version 3.5.90

* NEWS: Record release date.

.prev-version

@@ -1 +1 @@
-3.4.90
+3.5.4

.travis.yml

@@ -1,14 +1,8 @@
-# Travis defines and exports CC and CXX *after* we have defined our
-# environment variables via 'env'.  So, do not use 'env' to define them.
-# Instead, put their definitions in MATRIX_EVAL, which we eval after the
-# definitions from Travis.
-language: cpp
+version: ~> 1.0
 
-env:
-  global:
-    # ICC serial number.
-    # See https://github.com/nemequ/icc-travis.
-    secure: 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
+# If the language is set to C or C++, Travis defines and exports CC
+# and CXX *after* we have defined our environment variables via 'env'.
+language: minimal
 
 # Run in two steps:
 # 1. Build the tarball
@@ -73,21 +67,22 @@ jobs:
     ## First.  ##
     ## ------- ##
 
-    # Start with three completely different environments, to get
-    # errors asap.
+    # Start with three completely different environments, to get errors asap.
 
     - name: "GCC 9 -O3"
       stage: check
       os: linux
       dist: bionic
-      addons:
+      addons: &gcc9
         apt:
           sources:
             # See https://github.com/travis-ci/apt-source-safelist/issues/410.
             - sourceline: 'ppa:ubuntu-toolchain-r/test'
           packages: g++-9
       env:
-        - MATRIX_EVAL="CC=gcc-9 && CXX=g++-9 && CONFIGUREFLAGS='CPPFLAGS=-DNDEBUG CFLAGS=-O3 CXXFLAGS=-O3'"
+        - CC=gcc-9
+        - CXX=g++-9
+        - 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.
@@ -108,7 +103,8 @@ jobs:
             - libc++abi-9-dev
       env:
         # Do not use ASAN with ubuntu's libc++: https://bugs.llvm.org/show_bug.cgi?id=17379
-        - MATRIX_EVAL="CC='clang-9 -fsanitize=address' CXX='clang++-9 -fsanitize=address -stdlib=libc++'"
+        - CC='clang-9 -fsanitize=address'
+        - CXX='clang++-9 -fsanitize=address -stdlib=libc++'
         - PART=1
 
     - name: "Clang 9 libc++ and ASAN part 2"
@@ -118,26 +114,69 @@ jobs:
       addons: *clang9
       env:
         # Do not use ASAN with ubuntu's libc++: https://bugs.llvm.org/show_bug.cgi?id=17379
-        - MATRIX_EVAL="CC='clang-9 -fsanitize=address' CXX='clang++-9 -fsanitize=address -stdlib=libc++'"
+        - CC='clang-9 -fsanitize=address'
+        - CXX='clang++-9 -fsanitize=address -stdlib=libc++'
         - PART=2
 
-    # Currently no longer works (https://github.com/nemequ/icc-travis/issues/15).
-    # - name: "ICC"
-    #   stage: check
-    #   # We need the build-aux/install-icc.sh script.
-    #   git:
-    #     clone: true
-    #     submodules: false
-    #     depth: 1
-    #   os: linux
-    #   dist: xenial
-    #   env:
-    #     # ICC's warnings are often very wrong (e.g., it thinks foo ?
-    #     # "bar" : "baz" is char* instead of const char*), so don't try
-    #     # to work around the, and obviously, don't die on them.
-    #     - MATRIX_EVAL="CC=icc && CXX=icpc"
-    #     - MAKE_ARGS='WERROR_CFLAGS= WERROR_CXXFLAGS='
+    - name: "ICC"
+      stage: check
+      os: linux
+      compiler: icc
+      env:
+        - CC=icc
+        - CXX=icpc
+      install:
+        - source /opt/intel/inteloneapi/compiler/latest/env/vars.sh
+      addons:
+        apt:
+          sources:
+          - sourceline: 'deb https://apt.repos.intel.com/oneapi all main'
+            key_url: 'https://apt.repos.intel.com/intel-gpg-keys/GPG-PUB-KEY-INTEL-SW-PRODUCTS-2023.PUB'
+          packages:
+          - intel-oneapi-icc
 
+    ## ------- ##
+    ## First.  ##
+    ## ------- ##
+
+    # Start with three completely different environments, to get
+    # errors asap.
+
+    - name: "ARM64: GCC 9 -O3 part 1"
+      stage: check
+      os: linux
+      arch: arm64
+      dist: bionic
+      addons: *gcc9
+      env:
+        - CC=gcc-9
+        - CXX=g++-9
+        - CONFIGUREFLAGS='CPPFLAGS=-DNDEBUG CFLAGS=-O3 CXXFLAGS=-O3'
+        - PART=1
+
+    - name: "PPC64le: GCC 9 part 1"
+      stage: check
+      os: linux
+      arch: ppc64le
+      dist: bionic
+      addons: *gcc9
+      env:
+        - CC=gcc-9
+        - CXX=g++-9
+        - CONFIGUREFLAGS='CFLAGS=-O3 CXXFLAGS=-O3'
+        - PART=1
+
+    - name: "s390x: GCC 9 part 1"
+      stage: check
+      os: linux
+      arch: s390x
+      dist: bionic
+      addons: *gcc9
+      env:
+        - CC=gcc-9
+        - CXX=g++-9
+        - CONFIGUREFLAGS='CFLAGS=-O3 CXXFLAGS=-O3'
+        - PART=1
 
     ## ----- ##
     ## GCC.  ##
@@ -150,7 +189,8 @@ jobs:
         apt:
           packages: g++-8
       env:
-        - MATRIX_EVAL="CC='gcc-8 -fsanitize=undefined,address -fno-omit-frame-pointer' CXX='g++-8 -fsanitize=undefined,address -fno-omit-frame-pointer'"
+        - CC='gcc-8 -fsanitize=undefined,address -fno-omit-frame-pointer'
+        - CXX='g++-8 -fsanitize=undefined,address -fno-omit-frame-pointer'
         - CONFIGUREFLAGS='CFLAGS=-O1 CXXFLAGS=-O1'
         - PART=1
 
@@ -162,7 +202,8 @@ jobs:
         apt:
           packages: g++-8
       env:
-        - MATRIX_EVAL="CC=gcc-8 && CXX=g++-8"
+        - CC=gcc-8
+        - CXX=g++-8
 
     - name: "GCC 7"
       stage: check
@@ -172,7 +213,8 @@ jobs:
         apt:
           packages: g++-7
       env:
-        - MATRIX_EVAL="CC=gcc-7 && CXX=g++-7"
+        - CC=gcc-7
+        - CXX=g++-7
 
     - name: "GCC 6"
       stage: check
@@ -183,7 +225,8 @@ jobs:
           sources: ubuntu-toolchain-r-test
           packages: g++-6
       env:
-        - MATRIX_EVAL="CC=gcc-6 && CXX=g++-6"
+        - CC=gcc-6
+        - CXX=g++-6
 
     - name: "GCC 5"
       stage: check
@@ -194,7 +237,8 @@ jobs:
           sources: ubuntu-toolchain-r-test
           packages: g++-5
       env:
-         - MATRIX_EVAL="CC=gcc-5 && CXX=g++-5"
+         - CC=gcc-5
+         - CXX=g++-5
 
     - name: "GCC 4.9"
       stage: check
@@ -205,7 +249,8 @@ jobs:
           sources: ubuntu-toolchain-r-test
           packages: g++-4.9
       env:
-         - MATRIX_EVAL="CC=gcc-4.9 && CXX=g++-4.9"
+         - CC=gcc-4.9
+         - CXX=g++-4.9
 
     - name: "GCC 4.8"
       stage: check
@@ -216,7 +261,8 @@ jobs:
           sources: ubuntu-toolchain-r-test
           packages: g++-4.8
       env:
-         - MATRIX_EVAL="CC=gcc-4.8 && CXX=g++-4.8"
+         - CC=gcc-4.8
+         - CXX=g++-4.8
 
     - name: "GCC 4.7"
       stage: check
@@ -227,7 +273,8 @@ jobs:
           sources: ubuntu-toolchain-r-test
           packages: g++-4.7
       env:
-         - MATRIX_EVAL="CC=gcc-4.7 && CXX=g++-4.7"
+         - CC=gcc-4.7
+         - CXX=g++-4.7
 
     - name: "GCC 4.6"
       stage: check
@@ -238,7 +285,8 @@ jobs:
           sources: ubuntu-toolchain-r-test
           packages: g++-4.6
       env:
-         - MATRIX_EVAL="CC=gcc-4.6 && CXX=g++-4.6"
+         - CC=gcc-4.6
+         - CXX=g++-4.6
 
     ## ------- ##
     ## Clang.  ##
@@ -255,7 +303,8 @@ jobs:
             - libc++-8-dev
             - libc++abi-8-dev
       env:
-        - MATRIX_EVAL="CC=clang-8 && CXX='clang++-8 -stdlib=libc++'"
+        - CC=clang-8
+        - CXX='clang++-8 -stdlib=libc++'
         - CONFIGUREFLAGS='CPPFLAGS=-DNDEBUG CFLAGS=-O3 CXXFLAGS=-O3'
 
     - name: "Clang 7"
@@ -269,7 +318,8 @@ jobs:
             - libc++-7-dev
             - libc++abi-7-dev
       env:
-        - MATRIX_EVAL="CC=clang-7 && CXX='clang++-7 -stdlib=libc++'"
+        - CC=clang-7
+        - CXX='clang++-7 -stdlib=libc++'
 
     - name: "Clang 6 and libc++"
       stage: check
@@ -284,7 +334,8 @@ jobs:
             - clang-6.0
             - libc++-dev
       env:
-        - MATRIX_EVAL="CC=clang-6.0 && CXX='clang++-6.0 -stdlib=libc++'"
+        - CC=clang-6.0
+        - CXX='clang++-6.0 -stdlib=libc++'
 
     - name: "Clang 5"
       stage: check
@@ -297,7 +348,8 @@ jobs:
             - clang-5.0
             - libc++-dev
       env:
-        - MATRIX_EVAL="CC='clang-5.0' CXX='clang++-5.0'"
+        - CC='clang-5.0'
+        - CXX='clang++-5.0'
 
     - name: "Clang 4"
       stage: check
@@ -308,7 +360,8 @@ jobs:
           sources: llvm-toolchain-xenial-4.0
           packages: clang-4.0
       env:
-        - MATRIX_EVAL="CC=clang-4.0 && CXX=clang++-4.0"
+        - CC=clang-4.0
+        - CXX=clang++-4.0
 
     - name: "Clang 3.9"
       stage: check
@@ -319,7 +372,8 @@ jobs:
           sources: llvm-toolchain-xenial-3.9
           packages: clang-3.9
       env:
-        - MATRIX_EVAL="CC=clang-3.9 && CXX=clang++-3.9"
+        - CC=clang-3.9
+        - CXX=clang++-3.9
 
     - name: "Clang 3.8"
       stage: check
@@ -332,7 +386,8 @@ jobs:
             - llvm-toolchain-precise-3.8
           packages: clang-3.8
       env:
-        - MATRIX_EVAL="CC=clang-3.8 && CXX=clang++-3.8"
+        - CC=clang-3.8
+        - CXX=clang++-3.8
 
     - name: "CLang 3.7"
       stage: check
@@ -345,7 +400,8 @@ jobs:
             - llvm-toolchain-precise-3.7
           packages: clang-3.7
       env:
-        - MATRIX_EVAL="CC=clang-3.7 && CXX=clang++-3.7"
+        - CC=clang-3.7
+        - CXX=clang++-3.7
 
     - name: "Clang 3.6"
       stage: check
@@ -358,7 +414,8 @@ jobs:
             - llvm-toolchain-precise-3.6
           packages: clang-3.6
       env:
-        - MATRIX_EVAL="CC=clang-3.6 && CXX=clang++-3.6"
+        - CC=clang-3.6
+        - CXX=clang++-3.6
 
     - name: "Clang 3.5"
       stage: check
@@ -371,7 +428,8 @@ jobs:
             - llvm-toolchain-precise-3.5
           packages: clang-3.5
       env:
-        - MATRIX_EVAL="CC=clang-3.5 && CXX=clang++-3.5"
+        - CC=clang-3.5
+        - CXX=clang++-3.5
 
     - name: "Clang 3.4"
       stage: check
@@ -384,7 +442,8 @@ jobs:
       env:
         # No versioned name installed, but beware that Travis installs
         # a more modern clang earlier in the default PATH.
-        - MATRIX_EVAL='CC=/usr/bin/clang && CXX=/usr/bin/clang++'
+        - CC=/usr/bin/clang
+        - CXX=/usr/bin/clang++
 
     - name: "Clang 3.3"
       stage: check
@@ -396,7 +455,8 @@ jobs:
           packages: clang-3.3
       env:
         # See comment for 3.4.
-        - MATRIX_EVAL='CC=/usr/bin/clang && CXX=/usr/bin/clang++'
+        - CC=/usr/bin/clang
+        - CXX=/usr/bin/clang++
 
 ## From https://docs.gitlab.com/ce/ci/ssh_keys/#ssh-keys-when-using-the-docker-executor.
 ## Applies to Travis too.  Applied to all the 'script's (of all the jobs).
@@ -414,20 +474,16 @@ before_script:
 
 # Applies only to the jobs that don't have a 'script', i.e., applies to all the 'check' jobs, but not the 'dist' one.
 script:
-  - eval "$MATRIX_EVAL"
   # Beware not too leak $SSH_PRIVATE_KEY.
   # - env
   - sudo apt-get install -qq doxygen flex m4
-  # Install and activate ICC.
-  - if [[ $CC == "icc" ]]; then build-aux/install-icc.sh; fi
-  - if [[ -f ~/.bashrc ]]; then source ~/.bashrc; fi
   # Install and activate dmd.
   - mkdir -p ~/dlang && wget https://dlang.org/install.sh -O ~/dlang/install.sh
-  - source $(source ~/dlang/install.sh dmd -a)
+  - source $(source ~/dlang/install.sh dmd -a) || true
 
   - $CC --version
   - $CXX --version
-  - dmd --version
+  - dmd --version || true
   - doxygen --version
   - flex --version
   - ld --version
@@ -452,6 +508,3 @@ script:
   - if test ${PART-1} = 1; then make check                  VERBOSE=1 TESTSUITEFLAGS=-j2 || { cat test-suite.log && cat tests/testsuite.log && false; }; fi
   - if test ${PART-2} = 2; then make maintainer-check-posix VERBOSE=1 TESTSUITEFLAGS=-j2 || { cat tests/testsuite.log && false; }; fi
   - if test ${PART-2} = 2; then make maintainer-check-g++   VERBOSE=1 TESTSUITEFLAGS=-j2 || { cat tests/testsuite.log && false; }; fi
-
-after_script:
-  - uninstall_intel_software || true

AUTHORS

@@ -24,7 +24,7 @@ and nasty bugs.
 
 -----
 
-Copyright (C) 1998-2015, 2018-2019 Free Software Foundation, Inc.
+Copyright (C) 1998-2015, 2018-2020 Free Software Foundation, Inc.
 
 This file is part of Bison, the GNU Compiler Compiler.
 

ChangeLog-2012

@@ -26733,7 +26733,7 @@
 
 	-----
 
-	Copyright (C) 1987-1988, 1991-2015, 2018-2019 Free Software
+	Copyright (C) 1987-1988, 1991-2015, 2018-2020 Free Software
 	Foundation, Inc.
 
 	Copying and distribution of this file, with or without

Makefile.am

@@ -1,6 +1,6 @@
 ## Process this file with automake to produce Makefile.in.
 
-# Copyright (C) 2001-2015, 2018-2019 Free Software Foundation, Inc.
+# Copyright (C) 2001-2015, 2018-2020 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
@@ -42,7 +42,7 @@ dependencies = $(BISON_IN) $(src_bison_SOURCES) $(dist_skeletons_DATA)
 BISON = $(top_builddir)/tests/bison
 BISON_IN = $(top_srcdir)/tests/bison.in
 YACC = $(BISON) -o y.tab.c
-AM_YFLAGS_WITH_LINES = --defines -Werror -Wall --report=all
+AM_YFLAGS_WITH_LINES = --defines -Werror -Wall,dangling-alias --report=all
 AM_YFLAGS = $(AM_YFLAGS_WITH_LINES) --no-lines
 
 # Initialization before completion by local.mk's.

NEWS

@@ -1,8 +1,335 @@
 GNU Bison NEWS
 
-* Noteworthy changes in release 3.4.91 (2019-11-20) [beta]
+* Noteworthy changes in release 3.5.90 (2020-04-18) [beta]
 
-** New Features
+** Backward incompatible changes
+
+  TL;DR: replace "#define YYERROR_VERBOSE 1" by "%define parse.error verbose".
+
+  The YYERROR_VERBOSE macro is no longer supported; the parsers that still
+  depend on it will now produce Yacc-like error messages (just "syntax
+  error").  It was superseded by the "%error-verbose" directive in Bison
+  1.875 (2003-01-01).  Bison 2.6 (2012-07-19) clearly announced that support
+  for YYERROR_VERBOSE would be removed.  Note that since Bison 3.0
+  (2013-07-25), "%error-verbose" is deprecated in favor of "%define
+  parse.error verbose".
+
+** New features
+
+*** Improved syntax error messages
+
+  Two new values for the %define parse.error variable offer more control to
+  the user.  Available in all the skeletons (C, C++, Java).
+
+**** %define parse.error detailed
+
+  The behavior of "%define parse.error detailed" is closely resembling that
+  of "%define parse.error verbose" with a few exceptions.  First, it is safe
+  to use non-ASCII characters in token aliases (with 'verbose', the result
+  depends on the locale with which bison was run).  Second, a yysymbol_name
+  function is exposed to the user, instead of the yytnamerr function and the
+  yytname table.  Third, token internationalization is supported (see
+  below).
+
+**** %define parse.error custom
+
+  With this directive, the user forges and emits the syntax error message
+  herself by defining the yyreport_syntax_error function.  A new type,
+  yypcontext_t, captures the circumstances of the error, and provides the
+  user with functions to get details, such as yypcontext_expected_tokens to
+  get the list of expected token kinds.
+
+  A possible implementation of yyreport_syntax_error is:
+
+    int
+    yyreport_syntax_error (const yypcontext_t *ctx)
+    {
+      int res = 0;
+      YY_LOCATION_PRINT (stderr, *yypcontext_location (ctx));
+      fprintf (stderr, ": syntax error");
+      // Report the tokens expected at this point.
+      {
+        enum { TOKENMAX = 10 };
+        yysymbol_kind_t expected[TOKENMAX];
+        int n = yypcontext_expected_tokens (ctx, expected, TOKENMAX);
+        if (n < 0)
+          // Forward errors to yyparse.
+          res = n;
+        else
+          for (int i = 0; i < n; ++i)
+            fprintf (stderr, "%s %s",
+                     i == 0 ? ": expected" : " or", yysymbol_name (expected[i]));
+      }
+      // Report the unexpected token.
+      {
+        yysymbol_kind_t lookahead = yypcontext_token (ctx);
+        if (lookahead != YYSYMBOL_YYEMPTY)
+          fprintf (stderr, " before %s", yysymbol_name (lookahead));
+      }
+      fprintf (stderr, "\n");
+      return res;
+    }
+
+**** Token aliases internationalization
+
+  When the %define variable parse.error is set to `custom` or `detailed`,
+  one may specify which token aliases are to be translated using _().  For
+  instance
+
+    %token
+        PLUS   "+"
+        MINUS  "-"
+      <double>
+        NUM _("double precision number")
+      <symrec*>
+        FUN _("function")
+        VAR _("variable")
+
+  In that case the user must define _() and N_(), and yysymbol_name returns
+  the translated symbol (i.e., it returns '_("variable")' rather that
+  '"variable"').  In Java, the user must provide an i18n() function.
+
+*** List of expected tokens (yacc.c)
+
+  Push parsers may invoke yypstate_expected_tokens at any point during
+  parsing (including even before submitting the first token) to get the list
+  of possible tokens.  This feature can be used to propose autocompletion
+  (see below the "bistromathic" example).
+
+  It makes little sense to use this feature without enabling LAC (lookahead
+  correction).
+
+*** Deep overhaul of the symbol and token kinds
+
+  To avoid the confusion with types in programming languages, we now refer
+  to token and symbol "kinds" instead of token and symbol "types".  The
+  documentation and error messages have been revised.
+
+  All the skeletons have been updated to use dedicated enum types rather
+  than integral types.  Special symbols are now regular citizens, instead of
+  being declared in ad hoc ways.
+
+**** Token kinds
+
+  The "token kind" is what is returned by the scanner, e.g., PLUS, NUMBER,
+  LPAREN, etc.  While backward compatibility is of course ensured, users are
+  nonetheless invited to replace their uses of "enum yytokentype" by
+  "yytoken_kind_t".
+
+  This type now also includes tokens that were previously hidden: YYEOF (end
+  of input), YYUNDEF (undefined token), and YYERRCODE (error token).  They
+  now have string aliases, internationalized when internationalization is
+  enabled.  Therefore, by default, error messages now refer to "end of file"
+  (internationalized) rather than the cryptic "$end", or to "invaid token"
+  rather than "$undefined".
+
+  Therefore in most cases it is now useless to define the end-of-line token
+  as follows:
+
+    %token T_EOF 0 "end of file"
+
+  Rather simply use "YYEOF" in your scanner.
+
+**** Symbol kinds
+
+  The "symbol kinds" is what the parser actually uses.  (Unless the
+  api.token.raw %define variable is used, the symbol kind of a terminal
+  differs from the corresponding token kind.)
+
+  They are now exposed as a enum, "yysymbol_kind_t".
+
+  This allows users to tailor the error messages the way they want, or to
+  process some symbols in a specific way in autocompletion (see the
+  bistromathic example below).
+
+*** Modernize display of explanatory statements in diagnostics
+
+  Since Bison 2.7, output was indented four spaces for explanatory
+  statements.  For example:
+
+    input.y:2.7-13: error: %type redeclaration for exp
+    input.y:1.7-11:     previous declaration
+
+  Since the introduction of caret-diagnostics, it became less clear.  This
+  indentation has been removed and submessages are displayed similarly as in
+  GCC:
+
+    input.y:2.7-13: error: %type redeclaration for exp
+        2 | %type <float> exp
+          |       ^~~~~~~
+    input.y:1.7-11: note: previous declaration
+        1 | %type <int> exp
+          |       ^~~~~
+
+  Contributed by Victor Morales Cayuela.
+
+*** C++
+
+  The token and symbol kinds are yy::parser::token_kind_type and
+  yy::parser::symbol_kind_type.
+
+  The symbol_type::kind() member function allows to get the kind of a
+  symbol.  This can be used to write unit tests for scanners, e.g.,
+
+    yy::parser::symbol_type t = make_NUMBER ("123");
+    assert (t.kind () == yy::parser::symbol_kind::S_NUMBER);
+    assert (t.value.as<int> () == 123);
+
+** Documentation
+
+*** User Manual
+
+  In order to avoid ambiguities with "type" as in "typing", we now refer to
+  the "token kind" (e.g., `PLUS`, `NUMBER`, etc.) rather than the "token
+  type".  We now also refer to the "symbol type" (e.g., `PLUS`, `expr`,
+  etc.).
+
+*** Examples
+
+  There are now two examples in examples/java: a very simple calculator, and
+  one that tracks locations to provide accurate error messages.
+
+  The lexcalc example (a simple example in C based on Flex and Bison) now
+  also demonstrates location tracking.
+
+
+  A new C example, bistromathic, is a fully featured interactive calculator
+  using many Bison features: pure interface, push parser, autocompletion
+  based on the current parser state (using yypstate_expected_tokens),
+  location tracking, internationalized custom error messages, lookahead
+  correction, rich debug traces, etc.
+
+  It shows how to depend on the symbol kinds to tailor autocompletion.  For
+  instance it recognizes the symbol kind "VARIABLE" to propose
+  autocompletion on the existing variables, rather than of the word
+  "variable".
+
+* Noteworthy changes in release 3.5.4 (2020-04-05) [stable]
+
+** WARNING: Future backward-incompatibilities!
+
+  TL;DR: replace "#define YYERROR_VERBOSE 1" by "%define parse.error verbose".
+
+  Bison 3.6 will no longer support the YYERROR_VERBOSE macro; the parsers
+  that still depend on it will produce Yacc-like error messages (just
+  "syntax error").  It was superseded by the "%error-verbose" directive in
+  Bison 1.875 (2003-01-01).  Bison 2.6 (2012-07-19) clearly announced that
+  support for YYERROR_VERBOSE would be removed.  Note that since Bison 3.0
+  (2013-07-25), "%error-verbose" is deprecated in favor of "%define
+  parse.error verbose".
+
+** Bug fixes
+
+  Fix portability issues of the package itself on old compilers.
+
+  Fix api.token.raw support in Java.
+
+* Noteworthy changes in release 3.5.3 (2020-03-08) [stable]
+
+** Bug fixes
+
+  Error messages could quote lines containing zero-width characters (such as
+  \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.
+
+* Noteworthy changes in release 3.5.2 (2020-02-13) [stable]
+
+** Bug fixes
+
+  Portability issues and minor cosmetic issues.
+
+  The lalr1.cc skeleton properly rejects unsupported values for parse.lac
+  (as yacc.c does).
+
+* Noteworthy changes in release 3.5.1 (2020-01-19) [stable]
+
+** Bug fixes
+
+  Portability fixes.
+
+  Fix compiler warnings.
+
+* Noteworthy changes in release 3.5 (2019-12-11) [stable]
+
+** Backward incompatible changes
+
+  Lone carriage-return characters (aka \r or ^M) in the grammar files are no
+  longer treated as end-of-lines.  This changes the diagnostics, and in
+  particular their locations.
+
+  In C++, line numbers and columns are now represented as 'int' not
+  'unsigned', so that integer overflow on positions is easily checkable via
+  'gcc -fsanitize=undefined' and the like.  This affects the API for
+  positions.  The default position and location classes now expose
+  'counter_type' (int), used to define line and column numbers.
+
+** Deprecated features
+
+  The YYPRINT macro, which works only with yacc.c and only for tokens, was
+  obsoleted long ago by %printer, introduced in Bison 1.50 (November 2002).
+  It is deprecated and its support will be removed eventually.
+
+** New features
+
+*** Lookahead correction in C++
+
+  Contributed by Adrian Vogelsgesang.
+
+  The C++ deterministic skeleton (lalr1.cc) now supports LAC, via the
+  %define variable parse.lac.
+
+*** Variable api.token.raw: Optimized token numbers (all skeletons)
+
+  In the generated parsers, tokens have two numbers: the "external" token
+  number as returned by yylex (which starts at 257), and the "internal"
+  symbol number (which starts at 3).  Each time yylex is called, a table
+  lookup maps the external token number to the internal symbol number.
+
+  When the %define variable api.token.raw is set, tokens are assigned their
+  internal number, which saves one table lookup per token, and also saves
+  the generation of the mapping table.
+
+  The gain is typically moderate, but in extreme cases (very simple user
+  actions), a 10% improvement can be observed.
+
+*** Generated parsers use better types for states
+
+  Stacks now use the best integral type for state numbers, instead of always
+  using 15 bits.  As a result "small" parsers now have a smaller memory
+  footprint (they use 8 bits), and there is support for large automata (16
+  bits), and extra large (using int, i.e., typically 31 bits).
+
+*** Generated parsers prefer signed integer types
+
+  Bison skeletons now prefer signed to unsigned integer types when either
+  will do, as the signed types are less error-prone and allow for better
+  checking with 'gcc -fsanitize=undefined'.  Also, the types chosen are now
+  portable to unusual machines where char, short and int are all the same
+  width.  On non-GNU platforms this may entail including <limits.h> and (if
+  available) <stdint.h> to define integer types and constants.
+
+*** A skeleton for the D programming language
+
+  For the last few releases, Bison has shipped a stealth experimental
+  skeleton: lalr1.d.  It was first contributed by Oliver Mangold, based on
+  Paolo Bonzini's lalr1.java, and was cleaned and improved thanks to
+  H. S. Teoh.
+
+  However, because nobody has committed to improving, testing, and
+  documenting this skeleton, it is not clear that it will be supported in
+  the future.
+
+  The lalr1.d skeleton *is functional*, and works well, as demonstrated in
+  examples/d/calc.d.  Please try it, enjoy it, and... commit to support it.
+
+*** Debug traces in Java
+
+  The Java backend no longer emits code and data for parser tracing if the
+  %define variable parse.trace is not defined.
+
+** Diagnostics
 
 *** New diagnostic: -Wdangling-alias
 
@@ -53,7 +380,7 @@ GNU Bison NEWS
     %%
     expr:
 
-  gives, with -Wyacc
+  gives with -Wyacc
 
     input.y:2.15-20: warning: POSIX yacc reserves %type to nonterminals [-Wyacc]
         2 | %type  <ival> TOKEN1 TOKEN2 't'
@@ -65,50 +392,9 @@ GNU Bison NEWS
         2 | %type  <ival> TOKEN1 TOKEN2 't'
           |                      ^~~~~~
 
-* Noteworthy changes in release 3.4.90 (2019-10-29) [beta]
-
-** Backward incompatible changes
-
-  Lone carriage-return characters (aka \r or ^M) in the grammar files are no
-  longer treated as end-of-lines.  This changes the diagnostics, and in
-  particular their locations.
-
-  In C++, line numbers and columns are now represented as 'int' not
-  'unsigned', so that integer overflow on positions is easily checkable via
-  'gcc -fsanitize=undefined' and the like.  This affects the API for
-  positions.  The default position and location classes now expose
-  'counter_type' (int), used to define line and column numbers.
-
-** Bug fixes
-
-  In Java, %define api.prefix was ignored.  It now behaves as expected.
-
-** New features
-
-*** Lookahead correction in C++
-
-  Contributed by Adrian Vogelsgesang.
-
-  The C++ deterministic skeleton (lalr1.cc) now supports LAC, via the
-  %define variable parse.lac.
-
-*** Variable api.token.raw: Optimized token numbers (all skeletons)
-
-  In the generated parsers, tokens have two numbers: the "external" token
-  number as returned by yylex (which starts at 257), and the "internal"
-  symbol number (which starts at 3).  Each time yylex is called, a table
-  lookup maps the external token number to the internal symbol number.
-
-  When the %define variable api.token.raw is set, tokens are assigned their
-  internal number, which saves one table lookup per token, and also saves
-  the generation of the mapping table.
-
-  The gain is typically moderate, but in extreme cases (very simple user
-  actions), a 10% improvement can be observed.
-
 *** Diagnostics with insertion
 
-  The diagnostics now display suggestion below the underlined source.
+  The diagnostics now display the suggestion below the underlined source.
   Replacement for undeclared symbols are now also suggested.
 
     $ cat /tmp/foo.y
@@ -149,26 +435,28 @@ GNU Bison NEWS
         1 | %token FOO                     …
           |        ^~~
 
-*** Debug traces in Java
+** Changes
 
-  The Java backend no longer emits code and data for parser tracing if the
-  %define variable parse.trace is not defined.
+*** Debugging glr.c and glr.cc
 
-*** Generated parsers prefer signed integer types
+  The glr.c skeleton always had asserts to check its own behavior (not the
+  user's).  These assertions are now under the control of the parse.assert
+  %define variable (disabled by default).
 
-  Bison skeletons now prefer signed to unsigned integer types when either
-  will do, as the signed types are less error-prone and allow for better
-  checking with 'gcc -fsanitize=undefined'.  Also, the types chosen are now
-  portable to unusual machines where char, short and int are all the same
-  width.  On non-GNU platforms this may entail including <limits.h> and (if
-  available) <stdint.h> to define integer types and constants.
+*** Clean up
 
-*** Generated parsers use better types for states
+  Several new compiler warnings in the generated output have been avoided.
+  Some unused features are no longer emitted.  Cleaner generated code in
+  general.
 
-  Stacks now use the best integral type for state numbers, instead of always
-  using 15 bits.  As a result "small" parsers now have a smaller memory
-  footprint (they use 8 bits), and there is support for large automata (16
-  bits), and extra large (using int, i.e., typically 31 bits).
+** Bug Fixes
+
+  Portability issues in the test suite.
+
+  In theory, parsers using %nonassoc could crash when reporting verbose
+  error messages. This unlikely bug has been fixed.
+
+  In Java, %define api.prefix was ignored.  It now behaves as expected.
 
 * Noteworthy changes in release 3.4.2 (2019-09-12) [stable]
 
@@ -3774,7 +4062,7 @@ Output file does not redefine const for C++.
 
 -----
 
-Copyright (C) 1995-2015, 2018-2019 Free Software Foundation, Inc.
+Copyright (C) 1995-2015, 2018-2020 Free Software Foundation, Inc.
 
 This file is part of Bison, the GNU Parser Generator.
 
@@ -3820,7 +4108,13 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
  LocalWords:  Heimbigner AST src ast Makefile srcdir MinGW xxlex XXSTYPE
  LocalWords:  XXLTYPE strictfp IDEs ffixit fdiagnostics parseable fixits
  LocalWords:  Wdeprecated yytext Variadic variadic yyrhs yyphrs RCS README
- LocalWords:  noexcept constexpr ispell american deprecations backend
+ LocalWords:  noexcept constexpr ispell american deprecations backend Teoh
+ LocalWords:  YYPRINT Mangold Bonzini's Wdangling exVal baz checkable gcc
+ LocalWords:  fsanitize Vogelsgesang lis redeclared stdint automata yytname
+ LocalWords:  yysymbol yytnamerr yyreport ctx ARGMAX yysyntax stderr LPAREN
+ LocalWords:  symrec yypcontext TOKENMAX yyexpected YYEMPTY yypstate YYEOF
+ LocalWords:  autocompletion bistromathic submessages Cayuela lexcalc
+ LocalWords:  yytoken YYUNDEF YYERRCODE
 
 Local Variables:
 ispell-dictionary: "american"

PACKAGING

@@ -36,7 +36,7 @@ to the bison package.
 
 -----
 
-Copyright (C) 2002, 2005, 2009-2015, 2018-2019 Free Software Foundation,
+Copyright (C) 2002, 2005, 2009-2015, 2018-2020 Free Software Foundation,
 Inc.
 
 This file is part of Bison, the GNU Compiler Compiler.

