by Oliver Mangold, based on Paolo Bonzini's
+  lalr1.java, and was improved by H. S. Teoh.  Adela Vais then took over
+  maintenance and invested a lot of efforts to complete, test and document
+  it.
+
+  It now supports all the bells and whistles of the other deterministic
+  parsers, which include: pull/push interfaces, verbose and custom error
+  messages, lookahead correction, token constructors, internationalization,
+  locations, printers, token and symbol prefixes, etc.
+
+  Two examples demonstrate the D parsers: a basic one (examples/d/simple),
+  and an advanced one (examples/d/calc).
+
+*** Option -H, --header and directive %header
+
+  The option `-H`/`--header` supersedes the option `--defines`, and the
+  directive %header supersedes %defines.  Both `--defines` and `%defines`
+  are, of course, maintained for backward compatibility.
+
+*** Option --html
+
+  Since version 2.4 Bison can be used to generate HTML reports.  However it
+  was a two-step process: first bison must be invoked with option `--xml`,
+  and then xsltproc must be run to the convert the XML reports into HTML.
+
+  The new option `--html` combines these steps.  The xsltproc program must
+  be available.
+
+*** A C++ native GLR parser
+
+  A new version of the C++ GLR parser was added: "glr2.cc".  It generates
+  "true C++11", instead of a C++ wrapper around a C parser as does the
+  existing "glr.cc" parser.  As a first significant consequence, it supports
+  `%define api.value.type variant`, contrary to glr.cc.
+
+  It should be upward compatible in terms of interface, feature and
+  performance to "glr.cc". To try it out, simply use
+
+  %skeleton "glr2.cc"
+
+  It will eventually replace "glr.cc".  However we need user feedback on
+  this skeleton.  _Please_ report your results and comments about it.
+
+*** Counterexamples
+
+  Counterexamples now show the rule numbers, and always show ε for rules
+  with an empty right-hand side.  For instance
+
+    exp
+    ↳ 1: e1       e2     "a"
+         ↳ 3: ε • ↳ 1: ε
+
+  instead of
+
+    exp
+    ↳ e1  e2  "a"
+      ↳ • ↳ ε
+
+*** Lookahead correction in Java
+
+  The Java skeleton (lalr1.java) now supports LAC, via the `parse.lac`
+  %define variable.
+
+*** Abort parsing for memory exhaustion (C)
+
+  User actions may now use `YYNOMEM` (similar to `YYACCEPT` and `YYABORT`)
+  to abort the current parse with memory exhaustion.
+
+*** Printing locations in debug traces (C)
+
+  The `YYLOCATION_PRINT(File, Loc)` macro prints a location.  It is defined
+  when (i) locations are enabled, (ii) the default type for locations is
+  used, (iii) debug traces are enabled, and (iv) `YYLOCATION_PRINT` is not
+  already defined.
+
+  Users may define `YYLOCATION_PRINT` to cover other cases.
+
+*** GLR traces
+
+  There were no debug traces for deferred calls to user actions.  They are
+  logged now.
+
+
+* Noteworthy changes in release 3.7.6 (2021-03-08) [stable]
 
 ** Bug fixes
 
-  Portability issues.
+*** Reused Push Parsers
+
+  When a push-parser state structure is used for multiple parses, it was
+  possible for some state to leak from one run into the following one.
+
+*** Fix Table Generation
+
+  In some very rare conditions, when there are many useless tokens, it was
+  possible to generate incorrect parsers.
 
 
-* Noteworthy changes in release 3.6.92 (2020-07-19) [beta]
-
-Changes in the display of counterexamples.
-
-** Documentation
-
-*** Examples
-
-  The bistromathic demonstrates %param and how to quote sources in the error
-  messages:
-
-    > 123 456
-    1.5-7: syntax error: expected end of file or + or - or * or / or ^ before number
-        1 | 123 456
-          |     ^~~
-
-* Noteworthy changes in release 3.6.91 (2020-07-09) [beta]
+* Noteworthy changes in release 3.7.5 (2021-01-24) [stable]
 
 ** Bug fixes
 
-  Portability issues.
+*** Counterexample Generation
+
+  In some cases counterexample generation could crash.  This is fixed.
+
+*** Fix Table Generation
+
+  In some very rare conditions, when there are many useless tokens, it was
+  possible to generate incorrect parsers.
+
+*** GLR parsers now support %merge together with api.value.type=union.
+
+*** C++ parsers use noexcept in more places.
+
+*** Generated parsers avoid some warnings about signedness issues.
+
+*** C-language parsers now avoid warnings from pedantic clang.
+
+*** C-language parsers now work around quirks of HP-UX 11.23 (2003).
 
 
-* Noteworthy changes in release 3.6.90 (2020-07-04) [beta]
+* Noteworthy changes in release 3.7.4 (2020-11-14) [stable]
+
+** Bug fixes
+
+*** Bug fixes in yacc.c
+
+  In Yacc mode, all the tokens are defined twice: once as an enum, and then
+  as a macro.  YYEMPTY was missing its macro.
+
+*** Bug fixes in lalr1.cc
+
+  The lalr1.cc skeleton used to emit internal assertions (using YY_ASSERT)
+  even when the `parse.assert` %define variable is not enabled.  It no
+  longer does.
+
+  The private internal macro YY_ASSERT now obeys the `api.prefix` %define
+  variable.
+
+  When there is a very large number of tokens, some assertions could be long
+  enough to hit arbitrary limits in Visual C++.  They have been rewritten to
+  work around this limitation.
+
+** Changes
+
+  The YYBISON macro in generated "regular C parsers" (from the "yacc.c"
+  skeleton) used to be defined to 1.  It is now defined to the version of
+  Bison as an integer (e.g., 30704 for version 3.7.4).
+
+
+* Noteworthy changes in release 3.7.3 (2020-10-13) [stable]
+
+** Bug fixes
+
+  Fix concurrent build issues.
+
+  The bison executable is no longer linked uselessly against libreadline.
+
+  Fix incorrect use of yytname in glr.cc.
+
+
+* Noteworthy changes in release 3.7.2 (2020-09-05) [stable]
+
+  This release of Bison fixes all known bugs reported for Bison in MITRE's
+  Common Vulnerabilities and Exposures (CVE) system.  These vulnerabilities
+  are only about bison-the-program itself, not the generated code.
+
+  Although these bugs are typically irrelevant to how Bison is used, they
+  are worth fixing if only to give users peace of mind.
+
+  There is no known vulnerability in the generated parsers.
+
+** Bug fixes
+
+  Fix concurrent build issues (introduced in Bison 3.5).
+
+  Push parsers always use YYMALLOC/YYFREE (no direct calls to malloc/free).
+
+  Fix portability issues of the test suite, and of bison itself.
+
+  Some unlikely crashes found by fuzzing have been fixed.  This is only
+  about bison itself, not the generated parsers.
+
+
+* Noteworthy changes in release 3.7.1 (2020-08-02) [stable]
+
+** Bug fixes
+
+  Crash when a token alias contains a NUL byte.
+
+  Portability issues with libtextstyle.
+
+  Portability issues of Bison itself with MSVC.
+
+** Changes
+
+  Improvements and fixes in the documentation.
+
+  More precise location about symbol type redefinitions.
+
+
+* Noteworthy changes in release 3.7 (2020-07-23) [stable]
 
 ** Deprecated features
 
@@ -48,52 +257,114 @@ Changes in the display of counterexamples.
 
   Contributed by Vincent Imbimbo.
 
-  When given `--report=counterexamples` or `-Wcounterexamples`, bison will
-  now output counterexamples for conflicts in the grammar.  These are
-  strings in the grammar which can be parsed in two ways due to the
-  conflict.  For example:
+  When given `-Wcounterexamples`/`-Wcex`, bison will now output
+  counterexamples for conflicts.
 
-    Shift/reduce conflict on token "/":
-      Example              exp "+" exp • "/" exp
+**** Unifying Counterexamples
+
+  Unifying counterexamples are strings which can be parsed in two ways due
+  to the conflict.  For example on a grammar that contains the usual
+  "dangling else" ambiguity:
+
+    $ bison else.y
+    else.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
+    else.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
+
+    $ bison else.y -Wcex
+    else.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
+    else.y: warning: shift/reduce conflict on token "else" [-Wcounterexamples]
+      Example: "if" exp "then" "if" exp "then" exp • "else" exp
       Shift derivation
         exp
-        ↳ exp "+" exp
-                  ↳ exp • "/" exp
-      Example              exp "+" exp • "/" exp
+        ↳ "if" exp "then" exp
+                          ↳ "if" exp "then" exp • "else" exp
+      Example: "if" exp "then" "if" exp "then" exp • "else" exp
       Reduce derivation
         exp
-        ↳ exp             "/" exp
-          ↳ exp "+" exp •
+        ↳ "if" exp "then" exp                     "else" exp
+                          ↳ "if" exp "then" exp •
 
-  When Bison is installed with text styling enabled, the example is actually
-  shown twice, with colors highlighting the ambiguity.
+  When text styling is enabled, colors are used in the examples and the
+  derivations to highlight the structure of both analyses.  In this case,
 
-  This is a shift/reduce conflict caused by none of the operators having
-  precedence, so the example can be parsed in the two ways shown.  When
-  bison cannot find an example that can be derived in two ways, it instead
-  generates two examples that are the same up until the dot:
+    "if" exp "then" [ "if" exp "then" exp • ] "else" exp
 
-    First example        expr • ID ',' ID $end
-    Shift derivation
-      $accept
-      ↳ s                      $end
-        ↳ a                 ID
-          ↳ expr
-            ↳ expr • ID ','
-    Second example       expr • ID $end
-    Reduce derivation
-      $accept
-      ↳ s             $end
-        ↳ a        ID
-          ↳ expr •
+  vs.
+
+    "if" exp "then" [ "if" exp "then" exp • "else" exp ]
+
+
+  The counterexamples are "focused", in two different ways.  First, they do
+  not clutter the output with all the derivations from the start symbol,
+  rather they start on the "conflicted nonterminal". They go straight to the
+  point.  Second, they don't "expand" nonterminal symbols uselessly.
+
+**** Nonunifying Counterexamples
+
+  In the case of the dangling else, Bison found an example that can be
+  parsed in two ways (therefore proving that the grammar is ambiguous).
+  When it cannot find such an example, it instead generates two examples
+  that are the same up until the dot:
+
+    $ bison foo.y
+    foo.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
+    foo.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
+    foo.y:4.4-7: warning: rule useless in parser due to conflicts [-Wother]
+        4 | a: expr
+          |    ^~~~
+
+    $ bison -Wcex foo.y
+    foo.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
+    foo.y: warning: shift/reduce conflict on token ID [-Wcounterexamples]
+      First example: expr • ID ',' ID $end
+      Shift derivation
+        $accept
+        ↳ s                      $end
+          ↳ a                 ID
+            ↳ expr
+              ↳ expr • ID ','
+      Second example: expr • ID $end
+      Reduce derivation
+        $accept
+        ↳ s             $end
+          ↳ a        ID
+            ↳ expr •
+    foo.y:4.4-7: warning: rule useless in parser due to conflicts [-Wother]
+        4 | a: expr
+          |    ^~~~
 
   In these cases, the parser usually doesn't have enough lookahead to
   differentiate the two given examples.
 
-  The counterexamples are "focused" in two different ways.  First, they do
-  not clutter the output with all the derivations from the start symbol,
-  rather they start on the "conflicted nonterminal". They go straight to the
-  point.  Second, they don't "expand" nonterminal symbols uselessly.
+**** Reports
+
+  Counterexamples are also included in the report when given
+  `--report=counterexamples`/`-rcex` (or `--report=all`), with more
+  technical details:
+
+    State 7
+
+      1 exp: "if" exp "then" exp •  [$end, "then", "else"]
+      2    | "if" exp "then" exp • "else" exp
+
+      "else"  shift, and go to state 8
+
+      "else"    [reduce using rule 1 (exp)]
+      $default  reduce using rule 1 (exp)
+
+      shift/reduce conflict on token "else":
+          1 exp: "if" exp "then" exp •
+          2 exp: "if" exp "then" exp • "else" exp
+        Example: "if" exp "then" "if" exp "then" exp • "else" exp
+        Shift derivation
+          exp
+          ↳ "if" exp "then" exp
+                            ↳ "if" exp "then" exp • "else" exp
+        Example: "if" exp "then" "if" exp "then" exp • "else" exp
+        Reduce derivation
+          exp
+          ↳ "if" exp "then" exp                     "else" exp
+                            ↳ "if" exp "then" exp •
 
 *** File prefix mapping
 
@@ -107,6 +378,11 @@ Changes in the display of counterexamples.
 
 ** Changes
 
+*** Diagnostics
+
+  When text styling is enabled and the terminal supports it, the warnings
+  now include hyperlinks to the documentation.
+
 *** Relocatable installation
 
   When installed to be relocatable (via `configure --enable-relocatable`),
@@ -142,11 +418,23 @@ Changes in the display of counterexamples.
   parse errors, since `yynerrs` was also reset.  This can be especially
   troublesome when used in autocompletion, since a parser with error
   recovery would suggest (irrelevant) expected tokens even if there were
-  failure.
+  failures.
 
   Now the parser state can be examined when parsing is finished.  The parser
   state is reset when starting a new parse.
 
+** Documentation
+
+*** Examples
+
+  The bistromathic demonstrates %param and how to quote sources in the error
+  messages:
+
+    > 123 456
+    1.5-7: syntax error: expected end of file or + or - or * or / or ^ before number
+        1 | 123 456
+          |     ^~~
+
 ** Bug fixes
 
 *** Include the generated header (yacc.c)
@@ -488,7 +776,8 @@ Changes in the display of counterexamples.
   \005) with incorrect styling.  Fixes for similar issues with unexpectedly
   short lines (e.g., the file was changed between parsing and diagnosing).
 
-  Several unlikely crashes found by fuzzing have been fixed.
+  Some unlikely crashes found by fuzzing have been fixed.  This is only
+  about bison itself, not the generated parsers.
 
 
 * Noteworthy changes in release 3.5.2 (2020-02-13) [stable]
@@ -610,7 +899,7 @@ Changes in the display of counterexamples.
   Also, because string aliases need not be defined, typos such as "baz"
   instead of "bar" will be not reported.
 
-  The option -Wdangling-alias catches these situations.  On
+  The option `-Wdangling-alias` catches these situations.  On
 
     %token BAR "bar"
     %type <ival> foo "foo"
@@ -626,7 +915,7 @@ Changes in the display of counterexamples.
           | foo: "baz" {}
           |      ^~~~~
 
-   The -Wall option does not (yet?) include -Wdangling-alias.
+   The `-Wall` option does not (yet?) include `-Wdangling-alias`.
 
 *** Better POSIX Yacc compatibility diagnostics
 
@@ -3248,7 +3537,7 @@ Changes in the display of counterexamples.
   inherent flaws when %error-verbose or "#define YYERROR_VERBOSE" is
   used.  For a more detailed discussion, see:
 
-    http://lists.gnu.org/archive/html/bison-patches/2009-12/msg00024.html
+    https://lists.gnu.org/r/bison-patches/2009-12/msg00024.html
 
   The upcoming Bison 2.5 will remove YYFAIL from Java parsers, but
   deterministic parsers in C will continue to implement it.  However,
@@ -4004,7 +4293,7 @@ Changes in the display of counterexamples.
   error token.  The new behavior has long been the documented behavior,
   and has long been required by POSIX.  For more details, please see
   Paul Eggert, "Reductions during Bison error handling" (2002-05-20)
-  <http://lists.gnu.org/archive/html/bug-bison/2002-05/msg00038.html>.
+  <https://lists.gnu.org/r/bug-bison/2002-05/msg00038.html>.
 
 ** Traces
   Popped tokens and nonterminals are now reported.
@@ -4402,7 +4691,7 @@ LocalWords:  pragmas noreturn untyped Rozenman unexpanded Wojciech Polak
 LocalWords:  Alexandre MERCHANTABILITY yytype emplace ptr automove lvalues
 LocalWords:  nonterminal yy args Pragma dereference yyformat rhs docdir bw
 LocalWords:  Redeclarations rpcalc Autoconf YFLAGS Makefiles PROG DECL num
-LocalWords:  Heimbigner AST src ast Makefile srcdir MinGW xxlex XXSTYPE
+LocalWords:  Heimbigner AST src ast Makefile srcdir MinGW xxlex XXSTYPE CVE
 LocalWords:  XXLTYPE strictfp IDEs ffixit fdiagnostics parseable fixits
 LocalWords:  Wdeprecated yytext Variadic variadic yyrhs yyphrs RCS README
 LocalWords:  noexcept constexpr ispell american deprecations backend Teoh
@@ -4412,7 +4701,9 @@ LocalWords:  yysymbol yytnamerr yyreport ctx ARGMAX yysyntax stderr LPAREN
 LocalWords:  symrec yypcontext TOKENMAX yyexpected YYEMPTY yypstate YYEOF
 LocalWords:  autocompletion bistromathic submessages Cayuela lexcalc hoc
 LocalWords:  yytoken YYUNDEF YYerror basename Automake's UTF ifdef ffile
-LocalWords:  gotos readline Imbimbo Wcounterexamples
+LocalWords:  gotos readline Imbimbo Wcounterexamples Wcex Nonunifying rcex
+LocalWords:  Vais xsltproc YYNOMEM YYLOCATION signedness YYBISON MITRE's
+LocalWords:  libreadline YYMALLOC YYFREE MSVC redefinitions
 
 Local Variables:
 ispell-dictionary: "american"
@@ -4420,7 +4711,7 @@ mode: outline
 fill-column: 76
 End:
 
-Copyright (C) 1995-2015, 2018-2020 Free Software Foundation, Inc.
+Copyright (C) 1995-2015, 2018-2021 Free Software Foundation, Inc.
 
 This file is part of Bison, the GNU Parser Generator.
 

PACKAGING

@@ -36,7 +36,7 @@ to the bison package.
 
 -----
 
-Copyright (C) 2002, 2005, 2009-2015, 2018-2020 Free Software Foundation,
+Copyright (C) 2002, 2005, 2009-2015, 2018-2021 Free Software Foundation,
 Inc.
 
 This file is part of Bison, the GNU Compiler Compiler.
@@ -52,4 +52,4 @@ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.
 
 You should have received a copy of the GNU General Public License
-along with this program.  If not, see <http://www.gnu.org/licenses/>.
+along with this program.  If not, see <https://www.gnu.org/licenses/>.

README

@@ -7,7 +7,7 @@ simple desk calculators to complex programming languages.
 
 Bison is upward compatible with Yacc: all properly-written Yacc grammars
 work with Bison with no change.  Anyone familiar with Yacc should be able to
-use Bison with little trouble.  You need to be fluent in C, C++ or Java
+use Bison with little trouble.  You need to be fluent in C, C++, D or Java
 programming in order to use Bison.
 
 Bison and the parsers it generates are portable, they do not require any
@@ -27,7 +27,7 @@ Bison from the git repo.  Roughly, run:
 then proceed with the usual `configure && make` steps.
 
 ## Build from tarball
-See the [INSTALL file](INSTALL] for generic compilation and installation
+See the [INSTALL file](INSTALL) for generic compilation and installation
 instructions.
 
 Bison requires GNU m4 1.4.6 or later.  See
@@ -42,9 +42,11 @@ installing it.  In that case, do not use `src/bison`: it would use the
 As an experimental feature, diagnostics are now colored, controlled by the
 `--color` and `--style` options.
 
-To use them, install the libtextstyle library before configuring Bison.  It
-is available from https://alpha.gnu.org/gnu/gettext/, for instance
-https://alpha.gnu.org/pub/gnu/gettext/libtextstyle-0.20.5.tar.gz.
+To use them, install the libtextstyle library, 0.20.5 or newer, before
+configuring Bison.  It is available from https://alpha.gnu.org/gnu/gettext/,
+for instance https://alpha.gnu.org/gnu/gettext/libtextstyle-0.20.5.tar.gz,
+or as part of Gettext 0.21 or newer, for instance
+https://ftp.gnu.org/gnu/gettext/gettext-0.21.tar.gz.
 
 The option --color supports the following arguments:
 - always, yes: Enable colors.
@@ -61,6 +63,13 @@ To customize the styles, create a CSS file, say `bison-bw.css`, similar to
 then invoke bison with `--style=bison-bw.css`, or set the `BISON_STYLE`
 environment variable to `bison-bw.css`.
 
+In some diagnostics, bison uses libtextstyle to emit special escapes to
+generate clickable hyperlinks.  The environment variable
+`NO_TERM_HYPERLINKS` can be used to suppress them.  This may be useful for
+terminal emulators which produce garbage output when they receive the escape
+sequence for a hyperlink. Currently (as of 2020), this affects some versions
+of emacs, guake, konsole, lxterminal, rxvt, yakuake.
+
 ## Relocatability
 If you pass `--enable-relocatable` to `configure`, Bison is relocatable.
 
@@ -78,7 +87,7 @@ for the user-side parser execution).  The requirements between both differ:
 bison needs ngettext, the generated parsers do not.  To simplify the build
 system, neither are installed if ngettext is not supported, even if
 generated parsers could have been localized.  See
-http://lists.gnu.org/archive/html/bug-bison/2009-08/msg00006.html for more
+https://lists.gnu.org/r/bug-bison/2009-08/msg00006.html for more
 details.
 
 # Questions
@@ -111,7 +120,7 @@ fill-column: 76
 ispell-dictionary: "american"
 End:
 
-Copyright (C) 1992, 1998-1999, 2003-2005, 2008-2015, 2018-2020 Free
+Copyright (C) 1992, 1998-1999, 2003-2005, 2008-2015, 2018-2021 Free
 Software Foundation, Inc.
 
 This file is part of GNU bison, the GNU Compiler Compiler.

README-alpha

@@ -12,7 +12,7 @@ the problems you encounter.
 
 -----
 
-Copyright (C) 2002, 2004, 2009-2015, 2018-2020 Free Software Foundation,
+Copyright (C) 2002, 2004, 2009-2015, 2018-2021 Free Software Foundation,
 Inc.
 
 This file is part of GNU Bison.
@@ -28,4 +28,4 @@ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.
 
 You should have received a copy of the GNU General Public License
-along with this program.  If not, see <http://www.gnu.org/licenses/>.
+along with this program.  If not, see <https://www.gnu.org/licenses/>.

README-hacking.md

@@ -2,7 +2,7 @@ This file attempts to describe the rules to use when hacking Bison.
 Don't put this file into the distribution.
 
 Everything related to the development of Bison is on Savannah:
-http://savannah.gnu.org/projects/bison/.
+https://savannah.gnu.org/projects/bison/.
 
 
 Working from the Repository
@@ -19,21 +19,21 @@ requirements on anyone wishing to build from the just-checked-out sources.
 For example, you have to use the latest stable versions of the maintainer
 tools we depend upon, including:
 
-- Autoconf <http://www.gnu.org/software/autoconf/>
-- Automake <http://www.gnu.org/software/automake/>
-- Flex <http://www.gnu.org/software/flex/>
-- Gettext <http://www.gnu.org/software/gettext/>
-- Gperf <http://www.gnu.org/software/gperf/>
-- Graphviz <http://www.graphviz.org>
-- Gzip <http://www.gnu.org/software/gzip/>
-- Help2man <http://www.gnu.org/software/help2man/>
-- Perl <http://www.cpan.org/>
-- Rsync <http://samba.anu.edu.au/rsync/>
-- Tar <http://www.gnu.org/software/tar/>
-- Texinfo <http://www.gnu.org/software/texinfo/>
+- Autoconf <https://www.gnu.org/software/autoconf/>
+- Automake <https://www.gnu.org/software/automake/>
+- Flex <https://www.gnu.org/software/flex/>
+- Gettext <https://www.gnu.org/software/gettext/>
+- Gperf <https://www.gnu.org/software/gperf/>
+- Graphviz <https://www.graphviz.org>
+- Gzip <https://www.gnu.org/software/gzip/>
+- Help2man <https://www.gnu.org/software/help2man/>
+- Perl <https://www.cpan.org/>
+- Rsync <https://rsync.samba.org/>
+- Tar <https://www.gnu.org/software/tar/>
+- Texinfo <https://www.gnu.org/software/texinfo/>
 
-Valgrind <http://valgrind.org/> is also highly recommended, if it supports
-your architecture.
+Valgrind <https://www.valgrind.org/> is also highly recommended, if it
+supports your architecture.
 
 If you're using a GNU/Linux distribution, the easiest way to install the
 above packages depends on your system.  The following shell command should
@@ -57,7 +57,7 @@ might be needed.
 
 Obviously, if you are reading these notes, you did manage to check out this
 package from the repository.  For the record, you will find all the relevant
-information on http://savannah.gnu.org/git/?group=bison.
+information on https://savannah.gnu.org/git/?group=bison.
 
 Bison uses Git submodules: subscriptions to other Git repositories.  In
 particular it uses gnulib, the GNU portability library.  To ask Git to
@@ -139,7 +139,7 @@ Register your changes.
 
 For a suggestion of what gnulib commit might be stable enough for a formal
 release, see the ChangeLog in the latest gnulib snapshot at
-http://erislabs.net/ianb/projects/gnulib/.
+https://erislabs.net/ianb/projects/gnulib/.
 
 The Autoconf files we use are currently:
 - m4/m4.m4
@@ -246,7 +246,7 @@ Prefer `res` as the name of the local variable that will be "return"ed by
 the function.
 
 In writing arithmetic comparisons, use "<" and "<=" rather than ">" and ">="
-(http://www.gelato.unsw.edu.au/archives/git/0505/4507.html).
+<https://public-inbox.org/git/7vfyw7yebj.fsf_-_@assigned-by-dhcp.cox.net/>.
 
 ### Bison
 Follow the GNU Coding Standards.
@@ -325,7 +325,7 @@ about the C standard introducing such a name.
 
 #### C++
 Follow the [C++ Core
-Guidelines](http://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines).
+Guidelines](https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines).
 The [Google ones](https://google.github.io/styleguide/cppguide.html) may be
 interesting too.
 
@@ -346,12 +346,14 @@ and [Google Java Style
 Guide](https://google.github.io/styleguide/javaguide.html).  Unfortunately
 at some point some GNU Coding Style was installed in Java, but it's an
 error.  So we should for instance stop putting spaces in function calls.
-Because we are standardizing the code, it is currently inconsistent.
+Because we are standardizing the code, it is currently inconsistent.  Treat
+acronyms as words: `YYLacStack`, not `YYLACStack`.
 
 Use a 2-space indentation (Google) rather than 4 (Oracle).
 
-Don't use the "yy" prefix for public members: "getExpectedTokens", not
-"yyexpectedTokens" or "yygetExpectedTokens".
+Don't use the `yy` prefix for public members: `getExpectedTokens`, not
+`yyexpectedTokens` or `yygetExpectedTokens`.  Keep the `yy` prefix though
+for private details.
 
 ## Commit Messages
 Imitate the style we use.  Use `git log` to get sources of inspiration.
@@ -386,6 +388,11 @@ In examples/, there is a number of ready-to-use examples (see
 suites run by `make check`.  The test results are in local `*.log` files
 (e.g., `$build/examples/c/calc/calc.log`).
 
+To check only the examples, run `make check-examples`.  To check just one
+example,
+
+    make check-examples TESTS='examples/c/bistromathic/bistromathic.test'
+
 ### The Main Test Suite
 The main test suite, in tests/, is written on top of GNU Autotest, which is
 part of Autoconf.  Run `info autoconf 'Using Autotest'` to read the
@@ -399,28 +406,23 @@ contains lots of details that should help diagnosing issues, including build
 issues.  The per-test logs are more convenient when working locally.
 
 #### TESTSUITEFLAGS
-To run just the main test suite, run `make check-local`.
+To run just the main test suite, run `make check-tests`.
 
-The default is for make check-local to run all tests sequentially.  This can
-be very time consuming when checking repeatedly or on slower setups.  This
-can be sped up in two ways:
+The default is for `make check-tests` to run all tests sequentially.  This
+can be very time consuming when checking repeatedly or on slower setups.
+This can be sped up in two ways.
 
-Using -j, in a make-like fashion, for example:
+1. Using -j, in a make-like fashion, for example:
 
-    $ make check-local TESTSUITEFLAGS='-j8'
+    $ make check-tests TESTSUITEFLAGS='-j8'
 
-Actually, when using GNU Make, TESTSUITEFLAGS defaults to the -jN passed to
-it, so you may simply run
+When using GNU Make, TESTSUITEFLAGS defaults to the -jN passed to it, so you
+may simply run
 
-    $ make check-local -j8
+    $ make check-tests -j8
 
-Running only the tests of a certain category, as specified in the AT files
-with AT_KEYWORDS([[category]]). Categories include:
-- c++, for c++ parsers
-- deprec, for tests concerning deprecated constructs.
-- glr, for glr parsers
-- java, for java parsers
-- report, for automaton dumps
+2. Running only the tests of a certain category. See
+[tests/README.md](tests/README.md#keywords) for the list of categories.
 
 To get a list of all the tests (and their keywords for -k), run
 
@@ -428,11 +430,11 @@ To get a list of all the tests (and their keywords for -k), run
 
 To run a specific set of tests, use -k (for "keyword"). For example:
 
-    $ make check-local TESTSUITEFLAGS='-k c++'
+    $ make check-tests TESTSUITEFLAGS='-k c++'
 
 Both can be combined.
 
-    $ make check-local TESTSUITEFLAGS='-j8 -k c++'
+    $ make check-tests TESTSUITEFLAGS='-j8 -k c++'
 
 To rerun the tests that failed:
 
@@ -462,28 +464,55 @@ Use the `javaexec.sh` script.  For instance to run the parser of test case
 
 ## Using Sanitizers
 Address sanitizer (ASAN) and undefined-behavior sanitizer (UBSAN) are very
-useful.  Here's one way to set ASAN up with GCC 10 on Mac Ports
+useful.  Here's one way to set them up with GCC 10 on Mac Ports
 
 1. Configure with
-
-    $ ./configure -C --enable-gcc-warnings \
-        CPPFLAGS='-isystem /opt/local/include' \
-        CC='gcc-mp-10 -fsanitize=address' \
-        CFLAGS='-ggdb' \
-        CXX='g++-mp-10.0 -fsanitize=address' \
-        CXXFLAGS='-ggdb' \
-        LDFLAGS='-L/opt/local/lib'
+   ```
+   $ ./configure -C --enable-gcc-warnings \
+       CPPFLAGS='-isystem /opt/local/include' \
+       CC='gcc-mp-10 -fsanitize=address -fsanitize=undefined' \
+       CFLAGS='-ggdb' \
+       CXX='g++-mp-10.0 -fsanitize=address -fsanitize=undefined' \
+       CXXFLAGS='-ggdb' \
+       LDFLAGS='-L/opt/local/lib'
+   ```
 
 2. Compile
 
 3. Generate debug symbols:
 
-    $ dsymutil src/bison
+   ```
+   $ dsymutil src/bison
+   ```
 
 4. Run the tests with leak detection enabled
    (`ASAN_OPTIONS=detect_leaks=1`).  E.g. for counterexamples:
+   ```
+   $ make check-tests TESTSUITEFLAGS='-j5 -k cex' ASAN_OPTIONS=detect_leaks=1
+   ```
 
-    $ make check-local TESTSUITEFLAGS='-j5 -k cex' ASAN_OPTIONS=detect_leaks=1
+5. You might need a suppression file.  See
+   https://github.com/google/sanitizers/wiki/AddressSanitizerLeakSanitizer#suppressions.
+   With G++ on a Mac, you might need a suppression file (say `leak.supp`)
+   that contains:
+
+   ```
+   leak:std::clog
+   ```
+
+   and pass the additional flags
+   `LSAN_OPTIONS=suppressions=$PWD/leak.supp,print_suppressions=0`
+
+6. To run the debugger, you might want something like this:
+   ```
+   $ YYDEBUG=1 \
+     UBSAN_OPTIONS=print_stacktrace=1 \
+     LSAN_OPTIONS=suppressions=$PWD/leak.supp,print_suppressions=0 \
+     ASAN_OPTIONS=detect_leaks=1 \
+     lldb -- ./_build/tests/testsuite.dir/712/glr-regr2a ./_build/tests/testsuite.dir/712/input1.txt
+   ```
+
+   In lldb to set a break on ubsan, try `rbreak ^__ubsan_handle_`.
 
 ## make maintainer-check-valgrind
 This target uses valgrind both to check bison, and the generated parsers.
@@ -512,7 +541,7 @@ release:
 - Maybe build with -DGNULIB_POSIXCHECK, which suggests gnulib modules that
   can fix portability issues.  See if you really want to pay attention to
   its warnings; there's no need to obey blindly to it
-  (<http://lists.gnu.org/archive/html/bison-patches/2012-05/msg00057.html>).
+  (<https://lists.gnu.org/r/bison-patches/2012-05/msg00057.html>).
 
 - Check with `make syntax-check` if there are issues diagnosed by gnulib.
 
@@ -560,6 +589,46 @@ re-run the tests, run:
     make check
 
 
+## Docker
+
+Running old compilers is not very easy.  Docker can be used for some of
+them.  Have a look at .travis.yml for setups.  Move the tarball in `/tmp`
+and run, for instance:
+
+```
+docker run -v /tmp:/tmp -it ubuntu:xenial
+```
+
+This way, the host and guest machines share `/tmp`.
+
+### GCC 4.6
+On Ubuntu Xenial.
+
+```
+apt-get update
+apt-get install software-properties-common
+apt-add-repository -y "ppa:ubuntu-toolchain-r/test"
+apt-get update
+apt-get install -y gcc-4.6 g++-4.6 m4 make
+```
+
+## Stow
+
+If you want to install several versions of Bison using GNU Stow, do
+something like this:
+
+```
+for v in 3.7 3.7.1
+do
+  cd /tmp
+  wget https://ftp.gnu.org/gnu/bison/bison-$v.tar.xz
+  tar xf bison-$v.tar.xz
+  cd bison-$v
+  ./configure --prefix /usr/local/stow/bison-$v
+  make -j4
+  sudo make install
+done
+```
 
 Release Procedure
 =================
@@ -569,7 +638,7 @@ bootstrapped.
 
 <!--
 
-Copyright (C) 2002-2005, 2007-2015, 2018-2020 Free Software Foundation,
+Copyright (C) 2002-2005, 2007-2015, 2018-2021 Free Software Foundation,
 Inc.
 
 This file is part of GNU Bison.
@@ -585,7 +654,7 @@ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.
 
 You should have received a copy of the GNU General Public License
-along with this program.  If not, see <http://www.gnu.org/licenses/>.
+along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 Local Variables:
 mode: markdown

THANKS

@@ -34,6 +34,7 @@ Bob Rossi                 [email protected]
 Brandon Lucia             [email protected]
 Brooks Moses              [email protected]
 Bruce Lilly               [email protected]
+Bruno Belanyi             [email protected]
 Bruno Haible              [email protected]
 Charles-Henri de Boysson  [email protected]
 Christian Burger          [email protected]
@@ -106,9 +107,11 @@ Keith Browne              [email protected]
 Ken Moffat                [email protected]
 Kiyoshi Kanazawa          [email protected]
 Lars Maier                [email protected]
+Lars Wendler              [email protected]
 László Várady             [email protected]
 Laurent Mascherpa         [email protected]
 Lie Yan                   [email protected]
+Maarten De Braekeleer     [email protected]
 Magnus Fromreide          [email protected]
 Marc Autret               [email protected]
 Marc Mendiola             [email protected]
@@ -185,6 +188,7 @@ Simon Sobisch             [email protected]
 Stefano Lattarini         [email protected]
 Stephen Cameron           [email protected]
 Steve Murphy              [email protected]
+Suhwan Song               [email protected]
 Sum Wu                    [email protected]
 Théophile Ranquet         [email protected]
 Thiru Ramakrishnan        [email protected]
@@ -234,7 +238,7 @@ End:
 
 -----
 
-Copyright (C) 2000-2015, 2018-2020 Free Software Foundation, Inc.
+Copyright (C) 2000-2015, 2018-2021 Free Software Foundation, Inc.
 
 This file is part of Bison, the GNU Parser Generator.
 
@@ -249,4 +253,4 @@ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.
 
 You should have received a copy of the GNU General Public License
-along with this program.  If not, see <http://www.gnu.org/licenses/>.
+along with this program.  If not, see <https://www.gnu.org/licenses/>.

TODO

@@ -1,4 +1,42 @@
-* Bison 3.7
+* Soon
+** scan-code
+The default case is scanning char-per-char.
+
+    /* By default, grow the string obstack with the input.  */
+    .|\n        STRING_GROW ();
+
+make it more eager?
+
+** Missing tests
+commit 2c294c132528ede23d8ae4959783a67e9ff05ac5
+Author: Vincent Imbimbo <[email protected]>
+Date:   Sat Jan 23 13:25:18 2021 -0500
+
+    cex: fix state-item pruning
+
+See https://lists.gnu.org/r/bug-bison/2021-01/msg00002.html
+
+** pos_set_set
+The current approach is correct, but with poor performances.  Bitsets need
+to support 'assign' and 'shift'.  And instead of extending POS_SET just for
+the out-of-range new values, we need something like doubling the size.
+
+** glr
+There is no test with "Parse on stack %ld rejected by rule %d" in it.
+
+** yyrline etc.
+Clarify that rule numbers in the skeletons are 1-based.
+
+** Macros in C++
+There are many macros that should obey api.prefix: YY_CPLUSPLUS, YY_MOVE,
+etc.
+
+** yyerrok in Java
+And add tests in calc.at, to prepare work for D.
+
+** YYERROR and yynerrs
+We are missing some cases.  Write a test case, and check all the skeletons.
+
 ** Cex
 *** Improve gnulib
 Don't do this (counterexample.c):
@@ -48,13 +86,6 @@ Unless we play it dumb (little structure).
 
 - promote YYEOF rather than EOF.
 
-*** D
-- is there a way to attach yysymbol_name to the enum itself?  As we did
-  in Java.
-
-- It would be better to have TokenKind as return value.  Can we use
-  reflection to support both output types?
-
 ** YYerror
 https://git.savannah.gnu.org/gitweb/?p=gettext.git;a=blob;f=gettext-runtime/intl/plural.y;h=a712255af4f2f739c93336d4ff6556d932a426a5;hb=HEAD
 
@@ -65,10 +96,6 @@ enough.
 *** calc.at
 Stop hard-coding "Calc".  Adjust local.at (look for FIXME).
 
-** A dev warning for b4_
-Maybe we should check for m4_ and b4_ leaking out of the m4 processing, as
-Autoconf does.  It would have caught overquotation issues.
-
 ** doc
 I feel it's ugly to use the GNU style to declare functions in the doc.  It
 generates tons of white space in the page, and may contribute to bad page
@@ -88,7 +115,7 @@ push parsers on top of pull parser.  Which is currently not relevant, since
 push parsers are measurably slower.
 
 ** %define parse.error formatted
-How about pushing bistromathics' yyreport_syntax_error as another standard
+How about pushing Bistromathic's yyreport_syntax_error as another standard
 way to generate the error message, and leave to the user the task of
 providing the message formats?  Currently in bistro, it reads:
 
@@ -156,10 +183,48 @@ Les catégories d'avertissements incluent :
 
 Line -1 and -3 should mention CATEGORIE, not CATEGORY.
 
-* Bison 3.8
-** Rewrite glr.cc
-Get rid of scaffolding in glr.c.
+* Bison 3.9
+** Rewrite glr.cc (currently glr2.cc)
+*** custom error messages
 
+*** Remove jumps
+We can probably replace setjmp/longjmp with exceptions.  That would help
+tremendously other languages such as D and Java that probably have no
+similar feature.  If we remove jumps, we probably no longer need _Noreturn,
+so simplify `b4_attribute_define([noreturn])` into `b4_attribute_define`.
+
+After discussing with Valentin, it was decided that it's better to stay with
+jumps, since in some places exceptions are ruled out from C++.
+
+*** Coding style
+Move to our coding conventions.  In particular names such as yy_glr_stack,
+not yyGLRStack.
+
+*** yydebug
+It should be a member of the parser object, see lalr1.cc.  Let the parser
+object decide what the debug stream is, rather than open coding std::cerr.
+
+*** Avoid pointers
+There are many places where pointers should be replaced with references.
+Some occurrences were fixed, but now some have improper names:
+
+-yygetToken (int *yycharp, ]b4_namespace_ref[::]b4_parser_class[& yyparser][]b4_pure_if([, glr_stack* yystackp])[]b4_user_formals[)
++yygetToken (int& yycharp, ]b4_namespace_ref[::]b4_parser_class[& yyparser][]b4_pure_if([, glr_stack* yystackp])[]b4_user_formals[)
+
+yycharp is no longer a Pointer.  And yystackp should probably also be a reference.
+
+*** parse.assert
+Currently all the assertions are enabled.  Once we are confident in glr2.cc,
+let parse.assert use the same approach as in lalr1.cc.
+
+*** debug_stream
+Stop using std::cerr everywhere.
+
+*** glr.c
+When glr2.cc fully replaces glr.cc, get rid of the glr.cc scaffolding in
+glr.c.
+
+* Chains
 ** Unit rules / Injection rules (Akim Demaille)
 Maybe we could expand unit rules (or "injections", see
 https://homepages.cwi.nl/~daybuild/daily-books/syntax/2-sdf/sdf.html), i.e.,
@@ -202,18 +267,54 @@ The "automaton" and "set" categories are not so useful.  We should probably
 introduce lr(0) and lalr, just the way we have ielr categories.  The
 "closure" function is too verbose, it should probably have its own category.
 
-"set" can still be used for summariring the important sets.  That would make
+"set" can still be used for summarizing the important sets.  That would make
 tests easy to maintain.
 
 *** complain.*
 Rename these guys as "diagnostics.*" (or "diagnose.*"), since that's the
-name they have in gcc, clang, etc.  Likewise for the complain_* series of
+name they have in GCC, clang, etc.  Likewise for the complain_* series of
 functions.
 
 *** ritem
 states/nstates, rules/nrules, ..., ritem/nritems
 Fix the latter.
 
+*** m4: slot, type, type_tag
+The meaning of type_tag varies depending on api.value.type.  We should avoid
+that and using clear definitions with stable semantics.
+
+* D programming language
+There's a number of features that are missing, here sorted in _suggested_
+order of implementation.
+
+When copying code from other skeletons, keep the comments exactly as they
+are.  Keep the same variable names.  If you change the wording in one place,
+do it in the others too.  In other words: make sure to keep the
+maintenance *simple* by avoiding any gratuitous difference.
+
+** CI
+Check when gdc and ldc.
+
+** GLR Parser
+This is very ambitious.  That's the final boss.  There are currently no
+"clean" implementation to get inspiration from.
+
+glr.c is very clean but:
+- is low-level C
+- is a different skeleton from yacc.c
+
+glr.cc is (currently) an ugly hack: a C++ shell around glr.c.  Valentin
+Tolmer is currently rewriting glr.cc to be clean C++, but he is not
+finished.  There will be a lot a common code between lalr1.cc and glr.cc, so
+eventually I would like them to be fused into a single skeleton, supporting
+both deterministic and generalized parsing.
+
+It would be great for D to also support this.
+
+The basic ideas of GLR are explained here:
+
+https://www.codeproject.com/Articles/5259825/GLR-Parsing-in-Csharp-How-to-Use-The-Most-Powerful
+
 * Better error messages
 The users are not provided with enough tools to forge their error messages.
 See for instance "Is there an option to change the message produced by
@@ -231,9 +332,8 @@ and older C++ compilers.  Currently the code defaults to defining it to
 define it to the same type as the C ptrdiff_t type.
 