README

@@ -1,4 +1,19 @@
-This package contains the GNU Bison parser generator.
+GNU Bison is a general-purpose parser generator that converts an annotated
+context-free grammar into a deterministic LR or generalized LR (GLR) parser
+employing LALR(1) parser tables.  Bison can also generate IELR(1) or
+canonical LR(1) parser tables.  Once you are proficient with Bison, you can
+use it to develop a wide range of language parsers, from those used in
+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
+programming in order to use Bison.
+
+Bison and the parsers it generates are portable, they do not require any
+specific compilers.
+
+GNU Bison's home page is https://gnu.org/software/bison/.
 
 # Installation
 ## Build from git
@@ -9,8 +24,7 @@ Here are basic installation instructions for a repository checkout:
 
 then proceed with the usual `configure && make` steps.
 
-The file README-hacking.md contains all the needed information about
-building, modifying and checking Bison.
+The file README-hacking.md is about building, modifying and checking Bison.
 
 ## Build from tarball
 See the file INSTALL for generic compilation and installation instructions.
@@ -18,13 +32,18 @@ See the file INSTALL for generic compilation and installation instructions.
 Bison requires GNU m4 1.4.6 or later.  See
 https://ftp.gnu.org/gnu/m4/m4-1.4.6.tar.gz.
 
+## Running a non installed bison
+Once you ran `make`, you might want to toy with this fresh bison before
+installing it.  In that case, do not use `src/bison`: it would use the
+*installed* files (skeletons, etc.), not the local ones.  Use `tests/bison`.
+
 ## Colored diagnostics
 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/gnu/gettext/libtextstyle-0.8.tar.gz.
+https://alpha.gnu.org/pub/gnu/gettext/libtextstyle-0.20.5.tar.gz.
 
 The option --color supports the following arguments:
 - always, yes: Enable colors.
@@ -81,23 +100,17 @@ that the range specifies every single year in that closed interval.
 
 <!--
 
-Copyright (C) 1992, 1998-1999, 2003-2005, 2008-2015, 2018-2019 Free
+Copyright (C) 1992, 1998-1999, 2003-2005, 2008-2015, 2018-2020 Free
 Software Foundation, Inc.
 
 This file is part of GNU bison, the GNU Compiler Compiler.
 
-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 <http://www.gnu.org/licenses/>.
+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.
 
 Local Variables:
 mode: markdown
@@ -105,7 +118,8 @@ fill-column: 76
 ispell-dictionary: "american"
 End:
 
-LocalWords:  parsers ngettext Texinfo pdf html YYYY ZZZZ ispell american
-LocalWords:  MERCHANTABILITY
+LocalWords:  parsers ngettext Texinfo pdf html YYYY ZZZZ ispell american md
+LocalWords:  MERCHANTABILITY GLR LALR IELR submodule init README src bw
+LocalWords:  Relocatability symlinks symlink
 
 -->

README-alpha

@@ -12,7 +12,7 @@ the problems you encounter.
 
 -----
 
-Copyright (C) 2002, 2004, 2009-2015, 2018-2019 Free Software Foundation,
+Copyright (C) 2002, 2004, 2009-2015, 2018-2020 Free Software Foundation,
 Inc.
 
 This file is part of GNU Bison.

README-hacking.md

@@ -5,7 +5,8 @@ Everything related to the development of Bison is on Savannah:
 http://savannah.gnu.org/projects/bison/.
 
 
-# Administrivia
+Administrivia
+=============
 
 ## If you incorporate a change from somebody on the net:
 First, if it is a large change, you must make sure they have signed the
@@ -23,9 +24,11 @@ demonstrates the bug.  Then fix the bug, re-run the test suite, and check
 everything in.
 
 
-# Hacking
 
-## Visible changes
+Hacking
+=======
+
+## Visible Changes
 Which include serious bug fixes, must be mentioned in NEWS.
 
 ## Translations
@@ -34,15 +37,88 @@ Only user visible strings are to be translated: error messages, bits of the
 assert/abort), and all the --trace output which is meant for the maintainers
 only.
 
-## Horizontal tabs
+## Coding Style
 Do not add horizontal tab characters to any file in Bison's repository
 except where required.  For example, do not use tabs to format C code.
 However, make files, ChangeLog, and some regular expressions require tabs.
 Also, test cases might need to contain tabs to check that Bison properly
 processes tabs in its input.
 
+Prefer "res" as the name of the local variable that will be "return"ed by
+the function.
 
-# Working from the repository
+### Bison
+Follow the GNU Coding Standards.
+
+Don't reinvent the wheel: we use gnulib, which features many components.
+Actually, Bison has legacy code that we should replace with gnulib modules
+(e.g., many ad hoc implementations of lists).
+
+### Skeletons
+We try to use the "typical" coding style for each language.
+
+#### C/C++
+Follow the GNU Coding Standards.
+
+The `glr.c` skeleton was implemented with `camlCase`.  We are migrating it
+to `snake_case`.  Because we are standardizing the code, it is currently
+inconsistent.
+
+Use `YYFOO` and `yyfoo` for entities that are exposed to the user.  They are
+part of our contract with the users wrt backward compatibility.
+
+Use `YY_FOO` and `yy_foo` for private matters.  Users should not use them,
+we are free to change them without fear of backward compatibility issues.
+
+Use `*_t` for types, especially for `yy*_t` in which case we shouldn't worry
+about the C standard introducing such a name.
+
+#### C++
+Follow the C++ Core Guidelines
+(http://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines).  The Google
+ones may be interesting too
+(https://google.github.io/styleguide/cppguide.html).
+
+Our enumerators, such as the kinds (symbol and token kinds), should be lower
+case, but it was too late to follow that track for token kinds, and symbol
+kind enumerators are made to be consistent with them.
+
+Use `*_type` for type aliases.  Use `foo_get()` and `foo_set(v)` for
+accessors, or simply `foo()` and `foo(v)`.
+
+Use the `yy` prefix for private stuff, but there's no need for it in the
+public API.  The `yy` prefix is already taken care of via the namespace.
+
+#### Java
+We follow https://www.oracle.com/technetwork/java/codeconventions-150003.pdf
+and 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.
+
+Use a 2-space indentation (Google) rather than 4 (Oracle).
+
+Don't use the "yy" prefix for public members: "getExpectedTokens", not
+"yyexpectedTokens" or "yygetExpectedTokens".
+
+## Commit Messages
+Imitate the style we use.  Use `git log` to get sources of inspiration.
+
+If the changes have a small impact on Bison's generated parser, embed these
+changes in the commit itself.  If the impact is large, first push all the
+changes except those about src/parse-gram.[ch], and then another commit
+named "regen" which is only about them.
+
+## Debugging
+Bison supports tracing of its various steps, via the `--trace` option.
+Since it is not meant for the end user, it is not displayed by `bison
+--help`, nor is it documented in the manual.  Instead, run `bison
+--trace=help`.
+
+
+
+Working from the Repository
+===========================
 
 These notes intend to help people working on the checked-out sources.  These
 requirements do not apply when building from a distribution tarball.
@@ -185,29 +261,61 @@ These files don't change very often in Autoconf, so it should be relatively
 straight-forward to examine the differences in order to decide whether to
 update.
 
-# Test suite
+## Troubleshooting
+
+Bison is self-hosted: its parser is generated by Bison.  We don't force
+ourselves to use the previous release of Bison, we use the current git
+master for several reasons:
+- dogfooding: let Bison be its first user
+- monitoring: seeing the diff on the generated parsers with git is very
+  helpful, as it allows to see easily the impact of the changes on a real
+  case parser.
+
+If you are unlucky the generated files, src/parse-gram.[ch], may be older
+than their source, src/parse-gram.y.  And your current version of Bison
+might not be able to grok it.  In that case, first refresh the generated
+files:
+
+    $ touch src/parse-gram.[ch]
+
+Then proceed.
+
+In case you wrecked your current copy of the parser, get back the previous
+version, compile bison, then force it to recreate the files:
+
+    $ git checkout HEAD^ src/parse-gram.[ch]
+    $ make -C _build
+    $ touch src/parse-gram.y
+    $ make -C _build
+
+
+Test Suite
+==========
 
 ## make check
-Use liberally.
+Consume without moderation.  It is composed of two kinds of tests: the
+examples, and the main test suite.
 
-## Updating the expectations
-Sometimes some changes have a large impact on the test suite (e.g., when we
-added the `[-Wother]` part to all the warnings).  Part of the update can be
-done with a crude tool: `build-aux/update-test`.
+### The Examples
+In examples/, there is a number of ready-to-use examples (see
+examples/README.md).  These examples have small test suites run by `make
+check`.  The test results are in local `*.log` files (e.g.,
+`$build/examples/c/calc/calc.log`).
 
-Once you ran the test suite, and therefore have many testsuite.log files,
-run, from the source tree:
+### 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
+documentation, not only about how to write tests, but also where are the
+logs, how to read them etc.
 
-    $ ./build-aux/update-test _build/tests/testsuite.dir/*/testsuite.log
+The main test suite generates a log for each test (e.g.,
+`$build/tests/testsuite.dir/004/testsuite.log` for test #4), and a main log
+file in `$build/tests/testsuite.log`.  The latter is meant for end users: it
+contains lots of details that should help diagnosing issues, including build
+issues.  The per-test logs are more convenient when working locally.
 
-where `_build` would be your build tree.  This will hopefully update most
-tests.  Re-run the test suite.  It might be interesting to run `update-test`
-again, since some early failures may stop latter tests from being run.  Yet
-at some point, you'll have to fix remaining issues by hand...
-
-## TESTSUITEFLAGS
-To run just the test suite (not the tests related to the examples), run `make
-check-local`.
+#### TESTSUITEFLAGS
+To run just the main test suite, run `make check-local`.
 
 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
@@ -230,6 +338,10 @@ with AT_KEYWORDS([[category]]). Categories include:
 - java, for java parsers
 - report, for automaton dumps
 
+To get a list of all the tests (and their keywords for -k), run
+
+    $ ./tests/testsuite -l
+
 To run a specific set of tests, use -k (for "keyword"). For example:
 
     $ make check-local TESTSUITEFLAGS='-k c++'
@@ -242,18 +354,21 @@ To rerun the tests that failed:
 
     $ make recheck -j5
 
-## Typical errors
-If the test suite shows failures such as the following one
+#### Updating the Expectations
+Sometimes some changes have a large impact on the test suite (e.g., when we
+added the `[-Wother]` part to all the warnings).  Part of the update can be
+done with a crude tool: `build-aux/update-test`.
 
-    .../bison/lib/getopt.h:196:8: error: redefinition of 'struct option'
-    /usr/include/getopt.h:54:8: error: previous definition of 'struct option'
+Once you ran the test suite, and therefore have many `testsuite.log` files,
+run, from the source tree:
 
-it probably means that some file was compiled without
-`AT_DATA_SOURCE_PROLOGUE`.  This error is due to the fact that our -I
-options pick up gnulib's replacement headers, such as getopt.h, and this
-will go wrong if config.h was not included first.
+    $ ./build-aux/update-test $build/tests/testsuite.dir/*/testsuite.log
+
+where `$build` would be your build tree.  This will hopefully update most
+tests.  Re-run the test suite.  It might be interesting to run `update-test`
+again, since some early failures may stop latter tests from being run.  Yet
+at some point, you'll have to fix remaining issues by hand...
 
-See tests/local.at for details.
 
 ## make maintainer-check-valgrind
 This target uses valgrind both to check bison, and the generated parsers.
@@ -329,175 +444,16 @@ re-run the tests, run:
     ./configure -C CC='gcc-mp-8 -fsanitize=undefined' CFLAGS='-ggdb'
     make check
 
-# Release Procedure
-This section needs to be updated to take into account features from gnulib.
-In particular, be sure to read README-release.
 
-## Update the submodules.  See above.
 
-## Update maintainer tools, such as Autoconf.  See above.
-
-## Try to get the *.pot files to the Translation Project at least one
-week before a stable release, to give them time to translate them.  Before
-generating the *.pot files, make sure that po/POTFILES.in and
-runtime-po/POTFILES.in list all files with translatable strings.  This
-helps: `grep -l '\<_(' *`.
-
-## Tests
-See above.
-
-## Update the foreign files
-Running `./bootstrap` in the top level should update them all for you.  This
-covers PO files too.  Sometimes a PO file contains problems that causes it
-to be rejected by recent Gettext releases; please report these to the
-Translation Project.
-
-## Update README
-Make sure the information in README is current.  Most notably, make sure it
-recommends a version of GNU M4 that is compatible with the latest Bison
-sources.
-
-## Check copyright years.
-We update years in copyright statements throughout Bison once at the start
-of every year by running `make update-copyright`.  However, before a
-release, it's good to verify that it's actually been run.  Besides the
-copyright statement for each Bison file, check the copyright statements that
-the skeletons insert into generated parsers, and check all occurrences of
-PACKAGE_COPYRIGHT_YEAR in configure.ac.
-
-## Update NEWS, commit and tag.
-See do-release-commit-and-tag in README-release.  For a while, we used beta
-names such as `2.6_rc1`.  Now that we use gnulib in the release procedure,
-we must use `2.5.90`, which has the additional benefit of being properly
-sorted in `git tag -l`.
-
-## make alpha, beta, or stable
-See README-release.
-
-## Upload
-There are two ways to upload the tarballs to the GNU servers: using gnupload
-(from gnulib), or by hand.  Obviously prefer the former.  But in either
-case, be sure to read the following paragraph.
-
-### Setup
-You need `gnupg`.
-
-Make sure your public key has been uploaded at least to keys.gnupg.net.  You
-can upload it with:
-
-  gpg --keyserver keys.gnupg.net --send-keys F125BDF3
-
-where F125BDF3 should be replaced with your key ID.
-
-### Using gnupload
-You need `ncftp`.
-
-At the end `make stable` (or alpha/beta) will display the procedure to run.
-Just copy and paste it in your shell.
-
-### By hand
-
-The generic GNU upload procedure is at
-http://www.gnu.org/prep/maintain/maintain.html#Automated-FTP-Uploads.
-
-Follow the instructions there to register your information so you're permitted
-to upload.
-
-Here's a brief reminder of how to roll the tarballs and upload them:
-
-### make distcheck
-### gpg -b bison-2.3b.tar.gz
-### In a file named `bison-2.3b.tar.gz.directive`, type:
-
-    version: 1.1
-    directory: bison
-    filename: bison-2.3b.tar.gz
-
-### gpg --clearsign bison-2.3b.tar.gz.directive
-### ftp ftp-upload.gnu.org # Log in as anonymous.
-### cd /incoming/alpha # cd /incoming/ftp for full release.
-### put bison-2.3b.tar.gz # This can take a while.
-### put bison-2.3b.tar.gz.sig
-### put bison-2.3b.tar.gz.directive.asc
-### Repeat all these steps for bison-2.3b.tar.xz.
-
-## Update Bison manual on www.gnu.org.
-
-The instructions below are obsolete, and left in case one would like to run
-the commands by hand.  Today, one just needs to run
-
-    $ make web-manual-update
+Release Procedure
+=================
 
 See README-release.
 
-### You need a non-anonymous checkout of the web pages directory.
-
-    $ cvs -d YOUR_USERID@cvs.savannah.gnu.org:/web/bison checkout bison
-
-### Get familiar with the instructions for web page maintainers.
-http://www.gnu.org/server/standards/readme_index.html
-http://www.gnu.org/server/standards/README.software.html
-especially the note about symlinks.
-
-### Build the web pages.
-Assuming BISON_CHECKOUT refers to a checkout of the Bison dir, and
-BISON_WWW_CHECKOUT refers to the web directory created above, do:
-
-    $ cd $BISON_CHECKOUT/doc
-    $ make stamp-vti
-    $ ../build-aux/gendocs.sh -o "$BISON_WWW_CHECKOUT/manual" \
-      bison "Bison - GNU parser generator"
-    $ cd $BISON_WWW_CHECKOUT
-
-Verify that the result looks sane.
-
-### Commit the modified and the new files.
-
-### Remove old files.
-Find the files which have not been overwritten (because they belonged to
-sections that have been removed or renamed):
-
-     $ cd manual/html_node
-     $ ls -lt
-
-Remove these files and commit their removal to CVS.  For each of these
-files, add a line to the file .symlinks.  This will ensure that hyperlinks
-to the removed files will redirect to the entire manual; this is better than
-a 404 error.
-
-## Announce
-The "make release" command just created a template,
-`$HOME/announce-bison-X.Y`.  Otherwise, to generate it, run:
-
-    make RELEASE_TYPE=alpha gpg_key_ID=F125BDF3 announcement
-
-where alpha can be replaced by `beta` or `table` and F125BDF3 should be
-replaced with your key ID.
-
-Complete/fix the announcement file.  The generated list of recipients
-(info-gnu@gnu.org, bison-announce@gnu.org, bug-bison@gnu.org,
-help-bison@gnu.org, bison-patches@gnu.org, and
-coordinator@translationproject.org) is appropriate for a stable release or a
-"serious beta".  For any other release, drop at least info-gnu@gnu.org.  For
-an example of how to fill out the rest of the template, search the mailing
-list archives for the most recent release announcement.
-
-For a stable release, send the same announcement on the comp.compilers
-newsgroup by sending email to compilers@iecc.com.  Do not make any Cc as the
-moderator will throw away anything cross-posted or Cc'ed.  It really needs
-to be a separate message.
-
-## Prepare NEWS
-So that developers don't accidentally add new items to the old NEWS entry,
-create a new empty entry in line 3 (without the two leading spaces):
-
-  * Noteworthy changes in release ?.? (????-??-??) [?]
-
-Push these changes.
-
 <!--
 
-Copyright (C) 2002-2005, 2007-2015, 2018-2019 Free Software Foundation,
+Copyright (C) 2002-2005, 2007-2015, 2018-2020 Free Software Foundation,
 Inc.
 
 This file is part of GNU Bison.
@@ -526,9 +482,11 @@ LocalWords:  submodule init cd distcheck ChangeLog valgrind sigreturn sudo
 LocalWords:  UC gcc DGNULIB POSIXCHECK xml XSLT glr lalr README po runtime rc
 LocalWords:  gnupload gnupg gpg keyserver BDF ncftp filename clearsign cvs dir
 LocalWords:  symlinks vti html lt POSIX Cc'ed Graphviz Texinfo autoconf jN
-LocalWords:  automake autopoint graphviz texinfo PROG Wother parsers
-LocalWords:  TESTSUITEFLAGS deprec struct gnulib's getopt config ggdb
-LocalWords:  bitset fsanitize symlink CFLAGS MERCHANTABILITY ispell
-LocalWords:  american
+LocalWords:  automake autopoint graphviz texinfo PROG Wother parsers YYFOO
+LocalWords:  TESTSUITEFLAGS deprec struct gnulib's getopt config ggdb yyfoo
+LocalWords:  bitset fsanitize symlink CFLAGS MERCHANTABILITY ispell wrt YY
+LocalWords:  american Administrivia camlCase yy accessors namespace src
+LocalWords:  getExpectedTokens yyexpectedTokens yygetExpectedTokens
+LocalWords:  regen dogfooding Autotest testsuite
 
 -->

THANKS

@@ -4,8 +4,10 @@ it is today without the invaluable help of these people:
 Aaro Koskinen             [email protected]
 Аскар Сафин               [email protected]
 Adam Sampson              [email protected]
+Adrian Vogelsgesang       [email protected]
+Ahcheong Lee              [email protected]
 Airy Andre                [email protected]
-Akim Demaille             akim@lrde.epita.fr
+Akim Demaille             akim@gnu.org
 Albert Chin-A-Young       [email protected]
 Alexander Belopolsky      [email protected]
 Alexandre Duret-Lutz      [email protected]
@@ -60,6 +62,8 @@ Enrico Scholz             [email protected]
 Eric Blake                [email protected]
 Eric S. Raymond           [email protected]
 Étienne Renault           [email protected]
+Evan Lavelle              [email protected]
+Evan Nemerson             [email protected]
 Evgeny Stambulchik        [email protected]
 Fabrice Bauzac            [email protected]
 Ferdinand Thiessen        [email protected]
@@ -79,6 +83,7 @@ Hans Åberg                [email protected]
 Horst Von Brand           [email protected]
 Jan Nieuwenhuizen         [email protected]
 Jannick                   [email protected]
+Jeff Hammond              [email protected]
 Jerry Quinn               [email protected]
 Jesse Thilo               [email protected]
 Jim Kent                  [email protected]
@@ -128,6 +133,7 @@ Nick Bowler               [email protected]
 Nicolas Bedon             [email protected]
 Nicolas Burrus            [email protected]
 Nicolas Tisserand         [email protected]
+Nikki Valen               [email protected]
 Noah Friedman             [email protected]
 Odd Arild Olsen           [email protected]
 Oleg Smolsky              [email protected]
@@ -205,8 +211,9 @@ Wwp                       [email protected]
 xolodho                   [email protected]
 Yuichiro Kaneko           [email protected]
 Zack Weinberg             [email protected]
-長田偉伸                   [email protected]
 江 祖铭                    [email protected]
+長田偉伸                   [email protected]
+马俊                       [email protected]
 
 Many people are not named here because we lost track of them.  We
 thank them!  Please, help us keeping this list up to date.
@@ -218,7 +225,7 @@ End:
 
 -----
 
-Copyright (C) 2000-2015, 2018-2019 Free Software Foundation, Inc.
+Copyright (C) 2000-2015, 2018-2020 Free Software Foundation, Inc.
 
 This file is part of Bison, the GNU Parser Generator.
 

TODO

@@ -1,61 +1,65 @@
-* Bison 3.5
+* Bison 3.6
+** Questions
+*** Java
+- Should i18n be part of the Lexer?  Currently it's a static method of
+  Lexer.
+
+- is there a migration path that would allow to use TokenKinds in
+  yylex?
+
+*** 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?
+
+** Documentation
+- YYERRCODE, YYUNDEF, YYEOF
+- YYERRCODE and translation
+
+** Java
+*** Examples
+Have an example with a push parser.  Use autocompletion in that case.
+
+*** calc.at
+Stop hard-coding "Calc".  Adjust local.at (look for FIXME).
+
 ** doc
-I feel its ugly to use the GNU style to declare functions in the doc.  It
+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
 breaks.
 
-Also, we seem to teach YYPRINT very early on, although it should be
-considered deprecated: %printer is superior.
-
-** improve syntax errors (UTF-8, internationalization)
-Bison depends on the current locale.  For instance:
-
-%define parse.error verbose
-%code top {
- #include <stdio.h>
- #include <stdlib.h>
- void yyerror(const char* msg) { fprintf(stderr, "%s\n", msg); }
- int yylex() { return 0; }
-}
-%%
-exp: "↦" | "🎅🐃" | '\n'
-%%
-int main() { return yyparse(); }
-
-gives different results with/without LC_ALL=C.
-
-$ LC_ALL=C /opt/local/bin/bison /tmp/mangle.y -o ascii.c
-$ /opt/local/bin/bison /tmp/mangle.y -o utf8.c
-$ diff -u ascii.c utf8.c -I#line
---- ascii.c     2019-01-12 08:15:35.878010093 +0100
-+++ utf8.c      2019-01-12 08:15:38.856495929 +0100
-@@ -415,9 +415,8 @@
-    First, the terminals, then, starting at YYNTOKENS, nonterminals.  */
- static const char *const yytname[] =
- {
--  "$end", "error", "$undefined", "\"\\342\\206\\246\"",
--  "\"\\360\\237\\216\\205\\360\\237\\220\\203\"", "'\\n'", "$accept",
--  "exp", YY_NULLPTR
-+  "$end", "error", "$undefined", "\"↦\"", "\"🎅🐃\"", "'\\n'",
-+  "$accept", "exp", YY_NULLPTR
- };
- #endif
-
-$ gcc ascii.c -o ascii && ./ascii
-syntax error, unexpected $end, expecting "\342\206\246" or "\360\237\216\205\360\237\220\203" or '\n'
-$ gcc utf8.c -o utf8 && ./utf8
-syntax error, unexpected $end, expecting ↦ or 🎅🐃 or '\n'
-
-
-While at it, we should stop using "$end" by default, in favor of "end of
-file", or "end of input", whatever.  See how lalr1.java does that.
+** consistency
+token vs terminal, variable vs non terminal.
 
 ** api.token.raw
-Maybe we should exhibit the YYUNDEFTOK token.  It could also be assigned a
-semantic value so that yyerror could be used to report invalid lexemes.
-See also the item "$undefined" below.
+The YYUNDEFTOK could be assigned a semantic value so that yyerror could be
+used to report invalid lexemes.  See also the item "$undefined" below.
 
-* Bison 3.6
+** push parsers
+Consider deprecating impure push parsers.  They add a lot of complexity, for
+a bad feature.  On the other hand, that would make it much harder to sit
+push parsers on top of pull parser.  Which is currently not relevant, since
+push parsers are measurably slower.
+
+* Bison 3.7
+** Counter example generation
+See https://github.com/akimd/bison/pull/15.
+
+** Clean up
+Rename user_token_number for tokens as "code".  It's not a "user number",
+it's the token code, and the user can control it, but this code always
+exists.
+
+Rename endtoken as eoftoken.
+
+Also do it in data/skeletons.
+
+Don't rename in Bison 3.6 (it would be logical to do so) because that
+would probably create many conflicts in Vincent's work (see previous point).
+
+* Bison 3.8
 ** 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.,
@@ -110,6 +114,16 @@ functions.
 states/nstates, rules/nrules, ..., ritem/nritems
 Fix the latter.
 
+* 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
+YYERROR_VERBOSE?" by Simon Sobisch, on bison-help.
+
+See also
+https://www.cs.tufts.edu/~nr/cs257/archive/clinton-jefferey/lr-error-messages.pdf
+https://research.swtch.com/yyerror
+http://gallium.inria.fr/~fpottier/publis/fpottier-reachability-cc2016.pdf
+
 * Modernization
 Fix data/skeletons/yacc.c so that it defines YYPTRDIFF_T properly for modern
 and older C++ compilers.  Currently the code defaults to defining it to
@@ -119,10 +133,10 @@ define it to the same type as the C ptrdiff_t type.
 * Completion
 Several features are not available in all the backends.
 
-- push parsers: glr.cc, lalr1.cc
-- ielr: C++ and Java
-- glr: Java
-- token constructors: Java and C
+- push parsers: glr.c, glr.cc, lalr1.cc
+- lac: D, Java
+- glr: D, Java
+- token constructors: Java, C, D
 
 * Bugs
 ** Autotest has quotation issues
@@ -134,55 +148,12 @@ $ ./tests/testsuite -l | grep errors | sed q
   38: input.at:1730      errors
 
 * Short term
-** Stop indentation in diagnostics
-Before Bison 2.7, we printed "flatly" the dependencies in long diagnostics:
-
-    input.y:2.7-12: %type redeclaration for exp
-    input.y:1.7-12: previous declaration
-
-In Bison 2.7, we indented them
-
-    input.y:2.7-12: error: %type redeclaration for exp
-    input.y:1.7-12:     previous declaration
-
-Later we quoted the source in the diagnostics, and today we have:
-
-    /tmp/foo.y:1.12-14: warning: symbol FOO redeclared [-Wother]
-        1 | %token FOO FOO
-          |            ^~~
-    /tmp/foo.y:1.8-10:      previous declaration
-        1 | %token FOO FOO
-          |        ^~~
-
-The indentation is no longer helping.  We should probably get rid of it, or
-maybe keep it only when -fno-caret. GCC displays this as a "note":
-
-    $ g++-mp-9 -Wall /tmp/foo.c -c
-    /tmp/foo.c:1:10: error: redefinition of 'int foo'
-        1 | int foo, foo;
-          |          ^~~
-    /tmp/foo.c:1:5: note: 'int foo' previously declared here
-        1 | int foo, foo;
-          |     ^~~
-
-Likewise for Clang, contrary to what I believed (because "note:" is written
-in black, so it doesn't show in my terminal :-)
-
-    $ clang++-mp-8.0 -Wall /tmp/foo.c -c
-    clang: warning: treating 'c' input as 'c++' when in C++ mode, this behavior is deprecated [-Wdeprecated]
-    /tmp/foo.c:1:10: error: redefinition of 'foo'
-    int foo, foo;
-             ^
-    /tmp/foo.c:1:5: note: previous definition is here
-    int foo, foo;
-        ^
-    1 error generated.
-
-See also the item "Complaint submessage indentation" below.
+** 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 adhoc, it grew organically.  It
-works as a series of calls to several functions, with dependency of the
+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
 latter calls on the former.  For instance:
 
       complain (&sym->location,
@@ -214,20 +185,6 @@ page:
 
 https://gcc.gnu.org/onlinedocs/gcc/Diagnostic-Message-Formatting-Options.html
 
-** consistency
-token vs terminal, variable vs non terminal.
-
-** C++
-Move to int everywhere instead of unsigned?  stack_size, etc.  The parser
-itself uses int (for yylen for instance), yet stack is based on size_t.
-
-Maybe locations should also move to ints.
-
-Paul Eggert already covered most of this.  But before publishing these
-changes, we need to ask our C++ users if they agree with that change, or if
-we need some migration path.  Could be a %define variable, or simply
-%require "3.5".
-
 ** Graphviz display code thoughts
 The code for the --graph option is over two files: print_graph, and
 graphviz. This is because Bison used to also produce VCG graphs, but since
@@ -311,52 +268,7 @@ It would be a very nice source of inspiration for the other languages.
 
 Valentin Tolmer is working on this.
 
-** YYERRCODE
-Defined to 256, but not used, not documented.  Probably the token
-number for the error token, which POSIX wants to be 256, but which
-Bison might renumber if the user used number 256.  Keep fix and doc?
-Throw away?
-
-Also, why don't we output the token name of the error token in the
-output?  It is explicitly skipped:
-
-      /* Skip error token and tokens without identifier.  */
-      if (sym != errtoken && id)
-
-Of course there are issues with name spaces, but if we disable we have
-something which seems to be more simpler and more consistent instead
-of the special case YYERRCODE.
-
-   enum yytokentype {
-     error = 256,
-     // ...
-   };
-
-
-We could (should?) also treat the case of the undef_token, which is
-numbered 257 for yylex, and 2 internal.  Both appear for instance in
-toknum:
-
-  const unsigned short
-  parser::yytoken_number_[] =
-  {
-       0,   256,   257,   258,   259,   260,   261,   262,   263,   264,
-
-while here
-
-   enum yytokentype {
-     TOK_EOF = 0,
-     TOK_EQ = 258,
-
-so both 256 and 257 are "mysterious".
-
-  const char*
-  const parser::yytname_[] =
-  {
-  "\"end of command\"", "error", "$undefined", "\"=\"", "\"break\"",
-
-
-** yychar == yyempty_
+** yychar == YYEMPTY
 The code in yyerrlab reads:
 
       if (yychar <= YYEOF)
@@ -388,14 +300,6 @@ We need trustworthy benchmarks for Bison, for all our backends.  Akim has a
 few things scattered around; we need to put them in the repo, and make them
 more useful.
 
-** yysyntax_error
-The code bw glr.c and yacc.c is really alike, we can certainly factor
-some parts.
-
-This should be worked on when we also address the expected improvements for
-error generation (e.g., i18n).
-
-
 * Report
 
 ** Figures
@@ -433,6 +337,11 @@ An Experimental Ambiguity Detection Tool ∗ Sylvain Schmitz
 LORIA, INRIA Nancy - Grand Est, Nancy, France
 
 * Extensions
+** More languages?
+Well, only if there is really some demand for it.
+
+https://github.com/scfc/bison-php/blob/master/data/lalr1.php
+
 ** Multiple start symbols
 Would be very useful when parsing closely related languages.  The idea is to
 declare several start symbols, for instance
@@ -455,15 +364,6 @@ 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.
 
-** 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
-YYERROR_VERBOSE?" by Simon Sobisch, on bison-help.
-
-See also
-https://www.cs.tufts.edu/~nr/cs257/archive/clinton-jefferey/lr-error-messages.pdf
-and https://research.swtch.com/yyerror.
-
 ** %include
 This is a popular demand.  We already made many changes in the parser that
 should make this reasonably easy to implement.
@@ -600,23 +500,6 @@ to bison. If you're interested, I'll work on a patch.
 * Better graphics
 Equip the parser with a means to create the (visual) parse tree.
 
-* Complaint submessage indentation.
-We already have an implementation that works fairly well for named
-reference messages, but it would be nice to use it consistently for all
-submessages from Bison.  For example, the "previous definition"
-submessage or the list of correct values for a %define variable might
-look better with indentation.
-
-However, the current implementation makes the assumption that the
-location printed on the first line is not usually much shorter than the
-locations printed on the submessage lines that follow.  That assumption
-may not hold true as often for some kinds of submessages especially if
-we ever support multiple grammar files.
-
-Here's a proposal for how a new implementation might look:
-
-  http://lists.gnu.org/archive/html/bison-patches/2009-09/msg00086.html
-
 
 Local Variables:
 mode: outline
@@ -626,7 +509,7 @@ End:
 
 -----
 
-Copyright (C) 2001-2004, 2006, 2008-2015, 2018-2019 Free Software
+Copyright (C) 2001-2004, 2006, 2008-2015, 2018-2020 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=2019-01-04.17; # UTC
+scriptversion=2020-04-13.15; # UTC
 
 # Bootstrap this package from checked-out sources.
 
-# Copyright (C) 2003-2019 Free Software Foundation, Inc.
+# Copyright (C) 2003-2020 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
@@ -970,7 +970,7 @@ bootstrap_post_import_hook \
 # Uninitialized submodules are listed with an initial dash.
 if $use_git && git submodule | grep '^-' >/dev/null; then
   die "some git submodules are not initialized. "     \
-      "Run 'git submodule init' and bootstrap again."
+      "Run 'git submodule update --init' and bootstrap again."
 fi
 
 # Remove any dangling symlink matching "*.m4" or "*.[ch]" in some

bootstrap.conf

@@ -1,6 +1,6 @@
 # Bootstrap configuration.
 