 * Completion
-Several features are not available in all the backends.
+Several features are not available in all the back-ends.
 
-- lac: D, Java (easy)
 - push parsers: glr.c, glr.cc, lalr1.cc (not very difficult)
 - token constructors: Java, C, D (a bit difficult)
 - glr: D, Java (super difficult)
@@ -248,9 +348,6 @@ $ ./tests/testsuite -l | grep errors | sed q
   38: input.at:1730      errors
 
 * Short term
-** Get rid of YYPRINT and b4_toknum
-Besides yytoknum is wrong when api.token.raw is defined.
-
 ** Better design for diagnostics
 The current implementation of diagnostics is ad hoc, it grew organically.
 It works as a series of calls to several functions, with dependency of the
@@ -301,7 +398,7 @@ opposite side we have some use of \l, which is graphviz-specific, in what
 should be generic code.
 
 Little effort seems to have been given to factoring these files and their
-rint{,-xml} counterpart. We would very much like to re-use the pretty format
+print{,-xml} counterpart. We would very much like to re-use the pretty format
 of states from .output for the graphs, etc.
 
 Since graphviz dies on medium-to-big grammars, maybe consider an other tool?
@@ -368,23 +465,6 @@ It would be a very nice source of inspiration for the other languages.
 
 Valentin Tolmer is working on this.
 
-** yychar == YYEMPTY
-The code in yyerrlab reads:
-
-      if (yychar <= YYEOF)
-        {
-          /* Return failure if at end of input.  */
-          if (yychar == YYEOF)
-            YYABORT;
-        }
-
-There are only two yychar that can be <= YYEOF: YYEMPTY and YYEOF.
-But I can't produce the situation where yychar is YYEMPTY here, is it
-really possible?  The test suite does not exercise this case.
-
-This shows that it would be interesting to manage to install skeleton
-coverage analysis to the test suite.
-
 * From lalr1.cc to yacc.c
 ** Single stack
 Merging the three stacks in lalr1.cc simplified the code, prompted for
@@ -437,6 +517,9 @@ https://github.com/scfc/bison-php/blob/master/data/lalr1.php
 https://lists.gnu.org/r/bison-patches/2013-09/msg00000.html and following
 
 ** Multiple start symbols
+Revert a70e75b8a41755ab96ab211a0ea111ac68a4aadd.
+Revert tests: disable "Multistart reports".
+
 Would be very useful when parsing closely related languages.  The idea is to
 declare several start symbols, for instance
 
@@ -458,12 +541,27 @@ happen with yy_start: stmt | expr).  Then adjust the skeletons so that this
 initial token (YY_START_STMT, YY_START_EXPR) be shifted first in the
 corresponding parse function.
 
+*** Number of useless symbols
+AT_TEST(
+[[%start exp;
+exp: exp;]],
+[[input.y: warning: 2 nonterminals useless in grammar [-Wother]
+input.y: warning: 2 rules useless in grammar [-Wother]
+input.y:2.8-10: error: start symbol exp does not derive any sentence]])
+
+We should say "1 nonterminal": the other one is $accept, which should not
+participate in the count.
+
+*** Tokens
+Do we want to disallow terminal start symbols?  The limitation is not
+technical.  Can it be useful to someone to "parse" a token?
+
 ** %include
 This is a popular demand.  We already made many changes in the parser that
 should make this reasonably easy to implement.
 
 Bruce Mardle <[email protected]>
-https://lists.gnu.org/archive/html/bison-patches/2015-09/msg00000.html
+https://lists.gnu.org/r/bison-patches/2015-09/msg00000.html
 
 However, there are many other things to do before having such a feature,
 because I don't want a % equivalent to #include (which we all learned to
@@ -472,11 +570,11 @@ them together, paying attention to keep separate bits separated, in pseudo
 name spaces.
 
 ** Push parsers
-There is demand for push parsers in Java and C++.  And GLR I guess.
+There is demand for push parsers in C++.
 
 ** Generate code instead of tables
 This is certainly quite a lot of work.  See
-http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.50.4539.
+https://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.50.4539.
 
 ** $-1
 We should find a means to provide an access to values deep in the
@@ -579,15 +677,40 @@ to bison. If you're interested, I'll work on a patch.
 Equip the parser with a means to create the (visual) parse tree.
 
 
+-----
+
+# LocalWords:  Cex gnulib gl Bistromathic TokenKinds yylex enum YYEOF EOF
+# LocalWords:  YYerror gettext af hb YYERRCODE undef calc FIXME dev yyerror
+# LocalWords:  Autoconf YYUNDEFTOK lexemes parsers Bistromathic's yyreport
+# LocalWords:  const argc yacc yyclearin lookahead destructor Rici incluent
+# LocalWords:  yydestruct yydiscardin catégories d'avertissements sr activé
+# LocalWords:  conflits défaut rr l'alias chaîne n'est attaché un symbole
+# LocalWords:  obsolète règle vide midrule valeurs de intermédiaire ou avec
+# LocalWords:  définies inutilisées priorité associativité inutiles POSIX
+# LocalWords:  incompatibilités tous les autres avertissements sauf dans rp
+# LocalWords:  désactiver CATEGORIE traiter comme des erreurs glr Akim bool
+# LocalWords:  Demaille arith lalr goto struct pathlen nullable ntokens lr
+# LocalWords:  nterm bitsetv ielr ritem nstates nrules nritems yysymbol EQ
+# LocalWords:  SymbolKind YYEMPTY YYUNDEF YYTNAME NUM yyntokens yytname sed
+# LocalWords:  nonterminals yykind yycode YYNAMES yynames init getName conv
+# LocalWords:  TokenKind ival yychar yylval yylexer Tolmer hoc
+# LocalWords:  Sobisch YYPTRDIFF ptrdiff Autotest toknum yytoknum
+# LocalWords:  sym Wother stderr FP fixits xgettext fdiagnostics Graphviz
+# LocalWords:  graphviz VCG bitset xml bw maint yytoken YYABORT deps
+# LocalWords:  YYACCEPT yytranslate nonnegative destructors yyerrlab repo
+# LocalWords:  backends stmt expr yy Mardle baz qux Vadim Maslow CPP cpp
+# LocalWords:  yydebug gcc UCHAR EBCDIC gung PDP NUL Pre Florian Krohm utf
+# LocalWords:  YYACT YYLLOC YYLSP yyval yyvsp yylen yyloc yylsp endif
+# LocalWords:  ispell american
+
 Local Variables:
 mode: outline
 coding: utf-8
 fill-column: 76
+ispell-dictionary: "american"
 End:
 
------
-
-Copyright (C) 2001-2004, 2006, 2008-2015, 2018-2020 Free Software
+Copyright (C) 2001-2004, 2006, 2008-2015, 2018-2021 Free Software
 Foundation, Inc.
 
 This file is part of Bison, the GNU Compiler Compiler.

bootstrap

@@ -1,10 +1,10 @@
 #! /bin/sh
 # Print a version string.
-scriptversion=2020-04-13.15; # UTC
+scriptversion=2021-04-11.09; # UTC
 
 # Bootstrap this package from checked-out sources.
 
-# Copyright (C) 2003-2020 Free Software Foundation, Inc.
+# Copyright (C) 2003-2021 Free Software Foundation, Inc.
 
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -47,7 +47,7 @@ PERL="${PERL-perl}"
 
 me=$0
 
-default_gnulib_url=git://git.sv.gnu.org/gnulib
+default_gnulib_url=https://git.savannah.gnu.org/git/gnulib.git
 
 usage() {
   cat <<EOF
@@ -71,7 +71,9 @@ Options:
  --no-git                 do not use git to update gnulib.  Requires that
                           --gnulib-srcdir point to a correct gnulib snapshot
  --skip-po                do not download po files
-
+EOF
+  bootstrap_print_option_usage_hook
+  cat <<EOF
 If the file $me.conf exists in the same directory as this script, its
 contents are read as shell variables to configure the bootstrap.
 
@@ -113,6 +115,12 @@ Running without arguments will suffice in most cases.
 EOF
 }
 
+copyright_year=`echo "$scriptversion" | sed -e 's/[^0-9].*//'`
+copyright="Copyright (C) ${copyright_year} Free Software Foundation, Inc.
+License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>.
+This is free software: you are free to change and redistribute it.
+There is NO WARRANTY, to the extent permitted by law."
+
 # warnf_ FORMAT-STRING ARG1...
 warnf_ ()
 {
@@ -154,6 +162,18 @@ gnulib_files=
 : ${AUTOPOINT=autopoint}
 : ${AUTORECONF=autoreconf}
 
+# A function to be called for each unrecognized option.  Returns 0 if
+# the option in $1 has been processed by the function.  Returns 1 if
+# the option has not been processed by the function.  Override it via
+# your own definition in bootstrap.conf
+
+bootstrap_option_hook() { return 1; }
+
+# A function to be called in order to print the --help information
+# corresponding to user-defined command-line options.
+
+bootstrap_print_option_usage_hook() { :; }
+
 # A function to be called right after gnulib-tool is run.
 # Override it via your own definition in bootstrap.conf.
 bootstrap_post_import_hook() { :; }
@@ -170,7 +190,7 @@ po_download_command_format=\
  https://translationproject.org/latest/%s/"
 
 # Prefer a non-empty tarname (4th argument of AC_INIT if given), else
-# fall back to the package name (1st argument with munging)
+# fall back to the package name (1st argument with munging).
 extract_package_name='
   /^AC_INIT(\[*/{
      s///
@@ -187,8 +207,11 @@ extract_package_name='
      p
   }
 '
-package=$(sed -n "$extract_package_name" configure.ac) \
-  || die 'cannot find package name in configure.ac'
+package=$(${AUTOCONF:-autoconf} --trace AC_INIT:\$4 configure.ac 2>/dev/null)
+if test -z "$package"; then
+  package=$(sed -n "$extract_package_name" configure.ac) \
+      || die 'cannot find package name in configure.ac'
+fi
 gnulib_name=lib$package
 
 build_aux=build-aux
@@ -320,6 +343,12 @@ do
   --help)
     usage
     exit;;
+  --version)
+    set -e
+    echo "bootstrap $scriptversion"
+    echo "$copyright"
+    exit 0
+    ;;
   --gnulib-srcdir=*)
     GNULIB_SRCDIR=${option#--gnulib-srcdir=};;
   --skip-po)
@@ -335,7 +364,7 @@ do
   --no-git)
     use_git=false;;
   *)
-    die "$option: unknown option";;
+    bootstrap_option_hook $option || die "$option: unknown option";;
   esac
 done
 

bootstrap.conf

@@ -1,6 +1,6 @@
 # Bootstrap configuration.
 
-# Copyright (C) 2006-2015, 2018-2020 Free Software Foundation, Inc.
+# Copyright (C) 2006-2015, 2018-2021 Free Software Foundation, Inc.
 
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -13,7 +13,7 @@
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 # gnulib modules used by this package.
 gnulib_modules='
@@ -22,11 +22,12 @@ gnulib_modules='
   calloc-posix close closeout config-h c-strcase
   configmake
   dirname
-  error extensions
+  error execute extensions
   fdl fopen-safer fstrcmp
   getopt-gnu
   gettext-h git-version-gen gitlog-to-changelog
   gpl-3.0 intprops inttypes isnan javacomp-script
+  hash-map
   javaexec-script
   ldexpl
   libtextstyle-optional
@@ -44,7 +45,9 @@ gnulib_modules='
   realloc-posix
   relocatable-prog relocatable-script
   rename
-  spawn-pipe stdbool stpcpy strdup-posix strerror strverscmp
+  spawn-pipe stdbool stpcpy stpncpy strdup-posix strerror strverscmp
+  sys_ioctl
+  termios
   timevar
   unicodeio unistd unistd-safer unlink unlocked-io
   update-copyright unsetenv verify
@@ -56,7 +59,7 @@ gnulib_modules='
   xconcat-filename
   xhash
   xlist
-  xmemdup0
+  xmap xmemdup0
   xstrndup
 
   fprintf-posix printf-posix snprintf-posix sprintf-posix

build-aux/.gitignore

@@ -1,6 +1,7 @@
 /announce-gen
 /compile
 /config.guess
+/config.libpath
 /config.rpath
 /config.rpath~
 /config.sub
@@ -11,20 +12,19 @@
 /gitlog-to-changelog
 /gnu-web-doc-update
 /gnupload
+/install-reloc
 /install-sh
 /javacomp.sh.in
 /javaexec.sh.in
+/libtool-reloc
 /mdate-sh
 /missing
 /prefix-gnulib-mk
+/reloc-ldflags
+/relocatable.sh.in
 /test-driver
 /texinfo.tex
 /update-copyright
 /useless-if-before-free
 /vc-list-files
 /ylwrap
-/config.libpath
-/install-reloc
-/reloc-ldflags
-/relocatable.sh.in
-/libtool-reloc

build-aux/Darwin.valgrind

@@ -1,4 +1,4 @@
-# Copyright (C) 2012-2015, 2018-2020 Free Software Foundation, Inc.
+# Copyright (C) 2012-2015, 2018-2021 Free Software Foundation, Inc.
 
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -11,7 +11,7 @@
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 # Valgrind suppression file for Bison.
 

build-aux/Linux.valgrind

@@ -1,4 +1,4 @@
-# Copyright (C) 2012-2015, 2018-2020 Free Software Foundation, Inc.
+# Copyright (C) 2012-2015, 2018-2021 Free Software Foundation, Inc.
 
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -11,7 +11,7 @@
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 # Valgrind suppression file for Bison.
 

build-aux/cross-options.pl

@@ -2,7 +2,7 @@
 
 # Generate a release announcement message.
 
-# Copyright (C) 2007-2020 Free Software Foundation, Inc.
+# Copyright (C) 2007-2021 Free Software Foundation, Inc.
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by

build-aux/local.mk

@@ -1,4 +1,4 @@
-## Copyright (C) 2000-2015, 2018-2020 Free Software Foundation, Inc.
+## Copyright (C) 2000-2015, 2018-2021 Free Software Foundation, Inc.
 ##
 ## This program is free software: you can redistribute it and/or modify
 ## it under the terms of the GNU General Public License as published by
@@ -11,7 +11,7 @@
 ## GNU General Public License for more details.
 ##
 ## You should have received a copy of the GNU General Public License
-## along with this program.  If not, see <http://www.gnu.org/licenses/>.
+## along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 EXTRA_DIST +=					\
   build-aux/Darwin.valgrind			\

build-aux/update-b4-copyright

@@ -3,7 +3,7 @@
 # Update b4_copyright invocations or b4_copyright_years definitions to
 # include the current year.
 
-# Copyright (C) 2009-2015, 2018-2020 Free Software Foundation, Inc.
+# Copyright (C) 2009-2015, 2018-2021 Free Software Foundation, Inc.
 
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -16,7 +16,7 @@
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 use strict;
 use warnings;

build-aux/update-package-copyright-year

@@ -2,7 +2,7 @@
 
 # In configure.ac, update PACKAGE_COPYRIGHT_YEAR to the current year.
 
-# Copyright (C) 2010-2015, 2018-2020 Free Software Foundation, Inc.
+# Copyright (C) 2010-2015, 2018-2021 Free Software Foundation, Inc.
 #
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -15,7 +15,7 @@
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 use strict;
 use warnings;

build-aux/update-test

@@ -2,7 +2,7 @@
 
 # Update expectations in an Autotest test suite.
 
-# Copyright (C) 2019-2020 Free Software Foundation, Inc.
+# Copyright (C) 2019-2021 Free Software Foundation, Inc.
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by

cfg.mk

@@ -1,5 +1,5 @@
 ## Customize maint.mk                           -*- makefile -*-
-## Copyright (C) 2008-2015, 2018-2020 Free Software Foundation, Inc.
+## Copyright (C) 2008-2015, 2018-2021 Free Software Foundation, Inc.
 
 ## This program is free software: you can redistribute it and/or modify
 ## it under the terms of the GNU General Public License as published by
@@ -12,7 +12,7 @@
 ## GNU General Public License for more details.
 
 ## You should have received a copy of the GNU General Public License
-## along with this program.  If not, see <http://www.gnu.org/licenses/>.
+## along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 # Update version, then recompile so that tests/bison --version be
 # up-to-date, then compile our parser again with our up-to-date bison.
@@ -126,7 +126,7 @@ _sed_rm_comments_q = $(subst ','\'',$(_sed_remove_comments))
 
 _space_before_paren_exempt =? \\n\\$$
 _space_before_paren_exempt = \
-  (^ *\#|(LA)?LR\([01]\)|percent_(code|define)|b4_syncline|m4_(define|init)|symbol)
+  (^ *\#|(LA)?LR\([01]\)|percent_(code|define)|b4_syncline|m4_(define|init))
 # Ensure that there is a space before each open parenthesis in C code.
 sc_space_before_open_paren:
 	@if $(VC_LIST_EXCEPT) | grep -l '\.[ch]$$' > /dev/null; then	\
@@ -156,6 +156,8 @@ exclude = \
 $(call exclude,                                                                 \
   bindtextdomain=^lib/main.c$$                                                  \
   cast_of_argument_to_free=^src/muscle-tab.c$$                                  \
+  error_message_uppercase=etc/bench.pl.in$$                                     \
+  file_system=^doc/Doxyfile.in$$                                                \
   po_check=^tests|(^po/POTFILES.in|.md)$$                                       \
   preprocessor_indentation=^data/|^lib/|^src/parse-gram.[ch]$$                  \
   program_name=^lib/main.c$$                                                    \

configure.ac

@@ -1,6 +1,6 @@
 # Configure template for GNU Bison.                   -*-Autoconf-*-
 #
-# Copyright (C) 2001-2015, 2018-2020 Free Software Foundation, Inc.
+# Copyright (C) 2001-2015, 2018-2021 Free Software Foundation, Inc.
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -13,14 +13,9 @@
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
-# In order for some versions of Sun Studio to compile our C++ test cases
-# correctly, we need Autoconf 2.64 or better to handle the restrict
-# keyword in at least string.h from gnulib.  We need Autoconf 2.68 or
-# better to avoid a typo in the 'configure --help' entry for the YACC
-# environment variable.
-AC_PREREQ([2.68])
+AC_PREREQ([2.71])
 m4_pattern_forbid([^_?(gl_[A-Z]|AX_|BISON_)])
 m4_pattern_allow([^BISON_USE_NLS$])
 
@@ -29,7 +24,7 @@ AC_INIT([GNU Bison],
         [[email protected]],
         [],
         [https://www.gnu.org/software/bison/])
-AC_SUBST([PACKAGE_COPYRIGHT_YEAR], [2020])
+AC_SUBST([PACKAGE_COPYRIGHT_YEAR], [2021])
 AC_DEFINE_UNQUOTED([PACKAGE_COPYRIGHT_YEAR], [$PACKAGE_COPYRIGHT_YEAR],
                    [The copyright year for this package])
 
@@ -54,12 +49,15 @@ AM_SILENT_RULES([yes])
 AC_CONFIG_HEADERS([lib/config.h:lib/config.in.h])
 
 # Checks for the compiler.
-AC_PROG_CC_STDC
+AC_PROG_CC
 AC_PROG_CXX
 
 # Gnulib (early checks).
 gl_EARLY
 
+# We want ostream_printf and hyperlink support.
+gl_LIBTEXTSTYLE_OPTIONAL([0.20.5])
+
 # Gnulib uses '#pragma GCC diagnostic push' to silence some
 # warnings, but older gcc doesn't support this.
 AC_CACHE_CHECK([whether pragma GCC diagnostic push works],
@@ -81,7 +79,8 @@ BISON_CXXSTD([03])
 BISON_CXXSTD([11])
 BISON_CXXSTD([14])
 BISON_CXXSTD([17])
-BISON_CXXSTD([2a])
+BISON_CXXSTD([20])
+BISON_CXXSTD([2b])
 AM_CONDITIONAL([ENABLE_CXX11], [test x"$CXX11_CXXFLAGS" != x])
 AM_CONDITIONAL([ENABLE_CXX14], [test x"$CXX14_CXXFLAGS" != x])
 AC_LANG_POP([C++])
@@ -130,7 +129,7 @@ if test "$enable_gcc_warnings" = yes; then
   warn_common='-Wall -Wextra
     -Wcast-align -Wchar-subscripts
     -fparse-all-comments -Wdocumentation
-    -Wformat -Wimplicit-fallthrough -Wnull-dereference
+    -Wformat -Wimplicit-fallthrough -Wmismatched-dealloc -Wnull-dereference
     -Wno-sign-compare -Wno-tautological-constant-out-of-range-compare
     -Wpointer-arith -Wshadow -Wstrict-aliasing
     -Wwrite-strings
@@ -248,7 +247,7 @@ AM_CONDITIONAL([ENABLE_JAVA], [test x"$CONF_JAVAC" != x && test x"$CONF_JAVA" !=
 
 
 AC_ARG_ENABLE([yacc],
-  [AC_HELP_STRING([--disable-yacc],
+  [AS_HELP_STRING([--disable-yacc],
      [do not build a yacc command or an -ly library])],
   , [enable_yacc=yes])
 AM_CONDITIONAL([ENABLE_YACC], [test "$enable_yacc" = yes])

data/README.md

@@ -73,15 +73,29 @@ skeletons.  If you are to write a new skeleton, please, implement them for
 your language.  Overall, be sure to follow the same patterns as the existing
 skeletons.
 
+## Vocabulary
+
+We use "formal arguments", or "formals" for short, to denote the declared
+parameters of a function (e.g., `int argc, const char **argv`).  Yes, this
+is somewhat contradictory with `param` in the `%param` directives.
+
+We use "effective arguments", or "args" for short, to denote the values
+passed in function calls (e.g., `argc, argv`).
+
 ## Symbols
 
 ### `b4_symbol(NUM, FIELD)`
 In order to unify the handling of the various aspects of symbols (tag, type
 name, whether terminal, etc.), bison.exe defines one macro per (token,
 field), where field can `has_id`, `id`, etc.: see
-`prepare_symbols_definitions()` in `src/output.c`.
+`prepare_symbol_definitions()` in `src/output.c`.
 
-The macro `b4_symbol(NUM, FIELD)` gives access to the following FIELDS:
+NUM can be:
+- `empty` to denote the "empty" pseudo-symbol when it exists,
+- `eof`, `error`, or `undef`
+- a symbol number.
+
+FIELD can be:
 
 - `has_id`: 0 or 1
   Whether the symbol has an `id`.
@@ -142,11 +156,17 @@ The macro `b4_symbol(NUM, FIELD)` gives access to the following FIELDS:
   When api.value.type=union, the generated name for the union member.
   yytype_INT etc. for symbols that has_id, otherwise yytype_1 etc.
 
-- `type`
+- `type`: string
   If it has a semantic value, its type tag, or, if variant are used,
   its type.
   In the case of api.value.type=union, type is the real type (e.g. int).
 
+- `slot`: string
+  If it has a semantic value, the name of the union member (i.e., bounces to
+  either `type_tag` or `type`).  It would be better to fix our mess and
+  always use `type` for the true type of the member, and `type_tag` for the
+  name of the union member.
+
 - `has_printer`: 0, 1
 - `printer`: string
 - `printer_file`: string
@@ -187,7 +207,7 @@ fill-column: 76
 ispell-dictionary: "american"
 End:
 
-Copyright (C) 2002, 2008-2015, 2018-2020 Free Software Foundation, Inc.
+Copyright (C) 2002, 2008-2015, 2018-2021 Free Software Foundation, Inc.
 
 This file is part of GNU Bison.
 
@@ -202,6 +222,6 @@ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.
 
 You should have received a copy of the GNU General Public License
-along with this program.  If not, see <http://www.gnu.org/licenses/>.
+along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 -->

data/bison-default.css

@@ -1,5 +1,5 @@
 /* Default styling rules for Bison when doing terminal output.
-   Copyright (C) 2019-2020 Free Software Foundation, Inc.
+   Copyright (C) 2019-2021 Free Software Foundation, Inc.
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by

data/local.mk

@@ -1,4 +1,4 @@
-## Copyright (C) 2002, 2005-2015, 2018-2020 Free Software Foundation,
+## Copyright (C) 2002, 2005-2015, 2018-2021 Free Software Foundation,
 ## Inc.
 
 ## This program is free software: you can redistribute it and/or modify
@@ -12,7 +12,7 @@
 ## GNU General Public License for more details.
 ##
 ## You should have received a copy of the GNU General Public License
-## along with this program.  If not, see <http://www.gnu.org/licenses/>.
+## along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 dist_pkgdata_DATA =                             \
   data/README.md                                \
@@ -28,6 +28,7 @@ dist_skeletons_DATA =                           \
   data/skeletons/c.m4                           \
   data/skeletons/glr.c                          \
   data/skeletons/glr.cc                         \
+  data/skeletons/glr2.cc                        \
   data/skeletons/java-skel.m4                   \
   data/skeletons/java.m4                        \
   data/skeletons/lalr1.cc                       \
@@ -40,7 +41,6 @@ dist_skeletons_DATA =                           \
 
 # Experimental support for the D language.
 dist_skeletons_DATA +=                          \
-  data/skeletons/README-D.txt                   \
   data/skeletons/d-skel.m4                      \
   data/skeletons/d.m4                           \
   data/skeletons/lalr1.d

data/skeletons/README-D.txt

@@ -1,60 +0,0 @@
-Some usage notes for the D Parser:
-
-- it is a port of the Java parser, so interface is very similar.
-
-- the lexer class needs to implement the interface 'Lexer' (similar to
-  java). It typically (depending on options) looks like this:
-
-public interface Lexer
-{
-  /**
-   * Method to retrieve the beginning position of the last scanned token.
-   * @return the position at which the last scanned token starts.  */
-  @property YYPosition startPos ();
-
-  /**
-   * Method to retrieve the ending position of the last scanned token.
-   * @return the first position beyond the last scanned token.  */
-  @property YYPosition endPos ();
-
-  /**
-   * Method to retrieve the semantic value of the last scanned token.
-   * @return the semantic value of the last scanned token.  */
-  @property YYSemanticType semanticVal ();
-
-  /**
-   * Entry point for the scanner.  Returns the token identifier corresponding
-   * to the next token and prepares to return the semantic value
-   * and beginning/ending positions of the token.
-   * @return the token identifier corresponding to the next token. */
-  TokenKind yylex ();
-
-  /**
-   * Entry point for error reporting.  Emits an error
-   * referring to the given location in a user-defined way.
-   *
-   * @param loc The location of the element to which the
-   *                error message is related
-   * @param s The string for the error message.  */
-   void yyerror (YYLocation loc, string s);
-}
-
-- semantic types are handled by D unions (same as for C/C++ parsers)
-
-- the following (non-standard) %defines are supported:
-
-  %define package "<package_name>"
-  %define api.parser.class "my_class_name>"
-  %define position_type "my_position_type"
-  %define location_type "my_location_type"
-
-- the following declarations basically work like in C/C++:
-
-  %locations
-  %error-verbose
-  %parse-param
-  %initial-action
-  %code
-  %union
-
-- %destructor is not yet supported

data/skeletons/bison.m4

@@ -2,7 +2,7 @@
 
 # Language-independent M4 Macros for Bison.
 
-# Copyright (C) 2002, 2004-2015, 2018-2020 Free Software Foundation,
+# Copyright (C) 2002, 2004-2015, 2018-2021 Free Software Foundation,
 # Inc.
 
 # This program is free software: you can redistribute it and/or modify
@@ -16,7 +16,7 @@
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 
 
@@ -49,7 +49,7 @@ m4_define([m4_shift4], [m4_shift(m4_shift(m4_shift(m4_shift($@))))])
 # b4_generated_by
 # ---------------
 m4_define([b4_generated_by],
-[b4_comment([A Bison parser, made by GNU Bison b4_version.])
+[b4_comment([A Bison parser, made by GNU Bison b4_version_string.])
 ])
 
 # b4_copyright(TITLE, [YEARS])
@@ -74,7 +74,7 @@ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.
 
 You should have received a copy of the GNU General Public License
-along with this program.  If not, see <http://www.gnu.org/licenses/>.])
+along with this program.  If not, see <https://www.gnu.org/licenses/>.])
 
 b4_comment([As a special exception, you may create a larger work that contains
 part or all of the Bison parser skeleton and distribute that work
@@ -261,6 +261,13 @@ m4_define([b4_fatal_at],
 [b4_error([[fatal]], $@)dnl
 m4_exit(1)])
 
+# b4_canary(MSG)
+# --------------
+# Issue a warning on stderr and in the output.  Used in the test suite
+# to catch spurious m4 evaluations.
+m4_define([b4_canary],
+[m4_errprintn([dead canary: $1])DEAD CANARY($1)])
+
 
 ## ------------ ##
 ## Data Types.  ##
@@ -332,14 +339,14 @@ number is the opposite.  If YYTABLE_NINF, syntax error.]])
 $1([check], [b4_check])
 
 $1([stos], [b4_stos],
-   [[YYSTOS[STATE-NUM] -- The (internal number of the) accessing
-symbol of state STATE-NUM.]])
+   [[YYSTOS[STATE-NUM] -- The symbol kind of the accessing symbol of
+state STATE-NUM.]])
 
 $1([r1], [b4_r1],
-   [[YYR1[YYN] -- Symbol number of symbol that rule YYN derives.]])
+   [[YYR1[RULE-NUM] -- Symbol kind of the left-hand side of rule RULE-NUM.]])
 
 $1([r2], [b4_r2],
-   [[YYR2[YYN] -- Number of symbols on the right hand side of rule YYN.]])
+   [[YYR2[RULE-NUM] -- Number of symbols on the right-hand side of rule RULE-NUM.]])
 ])
 
 
@@ -391,9 +398,9 @@ m4_define([b4_$3_if],
 # b4_FLAG_if(IF-TRUE, IF-FALSE)
 # -----------------------------
 # Expand IF-TRUE, if FLAG is true, IF-FALSE otherwise.
-b4_define_flag_if([defines])            # Whether headers are requested.
 b4_define_flag_if([glr])                # Whether a GLR parser is requested.
 b4_define_flag_if([has_translations])   # Whether some tokens are internationalized.
+b4_define_flag_if([header])             # Whether a header is requested.
 b4_define_flag_if([nondeterministic])   # Whether conflicts should be handled.
 b4_define_flag_if([token_table])        # Whether yytoken_table is demanded.
 b4_define_flag_if([yacc])               # Whether POSIX Yacc is emulated.
@@ -402,7 +409,7 @@ b4_define_flag_if([yacc])               # Whether POSIX Yacc is emulated.
 # b4_glr_cc_if([IF-TRUE], [IF-FALSE])
 # -----------------------------------
 m4_define([b4_glr_cc_if],
-          [m4_if(b4_skeleton, ["glr.cc"], $@)])
+          [m4_if(m4_bregexp(b4_skeleton, [^"glr.cc"$]), [0], $@)])
 
 
 ## --------- ##
@@ -465,17 +472,35 @@ m4_case([$1],
 # but are S_YYEMPTY and symbol_kind::S_YYEMPTY in C++.
 m4_copy([b4_symbol_kind_base], [b4_symbol_kind])
 
+
+# b4_symbol_slot(NUM)
+# -------------------
+# The name of union member that contains the value of these symbols.
+# Currently, we are messy, this should actually be type_tag, but type_tag
+# has several meanings.
+m4_define([b4_symbol_slot],
+[m4_case(b4_percent_define_get([[api.value.type]]),
+         [union],   [b4_symbol([$1], [type_tag])],
+         [variant], [b4_symbol([$1], [type_tag])],
+         [b4_symbol([$1], [type])])])
+
+
 # b4_symbol(NUM, FIELD)
 # ---------------------
-# Fetch FIELD of symbol #NUM (or "orig NUM").  Fail if undefined.
+# Fetch FIELD of symbol #NUM (or "orig NUM", or "empty").  Fail if undefined.
 #
 # If FIELD = id, prepend the token prefix.
 m4_define([b4_symbol],
-[m4_case([$2],
-         [id],        [b4_symbol_token_kind([$1])],
-         [kind_base], [b4_symbol_kind_base([$1])],
-         [kind],      [b4_symbol_kind([$1])],
-         [_b4_symbol($@)])])
+[m4_if([$1], [empty], [b4_symbol([-2], [$2])],
+       [$1], [eof],   [b4_symbol([0], [$2])],
+       [$1], [error], [b4_symbol([1], [$2])],
+       [$1], [undef], [b4_symbol([2], [$2])],
+       [m4_case([$2],
+                [id],        [b4_symbol_token_kind([$1])],
+                [kind_base], [b4_symbol_kind_base([$1])],
+                [kind],      [b4_symbol_kind([$1])],
+                [slot],      [b4_symbol_slot([$1])],
+                [_b4_symbol($@)])])])
 
 
 # b4_symbol_if(NUM, FIELD, IF-TRUE, IF-FALSE)
@@ -537,7 +562,7 @@ m4_defn([b4_actions_])[]dnl
         break;
     }dnl
 ],
-[YYUSE (m4_default([$2], [yykind]));])dnl
+[b4_use(m4_default([$2], [yykind]));])dnl
 m4_popdef([b4_actions_])dnl
 ])
 
@@ -633,11 +658,11 @@ m4_define([_b4_type_action],
 
 ])])
 
-# b4_type_foreach(MACRO)
-# ----------------------
+# b4_type_foreach(MACRO, [SEP])
+# -----------------------------
 # Invoke MACRO(SYMBOL-NUMS) for each set of SYMBOL-NUMS for each type set.
 m4_define([b4_type_foreach],
-          [m4_map([$1], m4_defn([b4_type_names]))])
+          [m4_map_sep([$1], [$2], m4_defn([b4_type_names]))])
 
 
 
@@ -953,15 +978,18 @@ m4_define([b4_percent_define_flag_if],
 # For example:
 #
 #   b4_percent_define_default([[foo]], [[default value]])
+m4_define([_b4_percent_define_define],
+[m4_define([b4_percent_define(]$1[)], [$2])dnl
+m4_define([b4_percent_define_kind(]$1[)],
+          [m4_default([$3], [keyword])])dnl
+m4_define([b4_percent_define_loc(]$1[)],
+          [[[[<skeleton default value>:-1.-1]],
+            [[<skeleton default value>:-1.-1]]]])dnl
+m4_define([b4_percent_define_syncline(]$1[)], [[]])])
+
 m4_define([b4_percent_define_default],
 [_b4_percent_define_ifdef([$1], [],
-           [m4_define([b4_percent_define(]$1[)], [$2])dnl
-            m4_define([b4_percent_define_kind(]$1[)],
-                      [m4_default([$3], [keyword])])dnl
-            m4_define([b4_percent_define_loc(]$1[)],
-                      [[[[<skeleton default value>:-1.-1]],
-                        [[<skeleton default value>:-1.-1]]]])dnl
-            m4_define([b4_percent_define_syncline(]$1[)], [[]])])])
+                          [_b4_percent_define_define($@)])])
 
 
 # b4_percent_define_if_define(NAME, [VARIABLE = NAME])
@@ -971,11 +999,12 @@ m4_define([b4_percent_define_default],
 # to '_'.
 m4_define([_b4_percent_define_if_define],
 [m4_define(m4_bpatsubst([b4_$1_if], [[-.]], [_]),
-           [b4_percent_define_flag_if(m4_default([$2], [$1]),
-                                      [$3], [$4])])])
+           [b4_percent_define_default([m4_default([$2], [$1])], [[false]])dnl
+b4_percent_define_flag_if(m4_default([$2], [$1]),
+                                     [$3], [$4])])])
+
 m4_define([b4_percent_define_if_define],
-[b4_percent_define_default([m4_default([$2], [$1])], [[false]])
-_b4_percent_define_if_define([$1], [$2], $[1], $[2])])
+[_b4_percent_define_if_define([$1], [$2], $[1], $[2])])
 
 
 # b4_percent_define_check_kind(VARIABLE, KIND, [DIAGNOSTIC = complain])
@@ -1110,14 +1139,18 @@ m4_define([b4_parse_error_bmatch],
 
 
 
+# b4_union_if([IF-UNION-ARE-USED], [IF-NOT])
 # b4_variant_if([IF-VARIANT-ARE-USED], [IF-NOT])
 # ----------------------------------------------
-b4_percent_define_if_define([variant])
+# Depend on whether api.value.type is union, or variant.
+m4_define([b4_union_flag],   [[0]])
 m4_define([b4_variant_flag], [[0]])
 b4_percent_define_ifdef([[api.value.type]],
    [m4_case(b4_percent_define_get_kind([[api.value.type]]), [keyword],
-            [m4_case(b4_percent_define_get([[api.value.type]]), [variant],
-                    [m4_define([b4_variant_flag], [[1]])])])])
+            [m4_case(b4_percent_define_get([[api.value.type]]),
+                     [union],   [m4_define([b4_union_flag],   [[1]])],
+                     [variant], [m4_define([b4_variant_flag], [[1]])])])])
+b4_define_flag_if([union])
 b4_define_flag_if([variant])
 
 

data/skeletons/c++-skel.m4

@@ -2,7 +2,7 @@
 
 # C++ skeleton dispatching for Bison.
 
-# Copyright (C) 2006-2007, 2009-2015, 2018-2020 Free Software
+# Copyright (C) 2006-2007, 2009-2015, 2018-2021 Free Software
 # Foundation, Inc.
 
 # This program is free software: you can redistribute it and/or modify
@@ -16,7 +16,7 @@
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 b4_glr_if(             [m4_define([b4_used_skeleton], [b4_skeletonsdir/[glr.cc]])])
 b4_nondeterministic_if([m4_define([b4_used_skeleton], [b4_skeletonsdir/[glr.cc]])])

data/skeletons/c++.m4

@@ -2,7 +2,7 @@
 
 # C++ skeleton for Bison
 
-# Copyright (C) 2002-2020 Free Software Foundation, Inc.
+# Copyright (C) 2002-2021 Free Software Foundation, Inc.
 
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -15,7 +15,7 @@
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 # Sanity checks, before defaults installed by c.m4.
 b4_percent_define_ifdef([[api.value.union.name]],
@@ -109,7 +109,6 @@ b4_percent_define_default([[api.filename.type]], [[const std::string]])
 # Make it a warning for those who used betas of Bison 3.0.
 b4_percent_define_default([[api.namespace]], m4_defn([b4_prefix]))
 
-b4_percent_define_default([[global_tokens_and_yystype]], [[false]])
 b4_percent_define_default([[define_location_comparison]],
                           [m4_if(b4_percent_define_get([[filename_type]]),
                                  [std::string], [[true]], [[false]])])
@@ -193,7 +192,7 @@ m4_define([b4_declare_symbol_enum],
 [[enum symbol_kind_type
       {
         YYNTOKENS = ]b4_tokens_number[, ///< Number of tokens.
-        ]b4_symbol(-2, kind_base)[ = -2,
+        ]b4_symbol(empty, kind_base)[ = -2,
 ]b4_symbol_foreach([      b4_symbol_enum])dnl
 [      };]])
 
@@ -207,16 +206,16 @@ m4_define([b4_declare_symbol_enum],
 
 # b4_value_type_declare
 # ---------------------
-# Declare semantic_type.
+# Declare value_type.
 m4_define([b4_value_type_declare],
 [b4_value_type_setup[]dnl
 [    /// Symbol semantic values.
 ]m4_bmatch(b4_percent_define_get_kind([[api.value.type]]),
 [code],
-[[    typedef ]b4_percent_define_get([[api.value.type]])[ semantic_type;]],
+[[    typedef ]b4_percent_define_get([[api.value.type]])[ value_type;]],
 [m4_bmatch(b4_percent_define_get([[api.value.type]]),
 [union\|union-directive],
-[[    union semantic_type
+[[    union value_type
     {
 ]b4_user_union_members[
     };]])])dnl
@@ -228,11 +227,16 @@ m4_define([b4_value_type_declare],
 # Define the public types: token, semantic value, location, and so forth.
 # Depending on %define token_lex, may be output in the header or source file.
 m4_define([b4_public_types_declare],
-[[#ifndef ]b4_api_PREFIX[STYPE
-]b4_value_type_declare[
+[[#ifdef ]b4_api_PREFIX[STYPE
+# ifdef __GNUC__
+#  pragma GCC message "bison: do not #define ]b4_api_PREFIX[STYPE in C++, use %define api.value.type"
+# endif
+    typedef ]b4_api_PREFIX[STYPE value_type;
 #else
-    typedef ]b4_api_PREFIX[STYPE semantic_type;
-#endif]b4_locations_if([
+]b4_value_type_declare[
+#endif
+    /// Backward compatibility (Bison 3.8).
+    typedef value_type semantic_type;]b4_locations_if([
     /// Symbol locations.
     typedef b4_percent_define_get([[api.location.type]],
                                   [[location]]) location_type;])[
@@ -321,15 +325,16 @@ m4_define([b4_symbol_type_define],
       /// Copy constructor.
       basic_symbol (const basic_symbol& that);]b4_variant_if([[
 
-      /// Constructor for valueless symbols, and symbols from each type.
-]b4_type_foreach([b4_basic_symbol_constructor_define])], [[
+      /// Constructors for typed symbols.
+]b4_type_foreach([b4_basic_symbol_constructor_define], [
+])], [[
       /// Constructor for valueless symbols.
       basic_symbol (typename Base::kind_type t]b4_locations_if([,
                     YY_MOVE_REF (location_type) l])[);
 
       /// Constructor for symbols with semantic value.
       basic_symbol (typename Base::kind_type t,
-                    YY_RVREF (semantic_type) v]b4_locations_if([,
+                    YY_RVREF (value_type) v]b4_locations_if([,
                     YY_RVREF (location_type) l])[);
 ]])[
       /// Destroy the symbol.
@@ -339,7 +344,7 @@ m4_define([b4_symbol_type_define],
       }
 
       /// Destroy contents, and record that is empty.
-      void clear ()
+      void clear () YY_NOEXCEPT
       {]b4_variant_if([[
         // User destructor.
         symbol_kind_type yykind = this->kind ();
@@ -390,7 +395,7 @@ m4_define([b4_symbol_type_define],
       void move (basic_symbol& s);
 
       /// The semantic value.
-      semantic_type value;]b4_locations_if([
+      value_type value;]b4_locations_if([
 
       /// The location.
       location_type location;])[
@@ -423,7 +428,7 @@ m4_define([b4_symbol_type_define],
       by_kind (kind_type t);
 
       /// Record that this symbol is empty.
-      void clear ();
+      void clear () YY_NOEXCEPT;
 
       /// Steal the symbol kind from \a that.
       void move (by_kind& that);
@@ -453,7 +458,7 @@ m4_define([b4_symbol_type_define],
       symbol_type () {}
 
       /// Constructor for valueless symbols, and symbols from each type.
-]b4_type_foreach([_b4_token_constructor_define])dnl
+]b4_type_foreach([_b4_symbol_constructor_define])dnl
     ])[};
 ]])
 
@@ -487,7 +492,7 @@ m4_define([b4_public_types_define],
   template <typename Base>
   ]b4_parser_class[::basic_symbol<Base>::basic_symbol (]b4_join(
           [typename Base::kind_type t],
-          [YY_RVREF (semantic_type) v],
+          [YY_RVREF (value_type) v],
           b4_locations_if([YY_RVREF (location_type) l]))[)
     : Base (t)
     , value (]b4_variant_if([], [YY_MOVE (v)])[)]b4_locations_if([
@@ -507,7 +512,7 @@ m4_define([b4_public_types_define],
   bool
   ]b4_parser_class[::basic_symbol<Base>::empty () const YY_NOEXCEPT
   {
-    return this->kind () == ]b4_symbol(-2, kind)[;
+    return this->kind () == ]b4_symbol(empty, kind)[;
   }
 
   template <typename Base>
@@ -523,7 +528,7 @@ m4_define([b4_public_types_define],
 
   // by_kind.
   ]b4_inline([$1])b4_parser_class[::by_kind::by_kind ()
-    : kind_ (]b4_symbol(-2, kind)[)
+    : kind_ (]b4_symbol(empty, kind)[)
   {}
 
 #if 201103L <= YY_CPLUSPLUS
@@ -543,9 +548,9 @@ m4_define([b4_public_types_define],
   {}
 
   ]b4_inline([$1])[void
-  ]b4_parser_class[::by_kind::clear ()
+  ]b4_parser_class[::by_kind::clear () YY_NOEXCEPT
   {
-    kind_ = ]b4_symbol(-2, kind)[;
+    kind_ = ]b4_symbol(empty, kind)[;
   }
 
   ]b4_inline([$1])[void
@@ -571,7 +576,7 @@ m4_define([b4_public_types_define],
 
 # b4_token_constructor_define
 # ----------------------------
-# Define symbol constructors for all the value types.
+# Define make_FOO for all the token kinds.
 # Use at class-level.  Redefined in variant.hh.
 m4_define([b4_token_constructor_define], [])
 
@@ -600,7 +605,7 @@ m4_define([b4_yytranslate_define],
     if (t <= 0)
       return symbol_kind::]b4_symbol_prefix[YYEOF;
     else if (t <= code_max)
-      return YY_CAST (symbol_kind_type, translate_table[t]);
+      return static_cast <symbol_kind_type> (translate_table[t]);
     else
       return symbol_kind::]b4_symbol_prefix[YYUNDEF;]])[
   }

data/skeletons/c-like.m4

@@ -2,7 +2,7 @@
 
 # Common code for C-like languages (C, C++, Java, etc.)
 
-# Copyright (C) 2012-2015, 2018-2020 Free Software Foundation, Inc.
+# Copyright (C) 2012-2015, 2018-2021 Free Software Foundation, Inc.
 
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -15,7 +15,7 @@
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 
 # _b4_comment(TEXT, OPEN, CONTINUE, END)

data/skeletons/c-skel.m4

@@ -2,7 +2,7 @@
 
 # C skeleton dispatching for Bison.
 
-# Copyright (C) 2006-2007, 2009-2015, 2018-2020 Free Software
+# Copyright (C) 2006-2007, 2009-2015, 2018-2021 Free Software
 # Foundation, Inc.
 
 # This program is free software: you can redistribute it and/or modify
@@ -16,7 +16,7 @@
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 b4_glr_if(             [m4_define([b4_used_skeleton], [b4_skeletonsdir/[glr.c]])])
 b4_nondeterministic_if([m4_define([b4_used_skeleton], [b4_skeletonsdir/[glr.c]])])

data/skeletons/c.m4

@@ -2,7 +2,7 @@
 
 # C M4 Macros for Bison.
 
-# Copyright (C) 2002, 2004-2015, 2018-2020 Free Software Foundation,
+# Copyright (C) 2002, 2004-2015, 2018-2021 Free Software Foundation,
 # Inc.
 
 # This program is free software: you can redistribute it and/or modify
@@ -16,7 +16,7 @@
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 m4_include(b4_skeletonsdir/[c-like.m4])
 
@@ -58,11 +58,11 @@ m4_define([b4_cpp_guard_close],
 # b4_pull_flag if they use the values of the %define variables api.pure or
 # api.push-pull.
 m4_define([b4_identification],
-[[/* Identify Bison output.  */
-#define YYBISON 1
+[[/* Identify Bison output, and Bison version.  */
+#define YYBISON ]b4_version[
 
-/* Bison version.  */
-#define YYBISON_VERSION "]b4_version["
+/* Bison version string.  */
+#define YYBISON_VERSION "]b4_version_string["
 
 /* Skeleton name.  */
 #define YYSKELETON_NAME ]b4_skeleton[]m4_ifdef([b4_pure_flag], [[
@@ -107,27 +107,32 @@ b4_percent_define_default([[api.symbol.prefix]], [[YYSYMBOL_]])
 ## Pure/impure interfaces.  ##
 ## ------------------------ ##
 
-# b4_lex_formals
-# --------------
+# b4_yylex_formals
+# ----------------
 # All the yylex formal arguments.
 # b4_lex_param arrives quoted twice, but we want to keep only one level.
-m4_define([b4_lex_formals],
-[b4_pure_if([[[[YYSTYPE *yylvalp]], [[&yylval]]][]dnl
-b4_locations_if([, [[YYLTYPE *yyllocp], [&yylloc]]])])dnl
+m4_define([b4_yylex_formals],
+[b4_pure_if([[[b4_api_PREFIX[STYPE *yylvalp]], [[&yylval]]][]dnl
+b4_locations_if([, [b4_api_PREFIX[LTYPE *yyllocp], [&yylloc]]])])dnl
 m4_ifdef([b4_lex_param], [, ]b4_lex_param)])
 
 
-# b4_lex
-# ------
+# b4_yylex
+# --------
 # Call yylex.
-m4_define([b4_lex],
-[b4_function_call([yylex], [int], b4_lex_formals)])
+m4_define([b4_yylex],
+[b4_function_call([yylex], [int], b4_yylex_formals)])
 
 
 # b4_user_args
 # ------------
 m4_define([b4_user_args],
-[m4_ifset([b4_parse_param], [, b4_args(b4_parse_param)])])
+[m4_ifset([b4_parse_param], [, b4_user_args_no_comma])])
+
+# b4_user_args_no_comma
+# ---------------------
+m4_define([b4_user_args_no_comma],
+[m4_ifset([b4_parse_param], [b4_args(b4_parse_param)])])
 
 
 # b4_user_formals
@@ -158,13 +163,20 @@ m4_popdef([$2])dnl
 m4_popdef([$1])dnl
 ])])
 
+
+# b4_use(EXPR)
+# ------------
+# Pacify the compiler about some maybe unused value.
+m4_define([b4_use],
+[YY_USE ($1)])
+
 # b4_parse_param_use([VAL], [LOC])
 # --------------------------------
-# 'YYUSE' VAL, LOC if locations are enabled, and all the parse-params.
+# 'YY_USE' VAL, LOC if locations are enabled, and all the parse-params.
 m4_define([b4_parse_param_use],
-[m4_ifvaln([$1], [  YYUSE ([$1]);])dnl
-b4_locations_if([m4_ifvaln([$2], [  YYUSE ([$2]);])])dnl
-b4_parse_param_for([Decl], [Formal], [  YYUSE (Formal);
+[m4_ifvaln([$1], [  b4_use([$1]);])dnl
+b4_locations_if([m4_ifvaln([$2], [  b4_use([$2]);])])dnl
+b4_parse_param_for([Decl], [Formal], [  b4_use(Formal);
 ])dnl
 ])
 
@@ -242,6 +254,18 @@ typedef int_least16_t yytype_int16;
 typedef short yytype_int16;
 #endif
 
+/* Work around bug in HP-UX 11.23, which defines these macros
+   incorrectly for preprocessor constants.  This workaround can likely
+   be removed in 2023, as HPE has promised support for HP-UX 11.23
+   (aka HP-UX 11i v2) only through the end of 2022; see Table 2 of
+   <https://h20195.www2.hpe.com/V2/getpdf.aspx/4AA4-7673ENW.pdf>.  */
+#ifdef __hpux
+# undef UINT_LEAST8_MAX
+# undef UINT_LEAST16_MAX
+# define UINT_LEAST8_MAX 255
+# define UINT_LEAST16_MAX 65535
+#endif
+
 #if defined __UINT_LEAST8_MAX__ && __UINT_LEAST8_MAX__ <= __INT_MAX__
 typedef __UINT_LEAST8_TYPE__ yytype_uint8;
 #elif (!defined __UINT_LEAST8_MAX__ && defined YY_STDINT_H \
@@ -366,14 +390,16 @@ dnl use C' _Noreturn in C++, to avoid -Wc11-extensions warnings.
       && ((201103 <= __cplusplus && !(__GNUC__ == 4 && __GNUC_MINOR__ == 7)) \
           || (defined _MSC_VER && 1900 <= _MSC_VER)))
 #  define _Noreturn [[noreturn]]
-# elif (!defined __cplusplus                     \
-        && (201112 <= (defined __STDC_VERSION__ ? __STDC_VERSION__ : 0)  \
-            || 4 < __GNUC__ + (7 <= __GNUC_MINOR__) \
-            || (defined __apple_build_version__ \
-                ? 6000000 <= __apple_build_version__ \
-                : 3 < __clang_major__ + (5 <= __clang_minor__))))
+# elif ((!defined __cplusplus || defined __clang__) \
+        && (201112 <= (defined __STDC_VERSION__ ? __STDC_VERSION__ : 0) \
+            || (!defined __STRICT_ANSI__ \
+                && (4 < __GNUC__ + (7 <= __GNUC_MINOR__) \
+                    || (defined __apple_build_version__ \
+                        ? 6000000 <= __apple_build_version__ \
+                        : 3 < __clang_major__ + (5 <= __clang_minor__))))))
    /* _Noreturn works as-is.  */
-# elif 2 < __GNUC__ + (8 <= __GNUC_MINOR__) || 0x5110 <= __SUNPRO_C
+# elif (2 < __GNUC__ + (8 <= __GNUC_MINOR__) || defined __clang__ \
+        || 0x5110 <= __SUNPRO_C)
 #  define _Noreturn __attribute__ ((__noreturn__))
 # elif 1200 <= (defined _MSC_VER ? _MSC_VER : 0)
 #  define _Noreturn __declspec (noreturn)
@@ -384,17 +410,23 @@ dnl use C' _Noreturn in C++, to avoid -Wc11-extensions warnings.
 
 ]])[/* Suppress unused-variable warnings by "using" E.  */
 #if ! defined lint || defined __GNUC__
-# define YYUSE(E) ((void) (E))
+# define YY_USE(E) ((void) (E))
 #else
-# define YYUSE(E) /* empty */
+# define YY_USE(E) /* empty */
 #endif
 
-#if defined __GNUC__ && ! defined __ICC && 407 <= __GNUC__ * 100 + __GNUC_MINOR__
 /* Suppress an incorrect diagnostic about yylval being uninitialized.  */
-# define YY_IGNORE_MAYBE_UNINITIALIZED_BEGIN                            \
+#if defined __GNUC__ && ! defined __ICC && 406 <= __GNUC__ * 100 + __GNUC_MINOR__
+# if __GNUC__ * 100 + __GNUC_MINOR__ < 407
+#  define YY_IGNORE_MAYBE_UNINITIALIZED_BEGIN                           \
+    _Pragma ("GCC diagnostic push")                                     \
+    _Pragma ("GCC diagnostic ignored \"-Wuninitialized\"")
+# else
+#  define YY_IGNORE_MAYBE_UNINITIALIZED_BEGIN                           \
     _Pragma ("GCC diagnostic push")                                     \
     _Pragma ("GCC diagnostic ignored \"-Wuninitialized\"")              \
     _Pragma ("GCC diagnostic ignored \"-Wmaybe-uninitialized\"")
+# endif
 # define YY_IGNORE_MAYBE_UNINITIALIZED_END      \
     _Pragma ("GCC diagnostic pop")
 #else
@@ -474,7 +506,7 @@ m4_define([b4_null], [YY_NULLPTR])
 # -------------------------------------------------------------
 # Define "yy<TABLE-NAME>" whose contents is CONTENT.
 m4_define([b4_integral_parser_table_define],
-[m4_ifvaln([$3], [b4_comment([$3], [  ])])dnl
+[m4_ifvaln([$3], [b4_comment([$3])])dnl
 static const b4_int_type_for([$2]) yy$1[[]] =
 {
   $2
@@ -493,7 +525,7 @@ static const b4_int_type_for([$2]) yy$1[[]] =
 m4_define([b4_symbol(-2, id)],  [b4_api_PREFIX[][EMPTY]])
 m4_define([b4_symbol(-2, tag)], [[No symbol.]])
 
-m4_if(b4_symbol(0, id), [YYEOF],
+m4_if(b4_symbol(eof, id), [YYEOF],
      [m4_define([b4_symbol(0, id)],  [b4_api_PREFIX[][EOF]])])
 m4_define([b4_symbol(1, id)],  [b4_api_PREFIX[][error]])
 m4_define([b4_symbol(2, id)],  [b4_api_PREFIX[][UNDEF]])
@@ -509,10 +541,11 @@ m4_define([b4_token_define],
 # ----------------
 # Output the definition of the tokens.
 m4_define([b4_token_defines],
-[b4_any_token_visible_if([/* Token kinds.  */
-m4_join([
+[[/* Token kinds.  */
+#define ]b4_symbol(empty, [id])[ -2
+]m4_join([
 ], b4_symbol_map([b4_token_define]))
-])])
+])
 
 
 # b4_token_enum(TOKEN-NUM)
@@ -537,7 +570,7 @@ m4_define([b4_token_enums],
 # define ]b4_api_PREFIX[TOKENTYPE
   enum ]b4_api_prefix[tokentype
   {
-    ]b4_symbol([-2], [id])[ = -2,
+    ]b4_symbol(empty, [id])[ = -2,
 ]b4_symbol_foreach([b4_token_enum])dnl
 [  };
   typedef enum ]b4_api_prefix[tokentype ]b4_api_prefix[token_kind_t;
@@ -587,7 +620,7 @@ m4_define([b4_declare_symbol_enum],
 [[/* Symbol kind.  */
 enum yysymbol_kind_t
 {
-  ]b4_symbol([-2], kind_base)[ = -2,
+  ]b4_symbol(empty, [kind_base])[ = -2,
 ]b4_symbol_foreach([b4_symbol_enum])dnl
 [};
 typedef enum yysymbol_kind_t yysymbol_kind_t;
@@ -629,6 +662,14 @@ m4_define([b4_formal],
 [$1])
 
 
+# b4_function_declare(NAME, RETURN-VALUE, [DECL1, NAME1], ...)
+# ------------------------------------------------------------
+# Declare the function NAME.
+m4_define([b4_function_declare],
+[$2 $1 (b4_formals(m4_shift2($@)));[]dnl
+])
+
+
 
 ## --------------------- ##
 ## Calling C functions.  ##
@@ -728,13 +769,6 @@ yy_symbol_value_print (FILE *yyo,
 ]b4_parse_param_use([yyoutput], [yylocationp])dnl
 [  if (!yyvaluep)
     return;]
-dnl glr.c does not feature yytoknum.
-m4_if(b4_skeleton, ["yacc.c"],
-[[# ifdef YYPRINT
-  if (yykind < YYNTOKENS)
-    YYPRINT (yyo, yytoknum[yykind], *yyvaluep);
-# endif
-]])dnl
 b4_percent_code_get([[pre-printer]])dnl
   YY_IGNORE_MAYBE_UNINITIALIZED_BEGIN
   b4_symbol_actions([printer])
@@ -755,7 +789,7 @@ yy_symbol_print (FILE *yyo,
   YYFPRINTF (yyo, "%s %s (",
              yykind < YYNTOKENS ? "token" : "nterm", yysymbol_name (yykind));
 
-]b4_locations_if([  YY_LOCATION_PRINT (yyo, *yylocationp);
+]b4_locations_if([  YYLOCATION_PRINT (yyo, yylocationp);
   YYFPRINTF (yyo, ": ");
 ])dnl
 [  yy_symbol_value_print (yyo, yykind, yyvaluep]dnl
@@ -942,7 +976,7 @@ struct ]b4_api_PREFIX[LTYPE
 
 # b4_declare_yylstype
 # -------------------
-# Declarations that might either go into the header (if --defines) or
+# Declarations that might either go into the header (if --header) or
 # in the parser body.  Declare YYSTYPE/YYLTYPE, and yylval/yylloc.
 m4_define([b4_declare_yylstype],
 [b4_value_type_define[]b4_locations_if([
@@ -1012,17 +1046,24 @@ m4_define([b4_yylloc_default_define],
 #endif
 ]])
 
-# b4_yy_location_print_define
-# ---------------------------
-# Define YY_LOCATION_PRINT.
-m4_define([b4_yy_location_print_define],
+# b4_yylocation_print_define
+# --------------------------
+# Define YYLOCATION_PRINT.
+m4_define([b4_yylocation_print_define],
 [b4_locations_if([[
-/* YY_LOCATION_PRINT -- Print the location on the stream.
+/* YYLOCATION_PRINT -- Print the location on the stream.
    This macro was not mandated originally: define only if we know
    we won't break user code: when these are the locations we know.  */
 
-# ifndef YY_LOCATION_PRINT
-#  if defined ]b4_api_PREFIX[LTYPE_IS_TRIVIAL && ]b4_api_PREFIX[LTYPE_IS_TRIVIAL
+# ifndef YYLOCATION_PRINT
+
+#  if defined YY_LOCATION_PRINT
+
+   /* Temporary convenience wrapper in case some people defined the
+      undocumented and private YY_LOCATION_PRINT macros.  */
+#   define YYLOCATION_PRINT(File, Loc)  YY_LOCATION_PRINT(File, *(Loc))
+
+#  elif defined ]b4_api_PREFIX[LTYPE_IS_TRIVIAL && ]b4_api_PREFIX[LTYPE_IS_TRIVIAL
 
 /* Print *YYLOCP on YYO.  Private, do not rely on its existence. */
 
@@ -1050,19 +1091,23 @@ yy_location_print_ (FILE *yyo, YYLTYPE const * const yylocp)
         res += YYFPRINTF (yyo, "-%d", end_col);
     }
   return res;
- }
+}
 
-#   define YY_LOCATION_PRINT(File, Loc)          \
-  yy_location_print_ (File, &(Loc))
+#   define YYLOCATION_PRINT  yy_location_print_
+
+    /* Temporary convenience wrapper in case some people defined the
+       undocumented and private YY_LOCATION_PRINT macros.  */
+#   define YY_LOCATION_PRINT(File, Loc)  YYLOCATION_PRINT(File, &(Loc))
 
 #  else
-#   define YY_LOCATION_PRINT(File, Loc) ((void) 0)
+
+#   define YYLOCATION_PRINT(File, Loc) ((void) 0)
+    /* Temporary convenience wrapper in case some people defined the
+       undocumented and private YY_LOCATION_PRINT macros.  */
+#   define YY_LOCATION_PRINT  YYLOCATION_PRINT
+
 #  endif
-# endif /* !defined YY_LOCATION_PRINT */]],
-[[/* This macro is provided for backward compatibility. */
-# ifndef YY_LOCATION_PRINT
-#  define YY_LOCATION_PRINT(File, Loc) ((void) 0)
-# endif]])
+# endif /* !defined YYLOCATION_PRINT */]])
 ])
 
 # b4_yyloc_default

data/skeletons/d-skel.m4

@@ -2,7 +2,7 @@
 
 # D skeleton dispatching for Bison.
 
-# Copyright (C) 2018-2020 Free Software Foundation, Inc.
+# Copyright (C) 2018-2021 Free Software Foundation, Inc.
 
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -15,7 +15,7 @@
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 b4_glr_if(             [b4_complain([%%glr-parser not supported for D])])
 b4_nondeterministic_if([b4_complain([%%nondeterministic-parser not supported for D])])

data/skeletons/d.m4

@@ -2,7 +2,7 @@
 
 # D language support for Bison
 
-# Copyright (C) 2018-2020 Free Software Foundation, Inc.
+# Copyright (C) 2018-2021 Free Software Foundation, Inc.
 
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -15,27 +15,36 @@
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 
-# _b4_comment(TEXT, OPEN, CONTINUE, END)
-# --------------------------------------
-# Put TEXT in comment.  Avoid trailing spaces: don't indent empty lines.
-# Avoid adding indentation to the first line, as the indentation comes
-# from OPEN.  That's why we don't patsubst([$1], [^\(.\)], [   \1]).
-#
-# Prefix all the output lines with PREFIX.
-m4_define([_b4_comment],
-[$2[]m4_bpatsubst(m4_expand([[$1]]), [
-\(.\)], [
-$3\1])$4])
+m4_include(b4_skeletonsdir/[c-like.m4])
 
 
-# b4_comment(TEXT, [PREFIX])
-# --------------------------
-# Put TEXT in comment.  Prefix all the output lines with PREFIX.
-m4_define([b4_comment],
-[_b4_comment([$1], [$2/* ], [$2   ], [  */])])
+# b4_symbol_action(SYMBOL-NUM, ACTION)
+# ------------------------------------
+# Run the action ACTION ("destructor" or "printer") for SYMBOL-NUM.
+m4_define([b4_symbol_action],
+[b4_symbol_if([$1], [has_$2],
+[b4_dollar_pushdef([yyval],
+                   [$1],
+                   [],
+                   [yyloc])dnl
+    _b4_symbol_case([$1])[]dnl
+b4_syncline([b4_symbol([$1], [$2_line])], [b4_symbol([$1], [$2_file])])dnl
+b4_symbol([$1], [$2])
+b4_syncline([@oline@], [@ofile@])dnl
+        break;
+
+b4_dollar_popdef[]dnl
+])])
+
+
+# b4_use(EXPR)
+# ------------
+# Pacify the compiler about some maybe unused value.
+m4_define([b4_use],
+[])
 
 
 # b4_sync_start(LINE, FILE)
@@ -58,6 +67,23 @@ m4_define([b4_percent_define_get3],
           [m4_ifval(m4_quote(b4_percent_define_get([$1])),
                 [$2[]b4_percent_define_get([$1])[]$3], [$4])])
 
+# b4_percent_define_if_get2(ARG1, ARG2, DEF, NOT)
+# -----------------------------------------------
+# Expand to the value of DEF if ARG1 or ARG2 are %define'ed,
+# otherwise NOT.
+m4_define([b4_percent_define_if_get2],
+          [m4_ifval(m4_quote(b4_percent_define_get([$1])),
+                [$3], [m4_ifval(m4_quote(b4_percent_define_get([$2])),
+                      [$3], [$4])])])
+
+# b4_percent_define_class_before_interface(CLASS, INTERFACE)
+# ----------------------------------------------------------
+# Expand to a ', ' if both a class and an interface have been %define'ed
+m4_define([b4_percent_define_class_before_interface],
+          [m4_ifval(m4_quote(b4_percent_define_get([$1])),
+                [m4_ifval(m4_quote(b4_percent_define_get([$2])),
+                      [, ])])])
+
 
 # b4_flag_value(BOOLEAN-FLAG)
 # ---------------------------
@@ -78,8 +104,10 @@ b4_percent_define_flag_if([api.parser.public],   [public ])dnl
 b4_percent_define_flag_if([api.parser.abstract], [abstract ])dnl
 b4_percent_define_flag_if([api.parser.final],    [final ])dnl
 [class ]b4_parser_class[]dnl
-b4_percent_define_get3([api.parser.extends], [ extends ])dnl
-b4_percent_define_get3([api.parser.implements], [ implements ])])
+b4_percent_define_if_get2([api.parser.extends], [api.parser.implements], [ : ])dnl
+b4_percent_define_get([api.parser.extends])dnl
+b4_percent_define_class_before_interface([api.parser.extends], [api.parser.implements])dnl
+b4_percent_define_get([api.parser.implements])])
 
 
 # b4_lexer_if(TRUE, FALSE)
@@ -103,12 +131,12 @@ m4_define([b4_location_type_if],
 # b4_identification
 # -----------------
 m4_define([b4_identification],
-[/** Version number for the Bison executable that generated this parser.  */
-  public static immutable string yy_bison_version = "b4_version";
+[[/** Version number for the Bison executable that generated this parser.  */
+  public static immutable string yy_bison_version = "]b4_version_string[";
 
   /** Name of the skeleton that generated this parser.  */
-  public static immutable string yy_bison_skeleton = b4_skeleton;
-])
+  public static immutable string yy_bison_skeleton = ]b4_skeleton[;
+]])
 
 
 ## ------------ ##
@@ -153,6 +181,7 @@ private static immutable b4_int_type_for([$2])[[]] yy$1_ =
 ## ------------- ##
 
 m4_define([b4_symbol(-2, id)],  [[YYEMPTY]])
+b4_percent_define_default([[api.token.raw]], [[true]])
 
 # b4_token_enum(TOKEN-NAME, TOKEN-NUMBER)
 # ---------------------------------------
@@ -167,19 +196,49 @@ m4_define([b4_token_enum],
 m4_define([b4_token_enums],
 [/* Token kinds.  */
 public enum TokenKind {
-  ]b4_symbol_kind([-2])[ = -2,
+  ]b4_symbol(empty, id)[ = -2,
 b4_symbol_foreach([b4_token_enum])dnl
 }
 ])
 
+# b4_symbol_translate(STRING)
+# ---------------------------
+# Used by "bison" in the array of symbol names to mark those that
+# require translation.
+m4_define([b4_symbol_translate],
+[[_($1)]])
 
 
+# _b4_token_constructor_define(SYMBOL-NUM)
+# ----------------------------------------
+# Define Symbol.FOO for SYMBOL-NUM.
+m4_define([_b4_token_constructor_define],
+[b4_token_visible_if([$1],
+[[
+    static auto ]b4_symbol([$1], [id])[(]b4_symbol_if([$1], [has_type],
+[b4_union_if([b4_symbol([$1], [type]],
+[[typeof(YYSemanticType.]b4_symbol([$1], [type])[]])) [val]])dnl
+[]b4_locations_if([b4_symbol_if([$1], [has_type], [[, ]])[Location l]])[)
+    {
+      return Symbol(TokenKind.]b4_symbol([$1], [id])[]b4_symbol_if([$1], [has_type],
+      [[, val]])[]b4_locations_if([[, l]])[);
+    }]])])
+
+# b4_token_constructor_define
+# ---------------------------
+# Define Symbol.FOO for each token kind FOO.
+m4_define([b4_token_constructor_define],
+[[
+    /* Implementation of token constructors for each symbol type visible to
+     * the user. The code generates static methods that have the same names
+     * as the TokenKinds.
+     */]b4_symbol_foreach([_b4_token_constructor_define])dnl
+])
+
 ## -------------- ##
 ## Symbol kinds.  ##
 ## -------------- ##
 
-b4_percent_define_default([[api.symbol.prefix]], [[S_]])
-
 # b4_symbol_kind(NUM)
 # -------------------
 m4_define([b4_symbol_kind],
@@ -204,16 +263,46 @@ m4_define([b4_symbol_enum],
 # to use a signed type, which matters for yytoken.
 m4_define([b4_declare_symbol_enum],
 [[  /* Symbol kinds.  */
-  public enum SymbolKind
+  struct SymbolKind
   {
-    ]b4_symbol(-2, kind_base)[ = -2,  /* No symbol.  */
+    enum
+    {
+    ]b4_symbol(empty, kind_base)[ = -2,  /* No symbol.  */
 ]b4_symbol_foreach([b4_symbol_enum])dnl
-[  };
-]])])
+[    }
+
+    private int yycode_;
+    alias yycode_ this;
+
+    this(int code)
+    {
+      yycode_ = code;
+    }
+
+    /* Return YYSTR after stripping away unnecessary quotes and
+     backslashes, so that it's suitable for yyerror.  The heuristic is
+     that double-quoting is unnecessary unless the string contains an
+     apostrophe, a comma, or backslash (other than backslash-backslash).
+     YYSTR is taken from yytname.  */
+    final void toString(W)(W sink) const
+    if (isOutputRange!(W, char))
+    {
+      immutable string[] yy_sname = @{
+  ]b4_symbol_names[
+      @};]b4_has_translations_if([[
+      /* YYTRANSLATABLE[SYMBOL-NUM] -- Whether YY_SNAME[SYMBOL-NUM] is
+        internationalizable.  */
+      immutable ]b4_int_type_for([b4_translatable])[[] yytranslatable = @{
+  ]b4_translatable[
+      @};]])[
+
+      put(sink, yy_sname[yycode_]);
+    }
+  }
+]])
 
 
-
-# b4-case(ID, CODE, [COMMENTS])
+# b4_case(ID, CODE, [COMMENTS])
 # -----------------------------
 m4_define([b4_case], [    case $1:m4_ifval([$3], [ b4_comment([$3])])
 $2
@@ -240,6 +329,109 @@ m4_define([b4_location_type], b4_percent_define_ifdef([[location_type]],[b4_perc
 m4_define([b4_position_type], b4_percent_define_ifdef([[position_type]],[b4_percent_define_get([[position_type]])],[YYPosition]))
 
 
+## ---------------- ##
+## api.value.type.  ##
+## ---------------- ##
+
+
+# ---------------------- #
+# api.value.type=union.  #
+# ---------------------- #
+
+# b4_symbol_type_register(SYMBOL-NUM)
+# -----------------------------------
+# Symbol SYMBOL-NUM has a type (for union) instead of a type-tag.
+# Extend the definition of %union's body (b4_union_members) with a
+# field of that type, and extend the symbol's "type" field to point to
+# the field name, instead of the type name.
+m4_define([b4_symbol_type_register],
+[m4_define([b4_symbol($1, type_tag)],
+           [b4_symbol_if([$1], [has_id],
+                         [b4_symbol([$1], [id])],
+                         [yykind_[]b4_symbol([$1], [number])])])dnl
+m4_append([b4_union_members],
+m4_expand([m4_format([  %-40s %s],
+                     m4_expand([b4_symbol([$1], [type]) b4_symbol([$1], [type_tag]);]),
+                     [b4_symbol_tag_comment([$1])])]))
+])
+
+
+# b4_type_define_tag(SYMBOL1-NUM, ...)
+# ------------------------------------
+# For the batch of symbols SYMBOL1-NUM... (which all have the same
+# type), enhance the %union definition for each of them, and set
+# there "type" field to the field tag name, instead of the type name.
+m4_define([b4_type_define_tag],
+[b4_symbol_if([$1], [has_type],
+              [m4_map([b4_symbol_type_register], [$@])])
+])
+
+
+# b4_symbol_value_union(VAL, SYMBOL-NUM, [TYPE])
+# ----------------------------------------------
+# Same of b4_symbol_value, but when api.value.type=union.
+m4_define([b4_symbol_value_union],
+[m4_ifval([$3],
+          [(*($3*)(&$1))],
+          [m4_ifval([$2],
+                    [b4_symbol_if([$2], [has_type],
+                                  [($1.b4_symbol([$2], [type_tag]))],
+                                  [$1])],
+                    [$1])])])
+
+
+# b4_value_type_setup_union
+# -------------------------
+# Setup support for api.value.type=union.  Symbols are defined with a
+# type instead of a union member name: build the corresponding union,
+# and give the symbols their tag.
+m4_define([b4_value_type_setup_union],
+[m4_define([b4_union_members])
+b4_type_foreach([b4_type_define_tag])
+m4_copy_force([b4_symbol_value_union], [b4_symbol_value])
+])
+
+
+# _b4_value_type_setup_keyword
+# ----------------------------
+# api.value.type is defined with a keyword/string syntax.  Check if
+# that is properly defined, and prepare its use.
+m4_define([_b4_value_type_setup_keyword],
+[b4_percent_define_check_values([[[[api.value.type]],
+                                  [[none]],
+                                  [[union]],
+                                  [[union-directive]],
+                                  [[yystype]]]])dnl
+m4_case(b4_percent_define_get([[api.value.type]]),
+        [union],   [b4_value_type_setup_union])])
+
+
+# b4_value_type_setup
+# -------------------
+# Check if api.value.type is properly defined, and possibly prepare
+# its use.
+b4_define_silent([b4_value_type_setup],
+[
+# Define default value.
+b4_percent_define_ifdef([[api.value.type]], [],
+[# %union => api.value.type=union-directive
+m4_ifdef([b4_union_members],
+[m4_define([b4_percent_define_kind(api.value.type)], [keyword])
+m4_define([b4_percent_define(api.value.type)], [union-directive])],
+[# no tag seen => api.value.type={int}
+m4_if(b4_tag_seen_flag, 0,
+[m4_define([b4_percent_define_kind(api.value.type)], [code])
+m4_define([b4_percent_define(api.value.type)], [int])],
+[# otherwise api.value.type=yystype
+m4_define([b4_percent_define_kind(api.value.type)], [keyword])
+m4_define([b4_percent_define(api.value.type)], [yystype])])])])
+
+# Set up.
+m4_bmatch(b4_percent_define_get_kind([[api.value.type]]),
+   [keyword], [_b4_value_type_setup_keyword])
+])
+
+
 ## ----------------- ##
 ## Semantic Values.  ##
 ## ----------------- ##
@@ -286,7 +478,7 @@ m4_define([b4_lhs_location],
 # Expansion of @POS, where the current rule has RULE-LENGTH symbols
 # on RHS.
 m4_define([b4_rhs_location],
-[yystack.locationAt ([$1], [$2])])
+[yystack.locationAt (b4_subtract($@))])
 
 
 # b4_lex_param
@@ -371,3 +563,66 @@ m4_define([b4_var_decls],
 ], [$@])])
 m4_define([b4_var_decl],
           [    protected $1;])
+
+
+# b4_public_types_declare
+# -----------------------
+# Define the public types: token, semantic value, location, and so forth.
+# Depending on %define token_lex, may be output in the header or source file.
+m4_define([b4_public_types_declare],
+[[
+alias Symbol = ]b4_parser_class[.Symbol;
+alias Value = ]b4_yystype[;]b4_locations_if([[
+alias Location = ]b4_location_type[;
+alias Position = ]b4_position_type[;]b4_push_if([[
+alias PUSH_MORE = ]b4_parser_class[.YYPUSH_MORE;
+alias ABORT = ]b4_parser_class[.YYABORT;
+alias ACCEPT = ]b4_parser_class[.YYACCEPT;]])[]])[
+]])
+
+
+# b4_basic_symbol_constructor_define
+# ----------------------------------
+# Create Symbol struct constructors for all the visible types.
+m4_define([b4_basic_symbol_constructor_define],
+[b4_token_visible_if([$1],
+[[    this(TokenKind token]b4_symbol_if([$1], [has_type],
+[[, ]b4_union_if([], [[typeof(YYSemanticType.]])b4_symbol([$1], [type])dnl
+[]b4_union_if([], [[) ]])[ val]])[]b4_locations_if([[, Location loc]])[)
+    {
+      kind = yytranslate_(token);]b4_union_if([b4_symbol_if([$1], [has_type], [[
+      static foreach (member; __traits(allMembers, YYSemanticType))
+      {
+        static if (is(typeof(mixin("value_." ~ member)) == ]b4_symbol([$1], [type])[))
+        {
+          mixin("value_." ~ member ~ " = val;");
+        }
+      }]])], [b4_symbol_if([$1], [has_type], [[
+      value_.]b4_symbol([$1], [type])[ = val;]])])[]b4_locations_if([
+      location_ = loc;])[
+    }
+]])])
+
+
+# b4_symbol_type_define
+# ---------------------
+# Define symbol_type, the external type for symbols used for symbol
+# constructors.
+m4_define([b4_symbol_type_define],
+[[
+  /**
+    * A complete symbol
+    */
+  struct Symbol
+  {
+    private SymbolKind kind;
+    private Value value_;]b4_locations_if([[
+    private Location location_;]])[
+
+]b4_type_foreach([b4_basic_symbol_constructor_define])[
+    SymbolKind token() { return kind; }
+    Value value() { return value_; }]b4_locations_if([[
+    Location location() { return location_; }]])[
+]b4_token_ctor_if([b4_token_constructor_define])[
+  }
+]])

data/skeletons/glr.c

@@ -1,8 +1,8 @@
-                                                                    -*- C -*-
+#                                                             -*- C -*-
 
 # GLR skeleton for Bison
 
-# Copyright (C) 2002-2015, 2018-2020 Free Software Foundation, Inc.
+# Copyright (C) 2002-2015, 2018-2021 Free Software Foundation, Inc.
 
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -15,7 +15,7 @@
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 
 # If we are loaded by glr.cc, do not override c++.m4 definitions by
@@ -32,7 +32,9 @@ m4_if(b4_skeleton, ["glr.c"],
 m4_define_default([b4_stack_depth_max], [10000])
 m4_define_default([b4_stack_depth_init],  [200])
 
-
+# Included header.
+b4_percent_define_default([[api.header.include]],
+                          [["@basename(]b4_spec_header_file[@)"]])
 
 ## ------------------------ ##
 ## Pure/impure interfaces.  ##
@@ -122,7 +124,7 @@ m4_define([b4_rhs_data],
 # --------------------------------------------------
 # Expansion of $$ or $<TYPE>$, for symbol SYMBOL-NUM.
 m4_define([b4_rhs_value],
-[b4_symbol_value([b4_rhs_data([$1], [$2]).yysemantics.yysval], [$3], [$4])])
+[b4_symbol_value([b4_rhs_data([$1], [$2]).yysemantics.yyval], [$3], [$4])])
 
 
 
@@ -145,13 +147,22 @@ m4_define([b4_rhs_location],
 [(b4_rhs_data([$1], [$2]).yyloc)])
 
 
+# b4_call_merger(MERGER-NUM, MERGER-NAME, SYMBOL-SUM)
+# ---------------------------------------------------
+m4_define([b4_call_merger],
+[b4_case([$1],
+         [    b4_symbol_if([$3], [has_type],
+                           [yy0->b4_symbol($3, slot) = $2 (*yy0, *yy1);],
+                           [*yy0 = $2 (*yy0, *yy1);])])])
+
+
 ## -------------- ##
 ## Declarations.  ##
 ## -------------- ##
 
 # b4_shared_declarations
 # ----------------------
-# Declaration that might either go into the header (if --defines)
+# Declaration that might either go into the header (if --header)
 # or open coded in the parser body.  glr.cc has its own definition.
 m4_if(b4_skeleton, ["glr.c"],
 [m4_define([b4_shared_declarations],
@@ -185,10 +196,10 @@ int ]b4_prefix[parse (]m4_ifset([b4_parse_param], [b4_formals(b4_parse_param)],
 
 # glr.cc produces its own header.
 b4_glr_cc_if([],
-[b4_defines_if(
+[b4_header_if(
 [b4_output_begin([b4_spec_header_file])
 b4_copyright([Skeleton interface for Bison GLR parsers in C],
-             [2002-2015, 2018-2020])[
+             [2002-2015, 2018-2021])[
 ]b4_cpp_guard_open([b4_spec_mapped_header_file])[
 ]b4_shared_declarations[
 ]b4_cpp_guard_close([b4_spec_mapped_header_file])[
@@ -202,7 +213,7 @@ b4_copyright([Skeleton interface for Bison GLR parsers in C],
 
 b4_output_begin([b4_parser_file_name])
 b4_copyright([Skeleton implementation for Bison GLR parsers in C],
-             [2002-2015, 2018-2020])[
+             [2002-2015, 2018-2021])[
 /* C GLR parser skeleton written by Paul Hilfinger.  */
 
 ]b4_disclaimer[
@@ -215,7 +226,7 @@ b4_copyright([Skeleton implementation for Bison GLR parsers in C],
 #define YYLTYPE ]b4_api_PREFIX[LTYPE]])])[
 ]m4_if(b4_prefix, [yy], [],
 [[/* Substitute the variable and function names.  */
-#define yyparse ]b4_prefix[parse
+#define ]b4_glr_cc_if([yy_parse_impl], [yyparse])[ ]b4_prefix[]b4_glr_cc_if([_parse_impl], [parse])[
 #define yylex   ]b4_prefix[lex
 #define yyerror ]b4_prefix[error
 #define yydebug ]b4_prefix[debug]]b4_pure_if([], [[
@@ -228,8 +239,8 @@ b4_copyright([Skeleton implementation for Bison GLR parsers in C],
 ]b4_cast_define[
 ]b4_null_define[
 
-]b4_defines_if([[#include "@basename(]b4_spec_header_file[@)"]],
-               [b4_shared_declarations])[
+]b4_header_if([[#include ]b4_percent_define_get([[api.header.include]])],
+              [b4_shared_declarations])[
 
 ]b4_glr_cc_if([b4_glr_cc_setup],
               [b4_declare_symbol_enum])[
@@ -431,7 +442,7 @@ int yychar;])[
 
 enum { YYENOMEM = -2 };
 
-typedef enum { yyok, yyaccept, yyabort, yyerr } YYRESULTTAG;
+typedef enum { yyok, yyaccept, yyabort, yyerr, yynomem } YYRESULTTAG;
 
 #define YYCHK(YYE)                              \
   do {                                          \
@@ -496,10 +507,11 @@ typedef struct yySemanticOption yySemanticOption;
 typedef union yyGLRStackItem yyGLRStackItem;
 typedef struct yyGLRStack yyGLRStack;
 
-struct yyGLRState {
+struct yyGLRState
+{
   /** Type tag: always true.  */
   yybool yyisState;
-  /** Type tag for yysemantics.  If true, yysval applies, otherwise
+  /** Type tag for yysemantics.  If true, yyval applies, otherwise
    *  yyfirstVal applies.  */
   yybool yyresolved;
   /** Number of corresponding LALR(1) machine state.  */
@@ -514,24 +526,26 @@ struct yyGLRState {
      *  yynext.  */
     yySemanticOption* yyfirstVal;
     /** Semantic value for this state.  */
-    YYSTYPE yysval;
+    YYSTYPE yyval;
   } yysemantics;]b4_locations_if([[
   /** Source location for this state.  */
   YYLTYPE yyloc;]])[
 };
 
-struct yyGLRStateSet {
+struct yyGLRStateSet
+{
   yyGLRState** yystates;
   /** During nondeterministic operation, yylookaheadNeeds tracks which
    *  stacks have actually needed the current lookahead.  During deterministic
    *  operation, yylookaheadNeeds[0] is not maintained since it would merely
-   *  duplicate yychar != ]b4_symbol(-2, id)[.  */
+   *  duplicate yychar != ]b4_symbol(empty, id)[.  */
   yybool* yylookaheadNeeds;
   YYPTRDIFF_T yysize;
   YYPTRDIFF_T yycapacity;
 };
 
-struct yySemanticOption {
+struct yySemanticOption
+{
   /** Type tag: always false.  */
   yybool yyisState;
   /** Rule number for this reduction */
@@ -637,6 +651,13 @@ yysymbol_name (yysymbol_kind_t yysymbol)
 }]])[
 #endif
 
+/** Left-hand-side symbol for rule #YYRULE.  */
+static inline yysymbol_kind_t
+yylhsNonterm (yyRuleNum yyrule)
+{
+  return YY_CAST (yysymbol_kind_t, yyr1[yyrule]);
+}
+
 #if ]b4_api_PREFIX[DEBUG
 
 # ifndef YYFPRINTF
@@ -662,7 +683,7 @@ yysymbol_name (yysymbol_kind_t yysymbol)
     YY_IGNORE_USELESS_CAST_END                  \
   } while (0)
 
-]b4_yy_location_print_define[
+]b4_yylocation_print_define[
 
 ]b4_yy_symbol_print_define[
 
@@ -676,6 +697,16 @@ yysymbol_name (yysymbol_kind_t yysymbol)
       }                                                                 \
   } while (0)
 