-# Copyright (C) 2006-2015, 2018-2019 Free Software Foundation, Inc.
+# Copyright (C) 2006-2015, 2018-2020 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
@@ -37,6 +37,7 @@ gnulib_modules='
   obstack-printf
   perror progname
   quote quotearg
+  readline
   readme-release
   realloc-posix
   relocatable-prog relocatable-script

build-aux/Darwin.valgrind

@@ -1,4 +1,4 @@
-# Copyright (C) 2012-2015, 2018-2019 Free Software Foundation, Inc.
+# Copyright (C) 2012-2015, 2018-2020 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/Linux.valgrind

@@ -1,4 +1,4 @@
-# Copyright (C) 2012-2015, 2018-2019 Free Software Foundation, Inc.
+# Copyright (C) 2012-2015, 2018-2020 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/cross-options.pl

@@ -1,5 +1,24 @@
 #! /usr/bin/env perl
 
+# Generate a release announcement message.
+
+# Copyright (C) 2007-2020 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/>.
+#
+# Written by Akim Demaille.
+
 use warnings;
 use 5.005;
 use strict;

build-aux/local.mk

@@ -1,4 +1,4 @@
-## Copyright (C) 2000-2015, 2018-2019 Free Software Foundation, Inc.
+## Copyright (C) 2000-2015, 2018-2020 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/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, 2018-2019 Free Software Foundation, Inc.
+# Copyright (C) 2009-2015, 2018-2020 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/update-package-copyright-year

@@ -2,7 +2,7 @@
 
 # In configure.ac, update PACKAGE_COPYRIGHT_YEAR to the current year.
 
-# Copyright (C) 2010-2015, 2018-2019 Free Software Foundation, Inc.
+# Copyright (C) 2010-2015, 2018-2020 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/update-test

@@ -1,5 +1,24 @@
 #! /usr/bin/env python
 
+# Update expectations in an Autotest test suite.
+
+# Copyright (C) 2019-2020 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/>.
+#
+# Written by Akim Demaille.
+
 # usage:
 #
 #    update-test _build/8d/tests/testsuite.dir/*/testsuite.log
@@ -83,7 +102,7 @@ def update(at_file, logfile):
 def process(logfile):
     log = contents(logfile)
     # Look for the file to update.
-    m = re.search(r'^\d+\. ([-\w]+\.at):\d+: ', log, re.MULTILINE)
+    m = re.search(r'^\d+\. ([\-\+\w]+\.at):\d+: ', log, re.MULTILINE)
     if not m:
         trace("no diff found:", logfile)
         return

cfg.mk

@@ -1,5 +1,5 @@
 ## Customize maint.mk                           -*- makefile -*-
-## Copyright (C) 2008-2015, 2018-2019 Free Software Foundation, Inc.
+## Copyright (C) 2008-2015, 2018-2020 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
@@ -156,7 +156,7 @@ exclude = \
 $(call exclude,                                                                 \
   bindtextdomain=^lib/main.c$$                                                  \
   cast_of_argument_to_free=^src/muscle-tab.c$$                                  \
-  po_check=(^po/POTFILES.in|.md)$$		                                \
+  po_check=^(examples|tests)/|(^po/POTFILES.in|.md)$$                           \
   preprocessor_indentation=^data/|^lib/|^src/parse-gram.[ch]$$                  \
   program_name=^lib/main.c$$                                                    \
   prohibit_always-defined_macros=^data/skeletons/yacc.c$$                       \
@@ -165,7 +165,7 @@ $(call exclude,
   prohibit_doubled_word=^tests/named-refs.at$$                                  \
   prohibit_magic_number_exit=^doc/bison.texi$$                                  \
   prohibit_magic_number_exit+=?|^tests/(conflicts|regression).at$$              \
-  prohibit_strcmp=^doc/bison\.texi|examples|tests/local\.at$$                   \
+  prohibit_strcmp=^doc/bison\.texi|examples|tests                               \
   prohibit_tab_based_indentation=install-icc.sh|\.(am|mk)$$|^\.git|tests/input.at|Makefile$$   \
   require_config_h=^(lib/yyerror|data/skeletons/(glr|yacc))\.c$$                \
   require_config_h_first=^(lib/yyerror|data/skeletons/(glr|yacc))\.c$$          \

configure.ac

@@ -1,6 +1,6 @@
 # Configure template for GNU Bison.                   -*-Autoconf-*-
 #
-# Copyright (C) 2001-2015, 2018-2019 Free Software Foundation, Inc.
+# Copyright (C) 2001-2015, 2018-2020 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
@@ -26,8 +26,10 @@ m4_pattern_allow([^BISON_USE_NLS$])
 
 AC_INIT([GNU Bison],
         m4_esyscmd([build-aux/git-version-gen .tarball-version]),
-        [[email protected]])
-AC_SUBST([PACKAGE_COPYRIGHT_YEAR], [2019])
+        [[email protected]],
+        [],
+        [https://www.gnu.org/software/bison/])
+AC_SUBST([PACKAGE_COPYRIGHT_YEAR], [2020])
 AC_DEFINE_UNQUOTED([PACKAGE_COPYRIGHT_YEAR], [$PACKAGE_COPYRIGHT_YEAR],
                    [The copyright year for this package])
 
@@ -100,12 +102,41 @@ if test "$enable_gcc_warnings" = yes; then
   # -Wno-tautological-constant-out-of-range-compare for Clang 3.3 and
   # 3.4 on GNU/Linux that choke on intprops.h's INT_MULTIPLY_WRAPV,
   # etc.
-  warn_common='-Wall -Wextra -Wcast-align
+  #
+  # ICC: -wr188
+  #
+  # 1669  warnings warnings_default =
+  # ../src/complain.c(318): error #188: enumerated type mixed with another type
+  # 1670      Wconflicts_sr | Wconflicts_rr | Wdeprecated | Wother;
+  # 1671      ^
+  # 1672
+  # 1673../src/complain.c(393): error #188: enumerated type mixed with another type
+  # 1674          warnings w = 1 << wbit;
+  # 1675                       ^
+  #
+  # ICC: -wr3179
+  #
+  # char const *usefulness
+  #   = rule_useless_in_grammar_p (&rules[r]) ? "useless-in-grammar"
+  #   : rule_useless_in_parser_p (&rules[r])  ? "useless-in-parser"
+  #   :                                         "useful";
+  #
+  # gives
+  #
+  # error #3179: deprecated conversion of string literal to char* (should be const char*)
+  #
+  # ICC: -wr2259 (that's in C, in spite of what the error messages which seems to be about C++).
+  # error #2259: non-pointer conversion from "int" to "yybool={signed char}" may lose significant bits
+  #   yybool yynormal YY_ATTRIBUTE_UNUSED = yystackp->yysplitPoint == YY_NULLPTR;
+  #                                         ^
+  warn_common='-Wall -Wextra
+    -Wcast-align -Wchar-subscripts
     -fparse-all-comments -Wdocumentation
     -Wformat -Wimplicit-fallthrough -Wnull-dereference
     -Wno-sign-compare -Wno-tautological-constant-out-of-range-compare
     -Wpointer-arith -Wshadow
-    -Wwrite-strings'
+    -Wwrite-strings
+    -wr188 -wr2259 -wr3179'
   warn_c='-Wbad-function-cast -Wstrict-prototypes'
   warn_cxx='-Wextra-semi -Wnoexcept -Wold-style-cast -Wundefined-func-template
     -Wweak-vtables'
@@ -151,8 +182,6 @@ if test "$enable_gcc_warnings" = yes; then
 
   # Warnings for the test suite, and maybe for bison if GCC is modern
   # enough.
-  gl_WARN_ADD([-Wmissing-declarations], [WARN_CFLAGS_TEST])
-  gl_WARN_ADD([-Wmissing-prototypes], [WARN_CFLAGS_TEST])
   test $lv_cv_gcc_pragma_push_works = yes &&
     AS_VAR_APPEND([WARN_CFLAGS], [" $WARN_CFLAGS_TEST"])
 
@@ -179,6 +208,14 @@ if test "$enable_gcc_warnings" = yes; then
               [[if (sizeof (long) < sizeof (int)) return 1;]])])
   gl_WARN_ADD([-Wzero-as-null-pointer-constant], [WARN_CXXFLAGS],
               [AC_LANG_PROGRAM([], [nullptr])])
+  # Before GCC6, the pragmas don't work well enough to neutralize
+  # this warning.
+  gl_WARN_ADD([-Wuseless-cast], [WARN_CXXFLAGS],
+              [AC_LANG_PROGRAM([], [
+              #if defined __GNUC__ && ! defined __ICC && ! defined __clang__ && __GNUC__ < 6
+              syntax error
+              #endif
+              ])])
   gl_WARN_ADD([-Werror], [WERROR_CXXFLAGS])
   # Warnings for the test suite only.
   for i in $warn_tests;

data/README.md

@@ -83,18 +83,20 @@ field), where field can `has_id`, `id`, etc.: see
 
 The macro `b4_symbol(NUM, FIELD)` gives access to the following FIELDS:
 
-- `has_id`: 0 or 1.
-
+- `has_id`: 0 or 1
   Whether the symbol has an id.
 
 - `id`: string
   If has_id, the id (prefixed by api.token.prefix if defined), otherwise
-  defined as empty.  Guaranteed to be usable as a C identifier.
+  defined as empty.  Guaranteed to be usable as a C identifier.  This is
+  used to define the token kind (i.e., the enum used by the return value of
+  yylex).
 
-- `tag`: string.
-  A representation of the symbol.  Can be 'foo', 'foo.id', '"foo"' etc.
+- `tag`: string
+  A human representation of the symbol.  Can be 'foo', 'foo.id', '"foo"' etc.
 
 - `user_number`: integer
+  The code associated to the `id`.
   The external number as used by yylex.  Can be ASCII code when a character,
   some number chosen by bison, or some user number in the case of
   %token FOO <NUM>.  Corresponds to yychar in yacc.c.
@@ -102,7 +104,12 @@ The macro `b4_symbol(NUM, FIELD)` gives access to the following FIELDS:
 - `is_token`: 0 or 1
   Whether this is a terminal symbol.
 
+- `kind`: string
+  The symbol kind, i.e., the enumerator of this symbol (token or nonterminal)
+  which is mapping to its `number`.
+
 - `number`: integer
+  The code associated to the `kind`.
   The internal number (computed from the external number by yytranslate).
   Corresponds to yytoken in yacc.c.  This is the same number that serves as
   key in b4_symbol(NUM, FIELD).
@@ -174,7 +181,7 @@ fill-column: 76
 ispell-dictionary: "american"
 End:
 
-Copyright (C) 2002, 2008-2015, 2018-2019 Free Software Foundation, Inc.
+Copyright (C) 2002, 2008-2015, 2018-2020 Free Software Foundation, Inc.
 
 This file is part of GNU Bison.
 

data/bison-default.css

@@ -1,5 +1,5 @@
 /* Default styling rules for Bison when doing terminal output.
-   Copyright (C) 2019 Free Software Foundation, Inc.
+   Copyright (C) 2019-2020 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
@@ -29,3 +29,6 @@
 
 /* "Sections" in traces (--trace).  */
 .trace0    { color: green; }
+
+.expected   { color: green; }
+.unexpected { color: red; }

data/local.mk

@@ -1,4 +1,4 @@
-## Copyright (C) 2002, 2005-2015, 2018-2019 Free Software Foundation,
+## Copyright (C) 2002, 2005-2015, 2018-2020 Free Software Foundation,
 ## Inc.
 
 ## This program is free software: you can redistribute it and/or modify

data/skeletons/README-D.txt

@@ -27,7 +27,7 @@ public interface Lexer
    * 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. */
-  YYTokenType yylex ();
+  TokenKind yylex ();
 
   /**
    * Entry point for error reporting.  Emits an error
@@ -39,7 +39,7 @@ public interface Lexer
    void yyerror (YYLocation loc, string s);
 }
 
-- semantic types are handled by D usions (same as for C/C++ parsers)
+- semantic types are handled by D unions (same as for C/C++ parsers)
 
 - the following (non-standard) %defines are supported:
 

data/skeletons/bison.m4

@@ -2,7 +2,7 @@
 
 # Language-independent M4 Macros for Bison.
 
-# Copyright (C) 2002, 2004-2015, 2018-2019 Free Software Foundation,
+# Copyright (C) 2002, 2004-2015, 2018-2020 Free Software Foundation,
 # Inc.
 
 # This program is free software: you can redistribute it and/or modify
@@ -192,7 +192,7 @@ m4_define([b4_error],
 #   @warn(1@)
 #   @warn(1@,2@)
 m4_define([b4_warn],
-[b4_error([[warn]], [], [], $@)])
+[b4_warn_at([], [], $@)])
 
 # b4_warn_at(START, END, FORMAT, [ARG1], [ARG2], ...)
 # ---------------------------------------------------
@@ -210,7 +210,7 @@ m4_define([b4_warn_at],
 #
 # See b4_warn example.
 m4_define([b4_complain],
-[b4_error([[complain]], [], [], $@)])
+[b4_complain_at([], [], $@)])
 
 # b4_complain_at(START, END, FORMAT, [ARG1], [ARG2], ...)
 # -------------------------------------------------------
@@ -226,8 +226,7 @@ m4_define([b4_complain_at],
 #
 # See b4_warn example.
 m4_define([b4_fatal],
-[b4_error([[fatal]], [], [], $@)dnl
-m4_exit(1)])
+[b4_fatal_at([], [], $@)])
 
 # b4_fatal_at(START, END, FORMAT, [ARG1], [ARG2], ...)
 # ----------------------------------------------------
@@ -385,37 +384,64 @@ m4_define([b4_glr_cc_if],
 ## Symbols.  ##
 ## --------- ##
 
-# For a description of the Symbol handling, see README.
+# For a description of the Symbol handling, see README.md.
 #
 # The following macros provide access to symbol related values.
 
 # __b4_symbol(NUM, FIELD)
 # -----------------------
-# Recover a FIELD about symbol #NUM.  Thanks to m4_indir, fails if
-# undefined.
+# Fetch FIELD of symbol #NUM.  Fail if undefined.
 m4_define([__b4_symbol],
 [m4_indir([b4_symbol($1, $2)])])
 
 
 # _b4_symbol(NUM, FIELD)
 # ----------------------
-# Recover a FIELD about symbol #NUM (or "orig NUM").  Fails if
-# undefined.
+# Fetch FIELD of symbol #NUM (or "orig NUM", see README.md).
+# Fail if undefined.
 m4_define([_b4_symbol],
 [m4_ifdef([b4_symbol($1, number)],
           [__b4_symbol(m4_indir([b4_symbol($1, number)]), $2)],
           [__b4_symbol([$1], [$2])])])
 
 
+# b4_symbol_token_kind(NUM)
+# -------------------------
+# The token kind of this symbol.
+m4_define([b4_symbol_token_kind],
+[b4_percent_define_get([api.token.prefix])dnl
+_b4_symbol([$1], [id])])
+
+
+# b4_symbol_kind(NUM)
+# -------------------
+# Build the name of the kind of this symbol.  It must always exist,
+# otherwise some symbols might not be represented in the enum, which
+# might be compiled into too small a type to contain all the symbol
+# numbers.
+m4_define([b4_symbol_prefix], [b4_percent_define_get([api.symbol.prefix])])
+m4_define([b4_symbol_kind],
+[b4_percent_define_get([api.symbol.prefix])dnl
+m4_case([$1],
+  [-2],                             [[YYEMPTY]],
+  [0],                              [[YYEOF]],
+  [1],                              [[YYERROR]],
+  [2],                              [[YYUNDEF]],
+  [m4_case(b4_symbol([$1], [tag]),
+      [$accept],                    [[YYACCEPT]],
+      [b4_symbol_if([$1], [has_id], _b4_symbol([$1], [id]),
+                                    [m4_bpatsubst([$1-][]_b4_symbol([$1], [tag]), [[^a-zA-Z_0-9]+], [_])])])])])
+
 
 # b4_symbol(NUM, FIELD)
 # ---------------------
-# Recover a FIELD about symbol #NUM (or "orig NUM").  Fails if
-# undefined.  If FIELD = id, prepend the token prefix.
+# Fetch FIELD of symbol #NUM (or "orig NUM").  Fail if undefined.
+#
+# If FIELD = id, prepend the token prefix.
 m4_define([b4_symbol],
 [m4_case([$2],
-         [id],    [m4_do([b4_percent_define_get([api.token.prefix])],
-                         [_b4_symbol([$1], [id])])],
+         [id],    [b4_symbol_token_kind([$1])],
+         [kind],  [b4_symbol_kind([$1])],
          [_b4_symbol($@)])])
 
 
@@ -438,9 +464,9 @@ m4_define([b4_symbol_tag_comment],
 ])
 
 
-# b4_symbol_action(SYMBOL-NUM, KIND)
-# ----------------------------------
-# Run the action KIND (destructor or printer) for SYMBOL-NUM.
+# 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([(*yyvaluep)],
@@ -464,21 +490,21 @@ m4_define([b4_symbol_destructor], [b4_symbol_action([$1], [destructor])])
 m4_define([b4_symbol_printer],    [b4_symbol_action([$1], [printer])])
 
 
-# b4_symbol_actions(KIND, [TYPE = yytype])
-# ----------------------------------------
-# Emit the symbol actions for KIND ("printer" or "destructor").
-# Dispatch on TYPE.
+# b4_symbol_actions(ACTION, [KIND = yykind])
+# ------------------------------------------
+# Emit the symbol actions for ACTION ("destructor" or "printer").
+# Dispatch on KIND.
 m4_define([b4_symbol_actions],
 [m4_pushdef([b4_actions_], m4_expand([b4_symbol_foreach([b4_symbol_$1])]))dnl
 m4_ifval(m4_defn([b4_actions_]),
-[switch (m4_default([$2], [yytype]))
+[switch (m4_default([$2], [yykind]))
     {
 m4_defn([b4_actions_])[]dnl
       default:
         break;
     }dnl
 ],
-[YYUSE (m4_default([$2], [yytype]));])dnl
+[YYUSE (m4_default([$2], [yykind]));])dnl
 m4_popdef([b4_actions_])dnl
 ])
 
@@ -508,13 +534,14 @@ m4_define([b4_symbol_map],
 
 # b4_token_visible_if(NUM, IF-TRUE, IF-FALSE)
 # -------------------------------------------
-# Whether NUM denotes a token that has an exported definition (i.e.,
-# shows in enum yytokentype).
+# Whether NUM denotes a token kind that has an exported definition
+# (i.e., shows in enum yytokentype).
 m4_define([b4_token_visible_if],
 [b4_symbol_if([$1], [is_token],
               [b4_symbol_if([$1], [has_id], [$2], [$3])],
               [$3])])
 
+
 # b4_token_has_definition(NUM)
 # ----------------------------
 # 1 if NUM is visible, nothing otherwise.
@@ -531,13 +558,27 @@ m4_define([b4_any_token_visible_if],
 
 # b4_token_format(FORMAT, NUM)
 # ----------------------------
+# If token NUM has a visible ID, format FORMAT with ID, USER_NUMBER.
 m4_define([b4_token_format],
 [b4_token_visible_if([$2],
-[m4_quote(m4_format([$1],
-                     [b4_symbol([$2], [id])],
-                     [b4_symbol([$2], b4_api_token_raw_if([[number]], [[user_number]]))]))])])
+[m4_format([[$1]],
+           m4_expand(b4_symbol([$2], [id])),
+           m4_expand(b4_symbol([$2], b4_api_token_raw_if([[number]], [[user_number]]))))])])
 
 
+# b4_last_enum_token
+# ------------------
+# The code of the last token visible token.
+m4_define([_b4_last_enum_token],
+[b4_token_visible_if([$1],
+   [m4_define([b4_last_enum_token], [$1])])])
+b4_symbol_foreach([_b4_last_enum_token])
+
+# b4_last_symbol
+# --------------
+# The code of the last symbol.
+m4_define([b4_last_symbol], m4_eval(b4_tokens_number + b4_nterms_number - 1))
+
 ## ------- ##
 ## Types.  ##
 ## ------- ##
@@ -604,7 +645,7 @@ m4_define([b4_sync_end],   [ b4_comment([$2:$1])]
 # This generates dependencies on the Bison skeletons hence lots of
 # useless 'git diff'.  This location is useless for the regular
 # user (who does not care about the skeletons) and is actually not
-# useful for Bison developpers too (I, Akim, never used this to locate
+# useful for Bison developers too (I, Akim, never used this to locate
 # the code in skeletons that generated output).  So disable it
 # completely.  If someone thinks this was actually useful, a %define
 # variable should be provided to control the level of verbosity of
@@ -976,8 +1017,8 @@ m4_define([b4_percent_code_get],
 [m4_pushdef([b4_macro_name], [[b4_percent_code(]$1[)]])dnl
 m4_ifval([$1], [m4_define([b4_percent_code_bison_qualifiers(]$1[)])])dnl
 m4_ifdef(b4_macro_name,
-[b4_comment([m4_if([$#], [0], [[Unqualified %code]],
-                   [["%code ]$1["]])[ blocks.]])
+[b4_comment(m4_if([$#], [0], [[[Unqualified %code blocks.]]],
+                  [[["%code ]$1[" blocks.]]]))
 b4_user_code([m4_indir(b4_macro_name)])])dnl
 m4_popdef([b4_macro_name])])
 
@@ -1017,21 +1058,23 @@ m4_define([b4_bison_locations_if],
 [b4_locations_if([b4_percent_define_ifdef([[api.location.type]], [], [$1])])])
 
 
-# b4_error_verbose_if([IF-ERRORS-ARE-VERBOSE], [IF-NOT])
+
+# %define parse.error "(custom|detailed|simple|verbose)"
 # ------------------------------------------------------
-# Map %define parse.error "(simple|verbose)" to b4_error_verbose_if and
-# b4_error_verbose_flag.
 b4_percent_define_default([[parse.error]], [[simple]])
 b4_percent_define_check_values([[[[parse.error]],
-                                 [[simple]], [[verbose]]]])
-m4_define([b4_error_verbose_flag],
-          [m4_case(b4_percent_define_get([[parse.error]]),
-                   [simple],  [[0]],
-                   [verbose], [[1]])])
-b4_define_flag_if([error_verbose])
+                                 [[custom]], [[detailed]], [[simple]], [[verbose]]]])
+
+# b4_parse_error_case(CASE1, THEN1, CASE2, THEN2, ..., ELSE)
+# ----------------------------------------------------------
+m4_define([b4_parse_error_case],
+[m4_case(b4_percent_define_get([[parse.error]]), $@)])
+
+# b4_parse_error_bmatch(PATTERN1, THEN1, PATTERN2, THEN2, ..., ELSE)
+# ------------------------------------------------------------------
+m4_define([b4_parse_error_bmatch],
+[m4_bmatch(b4_percent_define_get([[parse.error]]), $@)])
 
-# yytoken_table is needed to support verbose errors.
-b4_error_verbose_if([m4_define([b4_token_table_flag], [1])])
 
 
 # b4_variant_if([IF-VARIANT-ARE-USED], [IF-NOT])
@@ -1117,3 +1160,11 @@ b4_percent_define_ifdef([api.value.type],
 
 # api.value.union.name.
 b4_percent_define_check_kind([api.value.union.name], [keyword])
+
+# parse.error (custom|detailed) >< token-table.
+b4_token_table_if(
+[b4_parse_error_bmatch([custom\|detailed],
+[b4_complain_at(b4_percent_define_get_loc([parse.error]),
+                [['%s' and '%s' cannot be used together]],
+                [%token-table],
+                [%define parse.error (custom|detailed)])])])

data/skeletons/c++-skel.m4

@@ -2,7 +2,7 @@
 
 # C++ skeleton dispatching for Bison.
 
-# Copyright (C) 2006-2007, 2009-2015, 2018-2019 Free Software
+# Copyright (C) 2006-2007, 2009-2015, 2018-2020 Free Software
 # Foundation, Inc.
 
 # This program is free software: you can redistribute it and/or modify

data/skeletons/c++.m4

@@ -2,7 +2,7 @@
 
 # C++ skeleton for Bison
 
-# Copyright (C) 2002-2019 Free Software Foundation, Inc.
+# Copyright (C) 2002-2020 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
@@ -22,6 +22,8 @@ b4_percent_define_ifdef([[api.value.union.name]],
   [b4_complain_at(b4_percent_define_get_loc([[api.value.union.name]]),
                   [named %union is invalid in C++])])
 
+b4_percent_define_default([[api.symbol.prefix]], [[S_]])
+
 m4_include(b4_skeletonsdir/[c.m4])
 
 b4_percent_define_check_kind([api.namespace], [code], [deprecated])
@@ -160,20 +162,42 @@ m4_bpatsubst(m4_dquote(m4_bpatsubst(m4_dquote(b4_namespace_ref[ ]),
              [::\([^][:]\|:[^:]\)*], [} ])[} // ]b4_namespace_ref])])
 
 
+## ------------- ##
+## Token kinds.  ##
+## ------------- ##
+
+
 # b4_token_enums
 # --------------
-# Output the definition of the tokens as enums.
+# Output the definition of the token kinds.
 m4_define([b4_token_enums],
-[[enum yytokentype
+[[enum token_kind_type
       {
-        ]m4_join([,
-        ],
-                 b4_symbol_map([b4_token_enum]))[
-      };]dnl
+        ]b4_symbol([-2], [id])[ = -2,
+]b4_symbol_foreach([b4_token_enum])dnl
+[      };]dnl
 ])
 
 
 
+## -------------- ##
+## Symbol kinds.  ##
+## -------------- ##
+
+# b4_declare_symbol_enum
+# ----------------------
+# The definition of the symbol internal numbers as an enum.
+# Defining YYEMPTY here is important: it forces the compiler
+# to use a signed type, which matters for yytoken.
+m4_define([b4_declare_symbol_enum],
+[[enum symbol_kind_type
+      {
+        YYNTOKENS = ]b4_tokens_number[, ///< Number of tokens.
+        ]b4_symbol_kind([-2])[ = -2,
+]b4_symbol_foreach([      b4_symbol_enum])dnl
+[      };]])
+
+
 
 ## ----------------- ##
 ## Semantic Values.  ##
@@ -231,23 +255,31 @@ m4_define([b4_public_types_declare],
       location_type location;])[
     };
 
-    /// Tokens.
+    /// Token kinds.
     struct token
     {
       ]b4_token_enums[
+      /// Backward compatibility alias.
+      typedef token_kind_type yytokentype;
     };
 
-    /// (External) token type, as returned by yylex.
-    typedef token::yytokentype token_type;
+    /// Token kind, as returned by yylex.
+    typedef token::yytokentype token_kind_type;
 
-    /// Symbol type: an internal symbol number.
-    typedef int symbol_number_type;
+    /// Backward compatibility alias.
+    typedef token_kind_type token_type;
 
-    /// The symbol type number to denote an empty symbol.
-    enum { empty_symbol = -2 };
+    /// Symbol kinds.
+    struct symbol_kind
+    {
+      ]b4_declare_symbol_enum[
+    };
 
-    /// Internal symbol number for tokens (subsumed by symbol_number_type).
-    typedef ]b4_int_type_for([b4_translate])[ token_number_type;
+    /// (Internal) symbol kind.
+    typedef symbol_kind::symbol_kind_type symbol_kind_type;
+
+    /// The number of tokens.
+    static const symbol_kind_type YYNTOKENS = symbol_kind::YYNTOKENS;
 ]])
 
 
@@ -258,8 +290,8 @@ m4_define([b4_public_types_declare],
 m4_define([b4_symbol_type_define],
 [[    /// A complete symbol.
     ///
-    /// Expects its Base type to provide access to the symbol type
-    /// via type_get ().
+    /// Expects its Base type to provide access to the symbol kind
+    /// via kind ().
     ///
     /// Provide access to semantic value]b4_locations_if([ and location])[.
     template <typename Base>
@@ -276,7 +308,14 @@ m4_define([b4_symbol_type_define],
 
 #if 201103L <= YY_CPLUSPLUS
       /// Move constructor.
-      basic_symbol (basic_symbol&& that);
+      basic_symbol (basic_symbol&& that)
+        : Base (std::move (that))
+        , value (]b4_variant_if([], [std::move (that.value)]))b4_locations_if([
+        , location (std::move (that.location))])[
+      {]b4_variant_if([
+        b4_symbol_variant([this->kind ()], [value], [move],
+                          [std::move (that.value)])
+      ])[}
 #endif
 
       /// Copy constructor.
@@ -303,10 +342,10 @@ m4_define([b4_symbol_type_define],
       void clear ()
       {]b4_variant_if([[
         // User destructor.
-        symbol_number_type yytype = this->type_get ();
+        symbol_kind_type yykind = this->kind ();
         basic_symbol<Base>& yysym = *this;
         (void) yysym;
-        switch (yytype)
+        switch (yykind)
         {
 ]b4_symbol_foreach([b4_symbol_destructor])dnl
 [       default:
@@ -314,10 +353,13 @@ m4_define([b4_symbol_type_define],
         }
 
         // Type destructor.
-]b4_symbol_variant([[yytype]], [[value]], [[template destroy]])])[
+]b4_symbol_variant([[yykind]], [[value]], [[template destroy]])])[
         Base::clear ();
       }
 
+      /// Backward compatibility.
+      symbol_kind_type type_get () const YY_NOEXCEPT;
+
       /// Whether empty.
       bool empty () const YY_NOEXCEPT;
 
@@ -351,8 +393,8 @@ m4_define([b4_symbol_type_define],
       /// Copy constructor.
       by_type (const by_type& that);
 
-      /// The symbol type as needed by the constructor.
-      typedef token_type kind_type;
+      /// The symbol kind as needed by the constructor.
+      typedef token_kind_type kind_type;
 
       /// Constructor from (external) token numbers.
       by_type (kind_type t);
@@ -360,20 +402,16 @@ m4_define([b4_symbol_type_define],
       /// Record that this symbol is empty.
       void clear ();
 
-      /// Steal the symbol type from \a that.
+      /// Steal the symbol kind from \a that.
       void move (by_type& that);
 
       /// The (internal) type number (corresponding to \a type).
       /// \a empty when empty.
-      symbol_number_type type_get () const YY_NOEXCEPT;
+      symbol_kind_type kind () const YY_NOEXCEPT;
 
-      /// The token.
-      token_type token () const YY_NOEXCEPT;
-
-      /// The symbol type.
-      /// \a empty_symbol when empty.
-      /// An int, not token_number_type, to be able to store empty_symbol.
-      int type;
+      /// The symbol kind.
+      /// \a ]b4_symbol_prefix[YYEMPTY when empty.
+      symbol_kind_type type;
     };
 
     /// "External" symbols: returned by the scanner.
@@ -396,25 +434,13 @@ m4_define([b4_symbol_type_define],
 # Provide the implementation needed by the public types.
 m4_define([b4_public_types_define],
 [[  // basic_symbol.
-#if 201103L <= YY_CPLUSPLUS
-  template <typename Base>
-  ]b4_parser_class[::basic_symbol<Base>::basic_symbol (basic_symbol&& that)
-    : Base (std::move (that))
-    , value (]b4_variant_if([], [std::move (that.value)]))b4_locations_if([
-    , location (std::move (that.location))])[
-  {]b4_variant_if([
-    b4_symbol_variant([this->type_get ()], [value], [move],
-                      [std::move (that.value)])
-  ])[}
-#endif
-
   template <typename Base>
   ]b4_parser_class[::basic_symbol<Base>::basic_symbol (const basic_symbol& that)
     : Base (that)
     , value (]b4_variant_if([], [that.value]))b4_locations_if([
     , location (that.location)])[
   {]b4_variant_if([
-    b4_symbol_variant([this->type_get ()], [value], [copy],
+    b4_symbol_variant([this->kind ()], [value], [copy],
                       [YY_MOVE (that.value)])
   ])[}
 
@@ -439,13 +465,20 @@ m4_define([b4_public_types_define],
     , location (YY_MOVE (l))])[
   {]b4_variant_if([[
     (void) v;
-    ]b4_symbol_variant([this->type_get ()], [value], [YY_MOVE_OR_COPY], [YY_MOVE (v)])])[}]])[
+    ]b4_symbol_variant([this->kind ()], [value], [YY_MOVE_OR_COPY], [YY_MOVE (v)])])[}]])[
+
+  template <typename Base>
+  ]b4_parser_class[::symbol_kind_type
+  ]b4_parser_class[::basic_symbol<Base>::type_get () const YY_NOEXCEPT
+  {
+    return this->kind ();
+  }
 
   template <typename Base>
   bool
   ]b4_parser_class[::basic_symbol<Base>::empty () const YY_NOEXCEPT
   {
-    return Base::type_get () == empty_symbol;
+    return this->kind () == symbol_kind::]b4_symbol_prefix[YYEMPTY;
   }
 
   template <typename Base>
@@ -453,7 +486,7 @@ m4_define([b4_public_types_define],
   ]b4_parser_class[::basic_symbol<Base>::move (basic_symbol& s)
   {
     super_type::move (s);
-    ]b4_variant_if([b4_symbol_variant([this->type_get ()], [value], [move],
+    ]b4_variant_if([b4_symbol_variant([this->kind ()], [value], [move],
                                       [YY_MOVE (s.value)])],
                    [value = YY_MOVE (s.value);])[]b4_locations_if([
     location = YY_MOVE (s.location);])[
@@ -461,7 +494,7 @@ m4_define([b4_public_types_define],
 
   // by_type.
   ]b4_inline([$1])b4_parser_class[::by_type::by_type ()
-    : type (empty_symbol)
+    : type (symbol_kind::]b4_symbol_prefix[YYEMPTY)
   {}
 
 #if 201103L <= YY_CPLUSPLUS
@@ -476,14 +509,14 @@ m4_define([b4_public_types_define],
     : type (that.type)
   {}
 
-  ]b4_inline([$1])b4_parser_class[::by_type::by_type (token_type t)
+  ]b4_inline([$1])b4_parser_class[::by_type::by_type (token_kind_type t)
     : type (yytranslate_ (t))
   {}
 
   ]b4_inline([$1])[void
   ]b4_parser_class[::by_type::clear ()
   {
-    type = empty_symbol;
+    type = symbol_kind::]b4_symbol_prefix[YYEMPTY;
   }
 
   ]b4_inline([$1])[void
@@ -493,27 +526,12 @@ m4_define([b4_public_types_define],
     that.clear ();
   }
 
-  ]b4_inline([$1])[int
-  ]b4_parser_class[::by_type::type_get () const YY_NOEXCEPT
+  ]b4_inline([$1])[]b4_parser_class[::symbol_kind_type
+  ]b4_parser_class[::by_type::kind () const YY_NOEXCEPT
   {
     return type;
   }
-]b4_token_ctor_if([[
-  ]b4_inline([$1])b4_parser_class[::token_type
-  ]b4_parser_class[::by_type::token () const YY_NOEXCEPT
-  {
-    // 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])[
-    yytoken_number_[] =
-    {
-  ]b4_toknum[
-    };
-    return token_type (yytoken_number_[type]);
-  }
-]])[]dnl
-])
+]])
 
 
 # b4_token_constructor_define
@@ -528,29 +546,27 @@ m4_define([b4_token_constructor_define], [])
 # Define yytranslate_.  Sometimes used in the header file ($1=hh),
 # sometimes in the cc file.
 m4_define([b4_yytranslate_define],
-[  b4_inline([$1])b4_parser_class[::token_number_type
-  ]b4_parser_class[::yytranslate_ (]b4_token_ctor_if([token_type],
-                                                          [int])[ t)
+[  b4_inline([$1])b4_parser_class[::symbol_kind_type
+  ]b4_parser_class[::yytranslate_ (int t)
   {
 ]b4_api_token_raw_if(
-[[    return static_cast<yy::parser::token_number_type> (t);]],
+[[    return static_cast<symbol_kind_type> (t);]],
 [[    // YYTRANSLATE[TOKEN-NUM] -- Symbol number corresponding to
     // TOKEN-NUM as returned by yylex.
     static
-    const token_number_type
+    const ]b4_int_type_for([b4_translate])[
     translate_table[] =
     {
   ]b4_translate[
     };
     const int user_token_number_max_ = ]b4_user_token_number_max[;
-    const token_number_type undef_token_ = ]b4_undef_token_number[;
 
-    if (static_cast<int> (t) <= yyeof_)
-      return yyeof_;
-    else if (static_cast<int> (t) <= user_token_number_max_)
-      return translate_table[t];
+    if (t <= 0)
+      return symbol_kind::]b4_symbol_prefix[YYEOF;
+    else if (t <= user_token_number_max_)
+      return YY_CAST (symbol_kind_type, translate_table[t]);
     else
-      return undef_token_;]])[
+      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, 2018-2019 Free Software Foundation, Inc.
+# Copyright (C) 2012-2015, 2018-2020 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/skeletons/c-skel.m4

@@ -2,7 +2,7 @@
 
 # C skeleton dispatching for Bison.
 
-# Copyright (C) 2006-2007, 2009-2015, 2018-2019 Free Software
+# Copyright (C) 2006-2007, 2009-2015, 2018-2020 Free Software
 # Foundation, Inc.
 