+static inline void
+yy_reduce_print (yybool yynormal, yyGLRStackItem* yyvsp, YYPTRDIFF_T yyk,
+                 yyRuleNum yyrule]b4_user_formals[);
+
+# define YY_REDUCE_PRINT(Args)          \
+  do {                                  \
+    if (yydebug)                        \
+      yy_reduce_print Args;             \
+  } while (0)
+
 /* Nonzero means print parse trace.  It is left uninitialized so that
    multiple parsers can coexist.  */
 int yydebug;
@@ -689,6 +720,7 @@ static void yypdumpstack (yyGLRStack* yystackp)
 
 # define YY_DPRINTF(Args) do {} while (yyfalse)
 # define YY_SYMBOL_PRINT(Title, Kind, Value, Location)
+# define YY_REDUCE_PRINT(Args)
 
 #endif /* !]b4_api_PREFIX[DEBUG */
 
@@ -791,9 +823,9 @@ yyfillin (yyGLRStackItem *yyvsp, int yylow0, int yylow1)
 #endif
       yyvsp[i].yystate.yyresolved = s->yyresolved;
       if (s->yyresolved)
-        yyvsp[i].yystate.yysemantics.yysval = s->yysemantics.yysval;
+        yyvsp[i].yystate.yysemantics.yyval = s->yysemantics.yyval;
       else
-        /* The effect of using yysval or yyloc (in an immediate rule) is
+        /* The effect of using yyval or yyloc (in an immediate rule) is
          * undefined.  */
         yyvsp[i].yystate.yysemantics.yyfirstVal = YY_NULLPTR;]b4_locations_if([[
       yyvsp[i].yystate.yyloc = s->yyloc;]])[
@@ -809,14 +841,14 @@ yygetToken (int *yycharp][]b4_pure_if([, yyGLRStack* yystackp])[]b4_user_formals
 {
   yysymbol_kind_t yytoken;
 ]b4_parse_param_use()dnl
-[  if (*yycharp == ]b4_symbol(-2, id)[)
+[  if (*yycharp == ]b4_symbol(empty, id)[)
     {
       YY_DPRINTF ((stderr, "Reading a token\n"));]b4_glr_cc_if([[
 #if YY_EXCEPTIONS
       try
         {
 #endif // YY_EXCEPTIONS
-          *yycharp = ]b4_lex[;
+          *yycharp = ]b4_yylex[;
 #if YY_EXCEPTIONS
         }
       catch (const ]b4_namespace_ref[::]b4_parser_class[::syntax_error& yyexc)
@@ -827,14 +859,14 @@ yygetToken (int *yycharp][]b4_pure_if([, yyGLRStack* yystackp])[]b4_user_formals
           // Map errors caught in the scanner to the undefined token,
           // so that error handling is started.  However, record this
           // with this special value of yychar.
-          *yycharp = ]b4_symbol(1, id)[;
+          *yycharp = ]b4_symbol(error, id)[;
         }
 #endif // YY_EXCEPTIONS]], [[
-      *yycharp = ]b4_lex[;]])[
+      *yycharp = ]b4_yylex[;]])[
     }
-  if (*yycharp <= ]b4_symbol(0, [id])[)
+  if (*yycharp <= ]b4_symbol(eof, [id])[)
     {
-      *yycharp = ]b4_symbol(0, [id])[;
+      *yycharp = ]b4_symbol(eof, [id])[;
       yytoken = ]b4_symbol_prefix[YYEOF;
       YY_DPRINTF ((stderr, "Now at end of input.\n"));
     }
@@ -866,28 +898,31 @@ yyfill (yyGLRStackItem *yyvsp, int *yylow, int yylow1, yybool yynormal)
  *  and top stack item YYVSP.  YYLVALP points to place to put semantic
  *  value ($$), and yylocp points to place for location information
  *  (@@$).  Returns yyok for normal return, yyaccept for YYACCEPT,
- *  yyerr for YYERROR, yyabort for YYABORT.  */
+ *  yyerr for YYERROR, yyabort for YYABORT, yynomem for YYNOMEM.  */
 static YYRESULTTAG
-yyuserAction (yyRuleNum yyn, int yyrhslen, yyGLRStackItem* yyvsp,
-              yyGLRStack* yystackp,
+yyuserAction (yyRuleNum yyrule, int yyrhslen, yyGLRStackItem* yyvsp,
+              yyGLRStack* yystackp, YYPTRDIFF_T yyk,
               YYSTYPE* yyvalp]b4_locuser_formals[)
 {
-  yybool yynormal YY_ATTRIBUTE_UNUSED = yystackp->yysplitPoint == YY_NULLPTR;
-  int yylow;
+  const yybool yynormal YY_ATTRIBUTE_UNUSED = yystackp->yysplitPoint == YY_NULLPTR;
+  int yylow = 1;
 ]b4_parse_param_use([yyvalp], [yylocp])dnl
-[  YYUSE (yyrhslen);
+[  YY_USE (yyk);
+  YY_USE (yyrhslen);
 # undef yyerrok
 # define yyerrok (yystackp->yyerrState = 0)
 # undef YYACCEPT
 # define YYACCEPT return yyaccept
 # undef YYABORT
 # define YYABORT return yyabort
+# undef YYNOMEM
+# define YYNOMEM return yynomem
 # undef YYERROR
 # define YYERROR return yyerrok, yyerr
 # undef YYRECOVERING
 # define YYRECOVERING() (yystackp->yyerrState != 0)
 # undef yyclearin
-# define yyclearin (yychar = ]b4_symbol(-2, id)[)
+# define yyclearin (yychar = ]b4_symbol(empty, id)[)
 # undef YYFILL
 # define YYFILL(N) yyfill (yyvsp, &yylow, (N), yynormal)
 # undef YYBACKUP
@@ -895,21 +930,23 @@ yyuserAction (yyRuleNum yyn, int yyrhslen, yyGLRStackItem* yyvsp,
   return yyerror (]b4_yyerror_args[YY_("syntax error: cannot back up")),     \
          yyerrok, yyerr
 
-  yylow = 1;
   if (yyrhslen == 0)
     *yyvalp = yyval_default;
   else
-    *yyvalp = yyvsp[YYFILL (1-yyrhslen)].yystate.yysemantics.yysval;]b4_locations_if([[
+    *yyvalp = yyvsp[YYFILL (1-yyrhslen)].yystate.yysemantics.yyval;]b4_locations_if([[
   /* Default location. */
   YYLLOC_DEFAULT ((*yylocp), (yyvsp - yyrhslen), yyrhslen);
-  yystackp->yyerror_range[1].yystate.yyloc = *yylocp;
-]])[]b4_glr_cc_if([[
+  yystackp->yyerror_range[1].yystate.yyloc = *yylocp;]])[
+  /* If yyk == -1, we are running a deferred action on a temporary
+     stack.  In that case, YY_REDUCE_PRINT must not play with YYFILL,
+     so pretend the stack is "normal". */
+  YY_REDUCE_PRINT ((yynormal || yyk == -1, yyvsp, yyk, yyrule]b4_user_args[));]b4_glr_cc_if([[
 #if YY_EXCEPTIONS
   typedef ]b4_namespace_ref[::]b4_parser_class[::syntax_error syntax_error;
   try
   {
 #endif // YY_EXCEPTIONS]])[
-  switch (yyn)
+  switch (yyrule)
     {
 ]b4_user_actions[
       default: break;
@@ -924,11 +961,13 @@ yyuserAction (yyRuleNum yyn, int yyrhslen, yyGLRStackItem* yyvsp,
       YYERROR;
     }
 #endif // YY_EXCEPTIONS]])[
+  YY_SYMBOL_PRINT ("-> $$ =", yylhsNonterm (yyrule), yyvalp, yylocp);
 
   return yyok;
 # undef yyerrok
 # undef YYABORT
 # undef YYACCEPT
+# undef YYNOMEM
 # undef YYERROR
 # undef YYBACKUP
 # undef yyclearin
@@ -939,8 +978,8 @@ yyuserAction (yyRuleNum yyn, int yyrhslen, yyGLRStackItem* yyvsp,
 static void
 yyuserMerge (int yyn, YYSTYPE* yy0, YYSTYPE* yy1)
 {
-  YYUSE (yy0);
-  YYUSE (yy1);
+  YY_USE (yy0);
+  YY_USE (yy1);
 
   switch (yyn)
     {
@@ -965,7 +1004,7 @@ yydestroyGLRState (char const *yymsg, yyGLRState *yys]b4_user_formals[)
 {
   if (yys->yyresolved)
     yydestruct (yymsg, yy_accessing_symbol (yys->yylrState),
-                &yys->yysemantics.yysval]b4_locuser_args([&yys->yyloc])[);
+                &yys->yysemantics.yyval]b4_locuser_args([&yys->yyloc])[);
   else
     {
 #if ]b4_api_PREFIX[DEBUG
@@ -992,13 +1031,6 @@ yydestroyGLRState (char const *yymsg, yyGLRState *yys]b4_user_formals[)
     }
 }
 
-/** Left-hand-side symbol for rule #YYRULE.  */
-static inline yysymbol_kind_t
-yylhsNonterm (yyRuleNum yyrule)
-{
-  return YY_CAST (yysymbol_kind_t, yyr1[yyrule]);
-}
-
 #define yypact_value_is_default(Yyn) \
   ]b4_table_value_equals([[pact]], [[Yyn]], [b4_pact_ninf], [YYPACT_NINF])[
 
@@ -1032,7 +1064,7 @@ static inline int
 yygetLRActions (yy_state_t yystate, yysymbol_kind_t yytoken, const short** yyconflicts)
 {
   int yyindex = yypact[yystate] + yytoken;
-  if (yytoken == ]b4_symbol(1, kind)[)
+  if (yytoken == ]b4_symbol(error, kind)[)
     {
       // This is the error token.
       *yyconflicts = yyconfl;
@@ -1119,7 +1151,7 @@ yyaddDeferredAction (yyGLRStack* yystackp, YYPTRDIFF_T yyk, yyGLRState* yystate,
       yynewOption->yyloc = yylloc;])[
     }
   else
-    yynewOption->yyrawchar = ]b4_symbol(-2, id)[;
+    yynewOption->yyrawchar = ]b4_symbol(empty, id)[;
   yynewOption->yynext = yystate->yysemantics.yyfirstVal;
   yystate->yysemantics.yyfirstVal = yynewOption;
 
@@ -1340,7 +1372,7 @@ yyglrShift (yyGLRStack* yystackp, YYPTRDIFF_T yyk, yy_state_t yylrState,
   yynewState->yyposn = yyposn;
   yynewState->yyresolved = yytrue;
   yynewState->yypred = yystackp->yytops.yystates[yyk];
-  yynewState->yysemantics.yysval = *yyvalp;]b4_locations_if([
+  yynewState->yysemantics.yyval = *yyvalp;]b4_locations_if([
   yynewState->yyloc = *yylocp;])[
   yystackp->yytops.yystates[yyk] = yynewState;
 
@@ -1368,14 +1400,7 @@ yyglrShiftDefer (yyGLRStack* yystackp, YYPTRDIFF_T yyk, yy_state_t yylrState,
   yyaddDeferredAction (yystackp, yyk, yynewState, yyrhs, yyrule);
 }
 
-#if !]b4_api_PREFIX[DEBUG
-# define YY_REDUCE_PRINT(Args)
-#else
-# define YY_REDUCE_PRINT(Args)          \
-  do {                                  \
-    if (yydebug)                        \
-      yy_reduce_print Args;             \
-  } while (0)
+#if ]b4_api_PREFIX[DEBUG
 
 /*----------------------------------------------------------------------.
 | Report that stack #YYK of *YYSTACKP is going to be reduced by YYRULE. |
@@ -1398,7 +1423,7 @@ yy_reduce_print (yybool yynormal, yyGLRStackItem* yyvsp, YYPTRDIFF_T yyk,
       YY_FPRINTF ((stderr, "   $%d = ", yyi + 1));
       yy_symbol_print (stderr,
                        yy_accessing_symbol (yyvsp[yyi - yynrhs + 1].yystate.yylrState),
-                       &yyvsp[yyi - yynrhs + 1].yystate.yysemantics.yysval]b4_locations_if([,
+                       &yyvsp[yyi - yynrhs + 1].yystate.yysemantics.yyval]b4_locations_if([,
                        &]b4_rhs_location(yynrhs, yyi + 1))[]dnl
                        b4_user_args[);
       if (!yyvsp[yyi - yynrhs + 1].yystate.yyresolved)
@@ -1429,8 +1454,7 @@ yydoAction (yyGLRStack* yystackp, YYPTRDIFF_T yyk, yyRuleNum yyrule,
       yystackp->yynextFree -= yynrhs;
       yystackp->yyspaceLeft += yynrhs;
       yystackp->yytops.yystates[0] = & yystackp->yynextFree[-1].yystate;
-      YY_REDUCE_PRINT ((yytrue, yyrhs, yyk, yyrule]b4_user_args[));
-      return yyuserAction (yyrule, yynrhs, yyrhs, yystackp,
+      return yyuserAction (yyrule, yynrhs, yyrhs, yystackp, yyk,
                            yyvalp]b4_locuser_args[);
     }
   else
@@ -1449,9 +1473,8 @@ yydoAction (yyGLRStack* yystackp, YYPTRDIFF_T yyk, yyRuleNum yyrule,
         }
       yyupdateSplit (yystackp, yys);
       yystackp->yytops.yystates[yyk] = yys;
-      YY_REDUCE_PRINT ((yyfalse, yyrhsVals + YYMAXRHS + YYMAXLEFT - 1, yyk, yyrule]b4_user_args[));
       return yyuserAction (yyrule, yynrhs, yyrhsVals + YYMAXRHS + YYMAXLEFT - 1,
-                           yystackp, yyvalp]b4_locuser_args[);
+                           yystackp, yyk, yyvalp]b4_locuser_args[);
     }
 }
 
@@ -1474,21 +1497,20 @@ yyglrReduce (yyGLRStack* yystackp, YYPTRDIFF_T yyk, yyRuleNum yyrule,
 
   if (yyforceEval || yystackp->yysplitPoint == YY_NULLPTR)
     {
-      YYSTYPE yysval;]b4_locations_if([[
+      YYSTYPE yyval;]b4_locations_if([[
       YYLTYPE yyloc;]])[
 
-      YYRESULTTAG yyflag = yydoAction (yystackp, yyk, yyrule, &yysval]b4_locuser_args([&yyloc])[);
+      YYRESULTTAG yyflag = yydoAction (yystackp, yyk, yyrule, &yyval]b4_locuser_args([&yyloc])[);
       if (yyflag == yyerr && yystackp->yysplitPoint != YY_NULLPTR)
         YY_DPRINTF ((stderr,
                      "Parse on stack %ld rejected by rule %d (line %d).\n",
-                     YY_CAST (long, yyk), yyrule - 1, yyrline[yyrule - 1]));
+                     YY_CAST (long, yyk), yyrule - 1, yyrline[yyrule]));
       if (yyflag != yyok)
         return yyflag;
-      YY_SYMBOL_PRINT ("-> $$ =", yylhsNonterm (yyrule), &yysval, &yyloc);
       yyglrShift (yystackp, yyk,
                   yyLRgotoState (yystackp->yytops.yystates[yyk]->yylrState,
                                  yylhsNonterm (yyrule)),
-                  yyposn, &yysval]b4_locations_if([, &yyloc])[);
+                  yyposn, &yyval]b4_locations_if([, &yyloc])[);
     }
   else
     {
@@ -1508,7 +1530,7 @@ yyglrReduce (yyGLRStack* yystackp, YYPTRDIFF_T yyk, yyRuleNum yyrule,
       YY_DPRINTF ((stderr,
                    "Reduced stack %ld by rule %d (line %d); action deferred.  "
                    "Now in state %d.\n",
-                   YY_CAST (long, yyk), yyrule - 1, yyrline[yyrule - 1],
+                   YY_CAST (long, yyk), yyrule - 1, yyrline[yyrule],
                    yynewLRState));
       for (yyi = 0; yyi < yystackp->yytops.yysize; yyi += 1)
         if (yyi != yyk && yystackp->yytops.yystates[yyi] != YY_NULLPTR)
@@ -1619,12 +1641,12 @@ yymergeOptionSets (yySemanticOption* yyy0, yySemanticOption* yyy1)
       else if (yys0->yyresolved)
         {
           yys1->yyresolved = yytrue;
-          yys1->yysemantics.yysval = yys0->yysemantics.yysval;
+          yys1->yysemantics.yyval = yys0->yysemantics.yyval;
         }
       else if (yys1->yyresolved)
         {
           yys0->yyresolved = yytrue;
-          yys0->yysemantics.yysval = yys1->yysemantics.yysval;
+          yys0->yysemantics.yyval = yys1->yysemantics.yyval;
         }
       else
         {
@@ -1678,8 +1700,8 @@ yypreference (yySemanticOption* y0, yySemanticOption* y1)
   return 0;
 }
 
-static YYRESULTTAG yyresolveValue (yyGLRState* yys,
-                                   yyGLRStack* yystackp]b4_user_formals[);
+static YYRESULTTAG
+yyresolveValue (yyGLRState* yys, yyGLRStack* yystackp]b4_user_formals[);
 
 
 /** Resolve the previous YYN states starting at and including state YYS
@@ -1735,7 +1757,7 @@ yyresolveAction (yySemanticOption* yyopt, yyGLRStack* yystackp,
     yylloc = yyopt->yyloc;])[
     yyflag = yyuserAction (yyopt->yyrule, yynrhs,
                            yyrhsVals + YYMAXRHS + YYMAXLEFT - 1,
-                           yystackp, yyvalp]b4_locuser_args[);
+                           yystackp, -1, yyvalp]b4_locuser_args[);
     yychar = yychar_current;
     yylval = yylval_current;]b4_locations_if([
     yylloc = yylloc_current;])[
@@ -1795,8 +1817,8 @@ static YYRESULTTAG
 yyreportAmbiguity (yySemanticOption* yyx0,
                    yySemanticOption* yyx1]b4_pure_formals[)
 {
-  YYUSE (yyx0);
-  YYUSE (yyx1);
+  YY_USE (yyx0);
+  YY_USE (yyx1);
 
 #if ]b4_api_PREFIX[DEBUG
   YY_FPRINTF ((stderr, "Ambiguity detected.\n"));
@@ -1870,7 +1892,7 @@ yyresolveValue (yyGLRState* yys, yyGLRStack* yystackp]b4_user_formals[)
   yySemanticOption* yybest = yyoptionList;
   yySemanticOption** yypp;
   yybool yymerge = yyfalse;
-  YYSTYPE yysval;
+  YYSTYPE yyval;
   YYRESULTTAG yyflag;]b4_locations_if([
   YYLTYPE *yylocp = &yys->yyloc;])[
 
@@ -1914,33 +1936,33 @@ yyresolveValue (yyGLRState* yys, yyGLRStack* yystackp]b4_user_formals[)
     {
       yySemanticOption* yyp;
       int yyprec = yydprec[yybest->yyrule];
-      yyflag = yyresolveAction (yybest, yystackp, &yysval]b4_locuser_args[);
+      yyflag = yyresolveAction (yybest, yystackp, &yyval]b4_locuser_args[);
       if (yyflag == yyok)
         for (yyp = yybest->yynext; yyp != YY_NULLPTR; yyp = yyp->yynext)
           {
             if (yyprec == yydprec[yyp->yyrule])
               {
-                YYSTYPE yysval_other;]b4_locations_if([
+                YYSTYPE yyval_other;]b4_locations_if([
                 YYLTYPE yydummy;])[
-                yyflag = yyresolveAction (yyp, yystackp, &yysval_other]b4_locuser_args([&yydummy])[);
+                yyflag = yyresolveAction (yyp, yystackp, &yyval_other]b4_locuser_args([&yydummy])[);
                 if (yyflag != yyok)
                   {
                     yydestruct ("Cleanup: discarding incompletely merged value for",
                                 yy_accessing_symbol (yys->yylrState),
-                                &yysval]b4_locuser_args[);
+                                &yyval]b4_locuser_args[);
                     break;
                   }
-                yyuserMerge (yymerger[yyp->yyrule], &yysval, &yysval_other);
+                yyuserMerge (yymerger[yyp->yyrule], &yyval, &yyval_other);
               }
           }
     }
   else
-    yyflag = yyresolveAction (yybest, yystackp, &yysval]b4_locuser_args([yylocp])[);
+    yyflag = yyresolveAction (yybest, yystackp, &yyval]b4_locuser_args([yylocp])[);
 
   if (yyflag == yyok)
     {
       yys->yyresolved = yytrue;
-      yys->yysemantics.yysval = yysval;
+      yys->yysemantics.yyval = yyval;
     }
   else
     yys->yysemantics.yyfirstVal = YY_NULLPTR;
@@ -1965,18 +1987,24 @@ yyresolveStack (yyGLRStack* yystackp]b4_user_formals[)
   return yyok;
 }
 
+/** Called when returning to deterministic operation to clean up the extra
+ * stacks. */
 static void
 yycompressStack (yyGLRStack* yystackp)
 {
-  yyGLRState* yyp, *yyq, *yyr;
+  /* yyr is the state after the split point.  */
+  yyGLRState *yyr;
 
   if (yystackp->yytops.yysize != 1 || yystackp->yysplitPoint == YY_NULLPTR)
     return;
 
-  for (yyp = yystackp->yytops.yystates[0], yyq = yyp->yypred, yyr = YY_NULLPTR;
-       yyp != yystackp->yysplitPoint;
-       yyr = yyp, yyp = yyq, yyq = yyp->yypred)
-    yyp->yypred = yyr;
+  {
+    yyGLRState *yyp, *yyq;
+    for (yyp = yystackp->yytops.yystates[0], yyq = yyp->yypred, yyr = YY_NULLPTR;
+         yyp != yystackp->yysplitPoint;
+         yyr = yyp, yyp = yyq, yyq = yyp->yypred)
+      yyp->yypred = yyr;
+  }
 
   yystackp->yyspaceLeft += yystackp->yynextFree - yystackp->yyitems;
   yystackp->yynextFree = YY_REINTERPRET_CAST (yyGLRStackItem*, yystackp->yysplitPoint) + 1;
@@ -2110,7 +2138,7 @@ yypcontext_expected_tokens (const yyGLRStack* yystackp,
       int yyxend = yychecklim < YYNTOKENS ? yychecklim : YYNTOKENS;
       int yyx;
       for (yyx = yyxbegin; yyx < yyxend; ++yyx)
-        if (yycheck[yyx + yyn] == yyx && yyx != ]b4_symbol(1, kind)[
+        if (yycheck[yyx + yyn] == yyx && yyx != ]b4_symbol(error, kind)[
             && !yytable_value_is_error (yytable[yyx + yyn]))
           {
             if (!yyarg)
@@ -2122,7 +2150,7 @@ yypcontext_expected_tokens (const yyGLRStack* yystackp,
           }
     }
   if (yyarg && yycount == 0 && 0 < yyargn)
-    yyarg[0] = ]b4_symbol(-2, kind)[;
+    yyarg[0] = ]b4_symbol(empty, kind)[;
   return yycount;
 }]])[
 
@@ -2140,19 +2168,19 @@ yypcontext_token (const yyGLRStack *yystackp) YY_ATTRIBUTE_UNUSED;
 static yysymbol_kind_t
 yypcontext_token (const yyGLRStack *yystackp)
 {
-  YYUSE (yystackp);
-  yysymbol_kind_t yytoken = yychar == ]b4_symbol(-2, id)[ ? ]b4_symbol(-2, kind)[ : YYTRANSLATE (yychar);
+  YY_USE (yystackp);
+  yysymbol_kind_t yytoken = yychar == ]b4_symbol(empty, id)[ ? ]b4_symbol(empty, kind)[ : YYTRANSLATE (yychar);
   return yytoken;
 }
 
 ]b4_locations_if([[/* The location of the lookahead of this context.  */
-static YYLTYPE *
+static const YYLTYPE *
 yypcontext_location (const yyGLRStack *yystackp) YY_ATTRIBUTE_UNUSED;
 
-static YYLTYPE *
+static const YYLTYPE *
 yypcontext_location (const yyGLRStack *yystackp)
 {
-  YYUSE (yystackp);
+  YY_USE (yystackp);
   return &yylloc;
 }]])],
          [detailed\|verbose],
@@ -2160,7 +2188,7 @@ yypcontext_location (const yyGLRStack *yystackp)
 yy_syntax_error_arguments (const yyGLRStack* yystackp,
                            yysymbol_kind_t yyarg[], int yyargn)
 {
-  yysymbol_kind_t yytoken = yychar == ]b4_symbol(-2, id)[ ? ]b4_symbol(-2, kind)[ : YYTRANSLATE (yychar);
+  yysymbol_kind_t yytoken = yychar == ]b4_symbol(empty, id)[ ? ]b4_symbol(empty, kind)[ : YYTRANSLATE (yychar);
   /* Actual size of YYARG. */
   int yycount = 0;
   /* There are many possibilities here to consider:
@@ -2176,12 +2204,7 @@ yy_syntax_error_arguments (const yyGLRStack* yystackp,
      - Don't assume there isn't a lookahead just because this state is a
        consistent state with a default action.  There might have been a
        previous inconsistent state, consistent state with a non-default
-       action, or user semantic action that manipulated yychar.]b4_lac_if([[
-       In the first two cases, it might appear that the current syntax
-       error should have been detected in the previous state when yy_lac
-       was invoked.  However, at that time, there might have been a
-       different syntax error that discarded a different initial context
-       during error recovery, leaving behind the current lookahead.]], [[
+       action, or user semantic action that manipulated yychar.
      - Of course, the expected token list depends on states to have
        correct lookahead information, and it depends on the parser not
        to perform extra reductions after fetching a lookahead from the
@@ -2189,9 +2212,9 @@ yy_syntax_error_arguments (const yyGLRStack* yystackp,
        (from LALR or IELR) and default reductions corrupt the expected
        token list.  However, the list is correct for canonical LR with
        one exception: it will still contain any token that will not be
-       accepted due to an error action in a later state.]])[
+       accepted due to an error action in a later state.
   */
-  if (yytoken != ]b4_symbol(-2, kind)[)
+  if (yytoken != ]b4_symbol(empty, kind)[)
     {
       int yyn;
       if (yyarg)
@@ -2318,9 +2341,9 @@ yyrecoverSyntaxError (yyGLRStack* yystackp]b4_user_formals[)
       {
         yysymbol_kind_t yytoken;
         int yyj;
-        if (yychar == ]b4_symbol(0, [id])[)
+        if (yychar == ]b4_symbol(eof, [id])[)
           yyFail (yystackp][]b4_lpure_args[, YY_NULLPTR);
-        if (yychar != ]b4_symbol(-2, id)[)
+        if (yychar != ]b4_symbol(empty, id)[)
           {]b4_locations_if([[
             /* We throw away the lookahead, but the error range
                of the shifted error token must take it into account.  */
@@ -2332,7 +2355,7 @@ yyrecoverSyntaxError (yyGLRStack* yystackp]b4_user_formals[)
             yytoken = YYTRANSLATE (yychar);
             yydestruct ("Error: discarding",
                         yytoken, &yylval]b4_locuser_args([&yylloc])[);
-            yychar = ]b4_symbol(-2, id)[;
+            yychar = ]b4_symbol(empty, id)[;
           }
         yytoken = ]b4_yygetToken_call[;
         yyj = yypact[yystackp->yytops.yystates[0]->yylrState];
@@ -2370,8 +2393,8 @@ yyrecoverSyntaxError (yyGLRStack* yystackp]b4_user_formals[)
       int yyj = yypact[yys->yylrState];
       if (! yypact_value_is_default (yyj))
         {
-          yyj += ]b4_symbol(1, kind)[;
-          if (0 <= yyj && yyj <= YYLAST && yycheck[yyj] == ]b4_symbol(1, kind)[
+          yyj += ]b4_symbol(error, kind)[;
+          if (0 <= yyj && yyj <= YYLAST && yycheck[yyj] == ]b4_symbol(error, kind)[
               && yyisShiftAction (yytable[yyj]))
             {
               /* Shift the error token.  */
@@ -2399,20 +2422,16 @@ yyrecoverSyntaxError (yyGLRStack* yystackp]b4_user_formals[)
     yyFail (yystackp][]b4_lpure_args[, YY_NULLPTR);
 }
 
-#define YYCHK1(YYE)                                                          \
-  do {                                                                       \
-    switch (YYE) {                                                           \
-    case yyok:                                                               \
-      break;                                                                 \
-    case yyabort:                                                            \
-      goto yyabortlab;                                                       \
-    case yyaccept:                                                           \
-      goto yyacceptlab;                                                      \
-    case yyerr:                                                              \
-      goto yyuser_error;                                                     \
-    default:                                                                 \
-      goto yybuglab;                                                         \
-    }                                                                        \
+#define YYCHK1(YYE)                             \
+  do {                                          \
+    switch (YYE) {                              \
+    case yyok:     break;                       \
+    case yyabort:  goto yyabortlab;             \
+    case yyaccept: goto yyacceptlab;            \
+    case yyerr:    goto yyuser_error;           \
+    case yynomem:  goto yyexhaustedlab;         \
+    default:       goto yybuglab;               \
+    }                                           \
   } while (0)
 
 /*----------.
@@ -2420,7 +2439,7 @@ yyrecoverSyntaxError (yyGLRStack* yystackp]b4_user_formals[)
 `----------*/
 
 int
-yyparse (]m4_ifset([b4_parse_param], [b4_formals(b4_parse_param)], [void])[)
+]b4_glr_cc_if([yy_parse_impl], [yyparse])[ (]m4_ifset([b4_parse_param], [b4_formals(b4_parse_param)], [void])[)
 {
   int yyresult;
   yyGLRStack yystack;
@@ -2429,7 +2448,7 @@ yyparse (]m4_ifset([b4_parse_param], [b4_formals(b4_parse_param)], [void])[)
 
   YY_DPRINTF ((stderr, "Starting parse\n"));
 
-  yychar = ]b4_symbol(-2, id)[;
+  yychar = ]b4_symbol(empty, id)[;
   yylval = yyval_default;]b4_locations_if([
   yylloc = yyloc_default;])[
 ]m4_ifdef([b4_initial_action], [
@@ -2483,7 +2502,7 @@ b4_dollar_popdef])[]dnl
               if (yyisShiftAction (yyaction))
                 {
                   YY_SYMBOL_PRINT ("Shifting", yytoken, &yylval, &yylloc);
-                  yychar = ]b4_symbol(-2, id)[;
+                  yychar = ]b4_symbol(empty, id)[;
                   yyposn += 1;
                   yyglrShift (&yystack, 0, yyaction, yyposn, &yylval]b4_locations_if([, &yylloc])[);
                   if (0 < yystack.yyerrState)
@@ -2494,7 +2513,7 @@ b4_dollar_popdef])[]dnl
                   yystack.yyerror_range[1].yystate.yyloc = yylloc;]])[
                   /* Issue an error message unless the scanner already
                      did. */
-                  if (yychar != ]b4_symbol(1, id)[)
+                  if (yychar != ]b4_symbol(error, id)[)
                     yyreportSyntaxError (&yystack]b4_user_args[);
                   goto yyuser_error;
                 }
@@ -2510,7 +2529,7 @@ b4_dollar_popdef])[]dnl
           YYPTRDIFF_T yys;
 
           for (yys = 0; yys < yystack.yytops.yysize; yys += 1)
-            yystackp->yytops.yylookaheadNeeds[yys] = yychar != ]b4_symbol(-2, id)[;
+            yystackp->yytops.yylookaheadNeeds[yys] = yychar != ]b4_symbol(empty, id)[;
 
           /* yyprocessOneStack returns one of three things:
 
@@ -2548,11 +2567,11 @@ b4_dollar_popdef])[]dnl
 
           /* If any yyglrShift call fails, it will fail after shifting.  Thus,
              a copy of yylval will already be on stack 0 in the event of a
-             failure in the following loop.  Thus, yychar is set to ]b4_symbol(-2, id)[
+             failure in the following loop.  Thus, yychar is set to ]b4_symbol(empty, id)[
              before the loop to make sure the user destructor for yylval isn't
              called twice.  */
           yytoken_to_shift = YYTRANSLATE (yychar);
-          yychar = ]b4_symbol(-2, id)[;
+          yychar = ]b4_symbol(empty, id)[;
           yyposn += 1;
           for (yys = 0; yys < yystack.yytops.yysize; yys += 1)
             {
@@ -2565,7 +2584,7 @@ b4_dollar_popdef])[]dnl
               YY_SYMBOL_PRINT ("shifting", yytoken_to_shift, &yylval, &yylloc);
               yyglrShift (&yystack, yys, yyaction, yyposn,
                           &yylval]b4_locations_if([, &yylloc])[);
-              YY_DPRINTF ((stderr, "Stack %ld now in state #%d\n",
+              YY_DPRINTF ((stderr, "Stack %ld now in state %d\n",
                            YY_CAST (long, yys),
                            yystack.yytops.yystates[yys]->yylrState));
             }
@@ -2586,7 +2605,7 @@ b4_dollar_popdef])[]dnl
 
  yyacceptlab:
   yyresult = 0;
-  goto yyreturn;
+  goto yyreturnlab;
 
  yybuglab:
   YY_ASSERT (yyfalse);
@@ -2594,15 +2613,15 @@ b4_dollar_popdef])[]dnl
 
  yyabortlab:
   yyresult = 1;
-  goto yyreturn;
+  goto yyreturnlab;
 
  yyexhaustedlab:
   yyerror (]b4_lyyerror_args[YY_("memory exhausted"));
   yyresult = 2;
-  goto yyreturn;
+  goto yyreturnlab;
 
- yyreturn:
-  if (yychar != ]b4_symbol(-2, id)[)
+ yyreturnlab:
+  if (yychar != ]b4_symbol(empty, id)[)
     yydestruct ("Cleanup: discarding lookahead",
                 YYTRANSLATE (yychar), &yylval]b4_locuser_args([&yylloc])[);
 
@@ -2640,6 +2659,7 @@ b4_dollar_popdef])[]dnl
 
 /* DEBUGGING ONLY */
 #if ]b4_api_PREFIX[DEBUG
+/* Print *YYS and its predecessors. */
 static void
 yy_yypstack (yyGLRState* yys)
 {
@@ -2651,22 +2671,25 @@ yy_yypstack (yyGLRState* yys)
   YY_FPRINTF ((stderr, "%d@@%ld", yys->yylrState, YY_CAST (long, yys->yyposn)));
 }
 
+/* Print YYS (possibly NULL) and its predecessors. */
 static void
-yypstates (yyGLRState* yyst)
+yypstates (yyGLRState* yys)
 {
-  if (yyst == YY_NULLPTR)
+  if (yys == YY_NULLPTR)
     YY_FPRINTF ((stderr, "<null>"));
   else
-    yy_yypstack (yyst);
+    yy_yypstack (yys);
   YY_FPRINTF ((stderr, "\n"));
 }
 
+/* Print the stack #YYK.  */
 static void
 yypstack (yyGLRStack* yystackp, YYPTRDIFF_T yyk)
 {
   yypstates (yystackp->yytops.yystates[yyk]);
 }
 
+/* Print all the stacks.  */
 static void
 yypdumpstack (yyGLRStack* yystackp)
 {

data/skeletons/glr.cc

@@ -1,6 +1,6 @@
 # C++ GLR skeleton for Bison
 
-# Copyright (C) 2002-2015, 2018-2020 Free Software Foundation, Inc.
+# Copyright (C) 2002-2015, 2018-2021 Free Software Foundation, Inc.
 
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -13,7 +13,7 @@
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 
 # This skeleton produces a C++ class that encapsulates a C glr parser.
@@ -78,7 +78,7 @@ m4_define([b4_yy_symbol_print_define],
 
 static void
 yy_symbol_print (FILE *, ]b4_namespace_ref::b4_parser_class[::symbol_kind_type yytoken,
-                 const ]b4_namespace_ref::b4_parser_class[::semantic_type *yyvaluep]b4_locations_if([[,
+                 const ]b4_namespace_ref::b4_parser_class[::value_type *yyvaluep]b4_locations_if([[,
                  const ]b4_namespace_ref::b4_parser_class[::location_type *yylocationp]])[]b4_user_formals[)
 {
 ]b4_parse_param_use[]dnl
@@ -144,7 +144,7 @@ m4_pushdef([b4_parse_param], m4_defn([b4_parse_param_orig]))dnl
   int
   ]b4_parser_class[::parse ()
   {
-    return ::yyparse (*this]b4_user_args[);
+    return ::yy_parse_impl (*this]b4_user_args[);
   }
 
 #if ]b4_api_PREFIX[DEBUG
@@ -154,25 +154,25 @@ m4_pushdef([b4_parse_param], m4_defn([b4_parse_param_orig]))dnl
 
   void
   ]b4_parser_class[::yy_symbol_value_print_ (symbol_kind_type yykind,
-                           const semantic_type* yyvaluep]b4_locations_if([[,
+                           const value_type* yyvaluep]b4_locations_if([[,
                            const location_type* yylocationp]])[) const
   {]b4_locations_if([[
-    YYUSE (yylocationp);]])[
-    YYUSE (yyvaluep);
+    YY_USE (yylocationp);]])[
+    YY_USE (yyvaluep);
     std::ostream& yyo = debug_stream ();
     std::ostream& yyoutput = yyo;
-    YYUSE (yyoutput);
+    YY_USE (yyoutput);
     ]b4_symbol_actions([printer])[
   }
 
 
   void
   ]b4_parser_class[::yy_symbol_print_ (symbol_kind_type yykind,
-                           const semantic_type* yyvaluep]b4_locations_if([[,
+                           const value_type* yyvaluep]b4_locations_if([[,
                            const location_type* yylocationp]])[) const
   {
     *yycdebug_ << (yykind < YYNTOKENS ? "token" : "nterm")
-               << ' ' << yytname[yykind] << " ("]b4_locations_if([[
+               << ' ' << yysymbol_name (yykind) << " ("]b4_locations_if([[
                << *yylocationp << ": "]])[;
     yy_symbol_value_print_ (yykind, yyvaluep]b4_locations_if([[, yylocationp]])[);
     *yycdebug_ << ')';
@@ -221,15 +221,33 @@ m4_define([b4_define_symbol_kind],
 # Setup redirections for glr.c: Map the names used in c.m4 to the ones used
 # in c++.m4.
 m4_define([b4_glr_cc_setup],
-[[#undef ]b4_symbol(-2, [id])[
-#define ]b4_symbol(-2, [id])[ ]b4_namespace_ref[::]b4_parser_class[::token::]b4_symbol(-2, [id])[
-#undef ]b4_symbol(0, [id])[
-#define ]b4_symbol(0, [id])[ ]b4_namespace_ref[::]b4_parser_class[::token::]b4_symbol(0, [id])[
-#undef ]b4_symbol(1, [id])[
-#define ]b4_symbol(1, [id])[ ]b4_namespace_ref[::]b4_parser_class[::token::]b4_symbol(1, [id])[
+[[]b4_attribute_define[
+]b4_null_define[
+
+// This skeleton is based on C, yet compiles it as C++.
+// So expect warnings about C style casts.
+#if defined __clang__ && 306 <= __clang_major__ * 100 + __clang_minor__
+# pragma clang diagnostic ignored "-Wold-style-cast"
+#elif defined __GNUC__ && 406 <= __GNUC__ * 100 + __GNUC_MINOR__
+# pragma GCC diagnostic ignored "-Wold-style-cast"
+#endif
+
+// On MacOS, PTRDIFF_MAX is defined as long long, which Clang's
+// -pedantic reports as being a C++11 extension.
+#if defined __APPLE__ && YY_CPLUSPLUS < 201103L \
+    && defined __clang__ && 4 <= __clang_major__
+# pragma clang diagnostic ignored "-Wc++11-long-long"
+#endif
+
+#undef ]b4_symbol(empty, [id])[
+#define ]b4_symbol(empty, [id])[ ]b4_namespace_ref[::]b4_parser_class[::token::]b4_symbol(empty, [id])[
+#undef ]b4_symbol(eof, [id])[
+#define ]b4_symbol(eof, [id])[ ]b4_namespace_ref[::]b4_parser_class[::token::]b4_symbol(eof, [id])[
+#undef ]b4_symbol(error, [id])[
+#define ]b4_symbol(error, [id])[ ]b4_namespace_ref[::]b4_parser_class[::token::]b4_symbol(error, [id])[
 
 #ifndef ]b4_api_PREFIX[STYPE
-# define ]b4_api_PREFIX[STYPE ]b4_namespace_ref[::]b4_parser_class[::semantic_type
+# define ]b4_api_PREFIX[STYPE ]b4_namespace_ref[::]b4_parser_class[::value_type
 #endif
 #ifndef ]b4_api_PREFIX[LTYPE
 # define ]b4_api_PREFIX[LTYPE ]b4_namespace_ref[::]b4_parser_class[::location_type
@@ -252,9 +270,9 @@ m4_define([b4_undef_symbol_kind],
 # -----------------
 # Remove redirections for glr.c.
 m4_define([b4_glr_cc_cleanup],
-[[#undef ]b4_symbol(-2, [id])[
-#undef ]b4_symbol(0, [id])[
-#undef ]b4_symbol(1, [id])[
+[[#undef ]b4_symbol(empty, [id])[
+#undef ]b4_symbol(eof, [id])[
+#undef ]b4_symbol(error, [id])[
 
 ]b4_undef_symbol_kind(-2)dnl
 b4_symbol_foreach([b4_undef_symbol_kind])dnl
@@ -263,7 +281,7 @@ b4_symbol_foreach([b4_undef_symbol_kind])dnl
 
 # b4_shared_declarations(hh|cc)
 # -----------------------------
-# Declaration that might either go into the header (if --defines, $1 = hh)
+# Declaration that might either go into the header (if --header, $1 = hh)
 # or in the implementation file.
 m4_define([b4_shared_declarations],
 [m4_pushdef([b4_parse_param], m4_defn([b4_parse_param_orig]))dnl
@@ -277,24 +295,6 @@ b4_percent_code_get([[requires]])[
           [[# include ]b4_location_include])[
 ]b4_variant_if([b4_variant_includes])[
 
-]b4_attribute_define[
-]b4_null_define[
-
-// This skeleton is based on C, yet compiles it as C++.
-// So expect warnings about C style casts.
-#if defined __clang__ && 306 <= __clang_major__ * 100 + __clang_minor__
-# pragma clang diagnostic ignored "-Wold-style-cast"
-#elif defined __GNUC__ && 406 <= __GNUC__ * 100 + __GNUC_MINOR__
-# pragma GCC diagnostic ignored "-Wold-style-cast"
-#endif
-
-// On MacOS, PTRDIFF_MAX is defined as long long, which Clang's
-// -pedantic reports as being a C++11 extension.
-#if defined __APPLE__ && YY_CPLUSPLUS < 201103L \
-    && defined __clang__ && 4 <= __clang_major__
-# pragma clang diagnostic ignored "-Wc++11-long-long"
-#endif
-
 // Whether we are compiled with exception support.
 #ifndef YY_EXCEPTIONS
 # if defined __GNUC__ && !defined __EXCEPTIONS
@@ -355,14 +355,14 @@ b4_percent_code_get([[requires]])[
     /// \param yyvaluep     Its semantic value.]b4_locations_if([[
     /// \param yylocationp  Its location.]])[
     virtual void yy_symbol_value_print_ (symbol_kind_type yykind,
-                                         const semantic_type* yyvaluep]b4_locations_if([[,
+                                         const value_type* yyvaluep]b4_locations_if([[,
                                          const location_type* yylocationp]])[) const;
     /// \brief Report a symbol on the debug stream.
     /// \param yykind       The symbol kind.
     /// \param yyvaluep     Its semantic value.]b4_locations_if([[
     /// \param yylocationp  Its location.]])[
     virtual void yy_symbol_print_ (symbol_kind_type yykind,
-                                   const semantic_type* yyvaluep]b4_locations_if([[,
+                                   const value_type* yyvaluep]b4_locations_if([[,
                                    const location_type* yylocationp]])[) const;
   private:
     /// Debug stream.
@@ -378,10 +378,10 @@ b4_percent_code_get([[requires]])[
 ]m4_popdef([b4_parse_param])dnl
 ])[
 
-]b4_defines_if(
+]b4_header_if(
 [b4_output_begin([b4_spec_header_file])
 b4_copyright([Skeleton interface for Bison GLR parsers in C++],
-             [2002-2015, 2018-2020])[
+             [2002-2015, 2018-2021])[
 // C++ GLR parser skeleton written by Akim Demaille.
 
 ]b4_disclaimer[

data/skeletons/java-skel.m4

@@ -2,7 +2,7 @@
 
 # Java skeleton dispatching for Bison.
 
-# Copyright (C) 2007, 2009-2015, 2018-2020 Free Software Foundation,
+# Copyright (C) 2007, 2009-2015, 2018-2021 Free Software Foundation,
 # Inc.
 
 # This program is free software: you can redistribute it and/or modify
@@ -16,7 +16,7 @@
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 b4_glr_if(             [b4_complain([%%glr-parser not supported for Java])])
 b4_nondeterministic_if([b4_complain([%%nondeterministic-parser not supported for Java])])

data/skeletons/java.m4

@@ -2,7 +2,7 @@
 
 # Java language support for Bison
 
-# Copyright (C) 2007-2015, 2018-2020 Free Software Foundation, Inc.
+# Copyright (C) 2007-2015, 2018-2021 Free Software Foundation, Inc.
 
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -15,7 +15,7 @@
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 m4_include(b4_skeletonsdir/[c-like.m4])
 
@@ -71,12 +71,12 @@ m4_define([b4_lexer_if],
 # b4_identification
 # -----------------
 m4_define([b4_identification],
-[  /** Version number for the Bison executable that generated this parser.  */
-  public static final String bisonVersion = "b4_version";
+[[  /** Version number for the Bison executable that generated this parser.  */
+  public static final String bisonVersion = "]b4_version_string[";
 
   /** Name of the skeleton that generated this parser.  */
-  public static final String bisonSkeleton = b4_skeleton;
-])
+  public static final String bisonSkeleton = ]b4_skeleton[;
+]])
 
 
 ## ------------ ##

data/skeletons/lalr1.cc

@@ -1,6 +1,6 @@
 # C++ skeleton for Bison
 
-# Copyright (C) 2002-2015, 2018-2020 Free Software Foundation, Inc.
+# Copyright (C) 2002-2015, 2018-2021 Free Software Foundation, Inc.
 
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -13,15 +13,14 @@
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 m4_include(b4_skeletonsdir/[c++.m4])
 
 # api.value.type=variant is valid.
 m4_define([b4_value_type_setup_variant])
 
-# Check the value of %define parse.lac, where LAC stands for lookahead
-# correction.
+# parse.lac
 b4_percent_define_default([[parse.lac]], [[none]])
 b4_percent_define_check_values([[[[parse.lac]], [[full]], [[none]]]])
 b4_define_flag_if([lac])
@@ -146,21 +145,21 @@ b4_dollar_popdef[]dnl
 ])])
 
 
-# b4_lex
-# ------
+# b4_yylex
+# --------
 # Call yylex.
-m4_define([b4_lex],
+m4_define([b4_yylex],
 [b4_token_ctor_if(
 [b4_function_call([yylex],
                   [symbol_type], m4_ifdef([b4_lex_param], b4_lex_param))],
 [b4_function_call([yylex], [int],
-                  [b4_api_PREFIX[STYPE*], [&yyla.value]][]dnl
-b4_locations_if([, [[location*], [&yyla.location]]])dnl
+                  [[value_type *], [&yyla.value]][]dnl
+b4_locations_if([, [[location_type *], [&yyla.location]]])dnl
 m4_ifdef([b4_lex_param], [, ]b4_lex_param))])])
 
 
 m4_pushdef([b4_copyright_years],
-           [2002-2015, 2018-2020])
+           [2002-2015, 2018-2021])
 
 m4_define([b4_parser_class],
           [b4_percent_define_get([[api.parser.class]])])
@@ -174,7 +173,7 @@ b4_variant_if([m4_include(b4_skeletonsdir/[variant.hh])])
 
 # b4_shared_declarations(hh|cc)
 # -----------------------------
-# Declaration that might either go into the header (if --defines, $1 = hh)
+# Declaration that might either go into the header (if --header, $1 = hh)
 # or in the implementation file.
 m4_define([b4_shared_declarations],
 [b4_percent_code_get([[requires]])[
@@ -271,9 +270,9 @@ m4_define([b4_shared_declarations],
     {
     public:
       context (const ]b4_parser_class[& yyparser, const symbol_type& yyla);
-      const symbol_type& lookahead () const { return yyla_; }
-      symbol_kind_type token () const { return yyla_.kind (); }]b4_locations_if([[
-      const location_type& location () const { return yyla_.location; }
+      const symbol_type& lookahead () const YY_NOEXCEPT { return yyla_; }
+      symbol_kind_type token () const YY_NOEXCEPT { return yyla_.kind (); }]b4_locations_if([[
+      const location_type& location () const YY_NOEXCEPT { return yyla_.location; }
 ]])[
       /// Put in YYARG at most YYARGN of the expected tokens, and return the
       /// number of tokens stored in YYARG.  If YYARG is null, return the
@@ -307,11 +306,11 @@ m4_define([b4_shared_declarations],
     /// Stored state numbers (used for stacks).
     typedef ]b4_int_type(0, m4_eval(b4_states_number - 1))[ state_type;
 ]b4_parse_error_bmatch(
-      [custom], [[
+[custom], [[
     /// Report a syntax error
     /// \param yyctx     the context in which the error occurred.
     void report_syntax_error (const context& yyctx) const;]],
-      [detailed\|verbose], [[
+[detailed\|verbose], [[
     /// The arguments of the error message.
     int yy_syntax_error_arguments_ (const context& yyctx,
                                     symbol_kind_type yyarg[], int yyargn) const;
@@ -408,7 +407,7 @@ m4_define([b4_shared_declarations],
       void move (by_state& that);
 
       /// The symbol kind (corresponding to \a state).
-      /// \a ]b4_symbol(-2, kind)[ when empty.
+      /// \a ]b4_symbol(empty, kind)[ when empty.
       symbol_kind_type kind () const YY_NOEXCEPT;
 
       /// The state number used to denote an empty symbol.
@@ -494,16 +493,21 @@ m4_define([b4_shared_declarations],
 ]b4_namespace_close[
 
 ]b4_percent_code_get([[provides]])[
-]])
+]])[
+
 
 ## -------------- ##
 ## Output files.  ##
 ## -------------- ##
 
-b4_defines_if(
-[b4_output_begin([b4_spec_header_file])
-b4_copyright([Skeleton interface for Bison LALR(1) parsers in C++])
-[
+# ------------- #
+# Header file.  #
+# ------------- #
+
+]b4_header_if([[
+]b4_output_begin([b4_spec_header_file])[
+]b4_copyright([Skeleton interface for Bison LALR(1) parsers in C++])[
+
 /**
  ** \file ]b4_spec_mapped_header_file[
  ** Define the ]b4_namespace_ref[::parser class.
@@ -516,10 +520,14 @@ b4_copyright([Skeleton interface for Bison LALR(1) parsers in C++])
 ]b4_shared_declarations(hh)[
 ]b4_cpp_guard_close([b4_spec_mapped_header_file])[
 ]b4_output_end[
-]])
+]])[
 
 
-b4_output_begin([b4_parser_file_name])[
+# --------------------- #
+# Implementation file.  #
+# --------------------- #
+
+]b4_output_begin([b4_parser_file_name])[
 ]b4_copyright([Skeleton implementation for Bison LALR(1) parsers in C++])[
 ]b4_disclaimer[
 ]b4_percent_code_get([[top]])[]dnl
@@ -530,7 +538,7 @@ m4_if(b4_prefix, [yy], [],
 
 ]b4_user_pre_prologue[
 
-]b4_defines_if([[#include "@basename(]b4_spec_header_file[@)"]],
+]b4_header_if([[#include "@basename(]b4_spec_header_file[@)"]],
                [b4_shared_declarations([cc])])[
 
 ]b4_user_post_prologue[
@@ -597,7 +605,7 @@ m4_if(b4_prefix, [yy], [],
 #else // !]b4_api_PREFIX[DEBUG
 
 # define YYCDEBUG if (false) std::cerr
-# define YY_SYMBOL_PRINT(Title, Symbol)  YYUSE (Symbol)
+# define YY_SYMBOL_PRINT(Title, Symbol)  YY_USE (Symbol)
 # define YY_REDUCE_PRINT(Rule)           static_cast<void> (0)
 # define YY_STACK_PRINT()                static_cast<void> (0)
 
@@ -665,7 +673,7 @@ m4_if(b4_prefix, [yy], [],
   ]b4_parser_class[::by_state::kind () const YY_NOEXCEPT
   {
     if (state == empty_state)
-      return ]b4_symbol(-2, kind)[;
+      return ]b4_symbol(empty, kind)[;
     else
       return YY_CAST (symbol_kind_type, yystos_[+state]);
   }
@@ -690,7 +698,7 @@ m4_if(b4_prefix, [yy], [],
     b4_symbol_variant([that.kind ()],
                       [value], [move], [YY_MOVE (that.value)])])[
     // that is emptied.
-    that.kind_ = ]b4_symbol(-2, kind)[;
+    that.kind_ = ]b4_symbol(empty, kind)[;
   }
 
 #if YY_CPLUSPLUS < 201103L
@@ -736,7 +744,7 @@ m4_if(b4_prefix, [yy], [],
   ]b4_parser_class[::yy_print_ (std::ostream& yyo, const basic_symbol<Base>& yysym) const
   {
     std::ostream& yyoutput = yyo;
-    YYUSE (yyoutput);
+    YY_USE (yyoutput);
     if (yysym.empty ())
       yyo << "empty symbol";
     else
@@ -851,8 +859,8 @@ m4_if(b4_prefix, [yy], [],
     /// The return value of parse ().
     int yyresult;]b4_lac_if([[
 
-    /// Discard the LAC context in case there still is one left from a
-    /// previous invocation.
+    // Discard the LAC context in case there still is one left from a
+    // previous invocation.
     yy_lac_discard_ ("init");]])[
 
 #if YY_EXCEPTIONS
@@ -904,9 +912,9 @@ b4_dollar_popdef])[]dnl
         try
 #endif // YY_EXCEPTIONS
           {]b4_token_ctor_if([[
-            symbol_type yylookahead (]b4_lex[);
+            symbol_type yylookahead (]b4_yylex[);
             yyla.move (yylookahead);]], [[
-            yyla.kind_ = yytranslate_ (]b4_lex[);]])[
+            yyla.kind_ = yytranslate_ (]b4_yylex[);]])[
           }
 #if YY_EXCEPTIONS
         catch (const syntax_error& yyexc)
@@ -919,13 +927,13 @@ b4_dollar_popdef])[]dnl
       }
     YY_SYMBOL_PRINT ("Next token is", yyla);
 
-    if (yyla.kind () == ]b4_symbol(1, kind)[)
+    if (yyla.kind () == ]b4_symbol(error, kind)[)
     {
       // The scanner already issued an error message, process directly
       // to error recovery.  But do not keep the error token as
       // lookahead, it is too special and may lead us to an endless
       // loop in error recovery. */
-      yyla.kind_ = ]b4_symbol(2, kind)[;
+      yyla.kind_ = ]b4_symbol(undef, kind)[;
       goto yyerrlab1;
     }
 
@@ -935,7 +943,7 @@ b4_dollar_popdef])[]dnl
     if (yyn < 0 || yylast_ < yyn || yycheck_[yyn] != yyla.kind ())
       {]b4_lac_if([[
         if (!yy_lac_establish_ (yyla.kind ()))
-           goto yyerrlab;]])[
+          goto yyerrlab;]])[
         goto yydefault;
       }
 
@@ -946,7 +954,7 @@ b4_dollar_popdef])[]dnl
         if (yy_table_value_is_error_ (yyn))
           goto yyerrlab;]b4_lac_if([[
         if (!yy_lac_establish_ (yyla.kind ()))
-           goto yyerrlab;
+          goto yyerrlab;
 ]])[
         yyn = -yyn;
         goto yyreduce;
@@ -979,11 +987,11 @@ b4_dollar_popdef])[]dnl
     yylen = yyr2_[yyn];
     {
       stack_symbol_type yylhs;
-      yylhs.state = yy_lr_goto_state_ (yystack_[yylen].state, yyr1_[yyn]);]b4_variant_if([
+      yylhs.state = yy_lr_goto_state_ (yystack_[yylen].state, yyr1_[yyn]);]b4_variant_if([[
       /* Variants are always initialized to an empty instance of the
          correct type. The default '$$ = $1' action is NOT applied
          when using variants.  */
-      b4_symbol_variant([[yyr1_@{yyn@}]], [yylhs.value], [emplace])], [
+      ]b4_symbol_variant([[yyr1_@{yyn@}]], [yylhs.value], [emplace])], [[
       /* If YYLEN is nonzero, implement the default value of the
          action: '$$ = $1'.  Otherwise, use the top of the stack.
 
@@ -993,7 +1001,7 @@ b4_dollar_popdef])[]dnl
       if (yylen)
         yylhs.value = yystack_@{yylen - 1@}.value;
       else
-        yylhs.value = yystack_@{0@}.value;])[
+        yylhs.value = yystack_@{0@}.value;]])[
 ]b4_locations_if([dnl
 [
       // Default location.
@@ -1062,7 +1070,7 @@ b4_dollar_popdef])[]dnl
            error, discard it.  */
 
         // Return failure if at end of input.
-        if (yyla.kind () == ]b4_symbol(0, kind)[)
+        if (yyla.kind () == ]b4_symbol(eof, kind)[)
           YYABORT;
         else if (!yyla.empty ())
           {
@@ -1103,9 +1111,9 @@ b4_dollar_popdef])[]dnl
         yyn = yypact_[+yystack_[0].state];
         if (!yy_pact_value_is_default_ (yyn))
           {
-            yyn += ]b4_symbol(1, kind)[;
+            yyn += ]b4_symbol(error, kind)[;
             if (0 <= yyn && yyn <= yylast_
-                && yycheck_[yyn] == ]b4_symbol(1, kind)[)
+                && yycheck_[yyn] == ]b4_symbol(error, kind)[)
               {
                 yyn = yytable_[yyn];
                 if (0 < yyn)
@@ -1297,8 +1305,8 @@ b4_dollar_popdef])[]dnl
     for (int yyx = 0; yyx < YYNTOKENS; ++yyx)
       {
         symbol_kind_type yysym = YY_CAST (symbol_kind_type, yyx);
-        if (yysym != ]b4_symbol(1, kind)[
-            && yysym != ]b4_symbol(2, kind)[
+        if (yysym != ]b4_symbol(error, kind)[
+            && yysym != ]b4_symbol(undef, kind)[
             && yyparser_.yy_lac_check_ (yysym))
           {
             if (!yyarg)
@@ -1309,18 +1317,18 @@ b4_dollar_popdef])[]dnl
               yyarg[yycount++] = yysym;
           }
       }]], [[
-    int yyn = yypact_[+yyparser_.yystack_[0].state];
+    const int yyn = yypact_[+yyparser_.yystack_[0].state];
     if (!yy_pact_value_is_default_ (yyn))
       {
         /* Start YYX at -YYN if negative to avoid negative indexes in
            YYCHECK.  In other words, skip the first -YYN actions for
            this state because they are default actions.  */
-        int yyxbegin = yyn < 0 ? -yyn : 0;
+        const int yyxbegin = yyn < 0 ? -yyn : 0;
         // Stay within bounds of both yycheck and yytname.
-        int yychecklim = yylast_ - yyn + 1;
-        int yyxend = yychecklim < YYNTOKENS ? yychecklim : YYNTOKENS;
+        const int yychecklim = yylast_ - yyn + 1;
+        const int yyxend = yychecklim < YYNTOKENS ? yychecklim : YYNTOKENS;
         for (int yyx = yyxbegin; yyx < yyxend; ++yyx)
-          if (yycheck_[yyx + yyn] == yyx && yyx != ]b4_symbol(1, kind)[
+          if (yycheck_[yyx + yyn] == yyx && yyx != ]b4_symbol(error, kind)[
               && !yy_table_value_is_error_ (yytable_[yyx + yyn]))
             {
               if (!yyarg)
@@ -1333,11 +1341,13 @@ b4_dollar_popdef])[]dnl
       }
 ]])[
     if (yyarg && yycount == 0 && 0 < yyargn)
-      yyarg[0] = ]b4_symbol(-2, kind)[;
+      yyarg[0] = ]b4_symbol(empty, kind)[;
     return yycount;
   }
 
-]])b4_lac_if([[
+]])[
+
+]b4_lac_if([[
   bool
   ]b4_parser_class[::yy_lac_check_ (symbol_kind_type yytoken) const
   {
@@ -1442,7 +1452,9 @@ b4_dollar_popdef])[]dnl
        follows.  If no initial context is currently established for the
        current lookahead, then check if that lookahead can eventually be
        shifted if syntactic actions continue from the current context.  */
-    if (!yy_lac_established_)
+    if (yy_lac_established_)
+      return true;
+    else
       {
 #if ]b4_api_PREFIX[DEBUG
         YYCDEBUG << "LAC: initial context established for "
@@ -1451,12 +1463,11 @@ b4_dollar_popdef])[]dnl
         yy_lac_established_ = true;
         return yy_lac_check_ (yytoken);
       }
-    return true;
   }
 
   // Discard any previous initial lookahead context.
   void
-  ]b4_parser_class[::yy_lac_discard_ (const char* evt)
+  ]b4_parser_class[::yy_lac_discard_ (const char* event)
   {
    /* Discard any previous initial lookahead context because of Event,
       which may be a lookahead change or an invalidation of the currently
@@ -1472,11 +1483,12 @@ b4_dollar_popdef])[]dnl
     if (yy_lac_established_)
       {
         YYCDEBUG << "LAC: initial context discarded due to "
-                 << evt << '\n';
+                 << event << '\n';
         yy_lac_established_ = false;
       }
-  }]])b4_parse_error_bmatch([detailed\|verbose], [[
+  }]])[
 
+]b4_parse_error_bmatch([detailed\|verbose], [[
   int
   ]b4_parser_class[::yy_syntax_error_arguments_ (const context& yyctx,
                                                  symbol_kind_type yyarg[], int yyargn) const

data/skeletons/lalr1.java

@@ -1,6 +1,6 @@
-# Java skeleton for Bison                           -*- autoconf -*-
+# Java skeleton for Bison                           -*- java -*-
 
-# Copyright (C) 2007-2015, 2018-2020 Free Software Foundation, Inc.
+# Copyright (C) 2007-2015, 2018-2021 Free Software Foundation, Inc.
 
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -13,11 +13,11 @@
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 m4_include(b4_skeletonsdir/[java.m4])
 
-b4_defines_if([b4_complain([%defines does not make sense in Java])])
+b4_header_if([b4_complain([%header/%defines does not make sense in Java])])
 
 m4_define([b4_symbol_no_destructor_assert],
 [b4_symbol_if([$1], [has_destructor],
@@ -25,7 +25,10 @@ m4_define([b4_symbol_no_destructor_assert],
                               [%destructor does not make sense in Java])])])
 b4_symbol_foreach([b4_symbol_no_destructor_assert])
 
-# Setup some macros for api.push-pull.
+## --------------- ##
+## api.push-pull.  ##
+## --------------- ##
+
 b4_percent_define_default([[api.push-pull]], [[pull]])
 b4_percent_define_check_values([[[[api.push-pull]],
                                  [[pull]], [[push]], [[both]]]])
@@ -52,7 +55,8 @@ b4_use_push_for_pull_if([
 # Define a macro to encapsulate the parse state variables.  This
 # allows them to be defined either in parse() when doing pull parsing,
 # or as class instance variable when doing push parsing.
-m4_define([b4_define_state],[[
+m4_define([b4_define_state],
+[[
     /* Lookahead token kind.  */
     int yychar = YYEMPTY_;
     /* Lookahead symbol kind.  */
@@ -74,17 +78,31 @@ m4_define([b4_define_state],[[
 
     /* Semantic value of the lookahead.  */
     ]b4_yystype[ yylval = null;
-]])[
+]])
 
-]b4_output_begin([b4_parser_file_name])[
+# parse.lac
+b4_percent_define_default([[parse.lac]], [[none]])
+b4_percent_define_check_values([[[[parse.lac]], [[full]], [[none]]]])
+b4_define_flag_if([lac])
+m4_define([b4_lac_flag],
+          [m4_if(b4_percent_define_get([[parse.lac]]),
+                 [none], [[0]], [[1]])])
+
+
+## ------------- ##
+## Parser File.  ##
+## ------------- ##
+
+b4_output_begin([b4_parser_file_name])[
 ]b4_copyright([Skeleton implementation for Bison LALR(1) parsers in Java],
-              [2007-2015, 2018-2020])[
+              [2007-2015, 2018-2021])[
 ]b4_disclaimer[
 ]b4_percent_define_ifdef([api.package], [package b4_percent_define_get([api.package]);[
 ]])[
 ]b4_user_pre_prologue[
 ]b4_user_post_prologue[
 import java.text.MessageFormat;
+import java.util.ArrayList;
 ]b4_percent_code_get([[imports]])[
 /**
  * A Bison parser, automatically generated from <tt>]m4_bpatsubst(b4_file_name, [^"\(.*\)"$], [\1])[</tt>.
@@ -157,11 +175,11 @@ import java.text.MessageFormat;
      * <code>]b4_position_type[</code> should override the <code>equals</code>
      * method.
      */
-    public String toString () {
+    public String toString() {
       if (begin.equals (end))
-        return begin.toString ();
+        return begin.toString();
       else
-        return begin.toString () + "-" + end.toString ();
+        return begin.toString() + "-" + end.toString();
     }
   }
 
@@ -181,8 +199,8 @@ import java.text.MessageFormat;
    */
   public interface Lexer {
 ]b4_token_enums[
-    /** Deprecated, use ]b4_symbol(0, id)[ instead.  */
-    public static final int EOF = ]b4_symbol(0, id)[;
+    /** Deprecated, use ]b4_symbol(eof, id)[ instead.  */
+    public static final int EOF = ]b4_symbol(eof, id)[;
 ]b4_pull_if([b4_locations_if([[
     /**
      * Method to retrieve the beginning position of the last scanned token.
@@ -226,7 +244,7 @@ import java.text.MessageFormat;
      *
      * @@param ctx  The context of the error.
      */
-     void reportSyntaxError (][Context ctx);
+     void reportSyntaxError(Context ctx);
 ]])[
   }
 
@@ -247,10 +265,12 @@ import java.text.MessageFormat;
   /**
    * Instantiates the Bison-generated parser.
    */
-  public ]b4_parser_class (b4_parse_param_decl([b4_lex_param_decl])[)]b4_maybe_throws([b4_init_throws])[
+  public ]b4_parser_class[(]b4_parse_param_decl([b4_lex_param_decl])[)]b4_maybe_throws([b4_init_throws])[
   {
-]b4_percent_code_get([[init]])[
-    this.yylexer = new YYLexer (]b4_lex_param_call[);
+]b4_percent_code_get([[init]])[]b4_lac_if([[
+    this.yylacStack = new ArrayList<Integer>();
+    this.yylacEstablished = false;]])[
+    this.yylexer = new YYLexer(]b4_lex_param_call[);
 ]b4_parse_param_cons[
   }
 ]])[
@@ -259,9 +279,11 @@ import java.text.MessageFormat;
    * Instantiates the Bison-generated parser.
    * @@param yylexer The scanner that will supply tokens to the parser.
    */
-  ]b4_lexer_if([[protected]], [[public]]) b4_parser_class[ (]b4_parse_param_decl([[Lexer yylexer]])[)]b4_maybe_throws([b4_init_throws])[
+  ]b4_lexer_if([[protected]], [[public]]) b4_parser_class[(]b4_parse_param_decl([[Lexer yylexer]])[)]b4_maybe_throws([b4_init_throws])[
   {
-]b4_percent_code_get([[init]])[
+]b4_percent_code_get([[init]])[]b4_lac_if([[
+    this.yylacStack = new ArrayList<Integer>();
+    this.yylacEstablished = false;]])[
     this.yylexer = yylexer;
 ]b4_parse_param_cons[
   }
@@ -272,13 +294,13 @@ import java.text.MessageFormat;
   /**
    * The <tt>PrintStream</tt> on which the debugging output is printed.
    */
-  public final java.io.PrintStream getDebugStream () { return yyDebugStream; }
+  public final java.io.PrintStream getDebugStream() { return yyDebugStream; }
 
   /**
    * Set the <tt>PrintStream</tt> on which the debug output is printed.
    * @@param s The stream that is used for debugging output.
    */
-  public final void setDebugStream (java.io.PrintStream s) { yyDebugStream = s; }
+  public final void setDebugStream(java.io.PrintStream s) { yyDebugStream = s; }
 
   private int yydebug = 0;
 
@@ -286,14 +308,14 @@ import java.text.MessageFormat;
    * Answer the verbosity of the debugging output; 0 means that all kinds of
    * output from the parser are suppressed.
    */
-  public final int getDebugLevel () { return yydebug; }
+  public final int getDebugLevel() { return yydebug; }
 
   /**
    * Set the verbosity of the debugging output; 0 means that all kinds of
    * output from the parser are suppressed.
    * @@param level The verbosity level for debugging output.
    */
-  public final void setDebugLevel (int level) { yydebug = level; }
+  public final void setDebugLevel(int level) { yydebug = level; }
 ]])[
 
   private int yynerrs = 0;
@@ -301,7 +323,7 @@ import java.text.MessageFormat;
   /**
    * The number of syntax errors so far.
    */
-  public final int getNumberOfErrors () { return yynerrs; }
+  public final int getNumberOfErrors() { return yynerrs; }
 
   /**
    * Print an error message via the lexer.
@@ -330,9 +352,14 @@ import java.text.MessageFormat;
       yylexer.yyerror(new ]b4_location_type[ (pos), msg);
   }]])[
 ]b4_parse_trace_if([[
-  protected final void yycdebug (String s) {
+  protected final void yycdebugNnl(String s) {
     if (0 < yydebug)
-      yyDebugStream.println (s);
+      yyDebugStream.print(s);
+  }
+
+  protected final void yycdebug(String s) {
+    if (0 < yydebug)
+      yyDebugStream.println(s);
   }]])[
 
   private final class YYStack {
@@ -343,65 +370,63 @@ import java.text.MessageFormat;
     public int size = 16;
     public int height = -1;
 
-    public final void push (int state, ]b4_yystype[ value]b4_locations_if([, ]b4_location_type[ loc])[) {
+    public final void push(int state, ]b4_yystype[ value]b4_locations_if([, ]b4_location_type[ loc])[) {
       height++;
-      if (size == height)
-        {
-          int[] newStateStack = new int[size * 2];
-          System.arraycopy (stateStack, 0, newStateStack, 0, height);
-          stateStack = newStateStack;]b4_locations_if([[
-          ]b4_location_type[[] newLocStack = new ]b4_location_type[[size * 2];
-          System.arraycopy (locStack, 0, newLocStack, 0, height);
-          locStack = newLocStack;]])
+      if (size == height) {
+        int[] newStateStack = new int[size * 2];
+        System.arraycopy(stateStack, 0, newStateStack, 0, height);
+        stateStack = newStateStack;]b4_locations_if([[
+        ]b4_location_type[[] newLocStack = new ]b4_location_type[[size * 2];
+        System.arraycopy(locStack, 0, newLocStack, 0, height);
+        locStack = newLocStack;]])
 
-          b4_yystype[[] newValueStack = new ]b4_yystype[[size * 2];
-          System.arraycopy (valueStack, 0, newValueStack, 0, height);
-          valueStack = newValueStack;
+        b4_yystype[[] newValueStack = new ]b4_yystype[[size * 2];
+        System.arraycopy(valueStack, 0, newValueStack, 0, height);
+        valueStack = newValueStack;
 
-          size *= 2;
-        }
+        size *= 2;
+      }
 
       stateStack[height] = state;]b4_locations_if([[
       locStack[height] = loc;]])[
       valueStack[height] = value;
     }
 
-    public final void pop () {
-      pop (1);
+    public final void pop() {
+      pop(1);
     }
 
-    public final void pop (int num) {
+    public final void pop(int num) {
       // Avoid memory leaks... garbage collection is a white lie!
       if (0 < num) {
-        java.util.Arrays.fill (valueStack, height - num + 1, height + 1, null);]b4_locations_if([[
-        java.util.Arrays.fill (locStack, height - num + 1, height + 1, null);]])[
+        java.util.Arrays.fill(valueStack, height - num + 1, height + 1, null);]b4_locations_if([[
+        java.util.Arrays.fill(locStack, height - num + 1, height + 1, null);]])[
       }
       height -= num;
     }
 
-    public final int stateAt (int i) {
+    public final int stateAt(int i) {
       return stateStack[height - i];
     }
 ]b4_locations_if([[
 
-    public final ]b4_location_type[ locationAt (int i) {
+    public final ]b4_location_type[ locationAt(int i) {
       return locStack[height - i];
     }
 ]])[
-    public final ]b4_yystype[ valueAt (int i) {
+    public final ]b4_yystype[ valueAt(int i) {
       return valueStack[height - i];
     }
 
     // Print the state stack on the debug stream.
-    public void print (java.io.PrintStream out) {
+    public void print(java.io.PrintStream out) {
       out.print ("Stack now");
 
-      for (int i = 0; i <= height; i++)
-        {
-          out.print (' ');
-          out.print (stateStack[i]);
-        }
-      out.println ();
+      for (int i = 0; i <= height; i++) {
+        out.print(' ');
+        out.print(stateStack[i]);
+      }
+      out.println();
     }
   }
 
@@ -458,8 +483,7 @@ import java.text.MessageFormat;
    * @@param yystate   the current state
    * @@param yysym     the nonterminal to push on the stack
    */
-  private int yyLRGotoState (int yystate, int yysym)
-  {
+  private int yyLRGotoState(int yystate, int yysym) {
     int yyr = yypgoto_[yysym - YYNTOKENS_] + yystate;
     if (0 <= yyr && yyr <= YYLAST_ && yycheck_[yyr] == yystate)
       return yytable_[yyr];
@@ -536,7 +560,12 @@ import java.text.MessageFormat;
     /* @@$.  */
     ]b4_location_type[ yyloc;]])[
 ]b4_push_if([],[[
-]b4_define_state[]b4_parse_trace_if([[
+]b4_define_state[
+]b4_lac_if([[
+    // Discard the LAC context in case there still is one left from a
+    // previous invocation.
+    yylacDiscard("init");]])[
+]b4_parse_trace_if([[
     yycdebug ("Starting parse");]])[
     yyerrstatus_ = 0;
     yynerrs = 0;
@@ -614,14 +643,14 @@ b4_dollar_popdef[]dnl
         yySymbolPrint("Next token is", yytoken,
                       yylval]b4_locations_if([, yylloc])[);]])[
 
-        if (yytoken == ]b4_symbol(1, kind)[)
+        if (yytoken == ]b4_symbol(error, kind)[)
           {
             // The scanner already issued an error message, process directly
             // to error recovery.  But do not keep the error token as
             // lookahead, it is too special and may lead us to an endless
             // loop in error recovery. */
-            yychar = Lexer.]b4_symbol(2, id)[;
-            yytoken = ]b4_symbol(2, kind)[;]b4_locations_if([[
+            yychar = Lexer.]b4_symbol(undef, id)[;
+            yytoken = ]b4_symbol(undef, kind)[;]b4_locations_if([[
             yyerrloc = yylloc;]])[
             label = YYERRLAB1;
           }
@@ -630,19 +659,24 @@ b4_dollar_popdef[]dnl
             /* If the proper action on seeing token YYTOKEN is to reduce or to
                detect an error, take that action.  */
             yyn += yytoken.getCode();
-            if (yyn < 0 || YYLAST_ < yyn || yycheck_[yyn] != yytoken.getCode())
+            if (yyn < 0 || YYLAST_ < yyn || yycheck_[yyn] != yytoken.getCode()) {]b4_lac_if([[
+              if (!yylacEstablish(yystack, yytoken)) {
+                label = YYERRLAB;
+              } else]])[
               label = YYDEFAULT;
+            }
 
             /* <= 0 means reduce or error.  */
             else if ((yyn = yytable_[yyn]) <= 0)
               {
-                if (yyTableValueIsError (yyn))
+                if (yyTableValueIsError(yyn)) {
                   label = YYERRLAB;
-                else
-                  {
-                    yyn = -yyn;
-                    label = YYREDUCE;
-                  }
+                }]b4_lac_if([[ else if (!yylacEstablish(yystack, yytoken)) {
+                  label = YYERRLAB;
+                }]])[ else {
+                  yyn = -yyn;
+                  label = YYREDUCE;
+                }
               }
 
             else
@@ -660,7 +694,8 @@ b4_dollar_popdef[]dnl
                   --yyerrstatus_;
 
                 yystate = yyn;
-                yystack.push (yystate, yylval]b4_locations_if([, yylloc])[);
+                yystack.push(yystate, yylval]b4_locations_if([, yylloc])[);]b4_lac_if([[
+                yylacDiscard("shift");]])[
                 label = YYNEWSTATE;
               }
           }
@@ -683,7 +718,7 @@ b4_dollar_popdef[]dnl
       case YYREDUCE:
         yylen = yyr2_[yyn];
         label = yyaction(yyn, yystack, yylen);
-        yystate = yystack.stateAt (0);
+        yystate = yystack.stateAt(0);
         break;
 
       /*------------------------------------.
@@ -696,7 +731,7 @@ b4_dollar_popdef[]dnl
             ++yynerrs;
             if (yychar == YYEMPTY_)
               yytoken = null;
-            yyreportSyntaxError (new Context (yystack, yytoken]b4_locations_if([[, yylloc]])[));
+            yyreportSyntaxError(new Context(this, yystack, yytoken]b4_locations_if([[, yylloc]])[));
           }
 ]b4_locations_if([[
         yyerrloc = yylloc;]])[
@@ -705,10 +740,10 @@ b4_dollar_popdef[]dnl
             /* If just tried and failed to reuse lookahead token after an
                error, discard it.  */
 
-            if (yychar <= Lexer.]b4_symbol(0, id)[)
+            if (yychar <= Lexer.]b4_symbol(eof, id)[)
               {
                 /* Return failure if at end of input.  */
-                if (yychar == Lexer.]b4_symbol(0, id)[)
+                if (yychar == Lexer.]b4_symbol(eof, id)[)
                   ]b4_push_if([{label = YYABORT; break;}], [return false;])[
               }
             else
@@ -729,7 +764,7 @@ b4_dollar_popdef[]dnl
            this YYERROR.  */
         yystack.pop (yylen);
         yylen = 0;
-        yystate = yystack.stateAt (0);
+        yystate = yystack.stateAt(0);
         label = YYERRLAB1;
         break;
 
@@ -745,9 +780,9 @@ b4_dollar_popdef[]dnl
             yyn = yypact_[yystate];
             if (!yyPactValueIsDefault (yyn))
               {
-                yyn += ]b4_symbol(1, kind)[.getCode();
+                yyn += ]b4_symbol(error, kind)[.getCode();
                 if (0 <= yyn && yyn <= YYLAST_
-                    && yycheck_[yyn] == ]b4_symbol(1, kind)[.getCode())
+                    && yycheck_[yyn] == ]b4_symbol(error, kind)[.getCode())
                   {
                     yyn = yytable_[yyn];
                     if (0 < yyn)
@@ -763,7 +798,7 @@ b4_dollar_popdef[]dnl
 ]b4_locations_if([[
             yyerrloc = yystack.locationAt (0);]])[
             yystack.pop ();
-            yystate = yystack.stateAt (0);]b4_parse_trace_if([[
+            yystate = yystack.stateAt(0);]b4_parse_trace_if([[
             if (0 < yydebug)
               yystack.print (yyDebugStream);]])[
           }
@@ -779,7 +814,8 @@ b4_dollar_popdef[]dnl
         yyloc = yylloc (yystack, 2);
         yystack.pop (2);]])[
 
-        /* Shift the error token.  */]b4_parse_trace_if([[
+        /* Shift the error token.  */]b4_lac_if([[
+        yylacDiscard("error recovery");]])[]b4_parse_trace_if([[
         yySymbolPrint("Shifting", SymbolKind.get(yystos_[yyn]),
                       yylval]b4_locations_if([, yyloc])[);]])[
 
@@ -815,7 +851,9 @@ b4_dollar_popdef[]dnl
     this.yyn = 0;
     this.yylen = 0;
     this.yystate = 0;
-    this.yystack = new YYStack ();
+    this.yystack = new YYStack();]b4_lac_if([[
+    this.yylacStack = new ArrayList<Integer>();
+    this.yylacEstablished = false;]])[
     this.label = YYNEWSTATE;
 
     /* Error handling.  */
@@ -875,23 +913,22 @@ b4_dollar_popdef[]dnl
    * Information needed to get the list of expected tokens and to forge
    * a syntax error diagnostic.
    */
-  public static final class Context
-  {
-    Context (YYStack stack, SymbolKind token]b4_locations_if([[, ]b4_location_type[ loc]])[)
-    {
+  public static final class Context {
+    Context(]b4_parser_class[ parser, YYStack stack, SymbolKind token]b4_locations_if([[, ]b4_location_type[ loc]])[) {
+      yyparser = parser;
       yystack = stack;
       yytoken = token;]b4_locations_if([[
       yylocation = loc;]])[
     }
 
+    private ]b4_parser_class[ yyparser;
     private YYStack yystack;
 
 
     /**
      * The symbol kind of the lookahead token.
      */
-    public final SymbolKind getToken ()
-    {
+    public final SymbolKind getToken() {
       return yytoken;
     }
 
@@ -900,8 +937,7 @@ b4_dollar_popdef[]dnl
     /**
      * The location of the lookahead.
      */
-    public final ]b4_location_type[ getLocation ()
-    {
+    public final ]b4_location_type[ getLocation() {
       return yylocation;
     }
 
@@ -914,16 +950,34 @@ b4_dollar_popdef[]dnl
      * YYARG is null, return the number of expected tokens (guaranteed to
      * be less than YYNTOKENS).
      */
-    int getExpectedTokens (SymbolKind yyarg[], int yyargn)
-    {
+    int getExpectedTokens(SymbolKind yyarg[], int yyargn) {
       return getExpectedTokens (yyarg, 0, yyargn);
     }
 
-    int getExpectedTokens (SymbolKind yyarg[], int yyoffset, int yyargn)
-    {
-      int yycount = yyoffset;
-      int yyn = yypact_[this.yystack.stateAt (0)];
-      if (!yyPactValueIsDefault (yyn))
+    int getExpectedTokens(SymbolKind yyarg[], int yyoffset, int yyargn) {
+      int yycount = yyoffset;]b4_lac_if([b4_parse_trace_if([[
+      // Execute LAC once. We don't care if it is successful, we
+      // only do it for the sake of debugging output.
+      if (!yyparser.yylacEstablished)
+        yyparser.yylacCheck(yystack, yytoken);
+]])[
+      for (int yyx = 0; yyx < YYNTOKENS_; ++yyx)
+        {
+          SymbolKind yysym = SymbolKind.get(yyx);
+          if (yysym != ]b4_symbol(error, kind)[
+              && yysym != ]b4_symbol(undef, kind)[
+              && yyparser.yylacCheck(yystack, yysym))
+            {
+              if (yyarg == null)
+                yycount += 1;
+              else if (yycount == yyargn)
+                return 0;
+              else
+                yyarg[yycount++] = yysym;
+            }
+        }]], [[
+      int yyn = yypact_[this.yystack.stateAt(0)];
+      if (!yyPactValueIsDefault(yyn))
         {
           /* Start YYX at -YYN if negative to avoid negative
              indexes in YYCHECK.  In other words, skip the first
@@ -934,7 +988,7 @@ b4_dollar_popdef[]dnl
           int yychecklim = YYLAST_ - yyn + 1;
           int yyxend = yychecklim < NTOKENS ? yychecklim : NTOKENS;
           for (int yyx = yyxbegin; yyx < yyxend; ++yyx)
-            if (yycheck_[yyx + yyn] == yyx && yyx != ]b4_symbol(1, kind)[.getCode()
+            if (yycheck_[yyx + yyn] == yyx && yyx != ]b4_symbol(error, kind)[.getCode()
                 && !yyTableValueIsError(yytable_[yyx + yyn]))
               {
                 if (yyarg == null)
@@ -944,17 +998,158 @@ b4_dollar_popdef[]dnl
                 else
                   yyarg[yycount++] = SymbolKind.get(yyx);
               }
-        }
+        }]])[
       if (yyarg != null && yycount == yyoffset && yyoffset < yyargn)
         yyarg[yycount] = null;
       return yycount - yyoffset;
     }
   }
 
+]b4_lac_if([[
+    /** Check the lookahead yytoken.
+     * \returns  true iff the token will be eventually shifted.
+     */
+    boolean yylacCheck(YYStack yystack, SymbolKind yytoken)
+    {
+      // Logically, the yylacStack's lifetime is confined to this function.
+      // Clear it, to get rid of potential left-overs from previous call.
+      yylacStack.clear();
+      // Reduce until we encounter a shift and thereby accept the token.
+      yycdebugNnl("LAC: checking lookahead " + yytoken.getName() + ":");
+      int lacTop = 0;
+      while (true)
+        {
+          int topState = (yylacStack.isEmpty()
+                          ? yystack.stateAt(lacTop)
+                          : yylacStack.get(yylacStack.size() - 1));
+          int yyrule = yypact_[topState];
+          if (yyPactValueIsDefault(yyrule)
+              || (yyrule += yytoken.getCode()) < 0 || YYLAST_ < yyrule
+              || yycheck_[yyrule] != yytoken.getCode())
+            {
+              // Use the default action.
+              yyrule = yydefact_[+topState];
+              if (yyrule == 0) {
+                yycdebug(" Err");
+                return false;
+              }
+            }
+          else
+            {
+              // Use the action from yytable.
+              yyrule = yytable_[yyrule];
+              if (yyTableValueIsError(yyrule)) {
+                yycdebug(" Err");
+                return false;
+              }
+              if (0 < yyrule) {
+                yycdebug(" S" + yyrule);
+                return true;
+              }
+              yyrule = -yyrule;
+            }
+          // By now we know we have to simulate a reduce.
+          yycdebugNnl(" R" + (yyrule - 1));
+          // Pop the corresponding number of values from the stack.
+          {
+            int yylen = yyr2_[yyrule];
+            // First pop from the LAC stack as many tokens as possible.
+            int lacSize = yylacStack.size();
+            if (yylen < lacSize) {
+              // yylacStack.setSize(lacSize - yylen);
+              for (/* Nothing */; 0 < yylen; yylen -= 1) {
+                yylacStack.remove(yylacStack.size() - 1);
+              }
+              yylen = 0;
+            } else if (lacSize != 0) {
+              yylacStack.clear();
+              yylen -= lacSize;
+            }
+            // Only afterwards look at the main stack.
+            // We simulate popping elements by incrementing lacTop.
+            lacTop += yylen;
+          }
+          // Keep topState in sync with the updated stack.
+          topState = (yylacStack.isEmpty()
+                      ? yystack.stateAt(lacTop)
+                      : yylacStack.get(yylacStack.size() - 1));
+          // Push the resulting state of the reduction.
+          int state = yyLRGotoState(topState, yyr1_[yyrule]);
+          yycdebugNnl(" G" + state);
+          yylacStack.add(state);
+        }
+    }
+
+    /** Establish the initial context if no initial context currently exists.
+     * \returns  true iff the token will be eventually shifted.
+     */
+    boolean yylacEstablish(YYStack yystack, SymbolKind yytoken) {
+      /* Establish the initial context for the current lookahead if no initial
+         context is currently established.
+
+         We define a context as a snapshot of the parser stacks.  We define
+         the initial context for a lookahead as the context in which the
+         parser initially examines that lookahead in order to select a
+         syntactic action.  Thus, if the lookahead eventually proves
+         syntactically unacceptable (possibly in a later context reached via a
+         series of reductions), the initial context can be used to determine
+         the exact set of tokens that would be syntactically acceptable in the
+         lookahead's place.  Moreover, it is the context after which any
+         further semantic actions would be erroneous because they would be
+         determined by a syntactically unacceptable token.
+
+         yylacEstablish should be invoked when a reduction is about to be
+         performed in an inconsistent state (which, for the purposes of LAC,
+         includes consistent states that don't know they're consistent because
+         their default reductions have been disabled).
+
+         For parse.lac=full, the implementation of yylacEstablish is as
+         follows.  If no initial context is currently established for the
+         current lookahead, then check if that lookahead can eventually be
+         shifted if syntactic actions continue from the current context.  */
+      if (yylacEstablished) {
+        return true;
+      } else {
+        yycdebug("LAC: initial context established for " + yytoken.getName());
+        yylacEstablished = true;
+        return yylacCheck(yystack, yytoken);
+      }
+    }
+
+    /** Discard any previous initial lookahead context because of event.
+     * \param event  the event which caused the lookahead to be discarded.
+     *               Only used for debbuging output.  */
+    void yylacDiscard(String event) {
+     /* Discard any previous initial lookahead context because of Event,
+        which may be a lookahead change or an invalidation of the currently
+        established initial context for the current lookahead.
+
+        The most common example of a lookahead change is a shift.  An example
+        of both cases is syntax error recovery.  That is, a syntax error
+        occurs when the lookahead is syntactically erroneous for the
+        currently established initial context, so error recovery manipulates
+        the parser stacks to try to find a new initial context in which the
+        current lookahead is syntactically acceptable.  If it fails to find
+        such a context, it discards the lookahead.  */
+      if (yylacEstablished) {
+        yycdebug("LAC: initial context discarded due to " + event);
+        yylacEstablished = false;
+      }
+    }
+
+    /** The stack for LAC.
+     * Logically, the yylacStack's lifetime is confined to the function
+     * yylacCheck. We just store it as a member of this class to hold
+     * on to the memory and to avoid frequent reallocations.
+     */
+    ArrayList<Integer> yylacStack;
+    /**  Whether an initial LAC context was established. */
+    boolean yylacEstablished;
+]])[
+
 ]b4_parse_error_bmatch(
 [detailed\|verbose], [[
-  private int yysyntaxErrorArguments (Context yyctx, SymbolKind[] yyarg, int yyargn)
-  {
+  private int yysyntaxErrorArguments(Context yyctx, SymbolKind[] yyarg, int yyargn) {
     /* There are many possibilities here to consider:
        - If this state is a consistent state with a default action,
          then the only way this function was invoked is if the
@@ -1032,8 +1227,7 @@ b4_dollar_popdef[]dnl
    * Whether the given <code>yypact_</code> value indicates a defaulted state.
    * @@param yyvalue   the value to check
    */
-  private static boolean yyPactValueIsDefault (int yyvalue)
-  {
+  private static boolean yyPactValueIsDefault(int yyvalue) {
     return yyvalue == yypact_ninf_;
   }
 
@@ -1042,8 +1236,7 @@ b4_dollar_popdef[]dnl
    * value indicates a syntax error.
    * @@param yyvalue the value to check
    */
-  private static boolean yyTableValueIsError (int yyvalue)
-  {
+  private static boolean yyTableValueIsError(int yyvalue) {
     return yyvalue == yytable_ninf_;
   }
 
@@ -1072,7 +1265,7 @@ b4_dollar_popdef[]dnl
     /* The symbols being reduced.  */
     for (int yyi = 0; yyi < yynrhs; yyi++)
       yySymbolPrint("   $" + (yyi + 1) + " =",
-                    SymbolKind.get(yystos_[yystack.stateAt (yynrhs - (yyi + 1))]),
+                    SymbolKind.get(yystos_[yystack.stateAt(yynrhs - (yyi + 1))]),
                     ]b4_rhs_data(yynrhs, yyi + 1)b4_locations_if([,
                     b4_rhs_location(yynrhs, yyi + 1)])[);
   }]])[
@@ -1089,11 +1282,11 @@ b4_dollar_popdef[]dnl
     // Last valid token kind.
     int code_max = ]b4_code_max[;
     if (t <= 0)
-      return ]b4_symbol(0, kind)[;
+      return ]b4_symbol(eof, kind)[;
     else if (t <= code_max)
       return SymbolKind.get(yytranslate_table_[t]);
     else
-      return ]b4_symbol(2, kind)[;
+      return ]b4_symbol(undef, kind)[;
   }
   ]b4_integral_parser_table_define([translate_table], [b4_translate])[
 ]])[

data/skeletons/location.cc

@@ -1,6 +1,6 @@
 # C++ skeleton for Bison
 
-# Copyright (C) 2002-2015, 2018-2020 Free Software Foundation, Inc.
+# Copyright (C) 2002-2015, 2018-2021 Free Software Foundation, Inc.
 