 # This program is free software: you can redistribute it and/or modify

data/skeletons/c.m4

@@ -2,7 +2,7 @@
 
 # C M4 Macros for Bison.
 
-# Copyright (C) 2002, 2004-2015, 2018-2019 Free Software Foundation,
+# Copyright (C) 2002, 2004-2015, 2018-2020 Free Software Foundation,
 # Inc.
 
 # This program is free software: you can redistribute it and/or modify
@@ -101,6 +101,7 @@ m4_define_default([b4_prefix], [b4_api_prefix])
 b4_percent_define_default([[api.value.union.name]],
                           [b4_api_PREFIX[][STYPE]])
 
+b4_percent_define_default([[api.symbol.prefix]], [[YYSYMBOL_]])
 
 ## ------------------------ ##
 ## Pure/impure interfaces.  ##
@@ -129,6 +130,13 @@ m4_define([b4_user_args],
 [m4_ifset([b4_parse_param], [, b4_args(b4_parse_param)])])
 
 
+# b4_user_formals
+# ---------------
+# The possible parse-params formal arguments preceded by a comma.
+m4_define([b4_user_formals],
+[m4_ifset([b4_parse_param], [, b4_formals(b4_parse_param)])])
+
+
 # b4_parse_param
 # --------------
 # If defined, b4_parse_param arrives double quoted, but below we prefer
@@ -327,11 +335,11 @@ m4_define([b4_attribute_define],
 
 #if defined __GNUC__ && ! defined __ICC && 407 <= __GNUC__ * 100 + __GNUC_MINOR__
 /* Suppress an incorrect diagnostic about yylval being uninitialized.  */
-# define YY_IGNORE_MAYBE_UNINITIALIZED_BEGIN \
-    _Pragma ("GCC diagnostic push") \
-    _Pragma ("GCC diagnostic ignored \"-Wuninitialized\"")\
+# define YY_IGNORE_MAYBE_UNINITIALIZED_BEGIN                            \
+    _Pragma ("GCC diagnostic push")                                     \
+    _Pragma ("GCC diagnostic ignored \"-Wuninitialized\"")              \
     _Pragma ("GCC diagnostic ignored \"-Wmaybe-uninitialized\"")
-# define YY_IGNORE_MAYBE_UNINITIALIZED_END \
+# define YY_IGNORE_MAYBE_UNINITIALIZED_END      \
     _Pragma ("GCC diagnostic pop")
 #else
 # define YY_INITIAL_VALUE(Value) Value
@@ -343,6 +351,18 @@ m4_define([b4_attribute_define],
 #ifndef YY_INITIAL_VALUE
 # define YY_INITIAL_VALUE(Value) /* Nothing. */
 #endif
+
+#if defined __cplusplus && defined __GNUC__ && ! defined __ICC && 6 <= __GNUC__
+# define YY_IGNORE_USELESS_CAST_BEGIN                          \
+    _Pragma ("GCC diagnostic push")                            \
+    _Pragma ("GCC diagnostic ignored \"-Wuseless-cast\"")
+# define YY_IGNORE_USELESS_CAST_END            \
+    _Pragma ("GCC diagnostic pop")
+#endif
+#ifndef YY_IGNORE_USELESS_CAST_BEGIN
+# define YY_IGNORE_USELESS_CAST_BEGIN
+# define YY_IGNORE_USELESS_CAST_END
+#endif
 ]])
 
 
@@ -406,9 +426,22 @@ static const b4_int_type_for([$2]) yy$1[[]] =
 ])
 
 
-## ------------------------- ##
-## Assigning token numbers.  ##
-## ------------------------- ##
+## ------------- ##
+## Token kinds.  ##
+## ------------- ##
+
+# Because C enums are not scoped, because tokens are exposed in the
+# header, and because these tokens are common to all the parsers, we
+# need to make sure their names don't collide: use the api.prefix.
+# YYEOF is special, since the user may give it a different name.
+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_define([b4_symbol(0, id)],  [b4_api_PREFIX[][EOF]])])
+m4_define([b4_symbol(1, id)],  [b4_api_PREFIX[][ERRCODE]])
+m4_define([b4_symbol(2, id)],  [b4_api_PREFIX[][UNDEF]])
+
 
 # b4_token_define(TOKEN-NUM)
 # --------------------------
@@ -420,7 +453,7 @@ m4_define([b4_token_define],
 # ----------------
 # Output the definition of the tokens.
 m4_define([b4_token_defines],
-[b4_any_token_visible_if([/* Tokens.  */
+[b4_any_token_visible_if([/* Token kinds.  */
 m4_join([
 ], b4_symbol_map([b4_token_define]))
 ])])
@@ -430,34 +463,81 @@ m4_join([
 # ------------------------
 # Output the definition of this token as an enum.
 m4_define([b4_token_enum],
-[b4_token_format([%s = %s], [$1])])
+[b4_token_visible_if([$1],
+    [m4_format([    %-30s %s],
+               m4_format([[%s = %s%s%s]],
+                         b4_symbol([$1], [id]),
+                         b4_symbol([$1], b4_api_token_raw_if([[number]], [[user_number]])),
+                         m4_if([$1], b4_last_enum_token, [], [[,]])),
+               [b4_symbol_tag_comment([$1])])])])
 
 
 # b4_token_enums
 # --------------
-# Output the definition of the tokens (if there are) as enums.
+# The definition of the token kinds.
 m4_define([b4_token_enums],
-[b4_any_token_visible_if([[/* Token type.  */
+[b4_any_token_visible_if([[/* Token kinds.  */
 #ifndef ]b4_api_PREFIX[TOKENTYPE
 # define ]b4_api_PREFIX[TOKENTYPE
   enum ]b4_api_prefix[tokentype
   {
-    ]m4_join([,
-    ],
-             b4_symbol_map([b4_token_enum]))[
-  };
+    ]b4_symbol([-2], [id])[ = -2,
+]b4_symbol_foreach([b4_token_enum])dnl
+[  };
+  typedef enum ]b4_api_prefix[tokentype ]b4_api_prefix[token_kind_t;
 #endif
 ]])])
 
 
 # b4_token_enums_defines
 # ----------------------
-# Output the definition of the tokens (if there are any) as enums and,
+# The definition of the tokens (if there are any) as enums and,
 # if POSIX Yacc is enabled, as #defines.
 m4_define([b4_token_enums_defines],
 [b4_token_enums[]b4_yacc_if([b4_token_defines])])
 
 
+# b4_symbol_translate(STRING)
+# ---------------------------
+# Used by "bison" in the array of symbol names to mark those that
+# require translation.
+m4_define([b4_symbol_translate],
+[[N_($1)]])
+
+
+
+## -------------- ##
+## Symbol kinds.  ##
+## -------------- ##
+
+# b4_symbol_enum(SYMBOL-NUM)
+# --------------------------
+# Output the definition of this symbol as an enum.
+m4_define([b4_symbol_enum],
+[m4_format([  %-40s %s],
+           m4_format([[%s = %s%s%s]],
+                     b4_symbol([$1], [kind]),
+                     [$1],
+                     m4_if([$1], b4_last_symbol, [], [[,]])),
+           [b4_symbol_tag_comment([$1])])])
+
+
+# b4_declare_symbol_enum
+# ----------------------
+# The definition of the symbol internal numbers as an enum.
+# Defining YYEMPTY here is important: it forces the compiler
+# to use a signed type, which matters for yytoken.
+m4_define([b4_declare_symbol_enum],
+[[/* Symbol kind.  */
+enum yysymbol_kind_t
+{
+  ]b4_symbol_kind([-2])[ = -2,
+]b4_symbol_foreach([b4_symbol_enum])dnl
+[};
+typedef enum yysymbol_kind_t yysymbol_kind_t;
+]])])
+
+
 ## ----------------- ##
 ## Semantic Values.  ##
 ## ----------------- ##
@@ -481,15 +561,6 @@ m4_define([b4_symbol_value],
 ## ---------------------- ##
 
 
-# b4_function_define(NAME, RETURN-VALUE, [DECL1, NAME1], ...)
-# -----------------------------------------------------------
-# Declare the function NAME in C.
-m4_define([b4_function_define],
-[$2
-$1 (b4_formals(m4_shift2($@)))[]dnl
-])
-
-
 # b4_formals([DECL1, NAME1], ...)
 # -------------------------------
 # The formal arguments of a C function definition.
@@ -503,21 +574,6 @@ m4_define([b4_formal],
 
 
 
-## ----------------------- ##
-## Declaring C functions.  ##
-## ----------------------- ##
-
-
-# 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.  ##
 ## --------------------- ##
@@ -581,18 +637,15 @@ m4_define_default([b4_yydestruct_define],
 | Release the memory associated to this symbol.  |
 `-----------------------------------------------*/
 
-]b4_function_define([yydestruct],
-    [static void],
-    [[const char *yymsg],    [yymsg]],
-    [[int yytype],           [yytype]],
-    [[YYSTYPE *yyvaluep],    [yyvaluep]][]dnl
-b4_locations_if(            [, [[YYLTYPE *yylocationp], [yylocationp]]])[]dnl
-m4_ifset([b4_parse_param], [, b4_parse_param]))[
+static void
+yydestruct (const char *yymsg,
+            yysymbol_kind_t yykind, YYSTYPE *yyvaluep]b4_locations_if(dnl
+[[, YYLTYPE *yylocationp]])[]b4_user_formals[)
 {
 ]b4_parse_param_use([yyvaluep], [yylocationp])dnl
 [  if (!yymsg)
     yymsg = "Deleting";
-  YY_SYMBOL_PRINT (yymsg, yytype, yyvaluep, yylocationp);
+  YY_SYMBOL_PRINT (yymsg, yykind, yyvaluep, yylocationp);
 
   YY_IGNORE_MAYBE_UNINITIALIZED_BEGIN
   ]b4_symbol_actions([destructor])[
@@ -610,13 +663,10 @@ m4_define_default([b4_yy_symbol_print_define],
 | Print this symbol's value on YYO.  |
 `-----------------------------------*/
 
-]b4_function_define([yy_symbol_value_print],
-    [static void],
-               [[FILE *yyo],                            [yyo]],
-               [[int yytype],                           [yytype]],
-               [[YYSTYPE const * const yyvaluep],       [yyvaluep]][]dnl
-b4_locations_if([, [[YYLTYPE const * const yylocationp], [yylocationp]]])[]dnl
-m4_ifset([b4_parse_param], [, b4_parse_param]))[
+static void
+yy_symbol_value_print (FILE *yyo,
+                       yysymbol_kind_t yykind, YYSTYPE const * const yyvaluep]b4_locations_if(dnl
+[[, YYLTYPE const * const yylocationp]])[]b4_user_formals[)
 {
   FILE *yyoutput = yyo;
 ]b4_parse_param_use([yyoutput], [yylocationp])dnl
@@ -625,8 +675,8 @@ m4_ifset([b4_parse_param], [, b4_parse_param]))[
 dnl glr.c does not feature yytoknum.
 m4_if(b4_skeleton, ["yacc.c"],
 [[# ifdef YYPRINT
-  if (yytype < YYNTOKENS)
-    YYPRINT (yyo, yytoknum[yytype], *yyvaluep);
+  if (yykind < YYNTOKENS)
+    YYPRINT (yyo, yytoknum[yykind], *yyvaluep);
 # endif
 ]])dnl
 b4_percent_code_get([[pre-printer]])dnl
@@ -641,21 +691,18 @@ b4_percent_code_get([[post-printer]])dnl
 | Print this symbol on YYO.  |
 `---------------------------*/
 
-]b4_function_define([yy_symbol_print],
-    [static void],
-               [[FILE *yyo],                            [yyo]],
-               [[int yytype],                           [yytype]],
-               [[YYSTYPE const * const yyvaluep],       [yyvaluep]][]dnl
-b4_locations_if([, [[YYLTYPE const * const yylocationp], [yylocationp]]])[]dnl
-m4_ifset([b4_parse_param], [, b4_parse_param]))[
+static void
+yy_symbol_print (FILE *yyo,
+                 yysymbol_kind_t yykind, YYSTYPE const * const yyvaluep]b4_locations_if(dnl
+[[, YYLTYPE const * const yylocationp]])[]b4_user_formals[)
 {
   YYFPRINTF (yyo, "%s %s (",
-             yytype < YYNTOKENS ? "token" : "nterm", yytname[yytype]);
+             yykind < YYNTOKENS ? "token" : "nterm", yysymbol_name (yykind));
 
 ]b4_locations_if([  YY_LOCATION_PRINT (yyo, *yylocationp);
   YYFPRINTF (yyo, ": ");
 ])dnl
-[  yy_symbol_value_print (yyo, yytype, yyvaluep]dnl
+[  yy_symbol_value_print (yyo, yykind, yyvaluep]dnl
 b4_locations_if([, yylocationp])[]b4_user_args[);
   YYFPRINTF (yyo, ")");
 }]dnl
@@ -681,11 +728,11 @@ m4_define([b4_symbol_type_register],
 [m4_define([b4_symbol($1, type_tag)],
            [b4_symbol_if([$1], [has_id],
                          [b4_symbol([$1], [id])],
-                         [yytype_[]b4_symbol([$1], [number])])])dnl
+                         [yykind_[]b4_symbol([$1], [number])])])dnl
 m4_append([b4_union_members],
-m4_expand([
-  b4_symbol_tag_comment([$1])dnl
-  b4_symbol([$1], [type]) b4_symbol([$1], [type_tag]);]))
+m4_expand([m4_format([  %-40s %s],
+                     m4_expand([b4_symbol([$1], [type]) b4_symbol([$1], [type_tag]);]),
+                     [b4_symbol_tag_comment([$1])])]))
 ])
 
 
@@ -924,10 +971,8 @@ m4_define([b4_yy_location_print_define],
 /* Print *YYLOCP on YYO.  Private, do not rely on its existence. */
 
 YY_ATTRIBUTE_UNUSED
-]b4_function_define([yy_location_print_],
-    [static int],
-               [[FILE *yyo],                    [yyo]],
-               [[YYLTYPE const * const yylocp], [yylocp]])[
+static int
+yy_location_print_ (FILE *yyo, YYLTYPE const * const yylocp)
 {
   int res = 0;
   int end_col = 0 != yylocp->last_column ? yylocp->last_column - 1 : 0;

data/skeletons/d-skel.m4

@@ -2,7 +2,7 @@
 
 # D skeleton dispatching for Bison.
 
-# Copyright (C) 2018-2019 Free Software Foundation, Inc.
+# Copyright (C) 2018-2020 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/skeletons/d.m4

@@ -2,7 +2,7 @@
 
 # D language support for Bison
 
-# Copyright (C) 2018-2019 Free Software Foundation, Inc.
+# Copyright (C) 2018-2020 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
@@ -148,9 +148,9 @@ private static immutable b4_int_type_for([$2])[[]] yy$1_ =
 ])
 
 
-## ------------------------- ##
-## Assigning token numbers.  ##
-## ------------------------- ##
+## ------------- ##
+## Token kinds.  ##
+## ------------- ##
 
 # b4_token_enum(TOKEN-NAME, TOKEN-NUMBER)
 # ---------------------------------------
@@ -159,19 +159,53 @@ m4_define([b4_token_enum],
 [b4_token_format([  %s = %s,
 ], [$1])])
 
-# b4_token_enums(LIST-OF-PAIRS-TOKEN-NAME-TOKEN-NUMBER)
-# -----------------------------------------------------
+# b4_token_enums
+# --------------
 # Output the definition of the tokens as enums.
 m4_define([b4_token_enums],
-[/* Tokens.  */
-public enum YYTokenType {
-
-  /** Token returned by the scanner to signal the end of its input.  */
-  EOF = 0,
-b4_symbol_foreach([b4_token_enum])
+[/* Token kinds.  */
+public enum TokenKind {
+  ]b4_symbol_kind([-2])[ = -2,
+b4_symbol_foreach([b4_token_enum])dnl
 }
 ])
 
+
+
+## -------------- ##
+## Symbol kinds.  ##
+## -------------- ##
+
+b4_percent_define_default([[api.symbol.prefix]], [[S_]])
+
+
+# b4_symbol_enum(SYMBOL-NUM)
+# --------------------------
+# Output the definition of this symbol as an enum.
+m4_define([b4_symbol_enum],
+[m4_format([    %-30s %s],
+           m4_format([[%s = %s,]],
+                     b4_symbol([$1], [kind]),
+                     [$1]),
+           [b4_symbol_tag_comment([$1])])])
+
+
+# b4_declare_symbol_enum
+# ----------------------
+# The definition of the symbol internal numbers as an enum.
+# Defining YYEMPTY here is important: it forces the compiler
+# to use a signed type, which matters for yytoken.
+m4_define([b4_declare_symbol_enum],
+[[  /* Symbol kinds.  */
+  public enum SymbolKind
+  {
+    ]b4_symbol_kind([-2])[ = -2,  /* No symbol.  */
+]b4_symbol_foreach([b4_symbol_enum])dnl
+[  };
+]])])
+
+
+
 # b4-case(ID, CODE)
 # -----------------
 m4_define([b4_case], [    case $1:

data/skeletons/glr.cc

@@ -1,6 +1,6 @@
 # C++ GLR skeleton for Bison
 
-# Copyright (C) 2002-2015, 2018-2019 Free Software Foundation, Inc.
+# Copyright (C) 2002-2015, 2018-2020 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
@@ -66,30 +66,29 @@ m4_defn([b4_parse_param]))],
            [[b4_namespace_ref::b4_parser_class[& yyparser], [[yyparser]]]])
 ])
 
+# b4_declare_symbol_enum
+# ----------------------
+m4_append([b4_declare_symbol_enum],
+[[typedef symbol_kind_type yysymbol_kind_t;
+]])
+
 
 # b4_yy_symbol_print_define
 # -------------------------
 # Bypass the default implementation to generate the "yy_symbol_print"
 # and "yy_symbol_value_print" functions.
 m4_define([b4_yy_symbol_print_define],
-[[
-/*--------------------.
+[[/*--------------------.
 | Print this symbol.  |
 `--------------------*/
 
-]b4_function_define([yy_symbol_print],
-    [static void],
-    [[FILE *],      []],
-    [[int yytype],  [yytype]],
-    [[const ]b4_namespace_ref::b4_parser_class[::semantic_type *yyvaluep],
-                    [yyvaluep]][]dnl
-b4_locations_if([,
-    [[const ]b4_namespace_ref::b4_parser_class[::location_type *yylocationp],
-                    [yylocationp]]]),
-    b4_parse_param)[
+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[::location_type *yylocationp]])[]b4_user_formals[)
 {
 ]b4_parse_param_use[]dnl
-[  yyparser.yy_symbol_print_ (yytype, yyvaluep]b4_locations_if([, yylocationp])[);
+[  yyparser.yy_symbol_print_ (yytoken, yyvaluep]b4_locations_if([, yylocationp])[);
 }
 ]])[
 
@@ -101,45 +100,30 @@ m4_defn([b4_initial_action])]))])[
 # Hijack the post prologue to declare yyerror.
 ]m4_append([b4_post_prologue],
 [b4_syncline([@oline@], [@ofile@])dnl
-b4_function_declare([yyerror],
-    [static void],b4_locations_if([
-    [[const ]b4_namespace_ref::b4_parser_class[::location_type *yylocationp],
-                        [yylocationp]],])
-    b4_parse_param,
-    [[const char* msg], [msg]])])[
+[static void
+yyerror (]b4_locations_if([[const ]b4_namespace_ref::b4_parser_class[::location_type *yylocationp,
+         ]])[]m4_ifset([b4_parse_param], [b4_formals(b4_parse_param),
+         ])[const char* msg);]])[
 
-
-#undef yynerrs
-#undef yychar
-#undef yylval]b4_locations_if([
-#undef yylloc])
-
-m4_if(b4_prefix, [yy], [],
-[[/* Substitute the variable and function names.  */
-#define yyparse ]b4_prefix[parse
-#define yylex   ]b4_prefix[lex
-#define yyerror ]b4_prefix[error
-#define yydebug ]b4_prefix[debug]]b4_pure_if([], [[
-#define yylval  ]b4_prefix[lval
-#define yychar  ]b4_prefix[char
-#define yynerrs ]b4_prefix[nerrs]b4_locations_if([[
-#define yylloc  ]b4_prefix[lloc]])]))
+]b4_percent_define_flag_if([[global_tokens_and_yystype]], [],
+[m4_define([b4_pre_epilogue],
+[[/* The user is using the C++ token kind, not the C one. */
+#undef ]b4_symbol(0, [id])
+])])[
 
 # Hijack the epilogue to define implementations (yyerror, parser member
 # functions etc.).
-m4_append([b4_epilogue],
+]m4_append([b4_epilogue],
 [b4_syncline([@oline@], [@ofile@])dnl
 [
 /*------------------.
 | Report an error.  |
 `------------------*/
 
-]b4_function_define([yyerror],
-    [static void],b4_locations_if([
-    [[const ]b4_namespace_ref::b4_parser_class[::location_type *yylocationp],
-                        [yylocationp]],])
-    b4_parse_param,
-    [[const char* msg], [msg]])[
+static void
+yyerror (]b4_locations_if([[const ]b4_namespace_ref::b4_parser_class[::location_type *yylocationp,
+         ]])[]m4_ifset([b4_parse_param], [b4_formals(b4_parse_param),
+         ])[const char* msg)
 {
 ]b4_parse_param_use[]dnl
 [  yyparser.error (]b4_locations_if([[*yylocationp, ]])[msg);
@@ -181,7 +165,7 @@ m4_pushdef([b4_parse_param], m4_defn([b4_parse_param_orig]))dnl
   `--------------------*/
 
   void
-  ]b4_parser_class[::yy_symbol_value_print_ (int yytype,
+  ]b4_parser_class[::yy_symbol_value_print_ (symbol_kind_type yykind,
                            const semantic_type* yyvaluep]b4_locations_if([[,
                            const location_type* yylocationp]])[)
   {]b4_locations_if([[
@@ -195,14 +179,14 @@ m4_pushdef([b4_parse_param], m4_defn([b4_parse_param_orig]))dnl
 
 
   void
-  ]b4_parser_class[::yy_symbol_print_ (int yytype,
+  ]b4_parser_class[::yy_symbol_print_ (symbol_kind_type yykind,
                            const semantic_type* yyvaluep]b4_locations_if([[,
                            const location_type* yylocationp]])[)
   {
-    *yycdebug_ << (yytype < YYNTOKENS ? "token" : "nterm")
-               << ' ' << yytname[yytype] << " ("]b4_locations_if([[
+    *yycdebug_ << (yykind < YYNTOKENS ? "token" : "nterm")
+               << ' ' << yytname[yykind] << " ("]b4_locations_if([[
                << *yylocationp << ": "]])[;
-    yy_symbol_value_print_ (yytype, yyvaluep]b4_locations_if([[, yylocationp]])[);
+    yy_symbol_value_print_ (yykind, yyvaluep]b4_locations_if([[, yylocationp]])[);
     *yycdebug_ << ')';
   }
 
@@ -265,6 +249,13 @@ b4_percent_code_get([[requires]])[
 # 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
@@ -321,17 +312,17 @@ b4_percent_code_get([[requires]])[
 # if ]b4_api_PREFIX[DEBUG
   public:
     /// \brief Report a symbol value on the debug stream.
-    /// \param yytype       The token type.
+    /// \param yykind       The symbol kind.
     /// \param yyvaluep     Its semantic value.]b4_locations_if([[
     /// \param yylocationp  Its location.]])[
-    virtual void yy_symbol_value_print_ (int yytype,
+    virtual void yy_symbol_value_print_ (symbol_kind_type yykind,
                                          const semantic_type* yyvaluep]b4_locations_if([[,
                                          const location_type* yylocationp]])[);
     /// \brief Report a symbol on the debug stream.
-    /// \param yytype       The token type.
+    /// \param yykind       The symbol kind.
     /// \param yyvaluep     Its semantic value.]b4_locations_if([[
     /// \param yylocationp  Its location.]])[
-    virtual void yy_symbol_print_ (int yytype,
+    virtual void yy_symbol_print_ (symbol_kind_type yykind,
                                    const semantic_type* yyvaluep]b4_locations_if([[,
                                    const location_type* yylocationp]])[);
   private:
@@ -344,8 +335,16 @@ b4_percent_code_get([[requires]])[
 
 ]dnl Redirections for glr.c.
 b4_percent_define_flag_if([[global_tokens_and_yystype]],
-[b4_token_defines])
-[
+[b4_token_defines
+])[
+]b4_namespace_close[
+
+]dnl Map the name used in c.m4 to the one used in c++.m4.
+[#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])[
+
 #ifndef ]b4_api_PREFIX[STYPE
 # define ]b4_api_PREFIX[STYPE ]b4_namespace_ref[::]b4_parser_class[::semantic_type
 #endif
@@ -353,7 +352,13 @@ b4_percent_define_flag_if([[global_tokens_and_yystype]],
 # define ]b4_api_PREFIX[LTYPE ]b4_namespace_ref[::]b4_parser_class[::location_type
 #endif
 
-]b4_namespace_close[
+]m4_define([b4_declare_symbol_enum],
+[[typedef ]b4_namespace_ref[::]b4_parser_class[::symbol_kind_type yysymbol_kind_t;
+#define ]b4_symbol_prefix[YYEMPTY ]b4_namespace_ref[::]b4_parser_class[::symbol_kind::]b4_symbol_prefix[YYEMPTY
+#define ]b4_symbol_prefix[YYERROR ]b4_namespace_ref[::]b4_parser_class[::symbol_kind::]b4_symbol_prefix[YYERROR
+#define ]b4_symbol_prefix[YYEOF   ]b4_namespace_ref[::]b4_parser_class[::symbol_kind::]b4_symbol_prefix[YYEOF
+#define ]b4_symbol_prefix[YYUNDEF ]b4_namespace_ref[::]b4_parser_class[::symbol_kind::]b4_symbol_prefix[YYUNDEF
+]])[
 ]b4_percent_code_get([[provides]])[
 ]m4_popdef([b4_parse_param])dnl
 ])
@@ -361,7 +366,7 @@ b4_percent_define_flag_if([[global_tokens_and_yystype]],
 b4_defines_if(
 [b4_output_begin([b4_spec_header_file])
 b4_copyright([Skeleton interface for Bison GLR parsers in C++],
-             [2002-2015, 2018-2019])[
+             [2002-2015, 2018-2020])[
 // 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, 2018-2019 Free Software Foundation,
+# Copyright (C) 2007, 2009-2015, 2018-2020 Free Software Foundation,
 # Inc.
 
 # This program is free software: you can redistribute it and/or modify

data/skeletons/java.m4

@@ -2,7 +2,7 @@
 
 # Java language support for Bison
 
-# Copyright (C) 2007-2015, 2018-2019 Free Software Foundation, Inc.
+# Copyright (C) 2007-2015, 2018-2020 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
@@ -106,10 +106,13 @@ m4_define([b4_null], [null])
 
 # b4_typed_parser_table_define(TYPE, NAME, DATA, COMMENT)
 # -------------------------------------------------------
+# We use intermediate functions (e.g., yypact_init) to work around the
+# 64KB limit for JVM methods.  See
+# https://lists.gnu.org/r/help-bison/2008-11/msg00004.html.
 m4_define([b4_typed_parser_table_define],
 [m4_ifval([$4], [b4_comment([$4])
   ])dnl
-[private static final ]$1[ yy$2_[] = yy$2_init();
+[private static final ]$1[[] yy$2_ = yy$2_init();
   private static final ]$1[[] yy$2_init()
   {
     return new ]$1[[]
@@ -125,9 +128,10 @@ m4_define([b4_integral_parser_table_define],
 [b4_typed_parser_table_define([b4_int_type_for([$2])], [$1], [$2], [$3])])
 
 
-## ------------------------- ##
-## Assigning token numbers.  ##
-## ------------------------- ##
+## ------------- ##
+## Token kinds.  ##
+## ------------- ##
+
 
 # b4_token_enum(TOKEN-NUM)
 # ------------------------
@@ -141,24 +145,129 @@ m4_define([b4_token_enum],
 # --------------
 # Output the definition of the tokens (if there are) as enums.
 m4_define([b4_token_enums],
-[b4_any_token_visible_if([/* Tokens.  */
+[b4_any_token_visible_if([    /* Token kinds.  */
 b4_symbol_foreach([b4_token_enum])])])
 
-# b4-case(ID, CODE)
+
+
+## -------------- ##
+## Symbol kinds.  ##
+## -------------- ##
+
+# b4_symbol_enum(SYMBOL-NUM)
+# --------------------------
+# Output the definition of this symbol as an enum.
+m4_define([b4_symbol_enum],
+[m4_format([    %-30s %s],
+           m4_format([[%s(%s)%s]],
+                     b4_symbol([$1], [kind]),
+                     [$1],
+                     m4_if([$1], b4_last_symbol, [[;]], [[,]])),
+           [b4_symbol_tag_comment([$1])])])
+
+
+# b4_declare_symbol_enum
+# ----------------------
+# The definition of the symbol internal numbers as an enum.
+m4_define([b4_declare_symbol_enum],
+[[  public enum SymbolKind
+  {
+]b4_symbol_foreach([b4_symbol_enum])[
+
+    private final int yycode_;
+
+    SymbolKind (int n) {
+      this.yycode_ = n;
+    }
+
+    private static final SymbolKind[] values_ = {
+      ]m4_map_args_sep([b4_symbol_kind(], [)], [,
+      ], b4_symbol_numbers)[
+    };
+
+    static final SymbolKind get(int code) {
+      return values_[code];
+    }
+
+    public final int getCode() {
+      return this.yycode_;
+    }
+
+]b4_parse_error_bmatch(
+[simple\|verbose],
+[[    /* 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.  */
+    private static String yytnamerr_(String yystr)
+    {
+      if (yystr.charAt (0) == '"')
+        {
+          StringBuffer yyr = new StringBuffer();
+          strip_quotes: for (int i = 1; i < yystr.length(); i++)
+            switch (yystr.charAt(i))
+              {
+              case '\'':
+              case ',':
+                break strip_quotes;
+
+              case '\\':
+                if (yystr.charAt(++i) != '\\')
+                  break strip_quotes;
+                /* Fall through.  */
+              default:
+                yyr.append(yystr.charAt(i));
+                break;
+
+              case '"':
+                return yyr.toString();
+              }
+        }
+      return yystr;
+    }
+
+    /* YYTNAME[SYMBOL-NUM] -- String name of the symbol SYMBOL-NUM.
+       First, the terminals, then, starting at \a YYNTOKENS_, nonterminals.  */
+    ]b4_typed_parser_table_define([String], [tname], [b4_tname])[
+
+    /* The user-facing name of this symbol.  */
+    public final String getName() {
+      return yytnamerr_(yytname_[yycode_]);
+    }
+]],
+[custom\|detailed],
+[[    /* YYNAMES_[SYMBOL-NUM] -- String name of the symbol SYMBOL-NUM.
+       First, the terminals, then, starting at \a YYNTOKENS_, nonterminals.  */
+    ]b4_typed_parser_table_define([String], [names], [b4_symbol_names])[
+
+    /* The user-facing name of this symbol.  */
+    public final String getName() {
+      return yynames_[yycode_];
+    }]])[
+  };
+]])])
+
+
+
+# b4_case(ID, CODE)
 # -----------------
 # We need to fool Java's stupid unreachable code detection.
-m4_define([b4_case], [  case $1:
+m4_define([b4_case],
+[  case $1:
   if (yyn == $1)
     $2;
   break;
-    ])
+])
+
 
 # b4_predicate_case(LABEL, CONDITIONS)
 # ------------------------------------
-m4_define([b4_predicate_case], [  case $1:
+m4_define([b4_predicate_case],
+[  case $1:
      if (! ($2)) YYERROR;
     break;
-    ])
+])
 
 
 ## -------- ##
@@ -183,6 +292,7 @@ b4_percent_define_check_kind([[throws]],            [code], [deprecated])
 
 m4_define([b4_yystype], [b4_percent_define_get([[api.value.type]])])
 b4_percent_define_default([[api.value.type]], [[Object]])
+b4_percent_define_default([[api.symbol.prefix]], [[S_]])
 
 # b4_api_prefix, b4_api_PREFIX
 # ----------------------------
@@ -222,6 +332,22 @@ m4_define([b4_position_type], [b4_percent_define_get([[api.position.type]])])
 ## ----------------- ##
 