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -13,17 +13,10 @@
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 m4_pushdef([b4_copyright_years],
-           [2002-2015, 2018-2020])
-
-
-# b4_position_file
-# ----------------
-# Name of the file containing the position class, if we want this file.
-b4_defines_if([b4_required_version_if([302], [],
-                                      [m4_define([b4_position_file], [position.hh])])])])
+           [2002-2015, 2018-2021])
 
 
 # b4_location_file
@@ -32,7 +25,7 @@ b4_defines_if([b4_required_version_if([302], [],
 # if we want this file.
 b4_percent_define_check_file([b4_location_file],
                              [[api.location.file]],
-                             b4_defines_if([[location.hh]]))
+                             b4_header_if([[location.hh]]))
 
 # b4_location_include
 # -------------------
@@ -54,6 +47,16 @@ m4_ifdef([b4_location_file],
  ])
 
 
+# b4_position_file
+# ----------------
+# Name of the file containing the position class, if we want this file.
+b4_header_if(
+  [b4_required_version_if(
+    [30200], [],
+    [m4_ifdef([b4_location_file],
+              [m4_define([b4_position_file], [position.hh])])])])
+
+
 
 # b4_location_define
 # ------------------

data/skeletons/stack.hh

@@ -1,6 +1,6 @@
 # C++ skeleton for Bison
 
-# Copyright (C) 2002-2015, 2018-2020 Free Software Foundation, Inc.
+# Copyright (C) 2002-2015, 2018-2021 Free Software Foundation, Inc.
 
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -13,14 +13,14 @@
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 
 # b4_stack_file
 # -------------
 # Name of the file containing the stack class, if we want this file.
-b4_defines_if([b4_required_version_if([302], [],
-                                      [m4_define([b4_stack_file], [stack.hh])])])
+b4_header_if([b4_required_version_if([30200], [],
+                                     [m4_define([b4_stack_file], [stack.hh])])])
 
 
 # b4_stack_define

data/skeletons/variant.hh

@@ -1,6 +1,6 @@
 # C++ skeleton for Bison
 
-# Copyright (C) 2002-2015, 2018-2020 Free Software Foundation, Inc.
+# Copyright (C) 2002-2015, 2018-2021 Free Software Foundation, Inc.
 
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -13,13 +13,20 @@
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 
 ## --------- ##
 ## variant.  ##
 ## --------- ##
 
+# b4_assert
+# ---------
+# The name of YY_ASSERT.
+m4_define([b4_assert],
+          [b4_api_PREFIX[]_ASSERT])
+
+
 # b4_symbol_variant(YYTYPE, YYVAL, ACTION, [ARGS])
 # ------------------------------------------------
 # Run some ACTION ("build", or "destroy") on YYVAL of symbol type
@@ -71,12 +78,12 @@ m4_map([      b4_symbol_tag_comment], [$@])dnl
 # -------------------
 # The needed includes for variants support.
 m4_define([b4_variant_includes],
-[b4_parse_assert_if([[#include <typeinfo>]])[
-#ifndef YY_ASSERT
+[b4_parse_assert_if([[#include <typeinfo>
+#ifndef ]b4_assert[
 # include <cassert>
-# define YY_ASSERT assert
+# define ]b4_assert[ assert
 #endif
-]])
+]])])
 
 
 
@@ -87,45 +94,45 @@ m4_define([b4_variant_includes],
 
 # b4_value_type_declare
 # ---------------------
-# Define semantic_type.
+# Define value_type.
 m4_define([b4_value_type_declare],
 [[  /// A buffer to store and retrieve objects.
   ///
   /// Sort of a variant, but does not keep track of the nature
   /// of the stored data, since that knowledge is available
   /// via the current parser state.
-  class semantic_type
+  class value_type
   {
   public:
     /// Type of *this.
-    typedef semantic_type self_type;
+    typedef value_type self_type;
 
     /// Empty construction.
-    semantic_type () YY_NOEXCEPT
-      : yybuffer_ ()]b4_parse_assert_if([
+    value_type () YY_NOEXCEPT
+      : yyraw_ ()]b4_parse_assert_if([
       , yytypeid_ (YY_NULLPTR)])[
     {}
 
     /// Construct and fill.
     template <typename T>
-    semantic_type (YY_RVREF (T) t)]b4_parse_assert_if([
+    value_type (YY_RVREF (T) t)]b4_parse_assert_if([
       : yytypeid_ (&typeid (T))])[
-    {
-      YY_ASSERT (sizeof (T) <= size);
+    {]b4_parse_assert_if([[
+      ]b4_assert[ (sizeof (T) <= size);]])[
       new (yyas_<T> ()) T (YY_MOVE (t));
     }
 
 #if 201103L <= YY_CPLUSPLUS
     /// Non copyable.
-    semantic_type (const self_type&) = delete;
+    value_type (const self_type&) = delete;
     /// Non copyable.
     self_type& operator= (const self_type&) = delete;
 #endif
 
     /// Destruction, allowed only if empty.
-    ~semantic_type () YY_NOEXCEPT
+    ~value_type () YY_NOEXCEPT
     {]b4_parse_assert_if([
-      YY_ASSERT (!yytypeid_);
+      ]b4_assert[ (!yytypeid_);
     ])[}
 
 # if 201103L <= YY_CPLUSPLUS
@@ -133,10 +140,10 @@ m4_define([b4_value_type_declare],
     template <typename T, typename... U>
     T&
     emplace (U&&... u)
-    {]b4_parse_assert_if([
-      YY_ASSERT (!yytypeid_);
-      YY_ASSERT (sizeof (T) <= size);
-      yytypeid_ = & typeid (T);])[
+    {]b4_parse_assert_if([[
+      ]b4_assert[ (!yytypeid_);
+      ]b4_assert[ (sizeof (T) <= size);
+      yytypeid_ = & typeid (T);]])[
       return *new (yyas_<T> ()) T (std::forward <U>(u)...);
     }
 # else
@@ -144,10 +151,10 @@ m4_define([b4_value_type_declare],
     template <typename T>
     T&
     emplace ()
-    {]b4_parse_assert_if([
-      YY_ASSERT (!yytypeid_);
-      YY_ASSERT (sizeof (T) <= size);
-      yytypeid_ = & typeid (T);])[
+    {]b4_parse_assert_if([[
+      ]b4_assert[ (!yytypeid_);
+      ]b4_assert[ (sizeof (T) <= size);
+      yytypeid_ = & typeid (T);]])[
       return *new (yyas_<T> ()) T ();
     }
 
@@ -155,10 +162,10 @@ m4_define([b4_value_type_declare],
     template <typename T>
     T&
     emplace (const T& t)
-    {]b4_parse_assert_if([
-      YY_ASSERT (!yytypeid_);
-      YY_ASSERT (sizeof (T) <= size);
-      yytypeid_ = & typeid (T);])[
+    {]b4_parse_assert_if([[
+      ]b4_assert[ (!yytypeid_);
+      ]b4_assert[ (sizeof (T) <= size);
+      yytypeid_ = & typeid (T);]])[
       return *new (yyas_<T> ()) T (t);
     }
 # endif
@@ -185,10 +192,10 @@ m4_define([b4_value_type_declare],
     template <typename T>
     T&
     as () YY_NOEXCEPT
-    {]b4_parse_assert_if([
-      YY_ASSERT (yytypeid_);
-      YY_ASSERT (*yytypeid_ == typeid (T));
-      YY_ASSERT (sizeof (T) <= size);])[
+    {]b4_parse_assert_if([[
+      ]b4_assert[ (yytypeid_);
+      ]b4_assert[ (*yytypeid_ == typeid (T));
+      ]b4_assert[ (sizeof (T) <= size);]])[
       return *yyas_<T> ();
     }
 
@@ -196,10 +203,10 @@ m4_define([b4_value_type_declare],
     template <typename T>
     const T&
     as () const YY_NOEXCEPT
-    {]b4_parse_assert_if([
-      YY_ASSERT (yytypeid_);
-      YY_ASSERT (*yytypeid_ == typeid (T));
-      YY_ASSERT (sizeof (T) <= size);])[
+    {]b4_parse_assert_if([[
+      ]b4_assert[ (yytypeid_);
+      ]b4_assert[ (*yytypeid_ == typeid (T));
+      ]b4_assert[ (sizeof (T) <= size);]])[
       return *yyas_<T> ();
     }
 
@@ -214,9 +221,9 @@ m4_define([b4_value_type_declare],
     template <typename T>
     void
     swap (self_type& that) YY_NOEXCEPT
-    {]b4_parse_assert_if([
-      YY_ASSERT (yytypeid_);
-      YY_ASSERT (*yytypeid_ == *that.yytypeid_);])[
+    {]b4_parse_assert_if([[
+      ]b4_assert[ (yytypeid_);
+      ]b4_assert[ (*yytypeid_ == *that.yytypeid_);]])[
       std::swap (as<T> (), that.as<T> ());
     }
 
@@ -267,7 +274,7 @@ m4_define([b4_value_type_declare],
   private:
 #if YY_CPLUSPLUS < 201103L
     /// Non copyable.
-    semantic_type (const self_type&);
+    value_type (const self_type&);
     /// Non copyable.
     self_type& operator= (const self_type&);
 #endif
@@ -277,7 +284,7 @@ m4_define([b4_value_type_declare],
     T*
     yyas_ () YY_NOEXCEPT
     {
-      void *yyp = yybuffer_.yyraw;
+      void *yyp = yyraw_;
       return static_cast<T*> (yyp);
      }
 
@@ -286,7 +293,7 @@ m4_define([b4_value_type_declare],
     const T*
     yyas_ () const YY_NOEXCEPT
     {
-      const void *yyp = yybuffer_.yyraw;
+      const void *yyp = yyraw_;
       return static_cast<const T*> (yyp);
      }
 
@@ -301,10 +308,10 @@ m4_define([b4_value_type_declare],
     union
     {
       /// Strongest alignment constraints.
-      long double yyalign_me;
+      long double yyalign_me_;
       /// A buffer large enough to store any of the semantic values.
-      char yyraw[size];
-    } yybuffer_;]b4_parse_assert_if([
+      char yyraw_[size];
+    };]b4_parse_assert_if([
 
     /// Whether the content is built: if defined, the name of the stored type.
     const std::type_info *yytypeid_;])[
@@ -388,18 +395,74 @@ m4_define([_b4_token_maker_define],
 ])])
 
 
-m4_define([_b4_type_clause],
-[b4_symbol_if([$1], [is_token],
-              [b4_symbol_if([$1], [has_id],
-                            [tok == token::b4_symbol([$1], [id])],
-                            [tok == b4_symbol([$1], [code])])])])
+# b4_token_kind(SYMBOL-NUM)
+# -------------------------
+# Some tokens don't have an ID.
+m4_define([b4_token_kind],
+[b4_symbol_if([$1], [has_id],
+              [token::b4_symbol([$1], [id])],
+              [b4_symbol([$1], [code])])])
 
 
-# _b4_token_constructor_define(SYMBOL-NUM...)
-# -------------------------------------------
-# Define a unique make_symbol for all the SYMBOL-NUM (they
+# _b4_tok_in(SYMBOL-NUM, ...)
+# ---------------------------
+# See b4_tok_in below.  The SYMBOL-NUMs... are tokens only.
+#
+# We iterate over the tokens to group them by "range" of token numbers (not
+# symbols numbers!).
+#
+# b4_fst is the start of that range.
+# b4_prev is the previous value.
+# b4_val is the current value.
+# If b4_val is the successor of b4_prev in token numbers, update the latter,
+#   otherwise emit the code for range b4_fst .. b4_prev.
+# $1 is also used as a terminator in the foreach, but it will not be printed.
+#
+m4_define([_b4_tok_in],
+[m4_pushdef([b4_prev], [$1])dnl
+m4_pushdef([b4_fst], [$1])dnl
+m4_pushdef([b4_sep], [])dnl
+m4_foreach([b4_val], m4_dquote(m4_shift($@, $1)),
+           [m4_if(b4_symbol(b4_val, [code]), m4_eval(b4_symbol(b4_prev, [code]) + 1), [],
+                  [b4_sep[]m4_if(b4_fst, b4_prev,
+                         [tok == b4_token_kind(b4_fst)],
+                         [(b4_token_kind(b4_fst) <= tok && tok <= b4_token_kind(b4_prev))])[]dnl
+m4_define([b4_fst], b4_val)dnl
+m4_define([b4_sep], [
+                   || ])])dnl
+m4_define([b4_prev], b4_val)])dnl
+m4_popdef([b4_sep])dnl
+m4_popdef([b4_fst])dnl
+m4_popdef([b4_prev])dnl
+])
+
+
+# _b4_filter_tokens(SYMBOL-NUM, ...)
+# ----------------------------------
+# Expand as the list of tokens amongst SYMBOL-NUM.
+m4_define([_b4_filter_tokens],
+[m4_pushdef([b4_sep])dnl
+m4_foreach([b4_val], [$@],
+           [b4_symbol_if(b4_val, [is_token], [b4_sep[]b4_val[]m4_define([b4_sep], [,])])])dnl
+m4_popdef([b4_sep])dnl
+])
+
+
+# b4_tok_in(SYMBOL-NUM, ...)
+# ---------------------------
+# A C++ conditional that checks that `tok` is a member of this list of symbol
+# numbers.
+m4_define([b4_tok_in],
+          [_$0(_b4_filter_tokens($@))])
+
+
+
+
+# _b4_symbol_constructor_define(SYMBOL-NUM...)
+# --------------------------------------------
+# Define a symbol_type constructor common to all the SYMBOL-NUM (they
 # have the same type).  Use at class-level.
-m4_define([_b4_token_constructor_define],
+m4_define([_b4_symbol_constructor_define],
 [m4_ifval(_b4_includes_tokens($@),
 [[#if 201103L <= YY_CPLUSPLUS
       symbol_type (]b4_join(
@@ -407,25 +470,24 @@ m4_define([_b4_token_constructor_define],
           b4_symbol_if([$1], [has_type],
                        [b4_symbol([$1], [type]) v]),
           b4_locations_if([location_type l]))[)
-        : super_type(]b4_join([token_type (tok)],
-                              b4_symbol_if([$1], [has_type], [std::move (v)]),
-                              b4_locations_if([std::move (l)]))[)
-      {
-        YY_ASSERT (]m4_join([ || ], m4_map_sep([_b4_type_clause], [, ], [$@]))[);
-      }
+        : super_type (]b4_join([token_type (tok)],
+                               b4_symbol_if([$1], [has_type], [std::move (v)]),
+                               b4_locations_if([std::move (l)]))[)
 #else
       symbol_type (]b4_join(
           [int tok],
           b4_symbol_if([$1], [has_type],
                        [const b4_symbol([$1], [type])& v]),
           b4_locations_if([const location_type& l]))[)
-        : super_type(]b4_join([token_type (tok)],
-                              b4_symbol_if([$1], [has_type], [v]),
-                              b4_locations_if([l]))[)
-      {
-        YY_ASSERT (]m4_join([ || ], m4_map_sep([_b4_type_clause], [, ], [$@]))[);
-      }
+        : super_type (]b4_join([token_type (tok)],
+                               b4_symbol_if([$1], [has_type], [v]),
+                               b4_locations_if([l]))[)
 #endif
+      {]b4_parse_assert_if([[
+#if !defined _MSC_VER || defined __clang__
+        ]b4_assert[ (]b4_tok_in($@)[);
+#endif
+      ]])[}
 ]])])
 
 
@@ -457,7 +519,7 @@ m4_define([b4_basic_symbol_constructor_define],
 
 # b4_token_constructor_define
 # ---------------------------
-# Define the overloaded versions of make_symbol for all the value types.
+# Define the overloaded versions of make_FOO for all the token kinds.
 m4_define([b4_token_constructor_define],
-[    // Implementation of make_symbol for each symbol type.
+[    // Implementation of make_symbol for each token kind.
 b4_symbol_foreach([_b4_token_maker_define])])

data/skeletons/yacc.c

@@ -1,11 +1,11 @@
 #                                                            -*- C -*-
 # Yacc compatible skeleton for Bison
 
-# Copyright (C) 1984, 1989-1990, 2000-2015, 2018-2020 Free Software
+# Copyright (C) 1984, 1989-1990, 2000-2015, 2018-2021 Free Software
 # Foundation, Inc.
 
 m4_pushdef([b4_copyright_years],
-           [1984, 1989-1990, 2000-2015, 2018-2020])
+           [1984, 1989-1990, 2000-2015, 2018-2021])
 
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -18,10 +18,11 @@ m4_pushdef([b4_copyright_years],
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 m4_include(b4_skeletonsdir/[c.m4])
 
+
 ## ---------- ##
 ## api.pure.  ##
 ## ---------- ##
@@ -101,6 +102,16 @@ m4_define([b4_yyerror_arg_loc_if],
                           [1], [m4_ifset([b4_parse_param], [$1])],
                           [2], [$1])])])
 
+# b4_yyerror_formals
+# ------------------
+m4_define([b4_yyerror_formals],
+[b4_pure_if([b4_locations_if([, [[const ]b4_api_PREFIX[LTYPE *yyllocp], [&yylloc]]])[]dnl
+m4_ifdef([b4_parse_param], [, b4_parse_param])[]dnl
+,])dnl
+[[const char *msg], [msg]]])
+
+
+
 # b4_yyerror_args
 # ---------------
 # Arguments passed to yyerror: user args plus yylloc.
@@ -115,6 +126,16 @@ m4_ifset([b4_parse_param], [b4_args(b4_parse_param), ])])
 ## ----------------- ##
 
 
+# b4_accept([SYMBOL-NUM])
+# -----------------------
+# Used in actions of the rules of accept, the initial symbol, to call
+# YYACCEPT.  If SYMBOL-NUM is specified, run "yyvalue->SLOT = $2;"
+# before, using the slot of SYMBOL-NUM.
+m4_define([b4_accept],
+[m4_ifval([$1],
+          [b4_symbol_value(yyimpl->yyvalue, [$1]) = b4_rhs_value(2, 1, [$1]); ]) YYACCEPT])
+
+
 # b4_lhs_value(SYMBOL-NUM, [TYPE])
 # --------------------------------
 # See README.
@@ -154,14 +175,61 @@ m4_define([b4_rhs_location],
 ## Declarations.  ##
 ## -------------- ##
 
+# _b4_declare_sub_yyparse(START-SYMBOL-NUM, SWITCHING-TOKEN-SYMBOL-NUM)
+# ---------------------------------------------------------------------
+# Define the return type of the parsing function for SYMBOL-NUM, and
+# declare its parsing function.
+m4_define([_b4_declare_sub_yyparse],
+[[
+// Return type when parsing one ]_b4_symbol($1, tag)[.
+typedef struct
+{]b4_symbol_if([$1], [has_type], [[
+  ]_b4_symbol($1, type)[ yyvalue;]])[
+  int yystatus;
+  int yynerrs;
+} ]b4_prefix[parse_]_b4_symbol($1, id)[_t;
+
+// Parse one ]_b4_symbol($1, tag)[.
+]b4_prefix[parse_]_b4_symbol($1, id)[_t ]b4_prefix[parse_]_b4_symbol($1, id)[ (]m4_ifset([b4_parse_param], [b4_formals(b4_parse_param)], [void])[);
+]])
+
+
+# _b4_first_switching_token
+# -------------------------
+m4_define([b4_first], [$1])
+m4_define([b4_second], [$2])
+m4_define([_b4_first_switching_token],
+[b4_second(b4_first(b4_start_symbols))])
+
+
+# _b4_define_sub_yyparse(START-SYMBOL-NUM, SWITCHING-TOKEN-SYMBOL-NUM)
+# --------------------------------------------------------------------
+# Define the parsing function for START-SYMBOL-NUM.
+m4_define([_b4_define_sub_yyparse],
+[[
+]b4_prefix[parse_]_b4_symbol($1, id)[_t
+]b4_prefix[parse_]_b4_symbol($1, id)[ (]m4_ifset([b4_parse_param], [b4_formals(b4_parse_param)], [void])[)
+{
+  ]b4_prefix[parse_]_b4_symbol($1, id)[_t yyres;
+  yy_parse_impl_t yyimpl;
+  yyres.yystatus = yy_parse_impl (]b4_symbol($2, id)[, &yyimpl]m4_ifset([b4_parse_param],
+                           [[, ]b4_args(b4_parse_param)])[);]b4_symbol_if([$1], [has_type], [[
+  yyres.yyvalue = yyimpl.yyvalue.]b4_symbol($1, slot)[;]])[
+  yyres.yynerrs = yyimpl.yynerrs;
+  return yyres;
+}
+]])
+
+
 # b4_declare_scanner_communication_variables
 # ------------------------------------------
 # Declare the variables that are global, or local to YYPARSE if
 # pure-parser.
 m4_define([b4_declare_scanner_communication_variables], [[
-/* Lookahead token kind.  */
+]m4_ifdef([b4_start_symbols], [],
+[[/* Lookahead token kind.  */
 int yychar;
-
+]])[
 ]b4_pure_if([[
 /* The semantic value of the lookahead symbol.  */
 /* Default value used for initialization, for pacifying older GCCs
@@ -276,11 +344,14 @@ int ]b4_prefix[push_parse (]b4_prefix[pstate *ps]b4_pure_if([[,
 void ]b4_prefix[pstate_delete (]b4_prefix[pstate *ps);
 ]])
 
+
 # _b4_declare_yyparse
 # -------------------
 # When not the push parser.
 m4_define([_b4_declare_yyparse],
-[[int ]b4_prefix[parse (]m4_ifset([b4_parse_param], [b4_formals(b4_parse_param)], [void])[);]])
+[[int ]b4_prefix[parse (]m4_ifset([b4_parse_param], [b4_formals(b4_parse_param)], [void])[);
+]m4_ifdef([b4_start_symbols],
+          [m4_map([_b4_declare_sub_yyparse], m4_defn([b4_start_symbols]))])])
 
 
 # b4_declare_yyparse
@@ -291,16 +362,32 @@ m4_define([b4_declare_yyparse],
 ])
 
 
+# b4_declare_yyerror_and_yylex
+# ----------------------------
+# Comply with POSIX Yacc.
+# <https://austingroupbugs.net/view.php?id=1388#c5220>
+m4_define([b4_declare_yyerror_and_yylex],
+[b4_yacc_if([[#if !defined ]b4_prefix[error && !defined ]b4_api_PREFIX[ERROR_IS_DECLARED
+]b4_function_declare([b4_prefix[error]], void, b4_yyerror_formals)[
+#endif
+#if !defined ]b4_prefix[lex && !defined ]b4_api_PREFIX[LEX_IS_DECLARED
+]b4_function_declare([b4_prefix[lex]], int, b4_yylex_formals)[
+#endif
+]])dnl
+])
+
+
 # b4_shared_declarations
 # ----------------------
-# Declaration that might either go into the header (if --defines)
-# or open coded in the parser body.
+# Declarations that might either go into the header (if --header)
+# or into the implementation file.
 m4_define([b4_shared_declarations],
 [b4_cpp_guard_open([b4_spec_mapped_header_file])[
 ]b4_declare_yydebug[
 ]b4_percent_code_get([[requires]])[
 ]b4_token_enums_defines[
 ]b4_declare_yylstype[
+]b4_declare_yyerror_and_yylex[
 ]b4_declare_yyparse[
 ]b4_percent_code_get([[provides]])[
 ]b4_cpp_guard_close([b4_spec_mapped_header_file])[]dnl
@@ -330,13 +417,13 @@ m4_if(b4_spec_header_file, [y.tab.h], [],
 ## -------------- ##
 
 
-b4_defines_if([[
+b4_header_if([[
 ]b4_output_begin([b4_spec_header_file])[
 ]b4_copyright([Bison interface for Yacc-like parsers in C])[
 ]b4_disclaimer[
 ]b4_shared_declarations[
 ]b4_output_end[
-]])# b4_defines_if
+]])# b4_header_if
 
 b4_output_begin([b4_parser_file_name])[
 ]b4_copyright([Bison implementation for Yacc-like parsers in C])[
@@ -641,15 +728,6 @@ yysymbol_name (yysymbol_kind_t yysymbol)
 }]])[
 #endif
 
-#ifdef YYPRINT
-/* YYTOKNUM[NUM] -- (External) token number corresponding to the
-   (internal) symbol number NUM (which must be that of a token).  */
-static const ]b4_int_type_for([b4_toknum])[ yytoknum[] =
-{
-  ]b4_toknum[
-};
-#endif
-
 #define YYPACT_NINF (]b4_pact_ninf[)
 
 #define yypact_value_is_default(Yyn) \
@@ -665,18 +743,19 @@ static const ]b4_int_type_for([b4_toknum])[ yytoknum[] =
 enum { YYENOMEM = -2 };
 
 #define yyerrok         (yyerrstatus = 0)
-#define yyclearin       (yychar = ]b4_symbol(-2, id)[)
+#define yyclearin       (yychar = ]b4_symbol(empty, id)[)
 
 #define YYACCEPT        goto yyacceptlab
 #define YYABORT         goto yyabortlab
 #define YYERROR         goto yyerrorlab
+#define YYNOMEM         goto yyexhaustedlab
 
 
 #define YYRECOVERING()  (!!yyerrstatus)
 
 #define YYBACKUP(Token, Value)                                    \
   do                                                              \
-    if (yychar == ]b4_symbol(-2, id)[)                                        \
+    if (yychar == ]b4_symbol(empty, id)[)                                        \
       {                                                           \
         yychar = (Token);                                         \
         yylval = (Value);                                         \
@@ -693,8 +772,8 @@ enum { YYENOMEM = -2 };
   while (0)
 
 /* Backward compatibility with an undocumented macro.
-   Use ]b4_symbol(1, id)[ or ]b4_symbol(2, id)[. */
-#define YYERRCODE ]b4_symbol(2, id)[
+   Use ]b4_symbol(error, id)[ or ]b4_symbol(undef, id)[. */
+#define YYERRCODE ]b4_symbol(undef, id)[
 ]b4_locations_if([[
 ]b4_yylloc_default_define[
 #define YYRHSLOC(Rhs, K) ((Rhs)[K])
@@ -714,7 +793,7 @@ do {                                            \
     YYFPRINTF Args;                             \
 } while (0)
 
-]b4_yy_location_print_define[
+]b4_yylocation_print_define[
 
 # define YY_SYMBOL_PRINT(Title, Kind, Value, Location)                    \
 do {                                                                      \
@@ -925,7 +1004,7 @@ do {                                                                    \
       switch (yy_lac (yyesa, &yyes, &yyes_capacity, yyssp, yytoken))    \
         {                                                               \
         case YYENOMEM:                                                  \
-          goto yyexhaustedlab;                                          \
+          YYNOMEM;                                                      \
         case 1:                                                         \
           goto yyerrlab;                                                \
         }                                                               \
@@ -1103,7 +1182,7 @@ yypcontext_expected_tokens (const yypcontext_t *yyctx,
   for (yyx = 0; yyx < YYNTOKENS; ++yyx)
     {
       yysymbol_kind_t yysym = YY_CAST (yysymbol_kind_t, yyx);
-      if (yysym != ]b4_symbol(1, kind)[ && yysym != ]b4_symbol_prefix[YYUNDEF)
+      if (yysym != ]b4_symbol(error, kind)[ && yysym != ]b4_symbol_prefix[YYUNDEF)
         switch (yy_lac (]b4_push_if([[yyps->yyesa, &yyps->yyes, &yyps->yyes_capacity, yyps->yyssp, yysym]],
                                     [[yyctx->yyesa, yyctx->yyes, yyctx->yyes_capacity, yyctx->yyssp, yysym]])[))
           {
@@ -1132,7 +1211,7 @@ yypcontext_expected_tokens (const yypcontext_t *yyctx,
       int yyxend = yychecklim < YYNTOKENS ? yychecklim : YYNTOKENS;
       int yyx;
       for (yyx = yyxbegin; yyx < yyxend; ++yyx)
-        if (yycheck[yyx + yyn] == yyx && yyx != ]b4_symbol(1, kind)[
+        if (yycheck[yyx + yyn] == yyx && yyx != ]b4_symbol(error, kind)[
             && !yytable_value_is_error (yytable[yyx + yyn]))
           {
             if (!yyarg)
@@ -1144,7 +1223,7 @@ yypcontext_expected_tokens (const yypcontext_t *yyctx,
           }
     }]])[
   if (yyarg && yycount == 0 && 0 < yyargn)
-    yyarg[0] = ]b4_symbol(-2, kind)[;
+    yyarg[0] = ]b4_symbol(empty, kind)[;
   return yycount;
 }
 
@@ -1307,7 +1386,7 @@ yy_syntax_error_arguments (const yypcontext_t *yyctx,
        one exception: it will still contain any token that will not be
        accepted due to an error action in a later state.]])[
   */
-  if (yyctx->yytoken != ]b4_symbol(-2, kind)[)
+  if (yyctx->yytoken != ]b4_symbol(empty, kind)[)
     {
       int yyn;]b4_lac_if([[
       YYDPRINTF ((stderr, "Constructing syntax error message\n"));]])[
@@ -1453,7 +1532,7 @@ yypull_parse (yypstate *yyps]b4_user_formals[)
   int yystatus;
   do {
 ]b4_pure_if([[    YYSTYPE yylval;
-    int ]])[yychar = ]b4_lex[;
+    int ]])[yychar = ]b4_yylex[;
     yystatus = yypush_parse (yyps]b4_pure_if([[, yychar, &yylval]b4_locations_if([[, &yylloc]])])m4_ifset([b4_parse_param], [, b4_args(b4_parse_param)])[);
   } while (yystatus == YYPUSH_MORE);
   return yystatus;
@@ -1486,7 +1565,7 @@ yypstate_new (void)
   yypstate *yyps;]b4_pure_if([], [[
   if (yypstate_allocated)
     return YY_NULLPTR;]])[
-  yyps = YY_CAST (yypstate *, malloc (sizeof *yyps));
+  yyps = YY_CAST (yypstate *, YYMALLOC (sizeof *yyps));
   if (!yyps)
     return YY_NULLPTR;]b4_pure_if([], [[
   yypstate_allocated = 1;]])[
@@ -1515,7 +1594,7 @@ yypstate_delete (yypstate *yyps)
 #endif]b4_lac_if([[
       if (yyes != yyesa)
         YYSTACK_FREE (yyes);]])[
-      free (yyps);]b4_pure_if([], [[
+      YYFREE (yyps);]b4_pure_if([], [[
       yypstate_allocated = 0;]])[
     }
 }
@@ -1534,8 +1613,31 @@ yypush_parse (yypstate *yyps]b4_pure_if([[,
 | yyparse.  |
 `----------*/
 
+]m4_ifdef([b4_start_symbols],
+[[// Extract data from the parser.
+typedef struct
+{
+  YYSTYPE yyvalue;
+  int yynerrs;
+} yy_parse_impl_t;
+
+// Run a full parse, using YYCHAR as switching token.
+static int
+yy_parse_impl (int yychar, yy_parse_impl_t *yyimpl]m4_ifset([b4_parse_param], [, b4_formals(b4_parse_param)])[);
+
+]m4_map([_b4_define_sub_yyparse], m4_defn([b4_start_symbols]))[
+
 int
-yyparse (]m4_ifset([b4_parse_param], [b4_formals(b4_parse_param)], [void])[)]])[
+yyparse (]m4_ifset([b4_parse_param], [b4_formals(b4_parse_param)], [void])[)
+{
+  return yy_parse_impl (]b4_symbol(_b4_first_switching_token, id)[, YY_NULLPTR]m4_ifset([b4_parse_param],
+                                                    [[, ]b4_args(b4_parse_param)])[);
+}
+
+static int
+yy_parse_impl (int yychar, yy_parse_impl_t *yyimpl]m4_ifset([b4_parse_param], [, b4_formals(b4_parse_param)])[)]],
+[[int
+yyparse (]m4_ifset([b4_parse_param], [b4_formals(b4_parse_param)], [void])[)]])])[
 {]b4_pure_if([b4_declare_scanner_communication_variables
 ])b4_push_if([b4_pure_if([], [[
   int yypushed_char = yychar;
@@ -1550,7 +1652,7 @@ yyparse (]m4_ifset([b4_parse_param], [b4_formals(b4_parse_param)], [void])[)]])[
   /* The return value of yyparse.  */
   int yyresult;
   /* Lookahead symbol kind.  */
-  yysymbol_kind_t yytoken = ]b4_symbol(-2, kind)[;
+  yysymbol_kind_t yytoken = ]b4_symbol(empty, kind)[;
   /* The variables used to return semantic value and location from the
      action routines.  */
   YYSTYPE yyval;]b4_locations_if([[
@@ -1573,19 +1675,23 @@ yyparse (]m4_ifset([b4_parse_param], [b4_formals(b4_parse_param)], [void])[)]])[
 
   switch (yyps->yynew)
     {
-    case 2:
-      yypstate_clear (yyps);
-      goto case_0;
-
-    case_0:
     case 0:
       yyn = yypact[yystate];
       goto yyread_pushed_token;
+
+    case 2:
+      yypstate_clear (yyps);
+      break;
+
+    default:
+      break;
     }]])[
 
   YYDPRINTF ((stderr, "Starting parse\n"));
 
-  yychar = ]b4_symbol(-2, id)[; /* Cause a token to be read.  */
+]m4_ifdef([b4_start_symbols], [],
+[[  yychar = ]b4_symbol(empty, id)[; /* Cause a token to be read.  */
+]])[
 ]m4_ifdef([b4_initial_action], [
 b4_dollar_pushdef([m4_define([b4_dollar_dollar_used])yylval], [], [],
                   [b4_push_if([b4_pure_if([*])yypushed_loc], [yylloc])])dnl
@@ -1620,7 +1726,7 @@ yysetstate:
 
   if (yyss + yystacksize - 1 <= yyssp)
 #if !defined yyoverflow && !defined YYSTACK_RELOCATE
-    goto yyexhaustedlab;
+    YYNOMEM;
 #else
     {
       /* Get the current used size of the three stacks, in elements.  */
@@ -1651,7 +1757,7 @@ yysetstate:
 # else /* defined YYSTACK_RELOCATE */
       /* Extend the stack our own way.  */
       if (YYMAXDEPTH <= yystacksize)
-        goto yyexhaustedlab;
+        YYNOMEM;
       yystacksize *= 2;
       if (YYMAXDEPTH < yystacksize)
         yystacksize = YYMAXDEPTH;
@@ -1662,7 +1768,7 @@ yysetstate:
           YY_CAST (union yyalloc *,
                    YYSTACK_ALLOC (YY_CAST (YYSIZE_T, YYSTACK_BYTES (yystacksize))));
         if (! yyptr)
-          goto yyexhaustedlab;
+          YYNOMEM;
         YYSTACK_RELOCATE (yyss_alloc, yyss);
         YYSTACK_RELOCATE (yyvs_alloc, yyvs);]b4_locations_if([
         YYSTACK_RELOCATE (yyls_alloc, yyls);])[
@@ -1686,8 +1792,9 @@ yysetstate:
     }
 #endif /* !defined yyoverflow && !defined YYSTACK_RELOCATE */
 
+]m4_ifdef([b4_start_symbols], [], [[
   if (yystate == YYFINAL)
-    YYACCEPT;
+    YYACCEPT;]])[
 
   goto yybackup;
 
@@ -1707,7 +1814,7 @@ yybackup:
   /* Not known => get a lookahead token if don't already have one.  */
 
   /* YYCHAR is either empty, or end-of-input, or a valid lookahead.  */
-  if (yychar == ]b4_symbol(-2, id)[)
+  if (yychar == ]b4_symbol(empty, id)[)
     {]b4_push_if([[
       if (!yyps->yynew)
         {]b4_use_push_for_pull_if([], [[
@@ -1729,23 +1836,23 @@ yyread_pushed_token:]])[
         yylval = *yypushed_val;]b4_locations_if([[
       if (yypushed_loc)
         yylloc = *yypushed_loc;]])])], [[
-      yychar = ]b4_lex[;]])[
+      yychar = ]b4_yylex[;]])[
     }
 
-  if (yychar <= ]b4_symbol(0, [id])[)
+  if (yychar <= ]b4_symbol(eof, [id])[)
     {
-      yychar = ]b4_symbol(0, [id])[;
-      yytoken = ]b4_symbol(0, [kind])[;
+      yychar = ]b4_symbol(eof, [id])[;
+      yytoken = ]b4_symbol(eof, [kind])[;
       YYDPRINTF ((stderr, "Now at end of input.\n"));
     }
-  else if (yychar == ]b4_symbol(1, [id])[)
+  else if (yychar == ]b4_symbol(error, [id])[)
     {
       /* The scanner already issued an error message, process directly
          to error recovery.  But do not keep the error token as
          lookahead, it is too special and may lead us to an endless
          loop in error recovery. */
-      yychar = ]b4_symbol(2, [id])[;
-      yytoken = ]b4_symbol(1, [kind])[;]b4_locations_if([[
+      yychar = ]b4_symbol(undef, [id])[;
+      yytoken = ]b4_symbol(error, [kind])[;]b4_locations_if([[
       yyerror_range[1] = yylloc;]])[
       goto yyerrlab1;
     }
@@ -1768,9 +1875,9 @@ yyread_pushed_token:]])[
   if (yyn <= 0)
     {
       if (yytable_value_is_error (yyn))
-        goto yyerrlab;]b4_lac_if([[
+        goto yyerrlab;
+      yyn = -yyn;]b4_lac_if([[
       YY_LAC_ESTABLISH;]])[
-      yyn = -yyn;
       goto yyreduce;
     }
 