 
+# b4_symbol_translate(STRING)
+# ---------------------------
+# Used by "bison" in the array of symbol names to mark those that
+# require translation.
+m4_define([b4_symbol_translate],
+[[i18n($1)]])
+
+
+# b4_trans(STRING)
+# ----------------
+# Translate a string if i18n is enabled.  Avoid collision with b4_translate.
+m4_define([b4_trans],
+[m4_if(b4_has_translations, 0, [$1], [i18n($1)])])
+
+
+
 # b4_symbol_value(VAL, [SYMBOL-NUM], [TYPE-TAG])
 # ----------------------------------------------
 # See README.
@@ -361,4 +487,4 @@ m4_define([b4_var_decl],
 # -----------------------
 # Expand to either an empty string or "throws THROWS".
 m4_define([b4_maybe_throws],
-          [m4_ifval($1, [throws $1])])
+          [m4_ifval($1, [ throws $1])])

data/skeletons/lalr1.cc

@@ -1,6 +1,6 @@
 # C++ skeleton for Bison
 
-# Copyright (C) 2002-2015, 2018-2019 Free Software Foundation, Inc.
+# Copyright (C) 2002-2015, 2018-2020 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
@@ -23,12 +23,22 @@ m4_define([b4_value_type_setup_variant])
 # Check the value of %define parse.lac, where LAC stands for lookahead
 # correction.
 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]])])
 
 
+# b4_tname_if(TNAME-NEEDED, TNAME-NOT-NEEDED)
+# -------------------------------------------
+m4_define([b4_tname_if],
+[m4_case(b4_percent_define_get([[parse.error]]),
+         [verbose],         [$1],
+         [b4_token_table_if([$1],
+                            [$2])])])
+
+
 # b4_integral_parser_table_declare(TABLE-NAME, CONTENT, COMMENT)
 # --------------------------------------------------------------
 # Declare "parser::yy<TABLE-NAME>_" whose contents is CONTENT.
@@ -143,7 +153,7 @@ m4_ifdef([b4_lex_param], [, ]b4_lex_param))])])
 
 
 m4_pushdef([b4_copyright_years],
-           [2002-2015, 2018-2019])
+           [2002-2015, 2018-2020])
 
 m4_define([b4_parser_class],
           [b4_percent_define_get([[api.parser.class]])])
@@ -225,7 +235,25 @@ m4_define([b4_shared_declarations],
     void error (const syntax_error& err);
 
 ]b4_token_constructor_define[
+]b4_parse_error_bmatch([custom\|detailed\|verbose], [[
+    class context
+    {
+    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; }
+]])[
+      /// 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
+      /// number of expected tokens (guaranteed to be less than YYNTOKENS).
+      int expected_tokens (symbol_kind_type yyarg[], int yyargn) const;
 
+    private:
+      const ]b4_parser_class[& yyparser_;
+      const symbol_type& yyla_;
+    };
+]])[
   private:
     /// This class is not copyable.
     ]b4_parser_class[ (const ]b4_parser_class[&);
@@ -233,10 +261,10 @@ m4_define([b4_shared_declarations],
 
     /// Check the lookahead yytoken.
     /// \returns  true iff the token will be eventually shifted.
-    bool yy_lac_check_ (int yytoken) const;
+    bool yy_lac_check_ (symbol_kind_type yytoken) const;
     /// Establish the initial context if no initial context currently exists.
     /// \returns  true iff the token will be eventually shifted.
-    bool yy_lac_establish_ (int yytoken);
+    bool yy_lac_establish_ (symbol_kind_type 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.
@@ -244,13 +272,19 @@ 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], [[
+    /// Report a syntax error
+    /// \param yyctx     the context in which the error occurred.
+    void report_syntax_error (const context& yyctx) const;]],
+      [detailed\|verbose], [[
+    /// The arguments of the error message.
+    int yy_syntax_error_arguments_ (const context& yyctx,
+                                    symbol_kind_type yyarg[], int yyargn) const;
 
     /// Generate an error message.
-    /// \param yystate   the state where the error occurred.
-    /// \param yyla      the lookahead token.
-    virtual std::string yysyntax_error_ (state_type yystate,
-                                         const symbol_type& yyla) const;
-
+    /// \param yyctx     the context in which the error occurred.
+    virtual std::string yysyntax_error_ (const context& yyctx) const;]])[
     /// Compute post-reduction state.
     /// \param yystate   the current state
     /// \param yysym     the nonterminal to push on the stack
@@ -267,19 +301,33 @@ m4_define([b4_shared_declarations],
     static const ]b4_int_type(b4_pact_ninf, b4_pact_ninf)[ yypact_ninf_;
     static const ]b4_int_type(b4_table_ninf, b4_table_ninf)[ yytable_ninf_;
 
-    /// Convert a scanner token number \a t to a symbol number.
-    static token_number_type yytranslate_ (]b4_token_ctor_if([token_type], [int])[ t);
+    /// Convert a scanner token kind \a t to a symbol kind.
+    /// In theory \a t should be a token_kind_type, but character literals
+    /// are valid, yet not members of the token_type enum.
+    static symbol_kind_type yytranslate_ (int t);
+]b4_parse_error_bmatch([custom\|detailed], [[
+   /// The user-facing name of the symbol whose (internal) number is
+   /// YYSYMBOL.  No bounds checking.
+   static const char *symbol_name (symbol_kind_type yysymbol);
+]])[
 
     // Tables.
-]b4_parser_tables_declare[]b4_error_verbose_if([
-
+]b4_parser_tables_declare[
+]b4_parse_error_case([verbose], [[
     /// Convert the symbol name \a n to a form suitable for a diagnostic.
-    static std::string yytnamerr_ (const char *n);])[
+    static std::string yytnamerr_ (const char *n);
 
-]b4_token_table_if([], [[#if ]b4_api_PREFIX[DEBUG]])[
     /// For a symbol, its name in clear.
     static const char* const yytname_[];
-]b4_token_table_if([[#if ]b4_api_PREFIX[DEBUG]])[
+]],
+[b4_token_table_if([], [[
+#if ]b4_api_PREFIX[DEBUG
+    /// For a symbol, its name in clear.
+    static const char* const yytname_[];
+#endif
+]])])[
+
+#if ]b4_api_PREFIX[DEBUG
 ]b4_integral_parser_table_declare([rline], [b4_rline],
      [[YYRLINE[YYN] -- Source line where rule number YYN was defined.]])[
     /// Report on the debug stream that the rule \a r is going to be reduced.
@@ -292,7 +340,7 @@ m4_define([b4_shared_declarations],
     /// Debug stream.
     std::ostream* yycdebug_;
 
-    /// \brief Display a symbol type, value and location.
+    /// \brief Display a symbol kind, value and location.
     /// \param yyo    The output stream.
     /// \param yysym  The symbol.
     template <typename Base>
@@ -313,7 +361,7 @@ m4_define([b4_shared_declarations],
       /// Default constructor.
       by_state () YY_NOEXCEPT;
 
-      /// The symbol type as needed by the constructor.
+      /// The symbol kind as needed by the constructor.
       typedef state_type kind_type;
 
       /// Constructor.
@@ -325,15 +373,16 @@ m4_define([b4_shared_declarations],
       /// Record that this symbol is empty.
       void clear () YY_NOEXCEPT;
 
-      /// Steal the symbol type from \a that.
+      /// Steal the symbol kind from \a that.
       void move (by_state& that);
 
-      /// The (internal) type number (corresponding to \a state).
-      /// \a empty_symbol when empty.
-      symbol_number_type type_get () const YY_NOEXCEPT;
+      /// The symbol kind (corresponding to \a state).
+      /// \a ]b4_symbol(-2, kind)[ when empty.
+      symbol_kind_type kind () const YY_NOEXCEPT;
 
       /// The state number used to denote an empty symbol.
-      enum { empty_state = -1 };
+      /// We use the initial state, as it does not have a value.
+      enum { empty_state = 0 };
 
       /// The state.
       /// \a empty when empty.
@@ -400,13 +449,9 @@ m4_define([b4_shared_declarations],
     /// Constants.
     enum
     {
-      yyeof_ = 0,
       yylast_ = ]b4_last[,     ///< Last index in yytable_.
       yynnts_ = ]b4_nterms_number[,  ///< Number of nonterminal symbols.
-      yyfinal_ = ]b4_final_state_number[, ///< Termination state number.
-      yyterror_ = 1,
-      yyerrcode_ = 256,
-      yyntokens_ = ]b4_tokens_number[  ///< Number of tokens.
+      yyfinal_ = ]b4_final_state_number[ ///< Termination state number.
     };
 
 ]b4_parse_param_vars[
@@ -537,7 +582,29 @@ m4_if(b4_prefix, [yy], [],
 #define YYERROR         goto yyerrorlab
 #define YYRECOVERING()  (!!yyerrstatus_)
 
-]b4_namespace_open[]b4_error_verbose_if([[
+]b4_namespace_open[]b4_parse_error_bmatch([custom\|detailed], [[
+  /* The user-facing name of the symbol whose (internal) number is
+     YYSYMBOL.  No bounds checking. */
+  const char *
+  ]b4_parser_class[::symbol_name (symbol_kind_type yysymbol)
+  {
+    static const char *const yy_sname[] =
+    {
+    ]b4_symbol_names[
+    };]m4_ifdef([b4_translatable], [[
+    /* YYTRANSLATABLE[SYMBOL-NUM] -- Whether YYTNAME[SYMBOL-NUM] is
+       internationalizable.  */
+    static ]b4_int_type_for([b4_translatable])[ yytranslatable[] =
+    {
+    ]b4_translatable[
+    };
+    return (yysymbol < YYNTOKENS && yytranslatable[yysymbol]
+            ? _(yy_sname[yysymbol])
+            : yy_sname[yysymbol]);]], [[
+    return yy_sname[yysymbol];]])[
+  }
+]])
+b4_parse_error_case([verbose], [[
 
   /* Return YYSTR after stripping away unnecessary quotes and
      backslashes, so that it's suitable for yyerror.  The heuristic is
@@ -598,7 +665,7 @@ m4_if(b4_prefix, [yy], [],
   {}
 
   /*---------------.
-  | Symbol types.  |
+  | symbol kinds.  |
   `---------------*/
 
 ]b4_token_ctor_if([], [b4_public_types_define([cc])])[
@@ -629,13 +696,13 @@ m4_if(b4_prefix, [yy], [],
     : state (s)
   {}
 
-  ]b4_parser_class[::symbol_number_type
-  ]b4_parser_class[::by_state::type_get () const YY_NOEXCEPT
+  ]b4_parser_class[::symbol_kind_type
+  ]b4_parser_class[::by_state::kind () const YY_NOEXCEPT
   {
     if (state == empty_state)
-      return empty_symbol;
+      return symbol_kind::]b4_symbol(-2, kind)[;
     else
-      return yystos_[state];
+      return YY_CAST (symbol_kind_type, yystos_[+state]);
   }
 
   ]b4_parser_class[::stack_symbol_type::stack_symbol_type ()
@@ -644,7 +711,7 @@ m4_if(b4_prefix, [yy], [],
   ]b4_parser_class[::stack_symbol_type::stack_symbol_type (YY_RVREF (stack_symbol_type) that)
     : super_type (YY_MOVE (that.state)]b4_variant_if([], [, YY_MOVE (that.value)])b4_locations_if([, YY_MOVE (that.location)])[)
   {]b4_variant_if([
-    b4_symbol_variant([that.type_get ()],
+    b4_symbol_variant([that.kind ()],
                       [value], [YY_MOVE_OR_COPY], [YY_MOVE (that.value)])])[
 #if 201103L <= YY_CPLUSPLUS
     // that is emptied.
@@ -655,10 +722,10 @@ m4_if(b4_prefix, [yy], [],
   ]b4_parser_class[::stack_symbol_type::stack_symbol_type (state_type s, YY_MOVE_REF (symbol_type) that)
     : super_type (s]b4_variant_if([], [, YY_MOVE (that.value)])[]b4_locations_if([, YY_MOVE (that.location)])[)
   {]b4_variant_if([
-    b4_symbol_variant([that.type_get ()],
+    b4_symbol_variant([that.kind ()],
                       [value], [move], [YY_MOVE (that.value)])])[
     // that is emptied.
-    that.type = empty_symbol;
+    that.type = symbol_kind::]b4_symbol(-2, kind)[;
   }
 
 #if YY_CPLUSPLUS < 201103L
@@ -666,7 +733,7 @@ m4_if(b4_prefix, [yy], [],
   ]b4_parser_class[::stack_symbol_type::operator= (const stack_symbol_type& that)
   {
     state = that.state;
-    ]b4_variant_if([b4_symbol_variant([that.type_get ()],
+    ]b4_variant_if([b4_symbol_variant([that.kind ()],
                                       [value], [copy], [that.value])],
                    [[value = that.value;]])[]b4_locations_if([
     location = that.location;])[
@@ -677,7 +744,7 @@ m4_if(b4_prefix, [yy], [],
   ]b4_parser_class[::stack_symbol_type::operator= (stack_symbol_type& that)
   {
     state = that.state;
-    ]b4_variant_if([b4_symbol_variant([that.type_get ()],
+    ]b4_variant_if([b4_symbol_variant([that.kind ()],
                                       [value], [move], [that.value])],
                    [[value = that.value;]])[]b4_locations_if([
     location = that.location;])[
@@ -695,7 +762,7 @@ m4_if(b4_prefix, [yy], [],
       YY_SYMBOL_PRINT (yymsg, yysym);]b4_variant_if([], [
 
     // User destructor.
-    b4_symbol_actions([destructor], [yysym.type_get ()])])[
+    b4_symbol_actions([destructor], [yysym.kind ()])])[
   }
 
 #if ]b4_api_PREFIX[DEBUG
@@ -706,15 +773,15 @@ m4_if(b4_prefix, [yy], [],
   {
     std::ostream& yyoutput = yyo;
     YYUSE (yyoutput);
-    symbol_number_type yytype = yysym.type_get ();
+    symbol_kind_type yykind = yysym.kind ();
 #if defined __GNUC__ && ! defined __clang__ && ! defined __ICC && __GNUC__ * 100 + __GNUC_MINOR__ <= 408
     // Avoid a (spurious) G++ 4.8 warning about "array subscript is
     // below array bounds".
     if (yysym.empty ())
       std::abort ();
 #endif
-    yyo << (yytype < yyntokens_ ? "token" : "nterm")
-        << ' ' << yytname_[yytype] << " ("]b4_locations_if([
+    yyo << (yykind < YYNTOKENS ? "token" : "nterm")
+        << ' ' << yytname_[yykind] << " ("]b4_locations_if([
         << yysym.location << ": "])[;
     ]b4_symbol_actions([printer])[
     yyo << ')';
@@ -776,11 +843,11 @@ m4_if(b4_prefix, [yy], [],
   ]b4_parser_class[::state_type
   ]b4_parser_class[::yy_lr_goto_state_ (state_type yystate, int yysym)
   {
-    int yyr = yypgoto_[yysym - yyntokens_] + yystate;
+    int yyr = yypgoto_[yysym - YYNTOKENS] + yystate;
     if (0 <= yyr && yyr <= yylast_ && yycheck_[yyr] == yystate)
       return yytable_[yyr];
     else
-      return yydefgoto_[yysym - yyntokens_];
+      return yydefgoto_[yysym - YYNTOKENS];
   }
 
   bool
@@ -848,6 +915,7 @@ b4_dollar_popdef])[]dnl
   `-----------------------------------------------*/
   yynewstate:
     YYCDEBUG << "Entering state " << int (yystack_[0].state) << '\n';
+    YY_STACK_PRINT ();
 
     // Accept?
     if (yystack_[0].state == yyfinal_)
@@ -861,14 +929,14 @@ b4_dollar_popdef])[]dnl
   `-----------*/
   yybackup:
     // Try to take a decision without lookahead.
-    yyn = yypact_[yystack_[0].state];
+    yyn = yypact_[+yystack_[0].state];
     if (yy_pact_value_is_default_ (yyn))
       goto yydefault;
 
     // Read a lookahead token.
     if (yyla.empty ())
       {
-        YYCDEBUG << "Reading a token: ";
+        YYCDEBUG << "Reading a token\n";
 #if YY_EXCEPTIONS
         try
 #endif // YY_EXCEPTIONS
@@ -890,10 +958,10 @@ b4_dollar_popdef])[]dnl
 
     /* If the proper action on seeing token YYLA.TYPE is to reduce or
        to detect an error, take that action.  */
-    yyn += yyla.type_get ();
-    if (yyn < 0 || yylast_ < yyn || yycheck_[yyn] != yyla.type_get ())
+    yyn += yyla.kind ();
+    if (yyn < 0 || yylast_ < yyn || yycheck_[yyn] != yyla.kind ())
       {]b4_lac_if([[
-        if (!yy_lac_establish_ (yyla.type_get ()))
+        if (!yy_lac_establish_ (yyla.kind ()))
            goto yyerrlab;]])[
         goto yydefault;
       }
@@ -904,7 +972,7 @@ b4_dollar_popdef])[]dnl
       {
         if (yy_table_value_is_error_ (yyn))
           goto yyerrlab;]b4_lac_if([[
-        if (!yy_lac_establish_ (yyla.type_get ()))
+        if (!yy_lac_establish_ (yyla.kind ()))
            goto yyerrlab;
 ]])[
         yyn = -yyn;
@@ -916,7 +984,7 @@ b4_dollar_popdef])[]dnl
       --yyerrstatus_;
 
     // Shift the lookahead token.
-    yypush_ ("Shifting", static_cast<state_type> (yyn), YY_MOVE (yyla));]b4_lac_if([[
+    yypush_ ("Shifting", state_type (yyn), YY_MOVE (yyla));]b4_lac_if([[
     yy_lac_discard_ ("shift");]])[
     goto yynewstate;
 
@@ -925,7 +993,7 @@ b4_dollar_popdef])[]dnl
   | yydefault -- do the default action for the current state.  |
   `-----------------------------------------------------------*/
   yydefault:
-    yyn = yydefact_[yystack_[0].state];
+    yyn = yydefact_[+yystack_[0].state];
     if (yyn == 0)
       goto yyerrlab;
     goto yyreduce;
@@ -986,7 +1054,6 @@ b4_dollar_popdef])[]dnl
       YY_SYMBOL_PRINT ("-> $$ =", yylhs);
       yypop_ (yylen);
       yylen = 0;
-      YY_STACK_PRINT ();
 
       // Shift the result of the reduction.
       yypush_ (YY_NULLPTR, YY_MOVE (yylhs));
@@ -1001,9 +1068,17 @@ b4_dollar_popdef])[]dnl
     // If not already recovering from an error, report this error.
     if (!yyerrstatus_)
       {
-        ++yynerrs_;
-        error (]b4_join(b4_locations_if([yyla.location]),
-                        [[yysyntax_error_ (yystack_[0].state, yyla)]])[);
+        ++yynerrs_;]b4_parse_error_case(
+                  [simple], [[
+        std::string msg = YY_("syntax error");
+        error (]b4_join(b4_locations_if([yyla.location]), [[YY_MOVE (msg)]])[);]],
+                  [custom], [[
+        context yyctx (*this, yyla);
+        report_syntax_error (yyctx);]],
+                  [[
+        context yyctx (*this, yyla);
+        std::string msg = yysyntax_error_ (yyctx);
+        error (]b4_join(b4_locations_if([yyla.location]), [[YY_MOVE (msg)]])[);]])[
       }
 
 ]b4_locations_if([[
@@ -1014,7 +1089,7 @@ b4_dollar_popdef])[]dnl
            error, discard it.  */
 
         // Return failure if at end of input.
-        if (yyla.type_get () == yyeof_)
+        if (yyla.kind () == symbol_kind::]b4_symbol_prefix[YYEOF)
           YYABORT;
         else if (!yyla.empty ())
           {
@@ -1040,6 +1115,7 @@ b4_dollar_popdef])[]dnl
        this YYERROR.  */
     yypop_ (yylen);
     yylen = 0;
+    YY_STACK_PRINT ();
     goto yyerrlab1;
 
 
@@ -1048,38 +1124,40 @@ b4_dollar_popdef])[]dnl
   `-------------------------------------------------------------*/
   yyerrlab1:
     yyerrstatus_ = 3;   // Each real token shifted decrements this.
+    // Pop stack until we find a state that shifts the error token.
+    for (;;)
+      {
+        yyn = yypact_[+yystack_[0].state];
+        if (!yy_pact_value_is_default_ (yyn))
+          {
+            yyn += symbol_kind::]b4_symbol_prefix[YYERROR;
+            if (0 <= yyn && yyn <= yylast_
+                && yycheck_[yyn] == symbol_kind::]b4_symbol_prefix[YYERROR)
+              {
+                yyn = yytable_[yyn];
+                if (0 < yyn)
+                  break;
+              }
+          }
+
+        // Pop the current state because it cannot handle the error token.
+        if (yystack_.size () == 1)
+          YYABORT;
+]b4_locations_if([[
+        yyerror_range[1].location = yystack_[0].location;]])[
+        yy_destroy_ ("Error: popping", yystack_[0]);
+        yypop_ ();
+        YY_STACK_PRINT ();
+      }
     {
       stack_symbol_type error_token;
-      for (;;)
-        {
-          yyn = yypact_[yystack_[0].state];
-          if (!yy_pact_value_is_default_ (yyn))
-            {
-              yyn += yyterror_;
-              if (0 <= yyn && yyn <= yylast_ && yycheck_[yyn] == yyterror_)
-                {
-                  yyn = yytable_[yyn];
-                  if (0 < yyn)
-                    break;
-                }
-            }
-
-          // Pop the current state because it cannot handle the error token.
-          if (yystack_.size () == 1)
-            YYABORT;
-]b4_locations_if([[
-          yyerror_range[1].location = yystack_[0].location;]])[
-          yy_destroy_ ("Error: popping", yystack_[0]);
-          yypop_ ();
-          YY_STACK_PRINT ();
-        }
 ]b4_locations_if([[
       yyerror_range[2].location = yyla.location;
       YYLLOC_DEFAULT (error_token.location, yyerror_range, 2);]])[
 
       // Shift the error token.]b4_lac_if([[
       yy_lac_discard_ ("error recovery");]])[
-      error_token.state = static_cast<state_type> (yyn);
+      error_token.state = state_type (yyn);
       yypush_ ("Shifting", YY_MOVE (error_token));
     }
     goto yynewstate;
@@ -1111,6 +1189,7 @@ b4_dollar_popdef])[]dnl
     /* Do not reclaim the symbols of the rule whose action triggered
        this YYABORT or YYACCEPT.  */
     yypop_ (yylen);
+    YY_STACK_PRINT ();
     while (1 < yystack_.size ())
       {
         yy_destroy_ ("Cleanup: popping", yystack_[0]);
@@ -1143,10 +1222,71 @@ b4_dollar_popdef])[]dnl
   {
     error (]b4_join(b4_locations_if([yyexc.location]),
                     [[yyexc.what ()]])[);
-  }]b4_lac_if([[
+  }]b4_parse_error_bmatch([custom\|detailed\|verbose], [[
 
+  // ]b4_parser_class[::context.
+  ]b4_parser_class[::context::context (const ]b4_parser_class[& yyparser, const symbol_type& yyla)
+    : yyparser_ (yyparser)
+    , yyla_ (yyla)
+  {}
+
+  int
+  ]b4_parser_class[::context::expected_tokens (symbol_kind_type yyarg[], int yyargn) const
+  {
+    // Actual number of expected tokens
+    int yycount = 0;
+]b4_lac_if([[
+#if ]b4_api_PREFIX[DEBUG
+    // Execute LAC once. We don't care if it is successful, we
+    // only do it for the sake of debugging output.
+    if (!yyparser_.yy_lac_established_)
+      yyparser_.yy_lac_check_ (yyla_.kind ());
+#endif
+
+    for (int yyx = 0; yyx < YYNTOKENS; ++yyx)
+      {
+        symbol_kind_type yysym = YY_CAST (symbol_kind_type, yyx);
+        if (yysym != symbol_kind::]b4_symbol_prefix[YYERROR
+            && yysym != symbol_kind::]b4_symbol_prefix[YYUNDEF
+            && yyparser_.yy_lac_check_ (yysym))
+          {
+            if (!yyarg)
+              ++yycount;
+            else if (yycount == yyargn)
+              return 0;
+            else
+              yyarg[yycount++] = yysym;
+          }
+      }]], [[
+    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;
+        // Stay within bounds of both yycheck and yytname.
+        int yychecklim = yylast_ - yyn + 1;
+        int yyxend = yychecklim < YYNTOKENS ? yychecklim : YYNTOKENS;
+        for (int yyx = yyxbegin; yyx < yyxend; ++yyx)
+          if (yycheck_[yyx + yyn] == yyx && yyx != symbol_kind::]b4_symbol_prefix[YYERROR
+              && !yy_table_value_is_error_ (yytable_[yyx + yyn]))
+            {
+              if (!yyarg)
+                ++yycount;
+              else if (yycount == yyargn)
+                return 0;
+              else
+                yyarg[yycount++] = YY_CAST (symbol_kind_type, yyx);
+            }
+      }
+]])[
+    return yycount;
+  }
+
+]])b4_lac_if([[
   bool
-  ]b4_parser_class[::yy_lac_check_ (int yytoken) const
+  ]b4_parser_class[::yy_lac_check_ (symbol_kind_type yytoken) const
   {
     // Logically, the yylac_stack's lifetime is confined to this function.
     // Clear it, to get rid of potential left-overs from previous call.
@@ -1161,13 +1301,13 @@ b4_dollar_popdef])[]dnl
         state_type top_state = (yylac_stack_.empty ()
                                 ? yystack_[lac_top].state
                                 : yylac_stack_.back ());
-        int yyrule = yypact_[top_state];
+        int yyrule = yypact_[+top_state];
         if (yy_pact_value_is_default_ (yyrule)
             || (yyrule += yytoken) < 0 || yylast_ < yyrule
             || yycheck_[yyrule] != yytoken)
           {
             // Use the default action.
-            yyrule = yydefact_[top_state];
+            yyrule = yydefact_[+top_state];
             if (yyrule == 0)
               {
                 YYCDEBUG << " Err\n";
@@ -1224,7 +1364,7 @@ b4_dollar_popdef])[]dnl
 
   // Establish the initial context if no initial context currently exists.
   bool
-  ]b4_parser_class[::yy_lac_establish_ (int yytoken)
+  ]b4_parser_class[::yy_lac_establish_ (symbol_kind_type yytoken)
   {
     /* Establish the initial context for the current lookahead if no initial
        context is currently established.
@@ -1282,22 +1422,12 @@ b4_dollar_popdef])[]dnl
                  << evt << '\n';
         yy_lac_established_ = false;
       }
-  }]])[
-
-  // Generate an error message.
-  std::string
-  ]b4_parser_class[::yysyntax_error_ (]dnl
-b4_error_verbose_if([state_type yystate, const symbol_type& yyla],
-                    [state_type, const symbol_type&])[) const
-  {]b4_error_verbose_if([[
-    // Number of reported tokens (one for the "unexpected", one per
-    // "expected").
-    std::ptrdiff_t yycount = 0;
-    // Its maximum.
-    enum { YYERROR_VERBOSE_ARGS_MAXIMUM = 5 };
-    // Arguments of yyformat.
-    char const *yyarg[YYERROR_VERBOSE_ARGS_MAXIMUM];
+  }]])b4_parse_error_bmatch([detailed\|verbose], [[
 
+  int
+  ]b4_parser_class[::yy_syntax_error_arguments_ (const context& yyctx,
+                                                 symbol_kind_type yyarg[], int yyargn) const
+  {
     /* 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 default action
@@ -1328,45 +1458,26 @@ b4_error_verbose_if([state_type yystate, const symbol_type& yyla],
          one exception: it will still contain any token that will not be
          accepted due to an error action in a later state.]])[
     */
-    if (!yyla.empty ())
+
+    if (!yyctx.lookahead ().empty ())
       {
-        int yytoken = yyla.type_get ();
-        yyarg[yycount++] = yytname_[yytoken];]b4_lac_if([[
-
-#if ]b4_api_PREFIX[DEBUG
-        // Execute LAC once. We don't care if it is succesful, we
-        // only do it for the sake of debugging output.
-        if (!yy_lac_established_)
-          yy_lac_check_ (yytoken);
-#endif]])[
-
-        int yyn = yypact_[yystate];
-        if (!yy_pact_value_is_default_ (yyn))
-          {]b4_lac_if([[
-            for (int yyx = 0; yyx < yyntokens_; ++yyx)
-              if (yyx != yyterror_ && yy_lac_check_(yyx))
-                {]], [[
-            /* 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;
-            // Stay within bounds of both yycheck and yytname.
-            int yychecklim = yylast_ - yyn + 1;
-            int yyxend = yychecklim < yyntokens_ ? yychecklim : yyntokens_;
-            for (int yyx = yyxbegin; yyx < yyxend; ++yyx)
-              if (yycheck_[yyx + yyn] == yyx && yyx != yyterror_
-                  && !yy_table_value_is_error_ (yytable_[yyx + yyn]))
-                {]])[
-                  if (yycount == YYERROR_VERBOSE_ARGS_MAXIMUM)
-                    {
-                      yycount = 1;
-                      break;
-                    }
-                  else
-                    yyarg[yycount++] = yytname_[yyx];
-                }
-          }
+        if (yyarg)
+          yyarg[0] = yyctx.token ();
+        int yyn = yyctx.expected_tokens (yyarg ? yyarg + 1 : yyarg, yyargn - 1);
+        return yyn + 1;
       }
+    return 0;
+  }
+
+  // Generate an error message.
+  std::string
+  ]b4_parser_class[::yysyntax_error_ (const context& yyctx) const
+  {
+    // Its maximum.
+    enum { YYARGS_MAX = 5 };
+    // Arguments of yyformat.
+    symbol_kind_type yyarg[YYARGS_MAX];
+    int yycount = yy_syntax_error_arguments_ (yyctx, yyarg, YYARGS_MAX);
 
     char const* yyformat = YY_NULLPTR;
     switch (yycount)
@@ -1391,14 +1502,15 @@ b4_error_verbose_if([state_type yystate, const symbol_type& yyla],
     for (char const* yyp = yyformat; *yyp; ++yyp)
       if (yyp[0] == '%' && yyp[1] == 's' && yyi < yycount)
         {
-          yyres += yytnamerr_ (yyarg[yyi++]);
+          yyres += ]b4_parse_error_case([verbose],
+                [[yytnamerr_ (yytname_[yyarg[yyi++]])]],
+                [[symbol_name (yyarg[yyi++])]])[;
           ++yyp;
         }
       else
         yyres += *yyp;
-    return yyres;]], [[
-    return YY_("syntax error");]])[
-  }
+    return yyres;
+  }]])[
 
 
   const ]b4_int_type(b4_pact_ninf, b4_pact_ninf) b4_parser_class::yypact_ninf_ = b4_pact_ninf[;
@@ -1407,19 +1519,19 @@ b4_error_verbose_if([state_type yystate, const symbol_type& yyla],
 
 ]b4_parser_tables_define[
 
-]b4_token_table_if([], [[#if ]b4_api_PREFIX[DEBUG]])[
+]b4_tname_if([], [[#if ]b4_api_PREFIX[DEBUG]])[
   // YYTNAME[SYMBOL-NUM] -- String name of the symbol SYMBOL-NUM.
-  // First, the terminals, then, starting at \a yyntokens_, nonterminals.
+  // First, the terminals, then, starting at \a YYNTOKENS, nonterminals.
   const char*
   const ]b4_parser_class[::yytname_[] =
   {
   ]b4_tname[
   };
+]b4_tname_if([], [[#endif]])[
 
-]b4_token_table_if([[#if ]b4_api_PREFIX[DEBUG]])[
+#if ]b4_api_PREFIX[DEBUG][
 ]b4_integral_parser_table_define([rline], [b4_rline])[
 
-  // Print the state stack on the debug stream.
   void
   ]b4_parser_class[::yystack_print_ ()
   {
@@ -1432,7 +1544,6 @@ b4_error_verbose_if([state_type yystate, const symbol_type& yyla],
     *yycdebug_ << '\n';
   }
 
-  // Report on the debug stream that the rule \a yyrule is going to be reduced.
   void
   ]b4_parser_class[::yy_reduce_print_ (int yyrule)
   {

data/skeletons/lalr1.d

@@ -1,6 +1,6 @@
 # D skeleton for Bison -*- autoconf -*-
 
-# Copyright (C) 2007-2012, 2019 Free Software Foundation, Inc.
+# Copyright (C) 2007-2012, 2019-2020 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
@@ -20,7 +20,7 @@ m4_include(b4_skeletonsdir/[d.m4])
 
 b4_output_begin([b4_parser_file_name])
 b4_copyright([Skeleton implementation for Bison LALR(1) parsers in D],
-             [2007-2012, 2019])[
+             [2007-2012, 2019-2020])[
 
 ]b4_percent_define_ifdef([package], [module b4_percent_define_get([package]);
 ])[
@@ -182,13 +182,12 @@ b4_user_union_members
 };],
 [m4_if(b4_tag_seen_flag, 0,
 [[private alias int YYSemanticType;]])])[
-]b4_token_enums(b4_tokens)[
+]b4_token_enums[
 ]b4_parser_class_declaration[
 {
   ]b4_identification[
 
-  /** True if verbose error messages are enabled.  */
-  public bool errorVerbose = ]b4_flag_value([error_verbose])[;
+]b4_declare_symbol_enum[
 
 ]b4_locations_if([[
   private final ]b4_location_type[ yylloc_from_stack (ref YYStack rhs, int n)
@@ -264,6 +263,11 @@ b4_user_union_members
   public final void setDebugLevel(int level) { yydebug = level; }
 
   protected final void yycdebug (string s) {
+    if (0 < yydebug)
+      yyDebugStream.write (s);
+  }
+
+  protected final void yycdebugln (string s) {
     if (0 < yydebug)
       yyDebugStream.writeln (s);
   }
@@ -338,7 +342,8 @@ b4_user_union_members
     }
 
 ]b4_parse_trace_if([[
-    yy_symbol_print ("-> $$ =", yyr1_[yyn], yyval]b4_locations_if([, yyloc])[);]])[
+    import std.conv : to;
+    yy_symbol_print ("-> $$ =", to!SymbolKind (yyr1_[yyn]), yyval]b4_locations_if([, yyloc])[);]])[
 
     yystack.pop (yylen);
     yylen = 0;
@@ -396,20 +401,21 @@ b4_user_union_members
   | Print this symbol on YYOUTPUT.  |
   `--------------------------------*/
 
-  private final void yy_symbol_print (string s, int yytype,
+  private final void yy_symbol_print (string s, SymbolKind yykind,
     ref ]b4_yystype[ yyvaluep]dnl
 b4_locations_if([, ref ]b4_location_type[ yylocationp])[)
   {
-    if (0 < yydebug) {
-      string message = s ~ (yytype < yyntokens_ ? " token " : " nterm ")
-              ~ yytname_[yytype] ~ " ("]b4_locations_if([
+    if (0 < yydebug)
+    {
+      string message = s ~ (yykind < yyntokens_ ? " token " : " nterm ")
+              ~ yytname_[yykind] ~ " ("]b4_locations_if([
               ~ yylocationp.toString() ~ ": "])[;
       static if (__traits(compiles, message ~= yyvaluep.toString ()))
               message ~= yyvaluep.toString ();
       else
               message ~= format ("%s", &yyvaluep);
       message ~= ")";
-      yycdebug (message);
+      yycdebugln (message);
     }
   }
 ]])[
@@ -423,8 +429,8 @@ b4_locations_if([, ref ]b4_location_type[ yylocationp])[)
   public bool parse ()
   {
     /// Lookahead and lookahead in internal form.
-    int yychar = yyempty_;
-    int yytoken = 0;
+    int yychar = TokenKind.YYEMPTY;
+    SymbolKind yytoken = SymbolKind.]b4_symbol(-2, kind)[;
 
     /* State.  */
     int yyn = 0;
@@ -447,9 +453,9 @@ b4_locations_if([, ref ]b4_location_type[ yylocationp])[)
     /// Semantic value of the lookahead.
     ]b4_yystype[ yylval;
 
-    int yyresult;]b4_parse_trace_if([[
+    bool yyresult;]b4_parse_trace_if([[
 
-    yycdebug ("Starting parse\n");]])[
+    yycdebugln ("Starting parse");]])[
     yyerrstatus_ = 0;
 
 ]m4_ifdef([b4_initial_action], [
@@ -470,7 +476,7 @@ m4_popdef([b4_at_dollar])])dnl
         /* New state.  Unlike in the C/C++ skeletons, the state is already
            pushed when we come here.  */
       case YYNEWSTATE:]b4_parse_trace_if([[
-        yycdebug (format("Entering state %d\n", yystate));
+        yycdebugln (format("Entering state %d", yystate));
         if (0 < yydebug)
           yystack.print (yyDebugStream);]])[
 
@@ -487,9 +493,9 @@ m4_popdef([b4_at_dollar])])dnl
         }
 
         /* Read a lookahead token.  */
-        if (yychar == yyempty_)
+        if (yychar == TokenKind.YYEMPTY)
         {]b4_parse_trace_if([[
-          yycdebug ("Reading a token: ");]])[
+          yycdebugln ("Reading a token");]])[
           yychar = yylex ();]b4_locations_if([[
           static if (yy_location_is_class) {
             yylloc = new ]b4_location_type[(yylexer.startPos, yylexer.endPos);
@@ -501,8 +507,7 @@ m4_popdef([b4_at_dollar])])dnl
 
         /* Convert token to internal form.  */
         yytoken = yytranslate_ (yychar);]b4_parse_trace_if([[
-        yy_symbol_print ("Next token is",
-                         yytoken, yylval]b4_locations_if([, yylloc])[);]])[
+        yy_symbol_print ("Next token is", yytoken, yylval]b4_locations_if([, yylloc])[);]])[
 
         /* If the proper action on seeing token YYTOKEN is to reduce or to
            detect an error, take that action.  */
@@ -524,11 +529,10 @@ m4_popdef([b4_at_dollar])])dnl
         else
         {
           /* Shift the lookahead token.  */]b4_parse_trace_if([[
-          yy_symbol_print ("Shifting", yytoken,
-                            yylval]b4_locations_if([, yylloc])[);]])[
+          yy_symbol_print ("Shifting", yytoken, yylval]b4_locations_if([, yylloc])[);]])[
 
           /* Discard the token being shifted.  */
-          yychar = yyempty_;
+          yychar = TokenKind.YYEMPTY;
 
           /* Count tokens shifted since error; after three, turn off error
            * status.  */
@@ -561,16 +565,16 @@ m4_popdef([b4_at_dollar])])dnl
         yystate = yystack.stateAt (0);
         break;
 
-      /*------------------------------------.
-      | yyerrlab -- here on detecting error |
-      `------------------------------------*/
+      /*--------------------------------------.
+      | yyerrlab -- here on detecting error.  |
+      `--------------------------------------*/
       case YYERRLAB:
         /* If not already recovering from an error, report this error.  */
         if (yyerrstatus_ == 0)
         {
           ++yynerrs_;
-          if (yychar == yyempty_)
-            yytoken = yyempty_;
+          if (yychar == TokenKind.YYEMPTY)
+            yytoken = SymbolKind.]b4_symbol(-2, kind)[;
           yyerror (]b4_locations_if([yylloc, ])[yysyntax_error (yystate, yytoken));
         }
 
@@ -580,14 +584,14 @@ m4_popdef([b4_at_dollar])])dnl
           /* If just tried and failed to reuse lookahead token after an
            * error, discard it.  */
 
-          if (yychar <= YYTokenType.EOF)
+          if (yychar <= TokenKind.]b4_symbol(0, [id])[)
           {
             /* Return failure if at end of input.  */
-            if (yychar == YYTokenType.EOF)
+            if (yychar == TokenKind.]b4_symbol(0, [id])[)
              return false;
           }
           else
-            yychar = yyempty_;
+            yychar = TokenKind.YYEMPTY;
         }
 
         /* Else will try to reuse lookahead token after shifting the error
@@ -614,13 +618,14 @@ m4_popdef([b4_at_dollar])])dnl
       case YYERRLAB1:
         yyerrstatus_ = 3;       /* Each real token shifted decrements this.  */
 
+        // Pop stack until we find a state that shifts the error token.
         for (;;)
         {
           yyn = yypact_[yystate];
           if (!yy_pact_value_is_default_ (yyn))
           {
-            yyn += yyterror_;
-            if (0 <= yyn && yyn <= yylast_ && yycheck_[yyn] == yyterror_)
+            yyn += SymbolKind.]b4_symbol_prefix[YYERROR;
+            if (0 <= yyn && yyn <= yylast_ && yycheck_[yyn] == SymbolKind.]b4_symbol_prefix[YYERROR)
             {
               yyn = yytable_[yyn];
               if (0 < yyn)
@@ -647,9 +652,8 @@ m4_popdef([b4_at_dollar])])dnl
         yystack.pop (2);])[
 
         /* Shift the error token.  */]b4_parse_trace_if([[
-        yy_symbol_print ("Shifting", yystos_[yyn],
-        yylval]b4_locations_if([, yyloc])[);]])[
-
+        import std.conv : to;
+        yy_symbol_print ("Shifting", to!SymbolKind (yystos_[yyn]), yylval]b4_locations_if([, yyloc])[);]])[
         yystate = yyn;
         yystack.push (yyn, yylval]b4_locations_if([, yyloc])[);
         label = YYNEWSTATE;
@@ -657,88 +661,93 @@ m4_popdef([b4_at_dollar])])dnl
 
       /* Accept.  */
       case YYACCEPT:
-        return true;
+        yyresult = true;
+        label = YYRETURN;
+        break;
 
       /* Abort.  */
       case YYABORT:
-        return false;
+        yyresult = false;
+        label = YYRETURN;
+        break;
+
+      case YYRETURN:]b4_parse_trace_if([[
+        if (0 < yydebug)
+          yystack.print (yyDebugStream);]])[
+        return yyresult;
     }
   }
 
   // Generate an error message.
-  private final string yysyntax_error (int yystate, int tok)
-  {
-    if (errorVerbose)
+  private final string yysyntax_error (int yystate, SymbolKind tok)
+  {]b4_parse_error_case([verbose], [[
+    /* There are many possibilities here to consider:
+       - Assume YYFAIL is not used.  It's too flawed to consider.
+         See
+         <http://lists.gnu.org/archive/html/bison-patches/2009-12/msg00024.html>
+         for details.  YYERROR is fine as it does not invoke this
+         function.
+       - If this state is a consistent state with a default action,
+         then the only way this function was invoked is if the
+         default action is an error action.  In that case, don't
+         check for expected tokens because there are none.
+       - The only way there can be no lookahead present (in tok) is
+         if this state is a consistent state with a default action.
+         Thus, detecting the absence of a lookahead is sufficient to
+         determine that there is no unexpected or expected token to
+         report.  In that case, just report a simple "syntax error".
+       - 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.  (However, yychar is currently out
+         of scope during semantic actions.)
+       - 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 scanner and before detecting a syntax
+         error.  Thus, state merging (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.
+      */
+    if (tok != SymbolKind.]b4_symbol(-2, kind)[)
     {
-      /* There are many possibilities here to consider:
-         - Assume YYFAIL is not used.  It's too flawed to consider.
-           See
-           <http://lists.gnu.org/archive/html/bison-patches/2009-12/msg00024.html>
-           for details.  YYERROR is fine as it does not invoke this
-           function.
-         - If this state is a consistent state with a default action,
-           then the only way this function was invoked is if the
-           default action is an error action.  In that case, don't
-           check for expected tokens because there are none.
-         - The only way there can be no lookahead present (in tok) is
-           if this state is a consistent state with a default action.
-           Thus, detecting the absence of a lookahead is sufficient to
-           determine that there is no unexpected or expected token to
-           report.  In that case, just report a simple "syntax error".
-         - 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.  (However, yychar is currently out
-           of scope during semantic actions.)
-         - 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 scanner and before detecting a syntax
-           error.  Thus, state merging (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.
-        */
-      if (tok != yyempty_)
+      // FIXME: This method of building the message is not compatible
+      // with internationalization.
+      string res = "syntax error, unexpected ";
+      res ~= yytnamerr_ (yytname_[tok]);
+      int yyn = yypact_[yystate];
+      if (!yy_pact_value_is_default_ (yyn))
       {
-        // FIXME: This method of building the message is not compatible
-        // with internationalization.
-        string res = "syntax error, unexpected ";
-        res ~= yytnamerr_ (yytname_[tok]);
-        int yyn = yypact_[yystate];
-        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;
-          /* Stay within bounds of both yycheck and yytname.  */
-          int yychecklim = yylast_ - yyn + 1;
-          int yyxend = yychecklim < yyntokens_ ? yychecklim : yyntokens_;
-          int count = 0;
-          for (int x = yyxbegin; x < yyxend; ++x)
-            if (yycheck_[x + yyn] == x && x != yyterror_
-                && !yy_table_value_is_error_ (yytable_[x + yyn]))
-               ++count;
-            if (count < 5)
-            {
-               count = 0;
-               for (int x = yyxbegin; x < yyxend; ++x)
-                 if (yycheck_[x + yyn] == x && x != yyterror_
-                     && !yy_table_value_is_error_ (yytable_[x + yyn]))
-                 {
-                    res ~= count++ == 0 ? ", expecting " : " or ";
-                    res ~= yytnamerr_ (yytname_[x]);
-                 }
-            }
-        }
-        return res;
+        /* 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;
+        /* Stay within bounds of both yycheck and yytname.  */
+        int yychecklim = yylast_ - yyn + 1;
+        int yyxend = yychecklim < yyntokens_ ? yychecklim : yyntokens_;
+        int count = 0;
+        for (int x = yyxbegin; x < yyxend; ++x)
+          if (yycheck_[x + yyn] == x && x != SymbolKind.]b4_symbol_prefix[YYERROR
+              && !yy_table_value_is_error_ (yytable_[x + yyn]))
+             ++count;
+          if (count < 5)
+          {
+             count = 0;
+             for (int x = yyxbegin; x < yyxend; ++x)
+               if (yycheck_[x + yyn] == x && x != SymbolKind.]b4_symbol_prefix[YYERROR
+                   && !yy_table_value_is_error_ (yytable_[x + yyn]))
+               {
+                  res ~= count++ == 0 ? ", expecting " : " or ";
+                  res ~= yytnamerr_ (yytname_[x]);
+               }
+          }
       }
-    }
-
+      return res;
+    }]])[
     return "syntax error";
   }
 
@@ -771,14 +780,6 @@ m4_popdef([b4_at_dollar])])dnl
 
   ]b4_parser_tables_define[
 
-  /* TOKEN_NUMBER_[YYLEX-NUM] -- Internal symbol number corresponding
-     to YYLEX-NUM.  */
-  private static immutable ]b4_int_type_for([b4_toknum])[[]
-  yytoken_number_ =
-  @{
-  ]b4_toknum[
-  @};
-
   /* YYTNAME[SYMBOL-NUM] -- String name of the symbol SYMBOL-NUM.
      First, the terminals, then, starting at \a yyntokens_, nonterminals.  */
   private static immutable string[] yytname_ =
@@ -802,48 +803,48 @@ m4_popdef([b4_at_dollar])])dnl
     int yylno = yyrline_[yyrule];
     int yynrhs = yyr2_[yyrule];
     /* Print the symbols being reduced, and their result.  */
-    yycdebug (format("Reducing stack by rule %d (line %d), ",
-              yyrule - 1, yylno));
+    yycdebugln (format("Reducing stack by rule %d (line %d):",
+                yyrule - 1, yylno));
 
     /* The symbols being reduced.  */
+    import std.conv : to;
     for (int yyi = 0; yyi < yynrhs; yyi++)
       yy_symbol_print (format("   $%d =", yyi + 1),
-                       yystos_[yystack.stateAt(yynrhs - (yyi + 1))],
+                       to!SymbolKind (yystos_[yystack.stateAt(yynrhs - (yyi + 1))]),
                        ]b4_rhs_value(yynrhs, yyi + 1)b4_locations_if([,
                        b4_rhs_location(yynrhs, yyi + 1)])[);
   }
 ]])[
 
-  private static ]b4_int_type_for([b4_translate])[ yytranslate_ (int t)
+  private static SymbolKind yytranslate_ (int t)
   {
 ]b4_api_token_raw_if(
 [[    import std.conv : to;
-    return to!byte (t);]],
+    return to!SymbolKind (t);]],
 [[    /* YYTRANSLATE(YYLEX) -- Bison symbol number corresponding to YYLEX.  */
     immutable ]b4_int_type_for([b4_translate])[[] translate_table =
     @{
   ]b4_translate[
     @};
 
+    immutable int user_token_number_max_ = ]b4_user_token_number_max[;
+
     if (t <= 0)
-      return YYTokenType.EOF;
-    else if (t <= yyuser_token_number_max_)
-      return translate_table[t];
+      return SymbolKind.]b4_symbol_prefix[YYEOF;
+    else if (t <= user_token_number_max_)
+      {
+        import std.conv : to;
+        return to!SymbolKind (translate_table[t]);
+      }
     else
-      return yyundef_token_;]])[
+      return SymbolKind.]b4_symbol_prefix[YYUNDEF;]])[
   }
 
   private static immutable int yylast_ = ]b4_last[;
   private static immutable int yynnts_ = ]b4_nterms_number[;
-  private static immutable int yyempty_ = -2;
   private static immutable int yyfinal_ = ]b4_final_state_number[;
-  private static immutable int yyterror_ = 1;
-  private static immutable int yyerrcode_ = 256;
   private static immutable int yyntokens_ = ]b4_tokens_number[;
 
-  private static immutable int yyuser_token_number_max_ = ]b4_user_token_number_max[;
-  private static immutable int yyundef_token_ = ]b4_undef_token_number[;
-
   private final struct YYStackElement {
     int state;
     ]b4_yystype[ value;]b4_locations_if(
@@ -899,9 +900,8 @@ m4_popdef([b4_at_dollar])])dnl
       stream.writeln ();
     }]])[
   }
-
-  /* User implementation code.  */
 ]b4_percent_code_get[
 }
-]b4_epilogue[]dnl
+]b4_percent_code_get([[epilogue]])[]dnl
+b4_epilogue[]dnl
 b4_output_end

data/skeletons/lalr1.java

@@ -1,6 +1,6 @@
 # Java skeleton for Bison                           -*- autoconf -*-
 
-# Copyright (C) 2007-2015, 2018-2019 Free Software Foundation, Inc.
+# Copyright (C) 2007-2015, 2018-2020 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
@@ -49,13 +49,13 @@ b4_use_push_for_pull_if([
   b4_push_if([m4_define([b4_use_push_for_pull_flag], [[0]])],
              [m4_define([b4_push_flag], [[1]])])])
 
-# 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.
+# 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],[[
     /* Lookahead and lookahead in internal form.  */
-    int yychar = yyempty_;
-    int yytoken = 0;
+    int yychar = YYEMPTY_;
+    SymbolKind yytoken = null;
 
     /* State.  */
     int yyn = 0;
@@ -64,9 +64,8 @@ m4_define([b4_define_state],[[
     YYStack yystack = new YYStack ();
     int label = YYNEWSTATE;
 
-    /* Error handling.  */
-    int yynerrs_ = 0;
-    ]b4_locations_if([[/* The location where the error started.  */
+]b4_locations_if([[
+    /* The location where the error started.  */
     ]b4_location_type[ yyerrloc = null;
 
     /* Location. */
@@ -78,11 +77,12 @@ m4_define([b4_define_state],[[
 
 ]b4_output_begin([b4_parser_file_name])[
 ]b4_copyright([Skeleton implementation for Bison LALR(1) parsers in Java],
-              [2007-2015, 2018-2019])[
+              [2007-2015, 2018-2020])[
 ]b4_percent_define_ifdef([package], [package b4_percent_define_get([package]);[
 ]])[
 ]b4_user_pre_prologue[
 ]b4_user_post_prologue[
+import java.text.MessageFormat;
 ]b4_percent_code_get([[imports]])[
 /**
  * A Bison parser, automatically generated from <tt>]m4_bpatsubst(b4_file_name, [^"\(.*\)"$], [\1])[</tt>.
@@ -91,8 +91,10 @@ m4_define([b4_define_state],[[
  */
 ]b4_parser_class_declaration[
 {
-  ]b4_identification[
-]b4_error_verbose_if([[
+]b4_identification[
+][
+]b4_parse_error_bmatch(
+           [detailed\|verbose], [[
   /**
    * True if verbose error messages are enabled.
    */
@@ -109,9 +111,9 @@ m4_define([b4_define_state],[[
    */
   public final void setErrorVerbose(boolean verbose)
   { yyErrorVerbose = verbose; }
-]])
+]])[
 
-b4_locations_if([[
+]b4_locations_if([[
   /**
    * A class defining a pair of positions.  Positions, defined by the
    * <code>]b4_position_type[</code> class, denote a point in the input.
@@ -161,9 +163,6 @@ b4_locations_if([[
     }
   }
 
-]])[
-
-]b4_locations_if([[
   private ]b4_location_type[ yylloc (YYStack rhs, int n)
   {
     if (0 < n)
@@ -172,17 +171,19 @@ b4_locations_if([[
       return new ]b4_location_type[ (rhs.locationAt (0).end);
   }]])[
 
+]b4_declare_symbol_enum[
+
   /**
    * Communication interface between the scanner and the Bison-generated
    * parser <tt>]b4_parser_class[</tt>.
    */
   public interface Lexer {
-    /** Token returned by the scanner to signal the end of its input.  */
-    public static final int EOF = 0;
-
 ]b4_token_enums[
+    /** Deprecated, use b4_symbol(0, id) instead.  */
+    public static final int EOF = ]b4_symbol(0, id)[;
 
-    ]b4_locations_if([[/**
+]b4_locations_if([[
+    /**
      * Method to retrieve the beginning position of the last scanned token.
      * @@return the position at which the last scanned token starts.
      */
@@ -206,17 +207,25 @@ b4_locations_if([[
      * ]b4_locations_if([and beginning/ending positions ])[of the token.
      * @@return the token identifier corresponding to the next token.
      */
-    int yylex () ]b4_maybe_throws([b4_lex_throws])[;
+    int yylex ()]b4_maybe_throws([b4_lex_throws])[;
 
     /**
      * Entry point for error reporting.  Emits an error
      * ]b4_locations_if([referring to the given location ])[in a user-defined way.
      *
-     * ]b4_locations_if([[@@param loc The location of the element to which the
+     *]b4_locations_if([[ @@param loc The location of the element to which the
      *                error message is related]])[
      * @@param msg The string for the error message.
      */
      void yyerror (]b4_locations_if([b4_location_type[ loc, ]])[String msg);
+
+]b4_parse_error_bmatch(
+           [custom], [[
+    /**
+     * Build and emit a syntax error message.
+     */
+     void reportSyntaxError (][Context yyctx);
+]])[
   }
 
 ]b4_lexer_if([[
@@ -224,22 +233,23 @@ b4_locations_if([[
 ]b4_percent_code_get([[lexer]])[
   }
 
-  ]])[/**
+]])[
+  /**
    * The object doing lexical analysis for us.
    */
   private Lexer yylexer;
 
-  ]b4_parse_param_vars[
+]b4_parse_param_vars[
 
 ]b4_lexer_if([[
   /**
    * 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_parse_param_cons[
+]b4_percent_code_get([[init]])[
+    this.yylexer = new YYLexer (]b4_lex_param_call[);
+]b4_parse_param_cons[
   }
 ]])[
 
@@ -247,11 +257,11 @@ b4_locations_if([[
    * 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]])[
     this.yylexer = yylexer;
-    ]b4_parse_param_cons[
+]b4_parse_param_cons[
   }
 
 ]b4_parse_trace_if([[
@@ -266,7 +276,7 @@ b4_locations_if([[
    * 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;
 
@@ -274,16 +284,23 @@ b4_locations_if([[
    * 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;
+
+  /**
+   * The number of syntax errors so far.
+   */
+  public final int getNumberOfErrors () { return yynerrs; }
+
   /**
    * Print an error message via the lexer.
    *]b4_locations_if([[ Use a <code>null</code> location.]])[
@@ -320,22 +337,20 @@ b4_locations_if([[
   }]])[
 
   private final class YYStack {
-    private int[] stateStack = new int[16];
-    ]b4_locations_if([[private ]b4_location_type[[] locStack = new ]b4_location_type[[16];]])[
+    private int[] stateStack = new int[16];]b4_locations_if([[
+    private ]b4_location_type[[] locStack = new ]b4_location_type[[16];]])[
     private ]b4_yystype[[] valueStack = new ]b4_yystype[[16];
 
     public int size = 16;
     public int height = -1;
 
-    public final void push (int state, ]b4_yystype[ value]dnl
-                            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([[
+          stateStack = newStateStack;]b4_locations_if([[
           ]b4_location_type[[] newLocStack = new ]b4_location_type[[size * 2];
           System.arraycopy (locStack, 0, newLocStack, 0, height);
           locStack = newLocStack;]])
@@ -347,8 +362,8 @@ b4_locations_if([[
           size *= 2;
         }
 
-      stateStack[height] = state;
-      ]b4_locations_if([[locStack[height] = loc;]])[
+      stateStack[height] = state;]b4_locations_if([[
+      locStack[height] = loc;]])[
       valueStack[height] = value;
     }
 
@@ -359,8 +374,8 @@ b4_locations_if([[
     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;
     }
@@ -368,12 +383,13 @@ b4_locations_if([[
     public final int stateAt (int i) {
       return stateStack[height - i];
     }
+]b4_locations_if([[
 
-    ]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];
     }
 
@@ -445,14 +461,14 @@ b4_locations_if([[
    */
   private int yyLRGotoState (int yystate, int yysym)
   {
-    int yyr = yypgoto_[yysym - yyntokens_] + yystate;
-    if (0 <= yyr && yyr <= yylast_ && yycheck_[yyr] == yystate)
+    int yyr = yypgoto_[yysym - YYNTOKENS_] + yystate;
+    if (0 <= yyr && yyr <= YYLAST_ && yycheck_[yyr] == yystate)
       return yytable_[yyr];
     else
-      return yydefgoto_[yysym - yyntokens_];
+      return yydefgoto_[yysym - YYNTOKENS_];
   }
 
-  private int yyaction (int yyn, YYStack yystack, int yylen) ]b4_maybe_throws([b4_throws])[
+  private int yyaction (int yyn, YYStack yystack, int yylen)]b4_maybe_throws([b4_throws])[
   {
     /* If YYLEN is nonzero, implement the default value of the action:
        '$$ = $1'.  Otherwise, use the top of the stack.
@@ -460,8 +476,8 @@ b4_locations_if([[
        Otherwise, the following line sets YYVAL to garbage.
        This behavior is undocumented and Bison
        users should not rely upon it.  */
-    ]b4_yystype[ yyval = (0 < yylen) ? yystack.valueAt (yylen - 1) : yystack.valueAt (0);
-    ]b4_locations_if([b4_location_type[ yyloc = yylloc (yystack, yylen);]])[]b4_parse_trace_if([[
+    ]b4_yystype[ yyval = (0 < yylen) ? yystack.valueAt (yylen - 1) : yystack.valueAt (0);]b4_locations_if([[
+    ]b4_location_type[ yyloc = yylloc (yystack, yylen);]])[]b4_parse_trace_if([[
 
     yyReducePrint (yyn, yystack);]])[
 
@@ -471,66 +487,29 @@ b4_locations_if([[
         default: break;
       }]b4_parse_trace_if([[
 
-    yySymbolPrint ("-> $$ =", yyr1_[yyn], yyval]b4_locations_if([, yyloc])[);]])[
+    yySymbolPrint ("-> $$ =", SymbolKind.get (yyr1_[yyn]), yyval]b4_locations_if([, yyloc])[);]])[
 
     yystack.pop (yylen);
     yylen = 0;
-
     /* Shift the result of the reduction.  */
     int yystate = yyLRGotoState (yystack.stateAt (0), yyr1_[yyn]);
     yystack.push (yystate, yyval]b4_locations_if([, yyloc])[);
     return YYNEWSTATE;
   }
 
-]b4_error_verbose_if([[
-  /* 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.  */
-  private final String yytnamerr_ (String yystr)
-  {
-    if (yystr.charAt (0) == '"')
-      {
-        StringBuffer yyr = new StringBuffer ();
-        strip_quotes: for (int i = 1; i < yystr.length (); i++)
-          switch (yystr.charAt (i))
-            {
-            case '\'':
-            case ',':
-              break strip_quotes;
-
-            case '\\':
-              if (yystr.charAt(++i) != '\\')
-                break strip_quotes;
-              /* Fall through.  */
-            default:
-              yyr.append (yystr.charAt (i));
-              break;
-
-            case '"':
-              return yyr.toString ();
-            }
-      }
-    else if (yystr.equals ("$end"))
-      return "end of input";
-
-    return yystr;
-  }
-]])[
 ]b4_parse_trace_if([[
   /*--------------------------------.
   | Print this symbol on YYOUTPUT.  |
   `--------------------------------*/
 
-  private void yySymbolPrint (String s, int yytype,
-                             ]b4_yystype[ yyvaluep]dnl
-                              b4_locations_if([, Object yylocationp])[)
+  private void yySymbolPrint(String s, SymbolKind yykind,
+                             ]b4_yystype[ yyvalue]b4_locations_if([, ]b4_location_type[ yylocation])[)
   {
-    yycdebug (s + (yytype < yyntokens_ ? " token " : " nterm ")
-              + yytname_[yytype] + " ("]b4_locations_if([
-              + yylocationp + ": "])[
-              + (yyvaluep == null ? "(null)" : yyvaluep.toString ()) + ")");
+    yycdebug (s
+              + (yykind.getCode() < YYNTOKENS_ ? " token " : " nterm ")
+              + yykind.getName() + " ("]b4_locations_if([
+              + yylocation + ": "])[
+              + (yyvalue == null ? "(null)" : yyvalue.toString()) + ")");
   }]])[
 
 ]b4_push_if([],[[
@@ -541,29 +520,29 @@ b4_locations_if([[
    * @@return <tt>true</tt> if the parsing succeeds.  Note that this does not
    *          imply that there were no syntax errors.
    */
-  public boolean parse () ]b4_maybe_throws([b4_list2([b4_lex_throws], [b4_throws])])[]])[
+  public boolean parse ()]b4_maybe_throws([b4_list2([b4_lex_throws], [b4_throws])])[]])[
 ]b4_push_if([
   /**
    * Push Parse input from external lexer
    *
    * @@param yylextoken current token
-   * @@param yylexval current lval
-]b4_locations_if([   * @@param yylexloc current position])[
+   * @@param yylexval current lval]b4_locations_if([[
+   * @@param yylexloc current position]])[
    *
    * @@return <tt>YYACCEPT, YYABORT, YYPUSH_MORE</tt>
    */
-  public int push_parse (int yylextoken, b4_yystype yylexval[]b4_locations_if([, b4_location_type yylexloc]))
-      b4_maybe_throws([b4_list2([b4_lex_throws], [b4_throws])])])[
-  {
-    ]b4_locations_if([/* @@$.  */
-    b4_location_type yyloc;])[
+  public int push_parse (int yylextoken, b4_yystype yylexval[]b4_locations_if([, b4_location_type yylexloc]))b4_maybe_throws([b4_list2([b4_lex_throws], [b4_throws])])])[
+  {]b4_locations_if([[
+    /* @@$.  */
+    ]b4_location_type[ yyloc;]])[
 ]b4_push_if([],[[
 ]b4_define_state[]b4_parse_trace_if([[
-    yycdebug ("Starting parse\n");]])[
+    yycdebug ("Starting parse");]])[
     yyerrstatus_ = 0;
+    yynerrs = 0;
 
     /* Initialize the stack.  */
-    yystack.push (yystate, yylval ]b4_locations_if([, yylloc])[);
+    yystack.push (yystate, yylval]b4_locations_if([, yylloc])[);
 ]m4_ifdef([b4_initial_action], [
 b4_dollar_pushdef([yylval], [], [], [yylloc])dnl
     b4_user_initial_action
@@ -579,7 +558,7 @@ b4_dollar_pushdef([yylval], [], [], [yylloc])dnl
     b4_user_initial_action
 b4_dollar_popdef[]dnl
 ])[]b4_parse_trace_if([[
-        yycdebug ("Starting parse\n");]])[
+        yycdebug ("Starting parse");]])[
         yyerrstatus_ = 0;
       } else
         label = YYGETTOKEN;
@@ -592,12 +571,12 @@ b4_dollar_popdef[]dnl
         /* New state.  Unlike in the C/C++ skeletons, the state is already
            pushed when we come here.  */
       case YYNEWSTATE:]b4_parse_trace_if([[
-        yycdebug ("Entering state " + yystate + "\n");
+        yycdebug ("Entering state " + yystate);
         if (0 < yydebug)
           yystack.print (yyDebugStream);]])[
 
         /* Accept?  */
-        if (yystate == yyfinal_)
+        if (yystate == YYFINAL_)
           ]b4_push_if([{label = YYACCEPT; break;}],
                       [return true;])[
 
@@ -612,17 +591,17 @@ b4_dollar_popdef[]dnl
 
       case YYGETTOKEN:])[
         /* Read a lookahead token.  */
-        if (yychar == yyempty_)
+        if (yychar == YYEMPTY_)
           {
 ]b4_push_if([[
             if (!push_token_consumed)
               return YYPUSH_MORE;]b4_parse_trace_if([[
-            yycdebug ("Reading a token: ");]])[
+            yycdebug ("Reading a token");]])[
             yychar = yylextoken;
             yylval = yylexval;]b4_locations_if([
             yylloc = yylexloc;])[
             push_token_consumed = false;]], [b4_parse_trace_if([[
-            yycdebug ("Reading a token: ");]])[
+            yycdebug ("Reading a token");]])[
             yychar = yylexer.yylex ();
             yylval = yylexer.getLVal ();]b4_locations_if([
             yylloc = new b4_location_type (yylexer.getStartPos (),
@@ -637,8 +616,8 @@ 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;
-        if (yyn < 0 || yylast_ < yyn || yycheck_[yyn] != yytoken)
+        yyn += yytoken.getCode ();
+        if (yyn < 0 || YYLAST_ < yyn || yycheck_[yyn] != yytoken.getCode ())
           label = YYDEFAULT;
 
         /* <= 0 means reduce or error.  */
@@ -660,7 +639,7 @@ b4_dollar_popdef[]dnl
                            yylval]b4_locations_if([, yylloc])[);
 ]])[
             /* Discard the token being shifted.  */
-            yychar = yyempty_;
+            yychar = YYEMPTY_;
 
             /* Count tokens shifted since error; after three, turn off error
                status.  */
@@ -700,26 +679,27 @@ b4_dollar_popdef[]dnl
         /* If not already recovering from an error, report this error.  */
         if (yyerrstatus_ == 0)
           {
-            ++yynerrs_;
-            if (yychar == yyempty_)
-              yytoken = yyempty_;
-            yyerror (]b4_locations_if([yylloc, ])[yysyntax_error (yystate, yytoken));
+            ++yynerrs;
+            if (yychar == YYEMPTY_)
+              yytoken = null;
+            yyreportSyntaxError (new Context (yystack, yytoken]b4_locations_if([[, yylloc]])[));
           }
 
-        ]b4_locations_if([yyerrloc = yylloc;])[
+]b4_locations_if([[
+        yyerrloc = yylloc;]])[
         if (yyerrstatus_ == 3)
           {
             /* If just tried and failed to reuse lookahead token after an
                error, discard it.  */
 
-            if (yychar <= Lexer.EOF)
+            if (yychar <= Lexer.]b4_symbol(0, id)[)
               {
                 /* Return failure if at end of input.  */
-                if (yychar == Lexer.EOF)
+                if (yychar == Lexer.]b4_symbol(0, id)[)
                   ]b4_push_if([{label = YYABORT; break;}], [return false;])[
               }
             else
-              yychar = yyempty_;
+              yychar = YYEMPTY_;
           }
 
         /* Else will try to reuse lookahead token after shifting the error
@@ -730,8 +710,8 @@ b4_dollar_popdef[]dnl
       /*-------------------------------------------------.
       | errorlab -- error raised explicitly by YYERROR.  |
       `-------------------------------------------------*/
-      case YYERROR:
-        ]b4_locations_if([yyerrloc = yystack.locationAt (yylen - 1);])[
+      case YYERROR:]b4_locations_if([[
+        yyerrloc = yystack.locationAt (yylen - 1);]])[
         /* Do not reclaim the symbols of the rule which action triggered
            this YYERROR.  */
         yystack.pop (yylen);
@@ -746,13 +726,15 @@ b4_dollar_popdef[]dnl
       case YYERRLAB1:
         yyerrstatus_ = 3;       /* Each real token shifted decrements this.  */
 