@@ -1788,7 +1895,7 @@ yyread_pushed_token:]])[
   *++yylsp = yylloc;])[
 
   /* Discard the shifted token.  */
-  yychar = ]b4_symbol(-2, id)[;]b4_lac_if([[
+  yychar = ]b4_symbol(empty, id)[;]b4_lac_if([[
   YY_LAC_DISCARD ("shift");]])[
   goto yynewstate;
 
@@ -1879,7 +1986,7 @@ yyreduce:
 yyerrlab:
   /* Make sure we have latest lookahead translation.  See comments at
      user semantic actions for why this is necessary.  */
-  yytoken = yychar == ]b4_symbol(-2, id)[ ? ]b4_symbol(-2, kind)[ : YYTRANSLATE (yychar);
+  yytoken = yychar == ]b4_symbol(empty, id)[ ? ]b4_symbol(empty, kind)[ : YYTRANSLATE (yychar);
   /* If not already recovering from an error, report this error.  */
   if (!yyerrstatus)
     {
@@ -1889,11 +1996,11 @@ yyerrlab:
 [[      {
         yypcontext_t yyctx
           = {]b4_push_if([[yyps]], [[yyssp]b4_lac_if([[, yyesa, &yyes, &yyes_capacity]])])[, yytoken]b4_locations_if([[, &yylloc]])[};]b4_lac_if([[
-        if (yychar != ]b4_symbol(-2, id)[)
+        if (yychar != ]b4_symbol(empty, id)[)
           YY_LAC_ESTABLISH;]])[
         if (yyreport_syntax_error (&yyctx]m4_ifset([b4_parse_param],
-                                  [[, ]b4_args(b4_parse_param)])[) == 2)
-          goto yyexhaustedlab;
+                                   [[, ]b4_args(b4_parse_param)])[) == 2)
+          YYNOMEM;
       }]],
          [simple],
 [[      yyerror (]b4_yyerror_args[YY_("syntax error"));]],
@@ -1902,7 +2009,7 @@ yyerrlab:
           = {]b4_push_if([[yyps]], [[yyssp]b4_lac_if([[, yyesa, &yyes, &yyes_capacity]])])[, yytoken]b4_locations_if([[, &yylloc]])[};
         char const *yymsgp = YY_("syntax error");
         int yysyntax_error_status;]b4_lac_if([[
-        if (yychar != ]b4_symbol(-2, id)[)
+        if (yychar != ]b4_symbol(empty, id)[)
           YY_LAC_ESTABLISH;]])[
         yysyntax_error_status = yysyntax_error (&yymsg_alloc, &yymsg, &yyctx);
         if (yysyntax_error_status == 0)
@@ -1928,7 +2035,7 @@ yyerrlab:
           }
         yyerror (]b4_yyerror_args[yymsgp);
         if (yysyntax_error_status == YYENOMEM)
-          goto yyexhaustedlab;
+          YYNOMEM;
       }]])[
     }
 ]b4_locations_if([[
@@ -1938,17 +2045,17 @@ yyerrlab:
       /* If just tried and failed to reuse lookahead token after an
          error, discard it.  */
 
-      if (yychar <= ]b4_symbol(0, [id])[)
+      if (yychar <= ]b4_symbol(eof, [id])[)
         {
           /* Return failure if at end of input.  */
-          if (yychar == ]b4_symbol(0, [id])[)
+          if (yychar == ]b4_symbol(eof, [id])[)
             YYABORT;
         }
       else
         {
           yydestruct ("Error: discarding",
                       yytoken, &yylval]b4_locations_if([, &yylloc])[]b4_user_args[);
-          yychar = ]b4_symbol(-2, id)[;
+          yychar = ]b4_symbol(empty, id)[;
         }
     }
 
@@ -1965,6 +2072,7 @@ yyerrorlab:
      label yyerrorlab therefore never appears in user code.  */
   if (0)
     YYERROR;
+  ++yynerrs;
 
   /* Do not reclaim the symbols of the rule whose action triggered
      this YYERROR.  */
@@ -1987,8 +2095,8 @@ yyerrlab1:
       yyn = yypact[yystate];
       if (!yypact_value_is_default (yyn))
         {
-          yyn += ]b4_symbol(1, kind)[;
-          if (0 <= yyn && yyn <= YYLAST && yycheck[yyn] == ]b4_symbol(1, kind)[)
+          yyn += ]b4_symbol(error, kind)[;
+          if (0 <= yyn && yyn <= YYLAST && yycheck[yyn] == ]b4_symbol(error, kind)[)
             {
               yyn = yytable[yyn];
               if (0 < yyn)
@@ -2032,7 +2140,7 @@ yyerrlab1:
 `-------------------------------------*/
 yyacceptlab:
   yyresult = 0;
-  goto yyreturn;
+  goto yyreturnlab;
 
 
 /*-----------------------------------.
@@ -2040,25 +2148,23 @@ yyacceptlab:
 `-----------------------------------*/
 yyabortlab:
   yyresult = 1;
-  goto yyreturn;
+  goto yyreturnlab;
 
 
-#if ]b4_lac_if([[1]], [b4_parse_error_case([simple], [[!defined yyoverflow]], [[1]])])[
-/*-------------------------------------------------.
-| yyexhaustedlab -- memory exhaustion comes here.  |
-`-------------------------------------------------*/
+/*-----------------------------------------------------------.
+| yyexhaustedlab -- YYNOMEM (memory exhaustion) comes here.  |
+`-----------------------------------------------------------*/
 yyexhaustedlab:
   yyerror (]b4_yyerror_args[YY_("memory exhausted"));
   yyresult = 2;
-  goto yyreturn;
-#endif
+  goto yyreturnlab;
 
 
-/*-------------------------------------------------------.
-| yyreturn -- parsing is finished, clean up and return.  |
-`-------------------------------------------------------*/
-yyreturn:
-  if (yychar != ]b4_symbol(-2, id)[)
+/*----------------------------------------------------------.
+| yyreturnlab -- parsing is finished, clean up and return.  |
+`----------------------------------------------------------*/
+yyreturnlab:
+  if (yychar != ]b4_symbol(empty, id)[)
     {
       /* Make sure we have latest lookahead translation.  See comments at
          user semantic actions for why this is necessary.  */
@@ -2092,7 +2198,9 @@ yypushreturn:]], [[
     YYSTACK_FREE (yyes);]])])[
 ]b4_parse_error_bmatch([detailed\|verbose],
 [[  if (yymsg != yymsgbuf)
-    YYSTACK_FREE (yymsg);]])[
+    YYSTACK_FREE (yymsg);]])[]m4_ifdef([b4_start_symbols], [[
+  if (yyimpl)
+    yyimpl->yynerrs = yynerrs;]])[
   return yyresult;
 }
 ]b4_push_if([b4_parse_state_variable_macros([b4_macro_undef])])[

data/xslt/bison.xsl

@@ -3,7 +3,7 @@
 <!--
     bison.xsl - common templates for Bison XSLT.
 
-    Copyright (C) 2007-2015, 2018-2020 Free Software Foundation, Inc.
+    Copyright (C) 2007-2015, 2018-2021 Free Software Foundation, Inc.
 
     This file is part of Bison, the GNU Compiler Compiler.
 
@@ -18,12 +18,12 @@
     GNU General Public License for more details.
 
     You should have received a copy of the GNU General Public License
-    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
   -->
 
 <xsl:stylesheet version="1.0"
   xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
-  xmlns:bison="http://www.gnu.org/software/bison/">
+  xmlns:bison="https://www.gnu.org/software/bison/">
 
 <xsl:key
   name="bison:symbolByName"

data/xslt/xml2dot.xsl

@@ -3,7 +3,7 @@
 <!--
     xml2dot.xsl - transform Bison XML Report into DOT.
 
-    Copyright (C) 2007-2015, 2018-2020 Free Software Foundation, Inc.
+    Copyright (C) 2007-2015, 2018-2021 Free Software Foundation, Inc.
 
     This file is part of Bison, the GNU Compiler Compiler.
 
@@ -18,14 +18,14 @@
     GNU General Public License for more details.
 
     You should have received a copy of the GNU General Public License
-    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
     Written by Wojciech Polak <polak@gnu.org>.
   -->
 
 <xsl:stylesheet version="1.0"
   xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
-  xmlns:bison="http://www.gnu.org/software/bison/">
+  xmlns:bison="https://www.gnu.org/software/bison/">
 
 <xsl:import href="bison.xsl"/>
 <xsl:output method="text" encoding="UTF-8" indent="no"/>

data/xslt/xml2text.xsl

@@ -3,7 +3,7 @@
 <!--
     xml2text.xsl - transform Bison XML Report into plain text.
 
-    Copyright (C) 2007-2015, 2018-2020 Free Software Foundation, Inc.
+    Copyright (C) 2007-2015, 2018-2021 Free Software Foundation, Inc.
 
     This file is part of Bison, the GNU Compiler Compiler.
 
@@ -18,14 +18,14 @@
     GNU General Public License for more details.
 
     You should have received a copy of the GNU General Public License
-    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
     Written by Wojciech Polak <polak@gnu.org>.
   -->
 
 <xsl:stylesheet version="1.0"
   xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
-  xmlns:bison="http://www.gnu.org/software/bison/">
+  xmlns:bison="https://www.gnu.org/software/bison/">
 
 <xsl:import href="bison.xsl"/>
 <xsl:output method="text" encoding="UTF-8" indent="no"/>

data/xslt/xml2xhtml.xsl

@@ -3,7 +3,7 @@
 <!--
     xml2html.xsl - transform Bison XML Report into XHTML.
 
-    Copyright (C) 2007-2015, 2018-2020 Free Software Foundation, Inc.
+    Copyright (C) 2007-2015, 2018-2021 Free Software Foundation, Inc.
 
     This file is part of Bison, the GNU Compiler Compiler.
 
@@ -18,7 +18,7 @@
     GNU General Public License for more details.
 
     You should have received a copy of the GNU General Public License
-    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
     Written by Wojciech Polak <polak@gnu.org>.
   -->
@@ -26,7 +26,7 @@
 <xsl:stylesheet version="1.0"
   xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
   xmlns="http://www.w3.org/1999/xhtml"
-  xmlns:bison="http://www.gnu.org/software/bison/">
+  xmlns:bison="https://www.gnu.org/software/bison/">
 
 <xsl:import href="bison.xsl"/>
 
@@ -88,7 +88,7 @@
       <xsl:apply-templates select="bison-xml-report"/>
       <xsl:text>&#10;&#10;</xsl:text>
       <div id="footer"><hr />This document was generated using
-      <a href="http://www.gnu.org/software/bison/" title="GNU Bison">
+      <a href="https://www.gnu.org/software/bison/" title="GNU Bison">
       GNU Bison <xsl:value-of select="/bison-xml-report/@version"/></a>
       XML Automaton Report.<br />
       <!-- default copying notice -->

doc/.gitignore

@@ -22,15 +22,15 @@
 /bison.ps
 /cross-options.texi
 /fdl.texi
+/figs/*.eps
+/figs/*.svg
 /gendocs_template
 /gendocs_template_min
 /gpl-3.0.texi
 /refcard.dvi
 /refcard.log
 /refcard.ps
+/relocatable.texi
 /stamp-vti
 /version.texi
 /yacc.1
-/relocatable.texi
-/figs/*.eps
-/figs/*.svg

doc/Doxyfile.in

@@ -1,4 +1,4 @@
-# Doxyfile 1.8.18
+# Doxyfile 1.9.1
 
 # This file describes the settings to be used by the documentation system
 # doxygen (www.doxygen.org) for a project.
@@ -32,13 +32,13 @@ DOXYFILE_ENCODING      = UTF-8
 # title of most generated pages and in a few other places.
 # The default value is: My Project.
 
-PROJECT_NAME           = "@PACKAGE_NAME@"
+PROJECT_NAME           = @PACKAGE_NAME@
 
 # The PROJECT_NUMBER tag can be used to enter a project or revision number. This
 # could be handy for archiving the generated documentation or if some version
 # control system is used.
 
-PROJECT_NUMBER         = "@PACKAGE_VERSION@"
+PROJECT_NUMBER         = @PACKAGE_VERSION@
 
 # Using the PROJECT_BRIEF tag one can provide an optional one line description
 # for a project that appears at the top of each page and should give viewer a
@@ -217,6 +217,14 @@ QT_AUTOBRIEF           = NO
 
 MULTILINE_CPP_IS_BRIEF = NO
 
+# By default Python docstrings are displayed as preformatted text and doxygen's
+# special commands cannot be used. By setting PYTHON_DOCSTRING to NO the
+# doxygen's special commands can be used and the contents of the docstring
+# documentation blocks is shown as doxygen documentation.
+# The default value is: YES.
+
+PYTHON_DOCSTRING       = YES
+
 # If the INHERIT_DOCS tag is set to YES then an undocumented member inherits the
 # documentation from any documented member that it re-implements.
 # The default value is: YES.
@@ -305,7 +313,10 @@ OPTIMIZE_OUTPUT_SLICE  = NO
 # Note: For files without extension you can use no_extension as a placeholder.
 #
 # Note that for custom extensions you also need to set FILE_PATTERNS otherwise
-# the files are not read by doxygen.
+# the files are not read by doxygen. When specifying no_extension you should add
+# * to the FILE_PATTERNS.
+#
+# Note see also the list of default file extension mappings.
 
 EXTENSION_MAPPING      =
 
@@ -439,6 +450,19 @@ TYPEDEF_HIDES_STRUCT   = NO
 
 LOOKUP_CACHE_SIZE      = 0
 
+# The NUM_PROC_THREADS specifies the number threads doxygen is allowed to use
+# during processing. When set to 0 doxygen will based this on the number of
+# cores available in the system. You can set it explicitly to a value larger
+# than 0 to get more control over the balance between CPU load and processing
+# speed. At this moment only the input processing can be done using multiple
+# threads. Since this is still an experimental feature the default is set to 1,
+# which efficively disables parallel processing. Please report any issues you
+# encounter. Generating dot graphs in parallel is controlled by the
+# DOT_NUM_THREADS setting.
+# Minimum value: 0, maximum value: 32, default value: 1.
+
+NUM_PROC_THREADS       = 1
+
 #---------------------------------------------------------------------------
 # Build related configuration options
 #---------------------------------------------------------------------------
@@ -502,6 +526,13 @@ EXTRACT_LOCAL_METHODS  = NO
 
 EXTRACT_ANON_NSPACES   = NO
 
+# If this flag is set to YES, the name of an unnamed parameter in a declaration
+# will be determined by the corresponding definition. By default unnamed
+# parameters remain unnamed in the output.
+# The default value is: YES.
+
+RESOLVE_UNNAMED_PARAMS = YES
+
 # If the HIDE_UNDOC_MEMBERS tag is set to YES, doxygen will hide all
 # undocumented members inside documented classes or files. If set to NO these
 # members will be included in the various overviews, but no documentation
@@ -539,11 +570,18 @@ HIDE_IN_BODY_DOCS      = NO
 
 INTERNAL_DOCS          = NO
 
-# If the CASE_SENSE_NAMES tag is set to NO then doxygen will only generate file
-# names in lower-case letters. If set to YES, upper-case letters are also
-# allowed. This is useful if you have classes or files whose names only differ
-# in case and if your file system supports case sensitive file names. Windows
-# (including Cygwin) ands Mac users are advised to set this option to NO.
+# With the correct setting of option CASE_SENSE_NAMES doxygen will better be
+# able to match the capabilities of the underlying filesystem. In case the
+# filesystem is case sensitive (i.e. it supports files in the same directory
+# whose names only differ in casing), the option must be set to YES to properly
+# deal with such files in case they appear in the input. For filesystems that
+# are not case sensitive the option should be be set to NO to properly deal with
+# output files written for symbols that only differ in casing, such as for two
+# classes, one named CLASS and the other named Class, and to also support
+# references to files without having to specify the exact matching casing. On
+# Windows (including Cygwin) and MacOS, users should typically set this option
+# to NO, whereas on Linux or other Unix flavors it should typically be set to
+# YES.
 # The default value is: system dependent.
 
 CASE_SENSE_NAMES       = YES
@@ -782,7 +820,10 @@ WARN_IF_DOC_ERROR      = YES
 WARN_NO_PARAMDOC       = NO
 
 # If the WARN_AS_ERROR tag is set to YES then doxygen will immediately stop when
-# a warning is encountered.
+# a warning is encountered. If the WARN_AS_ERROR tag is set to FAIL_ON_WARNINGS
+# then doxygen will continue running as if WARN_AS_ERROR tag is set to NO, but
+# at the end of the doxygen process doxygen will return with a non-zero status.
+# Possible values are: NO, YES and FAIL_ON_WARNINGS.
 # The default value is: NO.
 
 WARN_AS_ERROR          = NO
@@ -819,8 +860,8 @@ INPUT                  = @top_srcdir@/src \
 # This tag can be used to specify the character encoding of the source files
 # that doxygen parses. Internally doxygen uses the UTF-8 encoding. Doxygen uses
 # libiconv (or the iconv built into libc) for the transcoding. See the libiconv
-# documentation (see: https://www.gnu.org/software/libiconv/) for the list of
-# possible encodings.
+# documentation (see:
+# https://www.gnu.org/software/libiconv/) for the list of possible encodings.
 # The default value is: UTF-8.
 
 INPUT_ENCODING         = UTF-8
@@ -833,13 +874,15 @@ INPUT_ENCODING         = UTF-8
 # need to set EXTENSION_MAPPING for the extension otherwise the files are not
 # read by doxygen.
 #
+# Note the list of default checked file patterns might differ from the list of
+# default file extension mappings.
+#
 # If left blank the following patterns are tested:*.c, *.cc, *.cxx, *.cpp,
 # *.c++, *.java, *.ii, *.ixx, *.ipp, *.i++, *.inl, *.idl, *.ddl, *.odl, *.h,
 # *.hh, *.hxx, *.hpp, *.h++, *.cs, *.d, *.php, *.php4, *.php5, *.phtml, *.inc,
 # *.m, *.markdown, *.md, *.mm, *.dox (to be provided as doxygen C comment),
-# *.doc (to be provided as doxygen C comment), *.txt (to be provided as doxygen
-# C comment), *.py, *.pyw, *.f90, *.f95, *.f03, *.f08, *.f18, *.f, *.for, *.vhd,
-# *.vhdl, *.ucf, *.qsf and *.ice.
+# *.py, *.pyw, *.f90, *.f95, *.f03, *.f08, *.f18, *.f, *.for, *.vhd, *.vhdl,
+# *.ucf, *.qsf and *.ice.
 
 FILE_PATTERNS          = *.c \
                          *.h \
@@ -1069,13 +1112,6 @@ VERBATIM_HEADERS       = YES
 
 ALPHABETICAL_INDEX     = YES
 
-# The COLS_IN_ALPHA_INDEX tag can be used to specify the number of columns in
-# which the alphabetical index list will be split.
-# Minimum value: 1, maximum value: 20, default value: 5.
-# This tag requires that the tag ALPHABETICAL_INDEX is set to YES.
-
-COLS_IN_ALPHA_INDEX    = 5
-
 # In case all classes in a project start with a common prefix, all classes will
 # be put under the same header in the alphabetical index. The IGNORE_PREFIX tag
 # can be used to specify a prefix (or a list of prefixes) that should be ignored
@@ -1246,10 +1282,11 @@ HTML_INDEX_NUM_ENTRIES = 100
 
 # If the GENERATE_DOCSET tag is set to YES, additional index files will be
 # generated that can be used as input for Apple's Xcode 3 integrated development
-# environment (see: https://developer.apple.com/xcode/), introduced with OSX
-# 10.5 (Leopard). To create a documentation set, doxygen will generate a
-# Makefile in the HTML output directory. Running make will produce the docset in
-# that directory and running make install will install the docset in
+# environment (see:
+# https://developer.apple.com/xcode/), introduced with OSX 10.5 (Leopard). To
+# create a documentation set, doxygen will generate a Makefile in the HTML
+# output directory. Running make will produce the docset in that directory and
+# running make install will install the docset in
 # ~/Library/Developer/Shared/Documentation/DocSets so that Xcode will find it at
 # startup. See https://developer.apple.com/library/archive/featuredarticles/Doxy
 # genXcode/_index.html for more information.
@@ -1291,8 +1328,8 @@ DOCSET_PUBLISHER_NAME  = Publisher
 # If the GENERATE_HTMLHELP tag is set to YES then doxygen generates three
 # additional HTML index files: index.hhp, index.hhc, and index.hhk. The
 # index.hhp is a project file that can be read by Microsoft's HTML Help Workshop
-# (see: https://www.microsoft.com/en-us/download/details.aspx?id=21138) on
-# Windows.
+# (see:
+# https://www.microsoft.com/en-us/download/details.aspx?id=21138) on Windows.
 #
 # The HTML Help Workshop contains a compiler that can convert all HTML output
 # generated by doxygen into a single compiled HTML file (.chm). Compiled HTML
@@ -1322,7 +1359,7 @@ CHM_FILE               =
 HHC_LOCATION           =
 
 # The GENERATE_CHI flag controls if a separate .chi index file is generated
-# (YES) or that it should be included in the master .chm file (NO).
+# (YES) or that it should be included in the main .chm file (NO).
 # The default value is: NO.
 # This tag requires that the tag GENERATE_HTMLHELP is set to YES.
 
@@ -1367,7 +1404,8 @@ QCH_FILE               =
 
 # The QHP_NAMESPACE tag specifies the namespace to use when generating Qt Help
 # Project output. For more information please see Qt Help Project / Namespace
-# (see: https://doc.qt.io/archives/qt-4.8/qthelpproject.html#namespace).
+# (see:
+# https://doc.qt.io/archives/qt-4.8/qthelpproject.html#namespace).
 # The default value is: org.doxygen.Project.
 # This tag requires that the tag GENERATE_QHP is set to YES.
 
@@ -1375,8 +1413,8 @@ QHP_NAMESPACE          = org.doxygen.Project
 
 # The QHP_VIRTUAL_FOLDER tag specifies the namespace to use when generating Qt
 # Help Project output. For more information please see Qt Help Project / Virtual
-# Folders (see: https://doc.qt.io/archives/qt-4.8/qthelpproject.html#virtual-
-# folders).
+# Folders (see:
+# https://doc.qt.io/archives/qt-4.8/qthelpproject.html#virtual-folders).
 # The default value is: doc.
 # This tag requires that the tag GENERATE_QHP is set to YES.
 
@@ -1384,16 +1422,16 @@ QHP_VIRTUAL_FOLDER     = doc
 
 # If the QHP_CUST_FILTER_NAME tag is set, it specifies the name of a custom
 # filter to add. For more information please see Qt Help Project / Custom
-# Filters (see: https://doc.qt.io/archives/qt-4.8/qthelpproject.html#custom-
-# filters).
+# Filters (see:
+# https://doc.qt.io/archives/qt-4.8/qthelpproject.html#custom-filters).
 # This tag requires that the tag GENERATE_QHP is set to YES.
 
 QHP_CUST_FILTER_NAME   =
 
 # The QHP_CUST_FILTER_ATTRS tag specifies the list of the attributes of the
 # custom filter to add. For more information please see Qt Help Project / Custom
-# Filters (see: https://doc.qt.io/archives/qt-4.8/qthelpproject.html#custom-
-# filters).
+# Filters (see:
+# https://doc.qt.io/archives/qt-4.8/qthelpproject.html#custom-filters).
 # This tag requires that the tag GENERATE_QHP is set to YES.
 
 QHP_CUST_FILTER_ATTRS  =
@@ -1405,9 +1443,9 @@ QHP_CUST_FILTER_ATTRS  =
 
 QHP_SECT_FILTER_ATTRS  =
 
-# The QHG_LOCATION tag can be used to specify the location of Qt's
-# qhelpgenerator. If non-empty doxygen will try to run qhelpgenerator on the
-# generated .qhp file.
+# The QHG_LOCATION tag can be used to specify the location (absolute path
+# including file name) of Qt's qhelpgenerator. If non-empty doxygen will try to
+# run qhelpgenerator on the generated .qhp file.
 # This tag requires that the tag GENERATE_QHP is set to YES.
 
 QHG_LOCATION           =
@@ -1488,8 +1526,8 @@ EXT_LINKS_IN_WINDOW    = NO
 # tool (see https://github.com/dawbarton/pdf2svg) or inkscape (see
 # https://inkscape.org) to generate formulas as SVG images instead of PNGs for
 # the HTML output. These images will generally look nicer at scaled resolutions.
-# Possible values are: png The default and svg Looks nicer but requires the
-# pdf2svg tool.
+# Possible values are: png (the default) and svg (looks nicer but requires the
+# pdf2svg or inkscape tool).
 # The default value is: png.
 # This tag requires that the tag GENERATE_HTML is set to YES.
 
@@ -1534,7 +1572,7 @@ USE_MATHJAX            = NO
 
 # When MathJax is enabled you can set the default output format to be used for
 # the MathJax output. See the MathJax site (see:
-# http://docs.mathjax.org/en/latest/output.html) for more details.
+# http://docs.mathjax.org/en/v2.7-latest/output.html) for more details.
 # Possible values are: HTML-CSS (which is slower, but has the best
 # compatibility), NativeMML (i.e. MathML) and SVG.
 # The default value is: HTML-CSS.
@@ -1564,7 +1602,8 @@ MATHJAX_EXTENSIONS     =
 
 # The MATHJAX_CODEFILE tag can be used to specify a file with javascript pieces
 # of code that will be used on startup of the MathJax code. See the MathJax site
-# (see: http://docs.mathjax.org/en/latest/output.html) for more details. For an
+# (see:
+# http://docs.mathjax.org/en/v2.7-latest/output.html) for more details. For an
 # example see the documentation.
 # This tag requires that the tag USE_MATHJAX is set to YES.
 
@@ -1611,7 +1650,8 @@ SERVER_BASED_SEARCH    = NO
 #
 # Doxygen ships with an example indexer (doxyindexer) and search engine
 # (doxysearch.cgi) which are based on the open source search engine library
-# Xapian (see: https://xapian.org/).
+# Xapian (see:
+# https://xapian.org/).
 #
 # See the section "External Indexing and Searching" for details.
 # The default value is: NO.
@@ -1624,8 +1664,9 @@ EXTERNAL_SEARCH        = NO
 #
 # Doxygen ships with an example indexer (doxyindexer) and search engine
 # (doxysearch.cgi) which are based on the open source search engine library
-# Xapian (see: https://xapian.org/). See the section "External Indexing and
-# Searching" for details.
+# Xapian (see:
+# https://xapian.org/). See the section "External Indexing and Searching" for
+# details.
 # This tag requires that the tag SEARCHENGINE is set to YES.
 
 SEARCHENGINE_URL       =
@@ -1789,9 +1830,11 @@ LATEX_EXTRA_FILES      =
 
 PDF_HYPERLINKS         = YES
 
-# If the USE_PDFLATEX tag is set to YES, doxygen will use pdflatex to generate
-# the PDF file directly from the LaTeX files. Set this option to YES, to get a
-# higher quality PDF documentation.
+# If the USE_PDFLATEX tag is set to YES, doxygen will use the engine as
+# specified with LATEX_CMD_NAME to generate the PDF file directly from the LaTeX
+# files. Set this option to YES, to get a higher quality PDF documentation.
+#
+# See also section LATEX_CMD_NAME for selecting the engine.
 # The default value is: YES.
 # This tag requires that the tag GENERATE_LATEX is set to YES.
 
@@ -2304,10 +2347,32 @@ UML_LOOK               = NO
 # but if the number exceeds 15, the total amount of fields shown is limited to
 # 10.
 # Minimum value: 0, maximum value: 100, default value: 10.
-# This tag requires that the tag HAVE_DOT is set to YES.
+# This tag requires that the tag UML_LOOK is set to YES.
 
 UML_LIMIT_NUM_FIELDS   = 10
 
+# If the DOT_UML_DETAILS tag is set to NO, doxygen will show attributes and
+# methods without types and arguments in the UML graphs. If the DOT_UML_DETAILS
+# tag is set to YES, doxygen will add type and arguments for attributes and
+# methods in the UML graphs. If the DOT_UML_DETAILS tag is set to NONE, doxygen
+# will not generate fields with class member information in the UML graphs. The
+# class diagrams will look similar to the default class diagrams but using UML
+# notation for the relationships.
+# Possible values are: NO, YES and NONE.
+# The default value is: NO.
+# This tag requires that the tag UML_LOOK is set to YES.
+
+DOT_UML_DETAILS        = NO
+
+# The DOT_WRAP_THRESHOLD tag can be used to set the maximum number of characters
+# to display on a single line. If the actual line length exceeds this threshold
+# significantly it will wrapped across multiple lines. Some heuristics are apply
+# to avoid ugly line breaks.
+# Minimum value: 0, maximum value: 1000, default value: 17.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+DOT_WRAP_THRESHOLD     = 17
+
 # If the TEMPLATE_RELATIONS tag is set to YES then the inheritance and
 # collaboration graphs will show the relations between templates and their
 # instances.
@@ -2497,9 +2562,11 @@ DOT_MULTI_TARGETS      = NO
 
 GENERATE_LEGEND        = YES
 
-# If the DOT_CLEANUP tag is set to YES, doxygen will remove the intermediate dot
+# If the DOT_CLEANUP tag is set to YES, doxygen will remove the intermediate
 # files that are used to generate the various graphs.
+#
+# Note: This setting is not only used for dot files but also for msc and
+# plantuml temporary files.
 # The default value is: YES.
-# This tag requires that the tag HAVE_DOT is set to YES.
 
 DOT_CLEANUP            = YES

doc/calc.y

@@ -0,0 +1,23 @@
+%union
+{
+  int ival;
+  const char *sval;
+}
+
+%token <ival> NUM
+%nterm <ival> exp
+%token <sval> STR
+%nterm <sval> useless
+
+%left '+' '-'
+%left '*'
+
+%%
+exp:
+  exp '+' exp
+| exp '-' exp
+| exp '*' exp
+| exp '/' exp
+| NUM
+;
+useless: STR;

doc/else.y

@@ -0,0 +1,13 @@
+%%
+stmt:
+  expr
+| if_stmt
+;
+
+if_stmt:
+  "if" expr "then" stmt
+| "if" expr "then" stmt "else" stmt
+;
+
+expr:
+  "identifier"

doc/figs/example.gv

@@ -1,6 +1,6 @@
 // Generated by GNU Bison 2.6.90.
 // Report bugs to <[email protected]>.
-// Home page: <http://www.gnu.org/software/bison/>.
+// Home page: <https://www.gnu.org/software/bison/>.
 
 digraph "example.y"
 {

doc/ids.y

@@ -0,0 +1,5 @@
+%token ID
+%%
+s: a ID
+a: expr
+expr: %empty | expr ID ','

doc/local.mk

@@ -1,4 +1,4 @@
-## Copyright (C) 2001-2003, 2005-2015, 2018-2020 Free Software
+## Copyright (C) 2001-2003, 2005-2015, 2018-2021 Free Software
 ## Foundation, Inc.
 
 ## This program is free software: you can redistribute it and/or modify
@@ -12,7 +12,7 @@
 ## GNU General Public License for more details.
 ##
 ## You should have received a copy of the GNU General Public License
-## along with this program.  If not, see <http://www.gnu.org/licenses/>.
+## along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 AM_MAKEINFOFLAGS =                                              \
   --no-split                                                    \
@@ -56,8 +56,8 @@ MAINTAINERCLEANFILES = $(CROSS_OPTIONS_TEXI)
 
 
 # Fix Info's @code in @deftype
-# https://lists.gnu.org/archive/html/help-texinfo/2019-11/msg00004.html
-all: $(srcdir)/$(%C%_bison).info.bak
+# https://lists.gnu.org/r/help-texinfo/2019-11/msg00004.html
+all-local: $(srcdir)/$(%C%_bison).info.bak
 $(srcdir)/$(%C%_bison).info.bak: $(srcdir)/$(%C%_bison).info
 	$(AM_V_GEN) $(PERL) -pi.bak -0777	\
 	  -e 's{(^ --.*\n(?: {10}.*\n)*)}'	\

doc/refcard.tex

@@ -19,7 +19,7 @@
 \def\finalout{\overfullrule=0pt}
 %\finalout
 
-% Copyright (c) 1998, 2001, 2009--2015, 2018--2020 Free Software
+% Copyright (c) 1998, 2001, 2009--2015, 2018--2021 Free Software
 % Foundation, Inc.
 %
 % This file is part of Bison.
@@ -35,7 +35,7 @@
 % GNU General Public License for more details.
 %
 % You should have received a copy of the GNU General Public License
-% along with this program.  If not, see <http://www.gnu.org/licenses/>.
+% along with this program.  If not, see <https://www.gnu.org/licenses/>.
 %
 % This file is intended to be processed by plain TeX (TeX82).
 %

doc/sequence.y

@@ -0,0 +1,10 @@
+%%
+sequence:
+  %empty
+| maybeword
+| sequence "word"
+;
+maybeword:
+  %empty
+| "word"
+;

etc/README.md

@@ -22,7 +22,7 @@ fill-column: 76
 ispell-dictionary: "american"
 End:
 
-Copyright (C) 2006, 2009-2015, 2018-2020 Free Software Foundation, Inc.
+Copyright (C) 2006, 2009-2015, 2018-2021 Free Software Foundation, Inc.
 
 This file is part of Bison, the GNU Compiler Compiler.
 

etc/bench.pl.in

@@ -1,6 +1,6 @@
 #! /usr/bin/perl -w
 
-# Copyright (C) 2006, 2008-2015, 2018-2020 Free Software Foundation,
+# Copyright (C) 2006, 2008-2015, 2018-2021 Free Software Foundation,
 # Inc.
 #
 # This file is part of Bison, the GNU Compiler Compiler.
@@ -16,7 +16,7 @@
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 =head1 NAME
 
@@ -185,13 +185,13 @@ my $verbose = 1;
 
 =over 4
 
-=item C<verbose($level, $message)>
+=item C<verbose ($level, $message)>
 
 Report the C<$message> is C<$level> E<lt>= C<$verbose>.
 
 =cut
 
-sub verbose($$)
+sub verbose ($$)
 {
   my ($level, $message) = @_;
   print STDERR $message
@@ -201,13 +201,13 @@ sub verbose($$)
 
 ######################################################################
 
-=item C<directives($bench, @directive)>
+=item C<directives ($bench, @directive)>
 
 Format the list of directives for Bison for bench named C<$bench>.
 
 =cut
 
-sub directives($@)
+sub directives ($@)
 {
   my ($bench, @directive) = @_;
   my $res = "/* Directives for bench '$bench'. */\n";
@@ -218,6 +218,27 @@ sub directives($@)
 
 ######################################################################
 
+=item C<is_pure (@directive)>
+
+Whether api.pure is set.
+
+=cut
+
+sub is_pure (@)
+{
+  my (@directive) = @_;
+  for my $dir (@directive)
+    {
+      if ($dir =~ /\A%define api.pure/)
+        {
+          return 1;
+        }
+    }
+  return 0;
+}
+
+######################################################################
+
 =item C<generate_grammar_triangular ($base, $max, @directive)>
 
 Create a large triangular grammar which looks like :
@@ -389,18 +410,14 @@ sub generate_grammar_calc ($$@)
 %define api.value.type union
 $directives
 
-%{
+%code provides {
 static int power (int base, int exponent);
 /* yyerror receives the location if:
    - %location & %pure & %glr
    - %location & %pure & %yacc & %parse-param. */
 static void yyerror (const char *s);
-#if YYPURE
-static int yylex (YYSTYPE* yylvalp);
-#else
-static int yylex (void);
-#endif
-%}
+static int yylex (@{[is_pure (@directive) ? "YYSTYPE *yylvalp" : "void"]});
+}
 
 /* Bison Declarations */
 %token
@@ -467,12 +484,7 @@ yyerror (const char *s)
 }
 
 static int
-#if YYPURE
-# define yylval (*yylvalp)
-yylex (YYSTYPE* yylvalp)
-#else
-yylex (void)
-#endif
+yylex (@{[is_pure (@directive) ? "YYSTYPE *yylvalp" : "void"]})
 {
   int c;
 
@@ -498,7 +510,7 @@ yylex (void)
     case '5': case '6': case '7': case '8': case '9':
       {
         int nchars = 0;
-        int n = sscanf (input - 1, "%d%n", &yylval.NUM, &nchars);
+        int n = sscanf (input - 1, "%d%n", &@{[is_pure (@directive) ? "yylvalp->" : "yylval."]}NUM, &nchars);
         assert (n == 1);
         input += nchars - 1;
         return NUM;
@@ -506,7 +518,7 @@ yylex (void)
 
     default:
       yyerror ("error: invalid character");
-      return yylex ();
+      return yylex (@{[is_pure (@directive) ? "yylvalp" : ""]});
     }
 }
 EOF
@@ -569,7 +581,7 @@ sub generate_grammar_list ($$@)
     or die;
   print $out <<EOF;
 %language "C++"
-%defines
+%header
 %locations
 $directives
 
@@ -592,10 +604,10 @@ $directives
   // Prototype of the yylex function providing subsequent tokens.
   static
 #if USE_TOKEN_CTOR
-  yy::parser::symbol_type yylex();
+  yy::parser::symbol_type yylex ();
 #else
-  yy::parser::token_type yylex(yy::parser::semantic_type* yylvalp,
-                               yy::parser::location_type* yyllocp);
+  yy::parser::token_type yylex (yy::parser::semantic_type *yylvalp,
+                                yy::parser::location_type *yyllocp);
 #endif
 
   // Conversion to string.
@@ -618,8 +630,8 @@ EOF
       print $out <<'EOF';
 %token <std::string> TEXT
 %token <int> NUMBER
-%printer { std::cerr << "Number: " << $$; } <int>
-%printer { std::cerr << "Text: " << $$; } <std::string>
+%printer { yyo << "Number: " << $$; } <int>
+%printer { yyo << "Text: " << $$; } <std::string>
 %type <std::string> text result
 
 %%
@@ -641,8 +653,8 @@ EOF
 %union {int ival; std::string* sval;}
 %token <sval> TEXT
 %token <ival> NUMBER
-%printer { std::cerr << "Number: " << $$; } <ival>
-%printer { std::cerr << "Text: " << *$$; } <sval>
+%printer { yyo << "Number: " << $$; } <ival>
+%printer { yyo << "Text: " << *$$; } <sval>
 %type <sval> text result
 
 %%
@@ -664,10 +676,10 @@ EOF
 
 static
 #if USE_TOKEN_CTOR
-yy::parser::symbol_type yylex()
+yy::parser::symbol_type yylex ()
 #else
-yy::parser::token_type yylex(yy::parser::semantic_type* yylvalp,
-                             yy::parser::location_type* yyllocp)
+yy::parser::token_type yylex (yy::parser::semantic_type *yylvalp,
+                              yy::parser::location_type *yyllocp)
 #endif
 {
   typedef yy::parser::location_type location_type;
@@ -1060,7 +1072,7 @@ sub help ($)
 {
   my ($verbose) = @_;
   use Pod::Usage;
-  # See <URL:http://perldoc.perl.org/pod2man.html#NOTES>.
+  # See <URL:https://perldoc.perl.org/pod2man.html#NOTES>.
   pod2usage( { -message => "Bench Bison parsers",
                -exitval => 0,
                -verbose => $verbose,

etc/local.mk

@@ -1,4 +1,4 @@
-## Copyright (C) 2006, 2008-2015, 2018-2020 Free Software Foundation,
+## Copyright (C) 2006, 2008-2015, 2018-2021 Free Software Foundation,
 ## Inc.
 
 ## This program is free software: you can redistribute it and/or modify
@@ -12,7 +12,7 @@
 ## GNU General Public License for more details.
 ##
 ## You should have received a copy of the GNU General Public License
-## along with this program.  If not, see <http://www.gnu.org/licenses/>.
+## along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 dist_noinst_DATA = %D%/README.md
 nodist_noinst_SCRIPTS = %D%/bench.pl

examples/README.md

@@ -17,7 +17,7 @@ fill-column: 76
 ispell-dictionary: "american"
 End:
 
-Copyright (C) 2018-2020 Free Software Foundation, Inc.
+Copyright (C) 2018-2021 Free Software Foundation, Inc.
 
 Permission is granted to copy, distribute and/or modify this document
 under the terms of the GNU Free Documentation License, Version 1.3 or

examples/c++/Makefile

@@ -11,8 +11,8 @@ variant-11: CXXFLAGS = -std=c++11
 
 all: $(PROGS)
 
-%.cc %.hh: %.yy
-	$(BISON) $(BISONFLAGS) -o $*.cc $<
+%.cc %.hh %.html %.gv: %.yy
+	$(BISON) $(BISONFLAGS) --html --graph -o $*.cc $<
 
 %: %.cc
 	$(CXX) $(CXXFLAGS) -o$@ $<

examples/c++/README.md

@@ -46,7 +46,7 @@ fill-column: 76
 ispell-dictionary: "american"
 End:
 
-Copyright (C) 2018-2020 Free Software Foundation, Inc.
+Copyright (C) 2018-2021 Free Software Foundation, Inc.
 
 Permission is granted to copy, distribute and/or modify this document
 under the terms of the GNU Free Documentation License, Version 1.3 or

examples/c++/calc++/Makefile

@@ -5,12 +5,11 @@ BASE = calc++
 BISON = bison
 CXX = g++
 FLEX = flex
-XSLTPROC = xsltproc
 
 all: $(BASE)
 
-%.cc %.hh %.xml %.gv: %.yy
-	$(BISON) $(BISONFLAGS) --xml --graph=$*.gv -o $*.cc $<
+%.cc %.hh %.html %.gv: %.yy
+	$(BISON) $(BISONFLAGS) --html --graph -o $*.cc $<
 
 %.cc: %.ll
 	$(FLEX) $(FLEXFLAGS) -o$@ $<
@@ -29,10 +28,6 @@ run: $(BASE)
 	@echo "Type arithmetic expressions.  Quit with ctrl-d."
 	./$< -
 
-html: parser.html
-%.html: %.xml
-	$(XSLTPROC) $(XSLTPROCFLAGS) -o $@ $$($(BISON) --print-datadir)/xslt/xml2xhtml.xsl $<
-
 CLEANFILES =										\
   $(BASE) *.o										\
   parser.hh parser.cc parser.output parser.xml parser.html parser.gv location.hh	\

examples/c++/calc++/README.md

@@ -36,7 +36,7 @@ fill-column: 76
 ispell-dictionary: "american"
 End:
 
-Copyright (C) 2018-2020 Free Software Foundation, Inc.
+Copyright (C) 2018-2021 Free Software Foundation, Inc.
 