+        // Pop stack until we find a state that shifts the error token.
         for (;;)
           {
             yyn = yypact_[yystate];
             if (!yyPactValueIsDefault (yyn))
               {
-                yyn += yyterror_;
-                if (0 <= yyn && yyn <= yylast_ && yycheck_[yyn] == yyterror_)
+                yyn += SymbolKind.]b4_symbol_prefix[YYERROR.getCode ();
+                if (0 <= yyn && yyn <= YYLAST_
+                    && yycheck_[yyn] == SymbolKind.]b4_symbol_prefix[YYERROR.getCode ())
                   {
                     yyn = yytable_[yyn];
                     if (0 < yyn)
@@ -765,7 +747,8 @@ b4_dollar_popdef[]dnl
             if (yystack.height == 0)
               ]b4_push_if([{label = YYABORT; break;}],[return false;])[
 
-            ]b4_locations_if([yyerrloc = yystack.locationAt (0);])[
+]b4_locations_if([[
+            yyerrloc = yystack.locationAt (0);]])[
             yystack.pop ();
             yystate = yystack.stateAt (0);]b4_parse_trace_if([[
             if (0 < yydebug)
@@ -773,18 +756,18 @@ b4_dollar_popdef[]dnl
           }
 
         if (label == YYABORT)
-            /* Leave the switch.  */
-            break;
+          /* Leave the switch.  */
+          break;
 
-]b4_locations_if([
+]b4_locations_if([[
         /* Muck with the stack to setup for yylloc.  */
         yystack.push (0, null, yylloc);
         yystack.push (0, null, yyerrloc);
         yyloc = yylloc (yystack, 2);
-        yystack.pop (2);])[
+        yystack.pop (2);]])[
 
         /* Shift the error token.  */]b4_parse_trace_if([[
-        yySymbolPrint ("Shifting", yystos_[yyn],
+        yySymbolPrint ("Shifting", SymbolKind.get (yystos_[yyn]),
                        yylval]b4_locations_if([, yyloc])[);]])[
 
         yystate = yyn;
@@ -809,11 +792,11 @@ b4_dollar_popdef[]dnl
     /**
      * (Re-)Initialize the state of the push parser.
      */
-  public void push_parse_initialize()
+  public void push_parse_initialize ()
   {
     /* Lookahead and lookahead in internal form.  */
-    this.yychar = yyempty_;
-    this.yytoken = 0;
+    this.yychar = YYEMPTY_;
+    this.yytoken = null;
 
     /* State.  */
     this.yyn = 0;
@@ -823,10 +806,10 @@ b4_dollar_popdef[]dnl
     this.label = YYNEWSTATE;
 
     /* Error handling.  */
-    this.yynerrs_ = 0;
-    ]b4_locations_if([/* The location where the error started.  */
+    this.yynerrs = 0;]b4_locations_if([[
+    /* The location where the error started.  */
     this.yyerrloc = null;
-    this.yylloc = new b4_location_type (null, null);])[
+    this.yylloc = new ]b4_location_type[ (null, null);]])[
 
     /* Semantic value of the lookahead.  */
     this.yylval = null;
@@ -846,8 +829,7 @@ b4_dollar_popdef[]dnl
    *
    * @@return <tt>YYACCEPT, YYABORT, YYPUSH_MORE</tt>
    */
-  public int push_parse (int yylextoken, b4_yystype yylexval, b4_position_type yylexpos)
-      b4_maybe_throws([b4_list2([b4_lex_throws], [b4_throws])])
+  public int push_parse (int yylextoken, b4_yystype yylexval, b4_position_type yylexpos)b4_maybe_throws([b4_list2([b4_lex_throws], [b4_throws])])
   {
     return push_parse (yylextoken, yylexval, new b4_location_type (yylexpos));
   }
@@ -862,7 +844,7 @@ b4_dollar_popdef[]dnl
    * @@return <tt>true</tt> if the parsing succeeds.  Note that this does not
    *          imply that there were no syntax errors.
    */
-  public boolean parse () ]b4_maybe_throws([b4_list2([b4_lex_throws], [b4_throws])])[
+  public boolean parse ()]b4_maybe_throws([b4_list2([b4_lex_throws], [b4_throws])])[
   {
     if (yylexer == null)
       throw new NullPointerException("Null Lexer");
@@ -872,85 +854,167 @@ b4_dollar_popdef[]dnl
       ]b4_yystype[ lval = yylexer.getLVal();
 ]b4_locations_if([dnl
       b4_location_type yyloc = new b4_location_type (yylexer.getStartPos (),
-                                            yylexer.getEndPos ());])[
-      ]b4_locations_if([status = push_parse(token,lval,yyloc);],[
-      status = push_parse(token,lval);])[
+                                            yylexer.getEndPos ());])[]b4_locations_if([[
+      status = push_parse(token,lval,yyloc);]], [[
+      status = push_parse(token,lval);]])[
     } while (status == YYPUSH_MORE);
     return (status == YYACCEPT);
   }
 ]])[
 
-  // Generate an error message.
-  private String yysyntax_error (int yystate, int tok)
-  {]b4_error_verbose_if([[
+  /**
+   * 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]])[)
+    {
+      yystack = stack;
+      yytoken = token;]b4_locations_if([[
+      yylocation = loc;]])[
+    }
+
+    private YYStack yystack;
+
+
+    /**
+     * The symbol kind of the lookahead token.
+     */
+    public final SymbolKind getToken ()
+    {
+      return yytoken;
+    }
+
+    private SymbolKind yytoken;]b4_locations_if([[
+
+    /**
+     * The location of the lookahead.
+     */
+    public final ]b4_location_type[ getLocation ()
+    {
+      return yylocation;
+    }
+
+    private ]b4_location_type[ yylocation;]])[
+    static final int NTOKENS = ]b4_parser_class[.YYNTOKENS_;
+
+    /**
+     * Put in YYARG at most YYARGN of the expected tokens given the
+     * current YYCTX, and return the number of tokens stored in YYARG.  If
+     * YYARG is null, return the number of expected tokens (guaranteed to
+     * be less than YYNTOKENS).
+     */
+    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))
+        {
+          /* 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;
+          /* Stay within bounds of both yycheck and yytname.  */
+          int yychecklim = YYLAST_ - yyn + 1;
+          int yyxend = yychecklim < NTOKENS ? yychecklim : NTOKENS;
+          for (int yyx = yyxbegin; yyx < yyxend; ++yyx)
+            if (yycheck_[yyx + yyn] == yyx && yyx != SymbolKind.]b4_symbol_prefix[YYERROR.getCode ()
+                && !yyTableValueIsError (yytable_[yyx + yyn]))
+              {
+                if (yyarg == null)
+                  yycount += 1;
+                else if (yycount == yyargn)
+                  return 0; // FIXME: this is incorrect.
+                else
+                  yyarg[yycount++] = SymbolKind.get (yyx);
+              }
+        }
+      return yycount - yyoffset;
+    }
+  }
+
+]b4_parse_error_bmatch(
+[detailed\|verbose], [[
+  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
+         default action is an error action.  In that case, don't
+         check for expected tokens because there are none.
+       - The only way there can be no lookahead present (in tok) is
+         if this state is a consistent state with a default action.
+         Thus, detecting the absence of a lookahead is sufficient to
+         determine that there is no unexpected or expected token to
+         report.  In that case, just report a simple "syntax error".
+       - 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.  (However, yychar is currently out
+         of scope during semantic actions.)
+       - 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 scanner and before detecting a syntax
+         error.  Thus, state merging (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.
+    */
+    int yycount = 0;
+    if (yyctx.getToken () != null)
+      {
+        if (yyarg != null)
+          yyarg[yycount] = yyctx.getToken ();
+        yycount += 1;
+        yycount += yyctx.getExpectedTokens (yyarg, 1, yyargn);
+      }
+    return yycount;
+  }
+]])[
+
+/**
+   * Report a syntax error.
+   */
+  private void yyreportSyntaxError (Context yyctx)
+  {]b4_parse_error_bmatch(
+[custom], [[
+    yylexer.reportSyntaxError (yyctx);]],
+[detailed\|verbose], [[
     if (yyErrorVerbose)
       {
-        /* 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
-             default action is an error action.  In that case, don't
-             check for expected tokens because there are none.
-           - The only way there can be no lookahead present (in tok) is
-             if this state is a consistent state with a default action.
-             Thus, detecting the absence of a lookahead is sufficient to
-             determine that there is no unexpected or expected token to
-             report.  In that case, just report a simple "syntax error".
-           - 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.  (However, yychar is currently out
-             of scope during semantic actions.)
-           - 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 scanner and before detecting a syntax
-             error.  Thus, state merging (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.
-        */
-        if (tok != yyempty_)
+        final int argmax = 5;
+        SymbolKind[] yyarg = new SymbolKind[argmax];
+        int yycount = yysyntaxErrorArguments (yyctx, yyarg, argmax);
+        String[] yystr = new String[yycount];
+        for (int yyi = 0; yyi < yycount; ++yyi)
+          yystr[yyi] = yyarg[yyi].getName();
+        String yyformat;
+        switch (yycount)
           {
-            /* FIXME: This method of building the message is not compatible
-               with internationalization.  */
-            StringBuffer res =
-              new StringBuffer ("syntax error, unexpected ");
-            res.append (yytnamerr_ (yytname_[tok]));
-            int yyn = yypact_[yystate];
-            if (!yyPactValueIsDefault (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;
-                /* Stay within bounds of both yycheck and yytname.  */
-                int yychecklim = yylast_ - yyn + 1;
-                int yyxend = yychecklim < yyntokens_ ? yychecklim : yyntokens_;
-                int count = 0;
-                for (int x = yyxbegin; x < yyxend; ++x)
-                  if (yycheck_[x + yyn] == x && x != yyterror_
-                      && !yyTableValueIsError (yytable_[x + yyn]))
-                    ++count;
-                if (count < 5)
-                  {
-                    count = 0;
-                    for (int x = yyxbegin; x < yyxend; ++x)
-                      if (yycheck_[x + yyn] == x && x != yyterror_
-                          && !yyTableValueIsError (yytable_[x + yyn]))
-                        {
-                          res.append (count++ == 0 ? ", expecting " : " or ");
-                          res.append (yytnamerr_ (yytname_[x]));
-                        }
-                  }
-              }
-            return res.toString ();
+            default:
+            case 0: yyformat = ]b4_trans(["syntax error"])[; break;
+            case 1: yyformat = ]b4_trans(["syntax error, unexpected {0}"])[; break;
+            case 2: yyformat = ]b4_trans(["syntax error, unexpected {0}, expecting {1}"])[; break;
+            case 3: yyformat = ]b4_trans(["syntax error, unexpected {0}, expecting {1} or {2}"])[; break;
+            case 4: yyformat = ]b4_trans(["syntax error, unexpected {0}, expecting {1} or {2} or {3}"])[; break;
+            case 5: yyformat = ]b4_trans(["syntax error, unexpected {0}, expecting {1} or {2} or {3} or {4}"])[; break;
           }
+        yyerror (]b4_locations_if([[yyctx.yylocation, ]])[new MessageFormat (yyformat).format (yystr));
+        return;
       }
-]])[
-    return "syntax error";
+    yyerror (]b4_locations_if([[yyctx.yylocation, ]])["syntax error");]],
+[simple], [[
+    yyerror (]b4_locations_if([[yyctx.yylocation, ]])["syntax error");]])[
   }
 
   /**
@@ -975,14 +1039,7 @@ b4_dollar_popdef[]dnl
   private static final ]b4_int_type_for([b4_pact])[ yypact_ninf_ = ]b4_pact_ninf[;
   private static final ]b4_int_type_for([b4_table])[ yytable_ninf_ = ]b4_table_ninf[;
 
-  ]b4_parser_tables_define[
-  ]b4_integral_parser_table_define([token_number], [b4_toknum],
-     [[YYTOKEN_NUMBER[YYLEX-NUM] -- Internal symbol number corresponding
-   to YYLEX-NUM.]])[
-
-  /* YYTNAME[SYMBOL-NUM] -- String name of the symbol SYMBOL-NUM.
-     First, the terminals, then, starting at \a yyntokens_, nonterminals.  */
-  ]b4_typed_parser_table_define([String], [tname], [b4_tname])[
+]b4_parser_tables_define[
 
 ]b4_parse_trace_if([[
   ]b4_integral_parser_table_define([rline], [b4_rline],
@@ -999,50 +1056,43 @@ b4_dollar_popdef[]dnl
     int yynrhs = yyr2_[yyrule];
     /* Print the symbols being reduced, and their result.  */
     yycdebug ("Reducing stack by rule " + (yyrule - 1)
-              + " (line " + yylno + "), ");
+              + " (line " + yylno + "):");
 
     /* The symbols being reduced.  */
     for (int yyi = 0; yyi < yynrhs; yyi++)
       yySymbolPrint ("   $" + (yyi + 1) + " =",
-                     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)])[);
   }]])[
 
   /* YYTRANSLATE_(TOKEN-NUM) -- Symbol number corresponding to TOKEN-NUM
      as returned by yylex, with out-of-bounds checking.  */
-  private static final ]b4_int_type_for([b4_translate])[ yytranslate_ (int t)
+  private static final SymbolKind yytranslate_ (int t)
 ]b4_api_token_raw_if(dnl
 [[  {
-    return t;
+    return SymbolKind.get (t);
   }
 ]],
 [[  {
+    int user_token_number_max_ = ]b4_user_token_number_max[;
     if (t <= 0)
-      return Lexer.EOF;
-    else if (t <= yyuser_token_number_max_)
-      return yytranslate_table_[t];
+      return SymbolKind.]b4_symbol_prefix[YYEOF;
+    else if (t <= user_token_number_max_)
+      return SymbolKind.get (yytranslate_table_[t]);
     else
-      return yyundef_token_;
+      return SymbolKind.]b4_symbol_prefix[YYUNDEF;
   }
   ]b4_integral_parser_table_define([translate_table], [b4_translate])[
 ]])[
 
-  private static final int yylast_ = ]b4_last[;
-  private static final int yynnts_ = ]b4_nterms_number[;
-  private static final int yyempty_ = -2;
-  private static final int yyfinal_ = ]b4_final_state_number[;
-  private static final int yyterror_ = 1;
-  private static final int yyerrcode_ = 256;
-  private static final int yyntokens_ = ]b4_tokens_number[;
-
-  private static final int yyuser_token_number_max_ = ]b4_user_token_number_max[;
-  private static final int yyundef_token_ = ]b4_undef_token_number[;
-
-/* User implementation code.  */
-]b4_percent_code_get[]dnl
+  private static final int YYLAST_ = ]b4_last[;
+  private static final int YYEMPTY_ = -2;
+  private static final int YYFINAL_ = ]b4_final_state_number[;
+  private static final int YYNTOKENS_ = ]b4_tokens_number[;
 
+]b4_percent_code_get[
 }
-
+]b4_percent_code_get([[epilogue]])[]dnl
 b4_epilogue[]dnl
 b4_output_end

data/skeletons/location.cc

@@ -1,6 +1,6 @@
 # C++ skeleton for Bison
 
-# Copyright (C) 2002-2015, 2018-2019 Free Software Foundation, Inc.
+# Copyright (C) 2002-2015, 2018-2020 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 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 m4_pushdef([b4_copyright_years],
-           [2002-2015, 2018-2019])
+           [2002-2015, 2018-2020])
 
 
 # b4_position_file

data/skeletons/stack.hh

@@ -1,6 +1,6 @@
 # C++ skeleton for Bison
 
-# Copyright (C) 2002-2015, 2018-2019 Free Software Foundation, Inc.
+# Copyright (C) 2002-2015, 2018-2020 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
@@ -32,8 +32,8 @@ m4_define([b4_stack_define],
     {
     public:
       // Hide our reversed order.
-      typedef typename S::reverse_iterator iterator;
-      typedef typename S::const_reverse_iterator const_iterator;
+      typedef typename S::iterator iterator;
+      typedef typename S::const_iterator const_iterator;
       typedef typename S::size_type size_type;
       typedef typename std::ptrdiff_t index_type;
 
@@ -91,24 +91,18 @@ m4_define([b4_stack_define],
         return index_type (seq_.size ());
       }
 
-      std::ptrdiff_t
-      ssize () const YY_NOEXCEPT
-      {
-        return std::ptrdiff_t (size ());
-      }
-
       /// Iterator on top of the stack (going downwards).
       const_iterator
       begin () const YY_NOEXCEPT
       {
-        return seq_.rbegin ();
+        return seq_.begin ();
       }
 
       /// Bottom of the stack.
       const_iterator
       end () const YY_NOEXCEPT
       {
-        return seq_.rend ();
+        return seq_.end ();
       }
 
       /// Present a slice of the top of a stack.

data/skeletons/variant.hh

@@ -1,6 +1,6 @@
 # C++ skeleton for Bison
 
-# Copyright (C) 2002-2015, 2018-2019 Free Software Foundation, Inc.
+# Copyright (C) 2002-2015, 2018-2020 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
@@ -72,9 +72,9 @@ 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 YYASSERT
+#ifndef YY_ASSERT
 # include <cassert>
-# define YYASSERT assert
+# define YY_ASSERT assert
 #endif
 ]])
 
@@ -111,14 +111,14 @@ m4_define([b4_value_type_declare],
     semantic_type (YY_RVREF (T) t)]b4_parse_assert_if([
       : yytypeid_ (&typeid (T))])[
     {
-      YYASSERT (sizeof (T) <= size);
+      YY_ASSERT (sizeof (T) <= size);
       new (yyas_<T> ()) T (YY_MOVE (t));
     }
 
     /// Destruction, allowed only if empty.
     ~semantic_type () YY_NOEXCEPT
     {]b4_parse_assert_if([
-      YYASSERT (!yytypeid_);
+      YY_ASSERT (!yytypeid_);
     ])[}
 
 # if 201103L <= YY_CPLUSPLUS
@@ -127,8 +127,8 @@ m4_define([b4_value_type_declare],
     T&
     emplace (U&&... u)
     {]b4_parse_assert_if([
-      YYASSERT (!yytypeid_);
-      YYASSERT (sizeof (T) <= size);
+      YY_ASSERT (!yytypeid_);
+      YY_ASSERT (sizeof (T) <= size);
       yytypeid_ = & typeid (T);])[
       return *new (yyas_<T> ()) T (std::forward <U>(u)...);
     }
@@ -138,8 +138,8 @@ m4_define([b4_value_type_declare],
     T&
     emplace ()
     {]b4_parse_assert_if([
-      YYASSERT (!yytypeid_);
-      YYASSERT (sizeof (T) <= size);
+      YY_ASSERT (!yytypeid_);
+      YY_ASSERT (sizeof (T) <= size);
       yytypeid_ = & typeid (T);])[
       return *new (yyas_<T> ()) T ();
     }
@@ -149,8 +149,8 @@ m4_define([b4_value_type_declare],
     T&
     emplace (const T& t)
     {]b4_parse_assert_if([
-      YYASSERT (!yytypeid_);
-      YYASSERT (sizeof (T) <= size);
+      YY_ASSERT (!yytypeid_);
+      YY_ASSERT (sizeof (T) <= size);
       yytypeid_ = & typeid (T);])[
       return *new (yyas_<T> ()) T (t);
     }
@@ -179,9 +179,9 @@ m4_define([b4_value_type_declare],
     T&
     as () YY_NOEXCEPT
     {]b4_parse_assert_if([
-      YYASSERT (yytypeid_);
-      YYASSERT (*yytypeid_ == typeid (T));
-      YYASSERT (sizeof (T) <= size);])[
+      YY_ASSERT (yytypeid_);
+      YY_ASSERT (*yytypeid_ == typeid (T));
+      YY_ASSERT (sizeof (T) <= size);])[
       return *yyas_<T> ();
     }
 
@@ -190,9 +190,9 @@ m4_define([b4_value_type_declare],
     const T&
     as () const YY_NOEXCEPT
     {]b4_parse_assert_if([
-      YYASSERT (yytypeid_);
-      YYASSERT (*yytypeid_ == typeid (T));
-      YYASSERT (sizeof (T) <= size);])[
+      YY_ASSERT (yytypeid_);
+      YY_ASSERT (*yytypeid_ == typeid (T));
+      YY_ASSERT (sizeof (T) <= size);])[
       return *yyas_<T> ();
     }
 
@@ -208,8 +208,8 @@ m4_define([b4_value_type_declare],
     void
     swap (self_type& that) YY_NOEXCEPT
     {]b4_parse_assert_if([
-      YYASSERT (yytypeid_);
-      YYASSERT (*yytypeid_ == *that.yytypeid_);])[
+      YY_ASSERT (yytypeid_);
+      YY_ASSERT (*yytypeid_ == *that.yytypeid_);])[
       std::swap (as<T> (), that.as<T> ());
     }
 
@@ -401,7 +401,7 @@ m4_define([_b4_token_constructor_define],
                               b4_symbol_if([$1], [has_type], [std::move (v)]),
                               b4_locations_if([std::move (l)]))[)
       {
-        YYASSERT (]m4_join([ || ], m4_map_sep([_b4_type_clause], [, ], [$@]))[);
+        YY_ASSERT (]m4_join([ || ], m4_map_sep([_b4_type_clause], [, ], [$@]))[);
       }
 #else
       symbol_type (]b4_join(
@@ -413,7 +413,7 @@ m4_define([_b4_token_constructor_define],
                               b4_symbol_if([$1], [has_type], [v]),
                               b4_locations_if([l]))[)
       {
-        YYASSERT (]m4_join([ || ], m4_map_sep([_b4_type_clause], [, ], [$@]))[);
+        YY_ASSERT (]m4_join([ || ], m4_map_sep([_b4_type_clause], [, ], [$@]))[);
       }
 #endif
 ]])])

data/xslt/bison.xsl

@@ -3,7 +3,7 @@
 <!--
     bison.xsl - common templates for Bison XSLT.
 
-    Copyright (C) 2007-2015, 2018-2019 Free Software Foundation, Inc.
+    Copyright (C) 2007-2015, 2018-2020 Free Software Foundation, Inc.
 
     This file is part of Bison, the GNU Compiler Compiler.
 

data/xslt/xml2dot.xsl

@@ -3,7 +3,7 @@
 <!--
     xml2dot.xsl - transform Bison XML Report into DOT.
 
-    Copyright (C) 2007-2015, 2018-2019 Free Software Foundation, Inc.
+    Copyright (C) 2007-2015, 2018-2020 Free Software Foundation, Inc.
 
     This file is part of Bison, the GNU Compiler Compiler.
 

data/xslt/xml2text.xsl

@@ -3,7 +3,7 @@
 <!--
     xml2text.xsl - transform Bison XML Report into plain text.
 
-    Copyright (C) 2007-2015, 2018-2019 Free Software Foundation, Inc.
+    Copyright (C) 2007-2015, 2018-2020 Free Software Foundation, Inc.
 
     This file is part of Bison, the GNU Compiler Compiler.
 

data/xslt/xml2xhtml.xsl

@@ -3,7 +3,7 @@
 <!--
     xml2html.xsl - transform Bison XML Report into XHTML.
 
-    Copyright (C) 2007-2015, 2018-2019 Free Software Foundation, Inc.
+    Copyright (C) 2007-2015, 2018-2020 Free Software Foundation, Inc.
 
     This file is part of Bison, the GNU Compiler Compiler.
 

doc/.gitignore

@@ -16,6 +16,7 @@
 /bison.help
 /bison.html
 /bison.info
+/bison.info.bak
 /bison.log
 /bison.pdf
 /bison.ps

doc/local.mk

@@ -1,4 +1,4 @@
-## Copyright (C) 2001-2003, 2005-2015, 2018-2019 Free Software
+## Copyright (C) 2001-2003, 2005-2015, 2018-2020 Free Software
 ## Foundation, Inc.
 
 ## This program is free software: you can redistribute it and/or modify
@@ -20,36 +20,36 @@ AM_MAKEINFOFLAGS =                                              \
   --set-customization-variable=AVOID_MENU_REDUNDANCY=true       \
   --set-customization-variable=ICONS=true
 
-info_TEXINFOS = doc/bison.texi
-doc_bison_TEXINFOS =                            \
+info_TEXINFOS = %D%/bison.texi
+%C%_bison_TEXINFOS =                            \
   $(CROSS_OPTIONS_TEXI)                         \
-  doc/fdl.texi                                  \
-  doc/gpl-3.0.texi                              \
-  doc/relocatable.texi
+  %D%/fdl.texi                                  \
+  %D%/gpl-3.0.texi                              \
+  %D%/relocatable.texi
 
 # Cannot express dependencies directly on file names because of Automake.
 # Obfuscate with a variable.
-doc_bison = doc/bison
-$(doc_bison).dvi: $(FIGS_GV:.gv=.eps)
-$(doc_bison).info: $(FIGS_GV:.gv=.txt)
-$(doc_bison).pdf: $(FIGS_GV:.gv=.pdf)
-$(doc_bison).html: $(FIGS_GV:.gv=.svg)
+%C%_bison = %D%/bison
+$(%C%_bison).dvi: $(FIGS_GV:.gv=.eps)
+$(%C%_bison).info: $(FIGS_GV:.gv=.txt)
+$(%C%_bison).pdf: $(FIGS_GV:.gv=.pdf)
+$(%C%_bison).html: $(FIGS_GV:.gv=.svg)
 
-TEXI2DVI = texi2dvi --build-dir=doc/bison.t2d -I doc
-CLEANDIRS += doc/bison.t2d
+TEXI2DVI = texi2dvi --build-dir=%D%/bison.t2d -I %D%
+CLEANDIRS += %D%/bison.t2d
 
-MOSTLYCLEANFILES += $(top_srcdir)/doc/*.tmp
+MOSTLYCLEANFILES += $(top_srcdir)/%D%/*.tmp
 
 CROSS_OPTIONS_PL = $(top_srcdir)/build-aux/cross-options.pl
-CROSS_OPTIONS_TEXI = $(top_srcdir)/doc/cross-options.texi
-$(CROSS_OPTIONS_TEXI): doc/bison.help $(CROSS_OPTIONS_PL)
+CROSS_OPTIONS_TEXI = $(top_srcdir)/%D%/cross-options.texi
+$(CROSS_OPTIONS_TEXI): %D%/bison.help $(CROSS_OPTIONS_PL)
 # Create $@~ which is the previous contents.  Don't use 'mv' here so
 # that even if we are interrupted, the file is still available for
 # diff in the next run.  Note that $@ might not exist yet.
 	$(AM_V_GEN){ test ! -f $@ || cat $@; } >$@~
 	$(AM_V_at)test ! -f $@.tmp || rm -f $@.tmp
 	$(AM_V_at)$(PERL) $(CROSS_OPTIONS_PL) $(top_srcdir)/src/scan-gram.l \
-	  <$(top_srcdir)/doc/bison.help >$@.tmp
+	  <$(top_srcdir)/%D%/bison.help >$@.tmp
 	$(AM_V_at)diff -u $@~ $@.tmp || true
 	$(AM_V_at)mv $@.tmp $@
 MAINTAINERCLEANFILES = $(CROSS_OPTIONS_TEXI)
@@ -57,34 +57,34 @@ MAINTAINERCLEANFILES = $(CROSS_OPTIONS_TEXI)
 
 # Fix Info's @code in @deftype
 # https://lists.gnu.org/archive/html/help-texinfo/2019-11/msg00004.html
-all: $(srcdir)/$(doc_bison).info.bak
-$(srcdir)/$(doc_bison).info.bak: $(srcdir)/$(doc_bison).info
+all: $(srcdir)/$(%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)*)}'	\
 	  -e '{'				\
 	  -e '  $$def = $$1;'			\
 	  -e '  $$def =~ s/‘|’//g;'		\
 	  -e '  $$def;'				\
-	  -e '}gem;' $(srcdir)/$(doc_bison).info
+	  -e '}gem;' $(srcdir)/$(%C%_bison).info
 	@ touch $@
-EXTRA_DIST += $(srcdir)/$(doc_bison).info.bak
-MAINTAINERCLEANFILES += $(srcdir)/$(doc_bison).info.bak
+EXTRA_DIST += $(srcdir)/$(%C%_bison).info.bak
+MAINTAINERCLEANFILES += $(srcdir)/$(%C%_bison).info.bak
 
 
 ## ---------- ##
 ## Ref card.  ##
 ## ---------- ##
 
-EXTRA_DIST += doc/refcard.tex
-CLEANFILES += doc/refcard.pdf
+EXTRA_DIST += %D%/refcard.tex
+CLEANFILES += %D%/refcard.pdf
 
-doc/refcard.pdf: doc/refcard.tex
-	$(AM_V_GEN) cd doc && pdftex $(abs_top_srcdir)/doc/refcard.tex
+%D%/refcard.pdf: %D%/refcard.tex
+	$(AM_V_GEN) cd %D% && pdftex $(abs_top_srcdir)/%D%/refcard.tex
 
 
 
 ## ---------------- ##
-## doc/bison.help.  ##
+## %D%/bison.help.  ##
 ## ---------------- ##
 
 # Some of our targets (cross-options.texi, bison.1) use "bison --help".
@@ -106,18 +106,19 @@ doc/refcard.pdf: doc/refcard.tex
 # compilations of cross-options.texi and bison.1.  At the cost of
 # repeated builds of bison.help.
 
-EXTRA_DIST += $(top_srcdir)/doc/bison.help
+EXTRA_DIST += $(top_srcdir)/%D%/bison.help
 if ! CROSS_COMPILING
-MAINTAINERCLEANFILES += $(top_srcdir)/doc/bison.help
-$(top_srcdir)/doc/bison.help: src/bison$(EXEEXT)
-	$(AM_V_GEN)LC_ALL=C tests/bison --version >doc/bison.help.tmp
+MAINTAINERCLEANFILES += $(top_srcdir)/%D%/bison.help
+$(top_srcdir)/%D%/bison.help: src/bison$(EXEEXT)
+	$(AM_V_GEN)$(MKDIR_P) %D%
+	$(AM_V_at) LC_ALL=C tests/bison --version >%D%/bison.help.tmp
 	$(AM_V_at) LC_ALL=C tests/bison --help | \
 ## Avoid depending on the path to Bison.
 	  sed -e 's,^Usage: .*/bison \[OPTION\],Usage: bison [OPTION],g' \
 ## Avoid variations in the output depending on whether we are
 ## on a glibc system.
-	      -e '/translation bugs/d'  >>doc/bison.help.tmp
-	$(AM_V_at)$(top_srcdir)/build-aux/move-if-change doc/bison.help.tmp $@
+	      -e '/translation bugs/d'  >>%D%/bison.help.tmp
+	$(AM_V_at)$(top_srcdir)/build-aux/move-if-change %D%/bison.help.tmp $@
 endif ! CROSS_COMPILING
 
 
@@ -125,7 +126,7 @@ endif ! CROSS_COMPILING
 ## Man Pages.  ##
 ## ----------- ##
 
-dist_man_MANS = $(top_srcdir)/doc/bison.1
+dist_man_MANS = $(top_srcdir)/%D%/bison.1
 
 EXTRA_DIST += $(dist_man_MANS:.1=.x)
 MAINTAINERCLEANFILES += $(dist_man_MANS)
@@ -136,12 +137,12 @@ remove_time_stamp = \
 
 # Depend on configure to get version number changes.
 if ! CROSS_COMPILING
-MAN_DEPS = doc/bison.help doc/bison.x $(top_srcdir)/configure
+MAN_DEPS = %D%/bison.help %D%/bison.x $(top_srcdir)/configure
 endif
 
-$(top_srcdir)/doc/bison.1: $(MAN_DEPS)
+$(top_srcdir)/%D%/bison.1: $(MAN_DEPS)
 	$(AM_V_GEN)$(HELP2MAN)			\
-	    --include=$(top_srcdir)/doc/bison.x	\
+	    --include=$(top_srcdir)/%D%/bison.x	\
 	    --output=$@.tmp tests/bison
 	$(AM_V_at)if $(remove_time_stamp) $@ >$@a.tmp 2>/dev/null &&		\
 	   $(remove_time_stamp) $@.tmp | cmp $@a.tmp - >/dev/null 2>&1; then	\
@@ -152,7 +153,7 @@ $(top_srcdir)/doc/bison.1: $(MAN_DEPS)
 	$(AM_V_at)rm -f $@*.tmp
 
 if ENABLE_YACC
-nodist_man_MANS = doc/yacc.1
+nodist_man_MANS = %D%/yacc.1
 endif
 
 ## ----------------------------- ##
@@ -161,8 +162,8 @@ endif
 
 CLEANFILES += $(FIGS_GV:.gv=.eps) $(FIGS_GV:.gv=.pdf) $(FIGS_GV:.gv=.svg)
 FIGS_GV =                                               \
-  doc/figs/example.gv                                   \
-  doc/figs/example-reduce.gv doc/figs/example-shift.gv
+  %D%/figs/example.gv                                   \
+  %D%/figs/example-reduce.gv %D%/figs/example-shift.gv
 EXTRA_DIST +=                                                   \
   $(FIGS_GV) $(FIGS_GV:.gv=.txt)                                \
   $(FIGS_GV:.gv=.eps) $(FIGS_GV:.gv=.pdf) $(FIGS_GV:.gv=.svg)
@@ -193,8 +194,8 @@ DOXYGEN = doxygen
 
 doc: html
 
-html-local: doc/Doxyfile
-	$(AM_V_GEN) $(DOXYGEN) doc/Doxyfile
+html-local: %D%/Doxyfile
+	$(AM_V_GEN) $(DOXYGEN) %D%/Doxyfile
 
 edit = sed -e 's,@PACKAGE_NAME\@,$(PACKAGE_NAME),g' \
 	   -e 's,@PACKAGE_VERSION\@,$(PACKAGE_VERSION),g' \
@@ -202,11 +203,11 @@ edit = sed -e 's,@PACKAGE_NAME\@,$(PACKAGE_NAME),g' \
 	   -e 's,@top_builddir\@,$(top_builddir),g' \
 	   -e 's,@top_srcdir\@,$(top_srcdir),g'
 
-EXTRA_DIST += doc/Doxyfile.in
-CLEANFILES += doc/Doxyfile
+EXTRA_DIST += %D%/Doxyfile.in
+CLEANFILES += %D%/Doxyfile
 # Sed is used to generate Doxyfile from Doxyfile.in instead of
 # configure, because the former is way faster than the latter.
-doc/Doxyfile: $(top_srcdir)/doc/Doxyfile.in
-	$(AM_V_GEN) $(edit) $(top_srcdir)/doc/Doxyfile.in >doc/Doxyfile
+%D%/Doxyfile: $(top_srcdir)/%D%/Doxyfile.in
+	$(AM_V_GEN) $(edit) $(top_srcdir)/%D%/Doxyfile.in >%D%/Doxyfile
 
-CLEANDIRS += doc/html
+CLEANDIRS += %D%/html

doc/refcard.tex

@@ -19,7 +19,7 @@
 \def\finalout{\overfullrule=0pt}
 %\finalout
 
-% Copyright (c) 1998, 2001, 2009-2015, 2018-2019 Free Software
+% Copyright (c) 1998, 2001, 2009--2015, 2018--2020 Free Software
 % Foundation, Inc.
 %
 % This file is part of Bison.

etc/README

@@ -16,7 +16,7 @@ straightforward use of _build/src/bison would.)
 