 Permission is granted to copy, distribute and/or modify this document
 under the terms of the GNU Free Documentation License, Version 1.3 or

examples/c++/calc++/calc++.test

@@ -1,6 +1,6 @@
 #! /bin/sh
 
-# Copyright (C) 2005-2015, 2018-2020 Free Software Foundation, Inc.
+# Copyright (C) 2005-2015, 2018-2021 Free Software Foundation, Inc.
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -13,7 +13,7 @@
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 cat >input <<EOF
 toto := 1

examples/c++/calc++/local.mk

@@ -1,4 +1,4 @@
-## Copyright (C) 2005-2006, 2008-2015, 2018-2020 Free Software
+## Copyright (C) 2005-2006, 2008-2015, 2018-2021 Free Software
 ## Foundation, Inc.
 ##
 ## This program is free software: you can redistribute it and/or modify
@@ -12,13 +12,12 @@
 ## GNU General Public License for more details.
 ##
 ## You should have received a copy of the GNU General Public License
-## along with this program.  If not, see <http://www.gnu.org/licenses/>.
+## along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 ## ------------------- ##
 ## Parser generation.  ##
 ## ------------------- ##
 
-%D%/parser.stamp: $(dependencies)
 SUFFIXES += .yy .stamp
 .yy.stamp:
 	$(AM_V_YACC)rm -f $@
@@ -26,12 +25,13 @@ SUFFIXES += .yy .stamp
 	$(AM_V_at)$(YACCCOMPILE) -o $*.cc $<
 	$(AM_V_at)mv -f $@.tmp $@
 
+%D%/parser.stamp: $(dependencies)
 $(calcxx_sources_generated): %D%/parser.stamp
 	@test -f $@ || rm -f %D%/parser.stamp
 	@test -f $@ || $(MAKE) $(AM_MAKEFLAGS) %D%/parser.stamp
 CLEANFILES +=					\
   $(calcxx_sources_generated)			\
-  %D%/parser.dot				\
+  %D%/parser.gv					\
   %D%/parser.output				\
   %D%/parser.stamp				\
   %D%/scanner.cc

examples/c++/glr/Makefile

@@ -0,0 +1,23 @@
+# This Makefile is designed to be simple and readable.  It does not
+# aim at portability.  It requires GNU Make.
+
+BASE = c++-types
+BISON = bison
+
+all: $(BASE)
+
+%.c %.h %.html %.gv: %.y
+	$(BISON) $(BISONFLAGS) --header --html --graph -o $*.c $<
+
+$(BASE): $(BASE).o
+	$(CC) $(CFLAGS) -o $@ $^
+
+run: $(BASE)
+	@echo "Type C++ declarations or expressions.  Quit with ctrl-d."
+	./$<
+
+CLEANFILES =									\
+  $(BASE) *.o $(BASE).[ch] $(BASE).output $(BASE).xml $(BASE).html $(BASE).gv
+
+clean:
+	rm -f $(CLEANFILES)

examples/c++/glr/README.md

@@ -0,0 +1,24 @@
+# glr
+
+This example demonstrates the use of GLR parsers to handle (local)
+ambiguities in the C++ language.  See the node "Merging GLR Parses" in
+Bison's documentation.
+
+<!---
+Local Variables:
+fill-column: 76
+ispell-dictionary: "american"
+End:
+
+Copyright (C) 2020-2021 Free Software Foundation, Inc.
+
+This file is part of Bison, the GNU Compiler Compiler.
+
+Permission is granted to copy, distribute and/or modify this document
+under the terms of the GNU Free Documentation License, Version 1.3 or
+any later version published by the Free Software Foundation; with no
+Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
+Texts.  A copy of the license is included in the "GNU Free
+Documentation License" file as part of this distribution.
+
+--->

examples/c++/glr/ast.hh

@@ -0,0 +1,173 @@
+/*
+  Copyright (C) 2020-2021 Free Software Foundation, Inc.
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+
+#include <cstddef> // nullptr_t
+#include <iostream>
+#include <memory>
+
+// Type erasure 101 <https://stackoverflow.com/a/26199467/1353549>.
+class NodeInterface;
+
+class Node
+{
+public:
+  Node (const Node& node) = default;
+  Node (Node&& node) = default;
+  Node () = default;
+  ~Node () = default;
+
+  template <typename T,
+            // SFINAE block using this ctor as a copy/move ctor:
+            std::enable_if_t<!std::is_same<Node, std::decay_t<T>>::value, int>* = nullptr>
+  Node (T&& t);
+
+  Node& operator= (const Node& node) = default;
+  Node& operator= (Node&& node) = default;
+
+  explicit operator bool () const
+  {
+    return impl_ != nullptr;
+  }
+
+  std::ostream& print (std::ostream& o) const;
+
+  std::shared_ptr<NodeInterface> impl_;
+};
+
+static std::ostream&
+operator<< (std::ostream& o, const Node &node)
+{
+  return node.print (o);
+}
+
+class NodeInterface
+{
+public:
+  virtual ~NodeInterface () = default;
+  virtual std::ostream& print (std::ostream& o) const = 0;
+};
+
+
+std::ostream& Node::print (std::ostream& o) const
+{
+  if (impl_)
+    impl_->print (o);
+  return o;
+}
+
+
+template <typename T,
+          std::enable_if_t<!std::is_same<std::nullptr_t, std::decay_t<T>>::value, int>* = nullptr>
+struct NodeImpl : public NodeInterface
+{
+  template <typename U>
+  explicit NodeImpl (U&& u)
+    : t{std::forward<U> (u)}
+  {}
+  virtual ~NodeImpl () = default;
+  virtual std::ostream& print (std::ostream& o) const
+  {
+    return o << t;
+  }
+
+  T t;
+};
+
+
+template <typename T,
+          std::enable_if_t<!std::is_same<Node, std::decay_t<T>>::value, int>*>
+Node::Node (T&& t)
+  : impl_ (new NodeImpl<std::decay_t<T>>{std::forward<T> (t)})
+{}
+
+class Nterm
+{
+public:
+  Nterm (std::string form,
+         Node child0 = Node (), Node child1 = Node (), Node child2 = Node ())
+    : form_ (std::move (form))
+  {
+    children_[0] = child0;
+    children_[1] = child1;
+    children_[2] = child2;
+  }
+
+  friend std::ostream& operator<< (std::ostream& o, const Nterm& t)
+  {
+    o << t.form_;
+    if (t.children_[0])
+      {
+        o << '(' << t.children_[0];
+        if (t.children_[1])
+          o << ", " << t.children_[1];
+        if (t.children_[2])
+          o << ", " << t.children_[2];
+        o << ')';
+      }
+    return o;
+  }
+
+private:
+  std::string form_;
+  Node children_[3];
+};
+
+
+
+class Term
+{
+public:
+  Term (std::string text)
+    : text_ (std::move (text))
+  {}
+
+  friend std::ostream& operator<< (std::ostream& o, const Term& t)
+  {
+    return o << t.text_;
+  }
+
+private:
+  std::string text_;
+};
+
+#ifdef TEST
+int main ()
+{
+  Node n0;
+  std::cout << n0 << '\n';
+
+  Node n;
+  n = n0;
+  std::cout << n0 << '\n';
+
+  Term t1 = Term ("T");
+  std::cout << t1 << '\n';
+
+  n = t1;
+  std::cout << n << '\n';
+  std::cout << Nterm ("+", t1, t1) << '\n';
+
+  auto n1
+    = Nterm ("<OR>",
+             Nterm ("<declare>", Term ("T"), Term ("x")),
+             Nterm ("<cast>", Term ("x"), Term ("T")));
+  std::cout << n1 << '\n';
+
+  n = n1;
+  std::cout << n1 << '\n';
+}
+#endif

examples/c++/glr/c++-types.test

@@ -0,0 +1,50 @@
+#! /bin/sh
+
+# Copyright (C) 2020-2021 Free Software Foundation, Inc.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+cat >input <<EOF
+z + q;
+
+T x;
+
+T x = y;
+
+x = y;
+EOF
+run 0 "\
+1.0-5: +(z, q)
+3.0-3: <declare>(T, x)
+5.0-7: <init-declare>(T, x, y)
+7.0-5: =(x, y)"
+
+cat >input <<EOF
+T (x) + y;
+
+T (x);
+
+T (y) = z + q;
+
+T (y y) = z + q;
+
+z + q;
+EOF
+run 0 "\
+1.0-9: +(<cast>(x, T), y)
+3.0-5: <OR>(<declare>(T, x), <cast>(x, T))
+5.0-13: <OR>(<init-declare>(T, y, +(z, q)), =(<cast>(y, T), +(z, q)))
+7.0-15: <error>
+9.0-5: +(z, q)
+err: 7.5: syntax error, unexpected identifier, expecting = or + or )"

examples/c++/glr/c++-types.yy

@@ -0,0 +1,220 @@
+/*                                                       -*- C++ -*-
+  Copyright (C) 2020-2021 Free Software Foundation, Inc.
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+
+/* Simplified C++ Type and Expression Grammar.
+   Written by Paul Hilfinger for Bison's test suite.  */
+
+%require "3.8"
+%glr-parser
+%skeleton "glr2.cc"
+%define parse.assert
+%define api.token.constructor
+%header
+%locations
+%debug
+
+// Nice error messages with details.
+%define parse.error detailed
+
+%code requires
+{
+  #include "ast.hh"
+}
+
+%define api.value.type variant
+
+%code
+{
+  #include <cassert>
+  #include <cctype>
+  #include <fstream>
+  #include <cstring>
+
+  static Node
+  stmt_merge (const Node& x0, const Node& x1);
+
+  static yy::parser::symbol_type
+  yylex ();
+}
+
+%expect-rr 1
+
+%type <Node> TYPENAME ID stmt expr decl declarator
+%printer { yyo << $$; } <Node>
+
+%token
+  TYPENAME  "typename"
+  ID        "identifier"
+  SEMICOLON ";"
+  EQUAL     "="
+  PLUS      "+"
+  LPAREN    "("
+  RPAREN    ")"
+
+%right "="
+%left "+"
+
+%%
+
+prog : %empty
+     | prog stmt   { std::cout << @2 << ": " << $2 << '\n'; }
+     ;
+
+stmt : expr ";"  %merge <stmt_merge>   { $$ = $1; }
+     | decl      %merge <stmt_merge>
+     | error ";"                       { $$ = Nterm ("<error>"); }
+     ;
+
+expr : ID
+     | TYPENAME "(" expr ")"  { $$ = Nterm ("<cast>", $3, $1); }
+     | expr "+" expr          { $$ = Nterm ("+", $1, $3); }
+     | expr "=" expr          { $$ = Nterm ("=", $1, $3); }
+     ;
+
+decl : TYPENAME declarator ";"
+                        { $$ = Nterm ("<declare>", $1, $2); }
+     | TYPENAME declarator "=" expr ";"
+                        { $$ = Nterm ("<init-declare>", $1, $2, $4); }
+     ;
+
+declarator
+     : ID
+     | "(" declarator ")" { $$ = $2; }
+     ;
+
+%%
+std::istream* input = nullptr;
+yy::parser::location_type loc;
+
+// An error reporting function.
+void
+yy::parser::error (const location_type& l, const std::string& m)
+{
+  std::cerr << l << ": " << m << '\n';
+}
+
+static yy::parser::symbol_type
+yylex ()
+{
+  while (true)
+    {
+      loc.step ();
+      loc += 1;
+      assert (!input->eof ());
+      switch (int c = input->get ())
+        {
+        case EOF:
+          return yy::parser::make_YYEOF (loc);
+        case '\t':
+          loc.end.column = (loc.end.column + 7) & ~7;
+          loc.step ();
+          break;
+        case ' ': case '\f':
+          loc.step ();
+          break;
+        case '\n':
+          loc.lines (1);
+          loc.end.column = 0;
+          loc.step ();
+          break;
+        case '+':
+          return yy::parser::make_PLUS (loc);
+        case '=':
+          return yy::parser::make_EQUAL (loc);
+        case '(':
+          return yy::parser::make_LPAREN (loc);
+        case ')':
+          return yy::parser::make_RPAREN (loc);
+        case ';':
+          return yy::parser::make_SEMICOLON (loc);
+        default:
+          if (isalpha (c))
+            {
+              std::string form;
+              do
+                {
+                  form += static_cast<char> (c);
+                  loc += 1;
+                  c = input->get ();
+                }
+              while (isalnum (c) || c == '_');
+              input->unget ();
+              loc -= 1;
+              if (isupper (static_cast <unsigned char> (form[0])))
+                return yy::parser::make_TYPENAME (Term (form), loc);
+              else
+                return yy::parser::make_ID (Term (form), loc);
+            }
+          else
+            {
+              auto msg = "invalid character: " + std::string(1, static_cast<char> (c));
+              throw yy::parser::syntax_error (loc, msg);
+            }
+        }
+    }
+}
+
+static Node
+stmt_merge (const Node& x0, const Node& x1)
+{
+  return Nterm ("<OR>", x0, x1);
+}
+
+int
+process (yy::parser& parse, const std::string& file)
+{
+  bool is_stdin = file == "-" || file.empty ();
+  if (is_stdin)
+    input = &std::cin;
+  else
+    input = new std::ifstream (file.c_str ());
+  loc.initialize (nullptr, 1, 0);
+  int status = parse ();
+  if (!is_stdin)
+    delete input;
+  return status;
+}
+
+int
+main (int argc, char **argv)
+{
+  yy::parser parse;
+
+  if (getenv ("YYDEBUG"))
+    parse.set_debug_level (1);
+
+  bool ran = false;
+  for (int i = 1; i < argc; ++i)
+    // Enable parse traces on option -p.
+    if (strcmp (argv[i], "-p") == 0)
+      parse.set_debug_level (1);
+    else
+      {
+        int status = process (parse, argv[i]);
+        ran = true;
+        if (!status)
+          return status;
+      }
+
+  if (!ran)
+    {
+      int status = process (parse, "");
+      if (!status)
+        return status;
+    }
+  return 0;
+}

examples/c++/glr/local.mk

@@ -0,0 +1,52 @@
+## Copyright (C) 2020-2021 Free Software Foundation, Inc.
+##
+## This program is free software: you can redistribute it and/or modify
+## it under the terms of the GNU General Public License as published by
+## the Free Software Foundation, either version 3 of the License, or
+## (at your option) any later version.
+##
+## This program is distributed in the hope that it will be useful,
+## but WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+## GNU General Public License for more details.
+##
+## You should have received a copy of the GNU General Public License
+## along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+glrxxdir = $(docdir)/%D%
+
+## ----------- ##
+## c++-types.  ##
+## ----------- ##
+
+%D%/c++-types.stamp: $(dependencies)
+$(nodist_%C%_c___types_SOURCES): %D%/c++-types.stamp
+	@test -f $@ || rm -f %D%/c++-types.stamp
+	@test -f $@ || $(MAKE) $(AM_MAKEFLAGS) %D%/c++-types.stamp
+CLEANFILES +=					\
+  $(nodist_%C%_c___types_SOURCES)		\
+  %D%/c++-types.stamp				\
+  %D%/c++-types.output				\
+  %D%/location.hh
+CLEANDIRS += %D%/*.dSYM
+
+## -------------------- ##
+## Building & testing.  ##
+## -------------------- ##
+
+# Avoid using BUILT_SOURCES which is too global.
+$(%C%_c___types_OBJECTS): $(cxx_types_sources_generated)
+
+if ENABLE_CXX14
+  check_PROGRAMS += %D%/c++-types
+  dist_%C%_c___types_SOURCES =			\
+    %D%/ast.hh
+  nodist_%C%_c___types_SOURCES =		\
+    %D%/c++-types.cc				\
+    %D%/c++-types.hh
+  # Don't use gnulib's system headers.
+  %C%_c___types_CPPFLAGS = -I$(top_srcdir)/%D% -I$(top_builddir)/%D%
+  %C%_c___types_CXXFLAGS = $(CXX14_CXXFLAGS) $(WARN_CXXFLAGS_TEST)
+  TESTS += %D%/c++-types.test
+endif ENABLE_CXX14
+EXTRA_DIST += %D%/c++-types.yy %D%/c++-types.test

examples/c++/local.mk

@@ -1,4 +1,4 @@
-## Copyright (C) 2018-2020 Free Software Foundation, Inc.
+## Copyright (C) 2018-2021 Free Software Foundation, Inc.
 ##
 ## This program is free software: you can redistribute it and/or modify
 ## it under the terms of the GNU General Public License as published by
@@ -11,10 +11,11 @@
 ## GNU General Public License for more details.
 ##
 ## You should have received a copy of the GNU General Public License
-## along with this program.  If not, see <http://www.gnu.org/licenses/>.
+## along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 cxxdir = $(docdir)/%D%
 include %D%/calc++/local.mk
+include %D%/glr/local.mk
 
 ## -------- ##
 ## Simple.  ##
@@ -29,7 +30,7 @@ simple_extracted = %D%/simple.yy
 simple_sources = $(simple_extracted)
 extracted += $(simple_extracted)
 
-if ENABLE_CXX14
+if ENABLE_CXX11
   check_PROGRAMS += %D%/simple
   nodist_%C%_simple_SOURCES = $(simple_sources)
 

examples/c++/variant-11.test

@@ -1,6 +1,6 @@
 #! /bin/sh
 
-# Copyright (C) 2018-2020 Free Software Foundation, Inc.
+# Copyright (C) 2018-2021 Free Software Foundation, Inc.
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -13,7 +13,7 @@
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 : >input
 run 0 "{I have numbers for you., 1, 2, 3, And that's all!}" 4

examples/c++/variant-11.yy

@@ -1,5 +1,5 @@
 /*
-  Copyright (C) 2008-2015, 2018-2020 Free Software Foundation, Inc.
+  Copyright (C) 2008-2015, 2018-2021 Free Software Foundation, Inc.
 
   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -12,7 +12,7 @@
   GNU General Public License for more details.
 
   You should have received a copy of the GNU General Public License
-  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+  along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */
 
 %require "3.2"

examples/c++/variant.test

@@ -1,6 +1,6 @@
 #! /bin/sh
 
-# Copyright (C) 2018-2020 Free Software Foundation, Inc.
+# Copyright (C) 2018-2021 Free Software Foundation, Inc.
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -13,7 +13,7 @@
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 : >input
 run 0 "{I have three numbers for you., 1, 2, 3, And that's all!}"

examples/c++/variant.yy

@@ -1,5 +1,5 @@
 /*
-  Copyright (C) 2008-2015, 2018-2020 Free Software Foundation, Inc.
+  Copyright (C) 2008-2015, 2018-2021 Free Software Foundation, Inc.
 
   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -12,7 +12,7 @@
   GNU General Public License for more details.
 
   You should have received a copy of the GNU General Public License
-  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+  along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */
 
 %require "3.2"

examples/c/README.md

@@ -60,7 +60,7 @@ This example demonstrates best practices when using Bison.
   push-parser API to feed the parser with the incoming tokens.
 - It features an interactive command line with completion based on the
   parser state, based on `yyexpected_tokens`.
-- It uses Bison's standard catalogue for internationalization of generated
+- It uses Bison's standard catalog for internationalization of generated
   messages.
 - It uses a custom syntax error with location, lookahead correction and
   token internationalization.
@@ -81,7 +81,7 @@ fill-column: 76
 ispell-dictionary: "american"
 End:
 
-Copyright (C) 2018-2020 Free Software Foundation, Inc.
+Copyright (C) 2018-2021 Free Software Foundation, Inc.
 
 This file is part of GNU bison, the GNU Compiler Compiler.
 

examples/c/bistromathic/Makefile

@@ -3,14 +3,13 @@
 
 BASE = bistromathic
 BISON = bison
-XSLTPROC = xsltproc
 
 # We need to find the headers and libs for readline (and possibly intl).
 # You probably need to customize this for your own environment.
 CPPFLAGS = -I/opt/local/include
 LDFLAGS = -L/opt/local/lib
 
-# Find the translation catalogue for Bison's generated messagess.
+# Find the translation catalog for Bison's generated messagess.
 BISON_LOCALEDIR = $(shell $(BISON) $(BISON_FLAGS) --print-localedir)
 CPPFLAGS += -DENABLE_NLS -DBISON_LOCALEDIR='"$(BISON_LOCALEDIR)"'
 
@@ -18,8 +17,8 @@ LIBS = -lreadline -lm # In some environments, -lintl is needed.
 
 all: $(BASE)
 
-%.c %.h %.xml %.gv: %.y
-	$(BISON) $(BISONFLAGS) --defines --xml --graph=$*.gv -o $*.c $<
+%.c %.h %.html %.xml %.gv: %.y
+	$(BISON) $(BISONFLAGS) --header --html --graph -o $*.c $<
 
 $(BASE): parse.o
 	$(CC) $(CPPFLAGS) $(CFLAGS) -o $@ $^ $(LDFLAGS) $(LIBS)
@@ -28,10 +27,6 @@ run: $(BASE)
 	@echo "Type bistromathic expressions.  Quit with ctrl-d."
 	./$<
 
-html: $(BASE).html
-%.html: %.xml
-	$(XSLTPROC) $(XSLTPROCFLAGS) -o $@ $$($(BISON) --print-datadir)/xslt/xml2xhtml.xsl $<
-
 CLEANFILES =						\
   $(BASE) *.o						\
   parse.[ch] parse.output parse.xml parse.html parse.gv

examples/c/bistromathic/README.md

@@ -9,7 +9,7 @@ This example demonstrates best practices when using Bison.
   push-parser API to feed the parser with the incoming tokens.
 - It features an interactive command line with completion based on the
   parser state, based on `yyexpected_tokens`.
-- It uses Bison's standard catalogue for internationalization of generated
+- It uses Bison's standard catalog for internationalization of generated
   messages.
 - It uses a custom syntax error with location, lookahead correction and
   token internationalization.
@@ -32,7 +32,7 @@ fill-column: 76
 ispell-dictionary: "american"
 End:
 
-Copyright (C) 2020 Free Software Foundation, Inc.
+Copyright (C) 2020-2021 Free Software Foundation, Inc.
 
 This file is part of Bison, the GNU Compiler Compiler.
 

examples/c/bistromathic/bistromathic.test

@@ -1,6 +1,6 @@
 #! /bin/sh
 
-# Copyright (C) 2020 Free Software Foundation, Inc.
+# Copyright (C) 2020-2021 Free Software Foundation, Inc.
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -13,7 +13,7 @@
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 # Users may customize the behavior of readline, which might break our
 # expected results.
@@ -251,29 +251,29 @@ err: Next token is token ) (1.4: )
 err: Shifting token ) (1.4: )
 err: Entering state 20
 err: Stack now 0 2 10 20
-err: Reducing stack by rule 15 (line 151):
+err: Reducing stack by rule XX (line XXX):
 err:    $1 = token ( (1.1: )
 err:    $2 = token error (1.2-3: )
 err:    $3 = token ) (1.4: )
 err: -> $$ = nterm exp (1.1-4: 666)
-err: Entering state 7
-err: Stack now 0 7
+err: Entering state 8
+err: Stack now 0 8
 err: Return for a new token:
 err: Reading a token
 err: Now at end of input.
 err: LAC: initial context established for end of file
-err: LAC: checking lookahead end of file: R2 G8 S19
-err: Reducing stack by rule 2 (line 126):
+err: LAC: checking lookahead end of file: R2 G7 S14
+err: Reducing stack by rule XX (line XXX):
 err:    $1 = nterm exp (1.1-4: 666)
 err: -> $$ = nterm input (1.1-4: )
-err: Entering state 8
-err: Stack now 0 8
+err: Entering state 7
+err: Stack now 0 7
 err: Now at end of input.
 err: Shifting token end of file (1.5: )
 err: LAC: initial context discarded due to shift
-err: Entering state 19
-err: Stack now 0 8 19
-err: Stack now 0 8 19
+err: Entering state 14
+err: Stack now 0 7 14
+err: Stack now 0 7 14
 err: Cleanup: popping token end of file (1.5: )
 err: Cleanup: popping nterm input (1.1-4: )' -p
 
@@ -306,10 +306,17 @@ esac
 sed -e 's/\\t/	/g' >input <<EOF
 (1+\t\t
 EOF
-run 0 '> (1+
+# Nuke the possible trailing white spaces in the effective output.
+# This is to cope with some readlines that pad all the suggestions
+# with white spaces (for alignment), including the last one on a line.
+#
+# See for instance <https://trac.macports.org/ticket/59927#comment:48>
+# and its test-suite.log:
+# <https://trac.macports.org/attachment/ticket/59927/bison-3.7.6-test-10.13.test-suite.log>
+run -t 0 '> (1+
 (       -       atan    cos     exp     ln      number  sin     sqrt
 > (1+
-> ''
+>
 err: 1.4: syntax error: expected - or ( or number or function or variable before end of file
 err:     1 | (1+
 err:       |    ^'

examples/c/bistromathic/local.mk

@@ -1,4 +1,4 @@
-## Copyright (C) 2020 Free Software Foundation, Inc.
+## Copyright (C) 2020-2021 Free Software Foundation, Inc.
 ##
 ## This program is free software: you can redistribute it and/or modify
 ## it under the terms of the GNU General Public License as published by
@@ -11,7 +11,7 @@
 ## GNU General Public License for more details.
 ##
 ## You should have received a copy of the GNU General Public License
-## along with this program.  If not, see <http://www.gnu.org/licenses/>.
+## along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 bistromathicdir = $(docdir)/%D%
 

examples/c/bistromathic/parse.y

@@ -1,6 +1,6 @@
 /* Parser and scanner for bistromathic.   -*- C -*-
 
-   Copyright (C) 2019-2020 Free Software Foundation, Inc.
+   Copyright (C) 2019-2021 Free Software Foundation, Inc.
 
    This file is part of Bison, the GNU Compiler Compiler.
 
@@ -15,7 +15,7 @@
    GNU General Public License for more details.
 
    You should have received a copy of the GNU General Public License
-   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
 
 %require "3.7"
 
@@ -37,7 +37,7 @@
   # define YYENABLE_NLS 1
   # include <libintl.h>
   // Unless specified otherwise, we expect bistromathic's own
-  // catalogue to be installed in the same tree as Bison's catalogue.
+  // catalog to be installed in the same tree as Bison's catalog.
   # ifndef LOCALEDIR
   #  define LOCALEDIR BISON_LOCALEDIR
   # endif
@@ -87,13 +87,17 @@
   yytoken_kind_t
   yylex (const char **line, YYSTYPE *yylval, YYLTYPE *yylloc,
          const user_context *uctx);
-  void yyerror (YYLTYPE *loc, const user_context *uctx,
+  void yyerror (const YYLTYPE *loc, const user_context *uctx,
                 char const *format, ...)
     __attribute__ ((__format__ (__printf__, 3, 4)));
 }
 
 // Emitted in the implementation file.
 %code {
+  // Print *LOC on OUT.
+  static void location_print (FILE *out, YYLTYPE const * const loc);
+  #define YYLOCATION_PRINT location_print
+
   #if defined ENABLE_NLS && ENABLE_NLS
   # define _(Msgid)  gettext (Msgid)
   #else
@@ -117,13 +121,13 @@
 // with TOK_ (e.g., TOK_EOF).
 %define api.token.prefix {TOK_}
 
-// Customized syntax error messages (see yyreport_syntax_error).
+// Customized syntax error messages (see yyreport_syntax_error)...
 %define parse.error custom
 
-// with locations.
+// ... with locations...
 %locations
 
-// and accurate list of expected tokens.
+// ... and accurate list of expected tokens.
 %define parse.lac full
 
 // Generate the parser description file (calc.output).
@@ -187,7 +191,7 @@ exp:
   {
     if ($r == 0)
       {
-        yyerror (&@$, uctx, "error: division by zero");
+        yyerror (&@$, uctx, _("error: division by zero"));
         YYERROR;
       }
     else
@@ -269,6 +273,26 @@ symbol_count (void)
 }
 
 
+
+/*------------.
+| Locations.  |
+`------------*/
+
+// Print *LOC on OUT.  Do it in a compact way, that avoids redundancy.
+
+static void
+location_print (FILE *out, YYLTYPE const * const loc)
+{
+  fprintf (out, "%d.%d", loc->first_line, loc->first_column);
+
+  int end_col = 0 != loc->last_column ? loc->last_column - 1 : 0;
+  if (loc->first_line < loc->last_line)
+    fprintf (out, "-%d.%d", loc->last_line, end_col);
+  else if (loc->first_column < end_col)
+    fprintf (out, "-%d", end_col);
+}
+
+
 /*----------.
 | Scanner.  |
 `----------*/
@@ -345,7 +369,7 @@ yylex (const char **line, YYSTYPE *yylval, YYLTYPE *yylloc,
 
       // Stray characters.
     default:
-      yyerror (yylloc, uctx, "syntax error: invalid character: %c", c);
+      yyerror (yylloc, uctx, _("syntax error: invalid character: %c"), c);
       return TOK_YYerror;
     }
 }
@@ -403,7 +427,7 @@ yyreport_syntax_error (const yypcontext_t *ctx, const user_context *uctx)
     // %@: location.
     if (format[0] == '%' && format[1] == '@')
       {
-        YY_LOCATION_PRINT (stderr, *loc);
+        YYLOCATION_PRINT (stderr, loc);
         format += 2;
       }
     // %u: unexpected token.
@@ -442,12 +466,12 @@ yyreport_syntax_error (const yypcontext_t *ctx, const user_context *uctx)
 
 
 // Called by yyparse on error.
-void yyerror (YYLTYPE *loc, const user_context *uctx, char const *format, ...)
+void yyerror (const YYLTYPE *loc, const user_context *uctx, char const *format, ...)
 {
   if (uctx->silent)
     return;
 
-  YY_LOCATION_PRINT (stderr, *loc);
+  YYLOCATION_PRINT (stderr, loc);
   fputs (": ", stderr);
   va_list args;
   va_start (args, format);
@@ -638,10 +662,10 @@ main (int argc, char const* argv[])
 #if defined ENABLE_NLS && ENABLE_NLS
   // Set up internationalization.
   setlocale (LC_ALL, "");
-  // Use Bison's standard translation catalogue for error messages
+  // Use Bison's standard translation catalog for error messages
   // (the generated messages).
   bindtextdomain ("bison-runtime", BISON_LOCALEDIR);
-  // The translation catalogue of bistromathic is actually included in
+  // The translation catalog of bistromathic is actually included in
   // Bison's.  In your own project, use the name of your project.
   bindtextdomain ("bison", LOCALEDIR);
   textdomain ("bison");

examples/c/calc/Makefile

@@ -3,12 +3,11 @@
 
 BASE = calc
 BISON = bison
-XSLTPROC = xsltproc
 
 all: $(BASE)
 
-%.c %.h %.xml %.gv: %.y
-	$(BISON) $(BISONFLAGS) --defines --xml --graph=$*.gv -o $*.c $<
+%.c %.h %.html %.xml %.gv: %.y
+	$(BISON) $(BISONFLAGS) --header --html --graph -o $*.c $<
 
 $(BASE): $(BASE).o
 	$(CC) $(CFLAGS) -o $@ $^
@@ -17,10 +16,6 @@ run: $(BASE)
 	@echo "Type arithmetic expressions.  Quit with ctrl-d."
 	./$<
 
-html: $(BASE).html
-%.html: %.xml
-	$(XSLTPROC) $(XSLTPROCFLAGS) -o $@ $$($(BISON) --print-datadir)/xslt/xml2xhtml.xsl $<
-
 CLEANFILES =									\
   $(BASE) *.o $(BASE).[ch] $(BASE).output $(BASE).xml $(BASE).html $(BASE).gv
 

examples/c/calc/README.md

@@ -9,7 +9,7 @@ fill-column: 76
 ispell-dictionary: "american"
 End:
 
-Copyright (C) 2019-2020 Free Software Foundation, Inc.
+Copyright (C) 2019-2021 Free Software Foundation, Inc.
 
 This file is part of Bison, the GNU Compiler Compiler.
 

examples/c/calc/calc.test

@@ -1,6 +1,6 @@
 #! /bin/sh
 
-# Copyright (C) 2019-2020 Free Software Foundation, Inc.
+# Copyright (C) 2019-2021 Free Software Foundation, Inc.
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -13,7 +13,7 @@
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 cat >input <<EOF
 1+2*3

examples/c/calc/local.mk

@@ -1,4 +1,4 @@
-## Copyright (C) 2019-2020 Free Software Foundation, Inc.
+## Copyright (C) 2019-2021 Free Software Foundation, Inc.
 ##
 ## This program is free software: you can redistribute it and/or modify
 ## it under the terms of the GNU General Public License as published by
@@ -11,7 +11,7 @@
 ## GNU General Public License for more details.
 ##
 ## You should have received a copy of the GNU General Public License
-## along with this program.  If not, see <http://www.gnu.org/licenses/>.
+## along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 calcdir = $(docdir)/%D%
 

examples/c/glr/Makefile

@@ -0,0 +1,23 @@
+# This Makefile is designed to be simple and readable.  It does not
+# aim at portability.  It requires GNU Make.
+
+BASE = c++-types
+BISON = bison
+
+all: $(BASE)
+
+%.c %.h %.xml %.gv: %.y
+	$(BISON) $(BISONFLAGS) --header --graph -o $*.c $<
+
+$(BASE): $(BASE).o
+	$(CC) $(CFLAGS) -o $@ $^
+
+run: $(BASE)
+	@echo "Type C++ declarations or expressions.  Quit with ctrl-d."
+	./$<
+
+CLEANFILES =									\
+  $(BASE) *.o $(BASE).[ch] $(BASE).output $(BASE).xml $(BASE).html $(BASE).gv
+
+clean:
+	rm -f $(CLEANFILES)

examples/c/glr/README.md

@@ -0,0 +1,24 @@
+# glr
+
+This example demonstrates the use of GLR parsers to handle (local)
+ambiguities in the C++ language.  See the node "Merging GLR Parses" in
+Bison's documentation.
+
+<!---
+Local Variables:
+fill-column: 76
+ispell-dictionary: "american"
+End:
+
+Copyright (C) 2020-2021 Free Software Foundation, Inc.
+
+This file is part of Bison, the GNU Compiler Compiler.
+
+Permission is granted to copy, distribute and/or modify this document
+under the terms of the GNU Free Documentation License, Version 1.3 or
+any later version published by the Free Software Foundation; with no
+Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
+Texts.  A copy of the license is included in the "GNU Free
+Documentation License" file as part of this distribution.
+
+--->

examples/c/glr/c++-types.test

@@ -0,0 +1,47 @@
+#! /bin/sh
+
+# Copyright (C) 2020-2021 Free Software Foundation, Inc.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+cat >input <<EOF
+z + q;
+
+T x;
+
+T x = y;
+
+x = y;
+
+T (x) + y;
+
+T (x);
+
+T (y) = z + q;
+
+T (y y) = z + q;
+
+z + q;
+EOF
+run 0 "\
+1.0-5: +(z, q)
+3.0-3: <declare>(T, x)
+5.0-7: <init-declare>(T, x, y)
+7.0-5: =(x, y)
+9.0-9: +(<cast>(x, T), y)
+11.0-5: <OR>(<declare>(T, x), <cast>(x, T))
+13.0-13: <OR>(<init-declare>(T, y, +(z, q)), =(<cast>(y, T), +(z, q)))
+15.0-15: <error>
+17.0-5: +(z, q)
+err: 15.5: syntax error, unexpected identifier, expecting '=' or '+' or ')'"

examples/c/glr/c++-types.y

@@ -0,0 +1,340 @@
+/*                                                       -*- C -*-
+  Copyright (C) 2020-2021 Free Software Foundation, Inc.
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+
+/* Simplified C++ Type and Expression Grammar.
+   Written by Paul Hilfinger for Bison's test suite.  */
+
+%define api.pure
+%header
+%define api.header.include {"c++-types.h"}
+%locations
+%debug
+
+/* Nice error messages with details. */
+%define parse.error detailed
+
+%code requires
+{
+  union Node {
+    struct {
+      int isNterm;
+      int parents;
+    } nodeInfo;
+    struct {
+      int isNterm; /* 1 */
+      int parents;
+      char const *form;
+      union Node *children[3];
+    } nterm;
+    struct {
+      int isNterm; /* 0 */
+      int parents;
+      char *text;
+    } term;
+  };
+  typedef union Node Node;
+}
+
+%define api.value.type union
+
+%code
+{
+
+#include <assert.h>
+#include <ctype.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+  static Node *new_nterm (char const *, Node *, Node *, Node *);
+  static Node *new_term (char *);
+  static void free_node (Node *);
+  static char *node_to_string (const Node *);
+  static void node_print (FILE *, const Node *);
+  static Node *stmt_merge (YYSTYPE x0, YYSTYPE x1);
+
+  static void yyerror (YYLTYPE const * const loc, const char *msg);
+  static yytoken_kind_t yylex (YYSTYPE *lval, YYLTYPE *lloc);
+}
+
+%expect-rr 1
+
+%token
+  TYPENAME "typename"
+  ID "identifier"
+
+%right '='
+%left '+'
+
+%glr-parser
+
+%type <Node *> stmt expr decl declarator TYPENAME ID
+%destructor { free_node ($$); } <Node *>
+%printer { node_print (yyo, $$); } <Node *>
+
+%%
+
+prog : %empty
+     | prog stmt   {
+                     YYLOCATION_PRINT (stdout, &@2);
+                     fputs (": ", stdout);
+                     node_print (stdout, $2);
+                     putc ('\n', stdout);
+                     fflush (stdout);
+                     free_node ($2);
+                   }
+     ;
+
+stmt : expr ';'  %merge <stmt_merge>     { $$ = $1; }
+     | decl      %merge <stmt_merge>
+     | error ';'        { $$ = new_nterm ("<error>", NULL, NULL, NULL); }
+     ;
+
+expr : ID
+     | TYPENAME '(' expr ')'
+                        { $$ = new_nterm ("<cast>(%s, %s)", $3, $1, NULL); }
+     | expr '+' expr    { $$ = new_nterm ("+(%s, %s)", $1, $3, NULL); }
+     | expr '=' expr    { $$ = new_nterm ("=(%s, %s)", $1, $3, NULL); }
+     ;
+
+decl : TYPENAME declarator ';'
+                        { $$ = new_nterm ("<declare>(%s, %s)", $1, $2, NULL); }
+     | TYPENAME declarator '=' expr ';'
+                        { $$ = new_nterm ("<init-declare>(%s, %s, %s)", $1,
+                                          $2, $4); }
+     ;
+
+declarator
+     : ID
+     | '(' declarator ')' { $$ = $2; }
+     ;
+
+%%
+
+/* A C error reporting function.  */
+static void
+yyerror (YYLTYPE const * const loc, const char *msg)
+{
+  YYLOCATION_PRINT (stderr, loc);
+  fprintf (stderr, ": %s\n", msg);
+}
+
+/* The input file. */
+FILE * input = NULL;
+
+yytoken_kind_t
+yylex (YYSTYPE *lval, YYLTYPE *lloc)
+{
+  static int lineNum = 1;
+  static int colNum = 0;
+
+  while (1)
+    {
+      int c;
+      assert (!feof (input));
+      c = getc (input);
+      switch (c)
+        {
+        case EOF:
+          return 0;
+        case '\t':
+          colNum = (colNum + 7) & ~7;
+          break;
+        case ' ': case '\f':
+          colNum += 1;
+          break;
+        case '\n':
+          lineNum += 1;
+          colNum = 0;
+          break;
+        default:
+          {
+            yytoken_kind_t tok;
+            lloc->first_line = lloc->last_line = lineNum;
+            lloc->first_column = colNum;
+            if (isalpha (c))
+              {
+                char buffer[256];
+                unsigned i = 0;
+
+                do
+                  {
+                    buffer[i++] = (char) c;
+                    colNum += 1;
+                    assert (i != sizeof buffer - 1);
+                    c = getc (input);
+                  }
+                while (isalnum (c) || c == '_');
+
+                ungetc (c, input);
+                buffer[i++] = 0;
+                if (isupper ((unsigned char) buffer[0]))
+                  {
+                    tok = TYPENAME;
+                    lval->TYPENAME = new_term (strcpy (malloc (i), buffer));
+                  }
+                else
+                  {
+                    tok = ID;
+                    lval->ID = new_term (strcpy (malloc (i), buffer));
+                  }
+              }
+            else
+              {
+                colNum += 1;
+                tok = c;
+              }
+            lloc->last_column = colNum;
+            return tok;
+          }
+        }
+    }
+}
+
+static Node *
+new_nterm (char const *form, Node *child0, Node *child1, Node *child2)
+{
+  Node *res = malloc (sizeof *res);
+  res->nterm.isNterm = 1;
+  res->nterm.parents = 0;
+  res->nterm.form = form;
+  res->nterm.children[0] = child0;
+  if (child0)
+    child0->nodeInfo.parents += 1;
+  res->nterm.children[1] = child1;
+  if (child1)
+    child1->nodeInfo.parents += 1;
+  res->nterm.children[2] = child2;
+  if (child2)
+    child2->nodeInfo.parents += 1;
+  return res;
+}
+
+static Node *
+new_term (char *text)
+{
+  Node *res = malloc (sizeof *res);
+  res->term.isNterm = 0;
+  res->term.parents = 0;
+  res->term.text = text;
+  return res;
+}
+
+static void
+free_node (Node *node)
+{
+  if (!node)
+    return;
+  node->nodeInfo.parents -= 1;
+  /* Free only if 0 (last parent) or -1 (no parents).  */
+  if (node->nodeInfo.parents > 0)
+    return;
+  if (node->nodeInfo.isNterm == 1)
+    {
+      free_node (node->nterm.children[0]);
+      free_node (node->nterm.children[1]);
+      free_node (node->nterm.children[2]);
+    }
+  else
+    free (node->term.text);
+  free (node);
+}
+
+static char *
+node_to_string (const Node *node)
+{
+  char *res;
+  if (!node)
+    {
+      res = malloc (1);
+      res[0] = 0;
+    }
+  else if (node->nodeInfo.isNterm == 1)
+    {
+      char *child0 = node_to_string (node->nterm.children[0]);
+      char *child1 = node_to_string (node->nterm.children[1]);
+      char *child2 = node_to_string (node->nterm.children[2]);
+      res = malloc (strlen (node->nterm.form) + strlen (child0)
+                    + strlen (child1) + strlen (child2) + 1);
+      sprintf (res, node->nterm.form, child0, child1, child2);
+      free (child2);
+      free (child1);
+      free (child0);
+    }
+  else
+    res = strdup (node->term.text);
+  return res;
+}
+
+static void
+node_print (FILE *out, const Node *n)
+{
+  char *str = node_to_string (n);
+  fputs (str, out);
+  free (str);
+}
+
+
+static Node *
+stmt_merge (YYSTYPE x0, YYSTYPE x1)
+{
+  return new_nterm ("<OR>(%s, %s)", x0.stmt, x1.stmt, NULL);
+}
+
+static int
+process (const char *file)
+{
+  int is_stdin = !file || strcmp (file, "-") == 0;
+  if (is_stdin)
+    input = stdin;
+  else
+    input = fopen (file, "r");
+  assert (input);
+  int status = yyparse ();
+  if (!is_stdin)
+    fclose (input);
+  return status;
+}
+
+int
+main (int argc, char **argv)
+{
+  if (getenv ("YYDEBUG"))
+    yydebug = 1;
+
+  int ran = 0;
+  for (int i = 1; i < argc; ++i)
+    // Enable parse traces on option -p.
+    if (strcmp (argv[i], "-p") == 0)
+      yydebug = 1;
+    else
+      {
+        int status = process (argv[i]);
+        ran = 1;
+        if (!status)
+          return status;
+      }
+
+  if (!ran)
+    {
+      int status = process (NULL);
+      if (!status)
+        return status;
+    }
+  return 0;
+}