 --
 
-Copyright (C) 2006, 2009-2015, 2018-2019 Free Software Foundation, Inc.
+Copyright (C) 2006, 2009-2015, 2018-2020 Free Software Foundation, Inc.
 
 This file is part of Bison, the GNU Compiler Compiler.
 

etc/local.mk

@@ -1,4 +1,4 @@
-## Copyright (C) 2006, 2008-2015, 2018-2019 Free Software Foundation,
+## Copyright (C) 2006, 2008-2015, 2018-2020 Free Software Foundation,
 ## Inc.
 
 ## This program is free software: you can redistribute it and/or modify

examples/README.md

@@ -17,7 +17,7 @@ fill-column: 76
 ispell-dictionary: "american"
 End:
 
-Copyright (C) 2018-2019 Free Software Foundation, Inc.
+Copyright (C) 2018-2020 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++/README.md

@@ -8,7 +8,7 @@ afterwards.
 ## simple.yy - Simple example in C++14
 A very simple example in C++, based on variants and symbol constructors.
 Variants allow to use any C++ type as semantic value type, and symbol
-constructors ensure consistency between declared token type and effective
+constructors ensure consistency between declared token kind and effective
 semantic value.
 
 Run as `./simple`.
@@ -46,7 +46,7 @@ fill-column: 76
 ispell-dictionary: "american"
 End:
 
-Copyright (C) 2018-2019 Free Software Foundation, Inc.
+Copyright (C) 2018-2020 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
@@ -55,5 +55,5 @@ 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.
 
-# LocalWords:  mfcalc calc parsers yy ispell american
+LocalWords:  mfcalc calc parsers yy ispell american
 --->

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

@@ -36,22 +36,14 @@ fill-column: 76
 ispell-dictionary: "american"
 End:
 
-Copyright (C) 2018-2019 Free Software Foundation, Inc.
+Copyright (C) 2018-2020 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.
 
-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 <http://www.gnu.org/licenses/>.
-
-# LocalWords:  calc parsers yy MERCHANTABILITY Ctrl ispell american
+LocalWords:  calc parsers yy MERCHANTABILITY Ctrl ispell american
 --->

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

@@ -1,6 +1,6 @@
 #! /bin/sh
 
-# Copyright (C) 2005-2015, 2018-2019 Free Software Foundation, Inc.
+# Copyright (C) 2005-2015, 2018-2020 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
@@ -44,11 +44,18 @@ EOF
 run 0 9
 
 
+cat >input <<EOF
+1 +
+EOF
+run 1 'err: -:2.1: syntax error, unexpected end of file, expecting ( or identifier or number'
+
+
+# LAC finds many more tokens.
 cat >input <<EOF
 a := 1
 d := a + b * c
 EOF
-run 1 'err: -:3.1: syntax error, unexpected end of file, expecting ( or identifier or number'
+run 1 'err: -:3.1: syntax error, unexpected end of file'
 
 
 cat >input <<EOF

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

@@ -1,4 +1,4 @@
-## Copyright (C) 2005-2006, 2008-2015, 2018-2019 Free Software
+## Copyright (C) 2005-2006, 2008-2015, 2018-2020 Free Software
 ## Foundation, Inc.
 ##
 ## This program is free software: you can redistribute it and/or modify

examples/c++/local.mk

@@ -1,4 +1,4 @@
-## Copyright (C) 2018-2019 Free Software Foundation, Inc.
+## Copyright (C) 2018-2020 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

examples/c++/variant-11.test

@@ -1,6 +1,6 @@
 #! /bin/sh
 
-# Copyright (C) 2018-2019 Free Software Foundation, Inc.
+# Copyright (C) 2018-2020 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

examples/c++/variant-11.yy

@@ -1,5 +1,5 @@
 /*
-  Copyright (C) 2008-2015, 2018-2019 Free Software Foundation, Inc.
+  Copyright (C) 2008-2015, 2018-2020 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

examples/c++/variant.test

@@ -1,6 +1,6 @@
 #! /bin/sh
 
-# Copyright (C) 2018-2019 Free Software Foundation, Inc.
+# Copyright (C) 2018-2020 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

examples/c++/variant.yy

@@ -1,5 +1,5 @@
 /*
-  Copyright (C) 2008-2015, 2018-2019 Free Software Foundation, Inc.
+  Copyright (C) 2008-2015, 2018-2020 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

examples/c/README.md

@@ -28,7 +28,8 @@ Extracted from the documentation: "Multi-Function Calculator: mfcalc".
 https://www.gnu.org/software/bison/manual/html_node/Multi_002dfunction-Calc.html
 
 ## lexcalc - calculator with Flex and Bison
-The calculator, redux.  This time using a scanner generated by Flex.
+The calculator with precedence directives and location tracking.  It uses
+Flex to generate the scanner.
 
 ## reccalc - recursive calculator with Flex and Bison
 The example builds on top of the previous one to provide a reentrant parser.
@@ -37,6 +38,29 @@ recursively.  To demonstrate this feature, expressions in parentheses are
 tokenized as strings, and then recursively parsed from the parser.  So
 `(((1)+(2))*((3)+(4)))` uses eight parsers, with a depth of four.
 
+## pushcalc - calculator implemented with a push parser
+All the previous examples are so called "pull parsers": the user invokes the
+parser once, which repeatedly calls the scanner until the input is drained.
+
+This example demonstrates the "push parsers": the user calls the scanner to
+fetch the next token, passes it to the parser, and repeats the operation
+until the input is drained.
+
+This example is a straightforward conversion of the 'calc' example to the
+push-parser model.
+
+## bistromathic - all the bells and whistles
+This example demonstrates best practices when using Bison.
+- Its hand-written scanner tracks locations.
+- Its interface is pure.
+- Its interface is "incremental", well suited for interaction: it uses the
+  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 a custom syntax error with location, lookahead correction and
+  token internationalization.
+- It supports debug traces with semantic values.
+- It uses named references instead of the traditional $1, $2, etc.
 
 <!---
 
@@ -45,7 +69,9 @@ fill-column: 76
 ispell-dictionary: "american"
 End:
 
-Copyright (C) 2018-2019 Free Software Foundation, Inc.
+Copyright (C) 2018-2020 Free Software Foundation, Inc.
+
+This file is part of GNU 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
@@ -54,6 +80,8 @@ 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.
 
-# LocalWords:  mfcalc calc parsers yy rpcalc lexcalc redux reccalc ispell
-# LocalWords:  reentrant tokenized american postfix
---->
+LocalWords:  mfcalc calc parsers yy rpcalc lexcalc redux reccalc ispell
+LocalWords:  reentrant tokenized american postfix pushcalc bistromathic
+LocalWords:  lookahead
+
+-->

examples/c/bistromathic/Makefile

@@ -0,0 +1,35 @@
+# This Makefile is designed to be simple and readable.  It does not
+# aim at portability.  It requires GNU Make.
+
+BASE = bistromathic
+BISON = bison
+FLEX = flex
+XSLTPROC = xsltproc
+
+all: $(BASE)
+
+%.c %.h %.xml %.gv: %.y
+	$(BISON) $(BISONFLAGS) --defines --xml --graph=$*.gv -o $*.c $<
+
+%.c: %.l
+	$(FLEX) $(FLEXFLAGS) -o$*.c $<
+
+scan.o: parse.h
+$(BASE): parse.o scan.o
+	$(CC) $(CFLAGS) -o $@ $^
+
+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	\
+  scan.c
+
+clean:
+	rm -f $(CLEANFILES)

examples/c/bistromathic/README.md

@@ -0,0 +1,34 @@
+# bistromathic - all the bells and whistles
+This example demonstrates best practices when using Bison.
+- Its hand-written scanner tracks locations.
+- Its interface is pure.
+- Its interface is "incremental", well suited for interaction: it uses the
+  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 a custom syntax error with location, lookahead correction and
+  token internationalization.
+- It supports debug traces with semantic values.
+- It uses named references instead of the traditional $1, $2, etc.
+
+<!---
+Local Variables:
+fill-column: 76
+ispell-dictionary: "american"
+End:
+
+Copyright (C) 2020 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.
+
+LocalWords:  bistromathic yyexpected lookahead ispell american
+LocalWords:  MERCHANTABILITY
+
+--->

examples/c/bistromathic/bistromathic.test

@@ -0,0 +1,131 @@
+#! /bin/sh
+
+# Copyright (C) 2020 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 <http://www.gnu.org/licenses/>.
+
+# macOS' version of readline does not repeat stdin on stdout in
+# non-interactive mode.
+if ! echo '1-1' | prog | grep '1-1'; then
+   strip_prompt=true
+fi
+
+cat >input <<EOF
+1+2*3
+EOF
+run 0 '> 1+2*3
+7
+> '
+
+cat >input <<EOF
+(1+2) * 3
+EOF
+run 0  '> (1+2) * 3
+9
+> '
+run -noerr 0 '> (1+2) * 3
+9
+> ' -p
+
+cat >input <<EOF
+a = 256
+sqrt (a)
+EOF
+run 0 '> a = 256
+256
+> sqrt (a)
+16
+> '
+
+cat >input <<EOF
+a = .16
+b = 10 ^ 2
+sqrt (a * b)
+EOF
+run 0 '> a = .16
+0.16
+> b = 10 ^ 2
+100
+> sqrt (a * b)
+4
+> '
+
+cat >input <<EOF
+*
+EOF
+run 0 '> *
+> err: 1.1: syntax error: expected end of file or - or ( or exit or double precision number or function or variable before *'
+
+cat >input <<EOF
+1 + 2 * * 3
+EOF
+run 0 '> 1 + 2 * * 3
+> err: 1.9: syntax error: expected - or ( or double precision number or function or variable before *'
+
+cat >input <<EOF
+100%
+EOF
+run 0 '> 100%
+100
+> err: 1.4: error: invalid character'
+
+cat >input <<EOF
+1 / 0
+EOF
+run 0 '> 1 / 0
+> err: 1.1-5: error: division by zero'
+
+
+## ------------ ##
+## Completion.  ##
+## ------------ ##
+
+# From now on, the differences between versions of GNU Readline are
+# too painful to try to cope with.
+if $strip_prompt; then
+    echo "SKIP: this is not the GNU Readline we expect"
+    if $exit; then
+        exit 0
+    else
+        exit 1
+    fi
+fi
+
+# Check completion after an operator.
+sed -e 's/\\t/	/g' >input <<EOF
+(1+\t\t
+EOF
+run 0 '> (1+
+(                        cos                      ln
+-                        double precision number  sin
+atan                     exp                      sqrt
+> (1+
+> err: 1.4: syntax error: expected - or ( or double precision number or function or variable before end of file'
+
+# Check the completion of a word.
+sed -e 's/\\t/	/g' >input <<EOF
+(at\t\t
+EOF
+run 0 '> (atan ( ''
+> err: 1.9: syntax error: expected - or ( or double precision number or function or variable before end of file'
+
+# Check the completion at the very beginning.
+sed -e 's/\\t/	/g' >input <<EOF
+e\t\t
+EOF
+run 0 '> e
+end of file  exit         exp          ''
+> e
+0
+> err: '

examples/c/bistromathic/local.mk

@@ -0,0 +1,34 @@
+## Copyright (C) 2020 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 <http://www.gnu.org/licenses/>.
+
+bistromathicdir = $(docdir)/%D%
+
+## --------------- ##
+## Bistromathics.  ##
+## --------------- ##
+
+check_PROGRAMS += %D%/bistromathic
+TESTS += %D%/bistromathic.test
+EXTRA_DIST += %D%/bistromathic.test
+nodist_%C%_bistromathic_SOURCES = %D%/parse.y %D%/parse.h
+%D%/parse.c: $(dependencies)
+
+# Don't use gnulib's system headers.
+%C%_bistromathic_CPPFLAGS = -I$(top_srcdir)/%D% -I$(top_builddir)/%D%
+%C%_bistromathic_LDADD = -lm -lreadline
+
+dist_bistromathic_DATA = %D%/parse.y %D%/Makefile %D%/README.md
+CLEANFILES += %D%/parse.[ch] %D%/parse.output
+CLEANDIRS += %D%/*.dSYM

examples/c/bistromathic/parse.y

@@ -0,0 +1,486 @@
+%require "3.6"
+
+%code top {
+  #include <ctype.h>  // isdigit
+  #include <math.h>   // cos, sin, etc.
+  #include <stddef.h> // ptrdiff_t
+  #include <stdio.h>  // printf
+  #include <stdlib.h> // calloc.
+  #include <string.h> // strcmp
+
+  #include <readline/readline.h>
+  #include <readline/history.h>
+}
+
+%code requires {
+  // Function type.
+  typedef double (func_t) (double);
+
+  // Data type for links in the chain of symbols.
+  typedef struct symrec symrec;
+  struct symrec
+  {
+    char *name;  // name of symbol
+    int type;    // type of symbol: either VAR or FUN
+    union
+    {
+      double var;    // value of a VAR
+      func_t *fun;   // value of a FUN
+    } value;
+    symrec *next;  // link field
+  };
+
+  symrec *putsym (char const *name, int sym_type);
+  symrec *getsym (char const *name);
+}
+
+%code provides {
+  int yylex (const char **line, YYSTYPE *yylval, YYLTYPE *yylloc);
+  void yyerror (YYLTYPE *yylloc, char const *msg);
+}
+
+%code {
+#define N_
+#define _
+
+  // Whether to quit.
+  int done = 0;
+}
+
+// Don't share global variables between the scanner and the parser.
+%define api.pure full
+
+// Generate a push parser.
+%define api.push-pull push
+
+// To avoid name clashes (e.g., with C's EOF) prefix token definitions
+// with TOK_ (e.g., TOK_EOF).
+%define api.token.prefix {TOK_}
+
+// Customized syntax error messages (see yyreport_syntax_error).
+%define parse.error custom
+
+// with locations.
+%locations
+
+// and accurate list of expected tokens.
+%define parse.lac full
+
+// Generate the parser description file (calc.output).
+%verbose
+
+// Generate YYSTYPE from the types assigned to symbols.
+%define api.value.type union
+%token
+    PLUS   "+"
+    MINUS  "-"
+    STAR   "*"
+    SLASH  "/"
+    CARET  "^"
+    LPAREN "("
+    RPAREN ")"
+    EQUAL  "="
+    EXIT   "exit"
+  <double>
+    NUM _("double precision number")
+  <symrec*>
+    FUN _("function")
+    VAR _("variable")
+
+%nterm <double>  exp
+
+// Enable run-time traces (yydebug).
+%define parse.trace
+
+// Formatting semantic values in debug traces.
+%printer { fprintf (yyo, "%s", $$->name); } VAR;
+%printer { fprintf (yyo, "%s()", $$->name); } FUN;
+%printer { fprintf (yyo, "%g", $$); } <double>;
+
+
+// Precedence (from lowest to highest) and associativity.
+%precedence "="
+%left "+" "-"
+%left "*" "/"
+%precedence NEG // negation--unary minus
+%right "^"      // exponentiation
+
+%% // The grammar follows.
+input:
+  %empty
+| exp     { printf ("%.10g\n", $exp); }
+| "exit"  { done = 1; }
+;
+
+exp:
+  NUM
+| VAR               { $$ = $VAR->value.var; }
+| VAR "=" exp       { $$ = $3; $VAR->value.var = $3; }
+| FUN "(" exp ")"   { $$ = $FUN->value.fun ($3); }
+| exp[l] "+" exp[r] { $$ = $l + $r; }
+| exp[l] "-" exp[r] { $$ = $l - $r; }
+| exp[l] "*" exp[r] { $$ = $l * $r; }
+| exp[l] "/" exp[r]
+  {
+    if ($r == 0)
+      {
+        yyerror (&@$, "error: division by zero");
+        YYERROR;
+      }
+    else
+      $$ = $l / $r;
+  }
+| "-" exp  %prec NEG { $$ = -$2; }
+| exp[l] "^" exp[r]  { $$ = pow ($l, $r); }
+| "(" exp ")"        { $$ = $2; }
+;
+
+// End of grammar.
+%%
+
+/*------------.
+| Functions.  |
+`------------*/
+
+struct init
+{
+  char const *name;
+  func_t *fun;
+};
+
+static struct init const funs[] =
+{
+  { "atan", atan },
+  { "cos",  cos  },
+  { "exp",  exp  },
+  { "ln",   log  },
+  { "sin",  sin  },
+  { "sqrt", sqrt },
+  { 0, 0 },
+};
+
+// The symbol table: a chain of 'struct symrec'.
+static symrec *sym_table;
+
+// Put functions in table.
+static void
+init_table (void)
+{
+  for (int i = 0; funs[i].name; i++)
+    {
+      symrec *ptr = putsym (funs[i].name, TOK_FUN);
+      ptr->value.fun = funs[i].fun;
+    }
+}
+
+symrec *
+putsym (char const *name, int sym_type)
+{
+  symrec *res = (symrec *) malloc (sizeof (symrec));
+  res->name = strdup (name);
+  res->type = sym_type;
+  res->value.var = 0; // Set value to 0 even if fun.
+  res->next = sym_table;
+  sym_table = res;
+  return res;
+}
+
+symrec *
+getsym (char const *name)
+{
+  for (symrec *p = sym_table; p; p = p->next)
+    if (strcmp (p->name, name) == 0)
+      return p;
+  return NULL;
+}
+
+// How many symbols are registered.
+int
+symbol_count (void)
+{
+  int res = 0;
+  for (symrec *p = sym_table; p; p = p->next)
+    ++res;
+  return res;
+}
+
+
+/*----------.
+| Scanner.  |
+`----------*/
+
+int
+yylex (const char **line, YYSTYPE *yylval, YYLTYPE *yylloc)
+{
+  int c;
+
+  // Ignore white space, get first nonwhite character.
+  do {
+    // Move the first position onto the last.
+    yylloc->first_line = yylloc->last_line;
+    yylloc->first_column = yylloc->last_column;
+
+    yylloc->last_column += 1;
+    c = *((*line)++);
+  } while (c == ' ' || c == '\t');
+
+  switch (c)
+    {
+    case '+': return TOK_PLUS;
+    case '-': return TOK_MINUS;
+    case '*': return TOK_STAR;
+    case '/': return TOK_SLASH;
+    case '^': return TOK_CARET;
+    case '=': return TOK_EQUAL;
+    case '(': return TOK_LPAREN;
+    case ')': return TOK_RPAREN;
+
+    case '\0': return TOK_YYEOF;
+
+      // Numbers.
+    case '.':
+    case '0': case '1': case '2': case '3': case '4':
+    case '5': case '6': case '7': case '8': case '9':
+      {
+        int nchars = 0;
+        sscanf (*line - 1, "%lf%n", &yylval->TOK_NUM, &nchars);
+          *line += nchars - 1;
+          yylloc->last_column += nchars - 1;
+          return TOK_NUM;
+      }
+
+      // Identifiers.
+    case 'a': case 'b': case 'c': case 'd': case 'e':
+    case 'f': case 'g': case 'h': case 'i': case 'j':
+    case 'k': case 'l': case 'm': case 'n': case 'o':
+    case 'p': case 'q': case 'r': case 's': case 't':
+    case 'u': case 'v': case 'w': case 'x': case 'y':
+    case 'z':
+      {
+        int nchars = 0;
+        char buf[100];
+        sscanf (*line - 1, "%99[a-z]%n", buf, &nchars);
+        *line += nchars - 1;
+        yylloc->last_column += nchars - 1;
+        if (strcmp (buf, "exit") == 0)
+          return TOK_EXIT;
+        else
+          {
+            symrec *s = getsym (buf);
+            if (!s)
+              s = putsym (buf, TOK_VAR);
+            yylval->TOK_VAR = s;
+            return s->type;
+          }
+      }
+
+      // Stray characters.
+    default:
+      yyerror (yylloc, "error: invalid character");
+      return yylex (line, yylval, yylloc);
+    }
+}
+
+
+/*---------.
+| Parser.  |
+`---------*/
+
+int
+yyreport_syntax_error (const yypcontext_t *ctx)
+{
+  int res = 0;
+  YY_LOCATION_PRINT (stderr, *yypcontext_location (ctx));
+  fprintf (stderr, ": syntax error");
+  // Report the tokens expected at this point.
+  {
+    enum { TOKENMAX = 10 };
+    yysymbol_kind_t expected[TOKENMAX];
+    int n = yypcontext_expected_tokens (ctx, expected, TOKENMAX);
+    if (n < 0)
+      // Forward errors to yyparse.
+      res = n;
+    else
+      for (int i = 0; i < n; ++i)
+        fprintf (stderr, "%s %s",
+                 i == 0 ? ": expected" : " or", yysymbol_name (expected[i]));
+  }
+  // Report the unexpected token.
+  {
+    yysymbol_kind_t lookahead = yypcontext_token (ctx);
+    if (lookahead != YYSYMBOL_YYEMPTY)
+      fprintf (stderr, " before %s", yysymbol_name (lookahead));
+  }
+  fprintf (stderr, "\n");
+  return res;
+}
+
+// Called by yyparse on error.
+void yyerror (YYLTYPE *loc, char const *msg)
+{
+  YY_LOCATION_PRINT (stderr, *loc);
+  fprintf (stderr, ": %s\n", msg);
+}
+
+
+/*-----------.
+| Readline.  |
+`-----------*/
+
+// Parse (and execute) this line.
+int process_line (YYLTYPE *lloc, const char *line)
+{
+  yypstate *ps = yypstate_new ();
+  int status = 0;
+  do {
+    YYSTYPE lval;
+    status = yypush_parse (ps, yylex (&line, &lval, lloc), &lval, lloc);
+  } while (status == YYPUSH_MORE);
+  yypstate_delete (ps);
+  lloc->last_line++;
+  lloc->last_column = 1;
+  return status;
+}
+
+// Get the list of possible tokens after INPUT was read.
+int
+expected_tokens (const char *input,
+                 int *tokens, int ntokens)
+{
+  YYDPRINTF ((stderr, "expected_tokens (\"%s\")", input));
+
+  // Parse the current state of the line.
+  yypstate *ps = yypstate_new ();
+  int status = 0;
+  do {
+    YYLTYPE lloc;
+    YYSTYPE lval;
+    int token = yylex (&input, &lval, &lloc);
+    // Don't let the parse know when we reach the end of input.
+    if (!token)
+      break;
+    status = yypush_parse (ps, token, &lval, &lloc);
+  } while (status == YYPUSH_MORE);
+
+  // Then query for the accepted tokens at this point.
+  int res = yypstate_expected_tokens (ps, tokens, ntokens);
+  yypstate_delete (ps);
+  return res;
+}
+
+/* Attempt to complete on the contents of TEXT.  START and END bound the
+   region of rl_line_buffer that contains the word to complete.  TEXT is
+   the word to complete.  We can use the entire contents of rl_line_buffer
+   in case we want to do some simple parsing.  Return the array of matches,
+   or NULL if there aren't any. */
+char **
+completion (const char *text, int start, int end)
+{
+  YYDPRINTF ((stderr, "completion (\"%.*s[%.*s]%s\")\n",
+              start, rl_line_buffer,
+              end - start, rl_line_buffer + start,
+              rl_line_buffer + end));
+
+  // Get list of token numbers.
+  int tokens[YYNTOKENS];
+  char *line = strndup (rl_line_buffer, start);
+  int ntokens = expected_tokens (line, tokens, YYNTOKENS);
+  free (line);
+
+  // Build MATCHES, the list of possible completions.
+  const int len = strlen (text);
+  // Need initial prefix and final NULL.
+  char **matches = calloc (ntokens + symbol_count () + 2, sizeof *matches);
+  int match = 1;
+  for (int i = 0; i < ntokens; ++i)
+    switch (tokens[i])
+      {
+      case YYSYMBOL_FUN:
+        for (symrec *s = sym_table; s; s = s->next)
+          if (s->type == TOK_FUN && strncmp (text, s->name, len) == 0)
+            matches[match++] = strdup (s->name);
+        break;
+      case YYSYMBOL_VAR:
+        for (symrec *s = sym_table; s; s = s->next)
+          if (s->type == TOK_VAR && strncmp (text, s->name, len) == 0)
+            matches[match++] = strdup (s->name);
+        break;
+      default:
+        {
+          const char* token = yysymbol_name (tokens[i]);
+          if (strncmp (text, token, len) == 0)
+            matches[match++] = strdup (token);
+          break;
+        }
+      }
+
+  // Find the longest common prefix, and install it in matches[0], as
+  // required by readline.
+  if (match == 1)
+    matches[0] = strdup (text);
+  else
+    {
+      int lcplen = strlen (matches[1]);
+      for (int i = 2; i < match && lcplen; ++i)
+        for (int j = 0; j < lcplen; ++j)
+          if (matches[1][j] != matches[i][j])
+            lcplen = j;
+      matches[0] = strndup (matches[1], lcplen);
+    }
+
+  if (yydebug)
+    {
+      fprintf (stderr, "completion (\"%.*s[%.*s]%s\") = ",
+               start, rl_line_buffer,
+               end - start, rl_line_buffer + start,
+               rl_line_buffer + end);
+      for (int i = 1; matches[i]; ++i)
+        fprintf (stderr, "%s%s",
+                 i == 1 ? "{" : ", ",
+                 matches[i]);
+      fprintf (stderr, "}\n");
+    }
+
+  // Don't fall back to proposing file names.
+  rl_attempted_completion_over = 1;
+  return matches;
+}
+
+void init_readline (void)
+{
+  // Allow conditional parsing of the ~/.inputrc file.
+  rl_readline_name = "bistromathic";
+
+  // Tell the completer that we want a crack first.
+  rl_attempted_completion_function = completion;
+
+  // The basic list of characters that signal a break between words
+  // for the completer routine.
+  rl_basic_word_break_characters = " \t\n\"\\'`@$><=;|&{(+-*/^)";
+}
+
+
+
+/*-------.
+| Main.  |
+`-------*/
+
+int main (int argc, char const* argv[])
+{
+  // Enable parse traces on option -p.
+  if (argc == 2 && strcmp (argv[1], "-p") == 0)
+    yydebug = 1;
+  init_table ();
+  init_readline ();
+  YYLTYPE lloc = {1, 1, 1, 1};
+  while (!done)
+    {
+      char *line = readline ("> ");
+      if (!line)
+        return 0;
+      if (*line)
+        add_history (line);
+      process_line (&lloc, line);
+      free (line);
+    }
+}

examples/c/calc/README.md

@@ -9,20 +9,15 @@ fill-column: 76
 ispell-dictionary: "american"
 End:
 
-Copyright (C) 2019 Free Software Foundation, Inc.
+Copyright (C) 2019-2020 Free Software Foundation, Inc.
 
 This file is part of Bison, the GNU Compiler Compiler.
 
-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.
+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.
 
-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 <http://www.gnu.org/licenses/>.
 --->

examples/c/calc/calc.test

@@ -1,6 +1,6 @@
 #! /bin/sh
 
-# Copyright (C) 2019 Free Software Foundation, Inc.
+# Copyright (C) 2019-2020 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
@@ -34,4 +34,10 @@ cat >input <<EOF
 (1+2) * 3
 EOF
 run 0 9
+# Check the traces.
 run -noerr 0 9 -p
+
+cat >input <<EOF
+1++2
+EOF
+run 0 "err: syntax error, unexpected '+', expecting number or '('"

examples/c/calc/calc.y

@@ -8,16 +8,22 @@
 }
 
 %define api.header.include {"calc.h"}
-%define api.value.type union /* Generate YYSTYPE from these types:  */
+
+/* Generate YYSTYPE from the types used in %token and %type.  */
+%define api.value.type union
 %token <double> NUM "number"
 %type  <double> expr term fact
 
-/* Generate the parser description file.  */
+/* Generate the parser description file (calc.output).  */
 %verbose
+
+/* Nice error messages with details. */
+%define parse.error detailed
+
 /* Enable run-time traces (yydebug).  */
 %define parse.trace
 
-/* Formatting semantic values.  */
+/* Formatting semantic values in debug traces.  */
 %printer { fprintf (yyo, "%g", $$); } <double>;
 
 %% /* The grammar follows.  */

examples/c/calc/local.mk

@@ -1,4 +1,4 @@
-## Copyright (C) 2019 Free Software Foundation, Inc.
+## Copyright (C) 2019-2020 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

examples/c/lexcalc/README.md

@@ -3,26 +3,22 @@
 This directory contains lexcalc, the traditional example of using Flex and
 Bison to build a simple calculator.
 
+It features detailed syntax errors with locations.
+
 <!---
 Local Variables:
 fill-column: 76
 ispell-dictionary: "american"
 End:
 
-Copyright (C) 2018-2019 Free Software Foundation, Inc.
+Copyright (C) 2018-2020 Free Software Foundation, Inc.
 
 This file is part of Bison, the GNU Compiler Compiler.
 
-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 <http://www.gnu.org/licenses/>.
+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/lexcalc/lexcalc.test

@@ -1,6 +1,6 @@
 #! /bin/sh
 
-# Copyright (C) 2018-2019 Free Software Foundation, Inc.
+# Copyright (C) 2018-2020 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
@@ -29,4 +29,9 @@ run -noerr 0 9 -p
 cat >input <<EOF
 (1+2) *
 EOF
-run 1 'err: syntax error, unexpected end-of-line, expecting ( or number'
+run 1 'err: 1.8-2.0: syntax error, unexpected end of line, expecting ( or number'
+
+cat >input <<EOF
+1 / (2 - 2)
+EOF
+run 1 'err: 1.1-11: error: division by zero'

examples/c/lexcalc/local.mk

@@ -1,4 +1,4 @@
-## Copyright (C) 2018-2019 Free Software Foundation, Inc.
+## Copyright (C) 2018-2020 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

examples/c/lexcalc/parse.y

@@ -6,10 +6,10 @@
 {
   // Tell Flex the expected prototype of yylex.
 #define YY_DECL                                 \
-  enum yytokentype yylex (YYSTYPE* yylval, int *nerrs)
+  yytoken_kind_t yylex (YYSTYPE* yylval, YYLTYPE *yylloc, int *nerrs)
   YY_DECL;
 
-  void yyerror (int *nerrs, const char *msg);
+  void yyerror (YYLTYPE *loc, int *nerrs, const char *msg);
 }
 
 // Emitted on top of the implementation file.
@@ -19,12 +19,27 @@
 #include <stdlib.h> // getenv.
 }
 
+// Don't share global variables between the scanner and the parser.
 %define api.pure full
+
+// To avoid name clashes (e.g., with C's EOF) prefix token definitions
+// with TOK_ (e.g., TOK_EOF).
 %define api.token.prefix {TOK_}
+
+// %token and %type use genuine types (e.g., "%token <int>").  Let
+// %bison define YYSTYPE as a union of all these types.
 %define api.value.type union
-%define parse.error verbose
+
+// Generate detailed error messages.
+%define parse.error detailed
+
+// with locations.
+%locations
+
+// Enable debug traces (see yydebug in main).
 %define parse.trace
- // Error count, exchanged between main, yyparse and yylex.
+
+// Error count, exchanged between main, yyparse and yylex.
 %param {int *nerrs}
 
 %token
@@ -34,8 +49,7 @@
   SLASH  "/"
   LPAREN "("
   RPAREN ")"
-  EOL    "end-of-line"
-  EOF 0  "end-of-file"
+  EOL    "end of line"
 ;
 
 %token <int> NUM "number"
@@ -66,7 +80,7 @@ exp:
   {
     if ($3 == 0)
       {
-        yyerror (nerrs, "invalid division by zero");
+        yyerror (&@$, nerrs, "error: division by zero");
         YYERROR;
       }
     else
@@ -77,9 +91,11 @@ exp:
 ;
 %%
 // Epilogue (C code).
-void yyerror (int *nerrs, const char *msg)
+
+void yyerror (YYLTYPE *loc, int *nerrs, const char *msg)
 {
-  fprintf (stderr, "%s\n", msg);
+  YY_LOCATION_PRINT (stderr, *loc);
+  fprintf (stderr, ": %s\n", msg);
   ++*nerrs;
 }
 

examples/c/lexcalc/scan.l

@@ -1,4 +1,4 @@
-/* Prologue (directives).   -*- C++ -*- */
+/* Prologue (directives).   -*- C -*- */
 
 /* Disable Flex features we don't need, to avoid warnings. */
 %option nodefault noinput nounput noyywrap
@@ -9,9 +9,24 @@
 #include <stdlib.h> /* strtol */
 
 #include "parse.h"
+
+  // Each time a rule is matched, advance the end cursor/position.
+#define YY_USER_ACTION                          \
+  yylloc->last_column += yyleng;
+
+  // Move the first position onto the last.
+#define LOCATION_STEP()                         \
+  do {                                          \
+    yylloc->first_line = yylloc->last_line;     \
+    yylloc->first_column = yylloc->last_column; \
+  } while (0)
 %}
 
 %%
+%{
+  // Each time yylex is called, move the head position to the end one.
+  LOCATION_STEP ();
+%}
  /* Rules.  */
 
 "+"      return TOK_PLUS;
@@ -27,18 +42,18 @@
   errno = 0;
   long n = strtol (yytext, NULL, 10);
   if (! (INT_MIN <= n && n <= INT_MAX && errno != ERANGE))
-    yyerror (nerrs, "integer is out of range");
+    yyerror (yylloc, nerrs, "integer is out of range");
   yylval->TOK_NUM = (int) n;
   return TOK_NUM;
 }
 
+"\n"     yylloc->last_line++; yylloc->last_column = 1; return TOK_EOL;
+
  /* Ignore white spaces. */
-[ \t]+   continue;
+[ \t]+   LOCATION_STEP (); continue;
 
-"\n"     return TOK_EOL;
+.        yyerror (yylloc, nerrs, "syntax error, invalid character"); continue;
 
-.        yyerror (nerrs, "syntax error, invalid character");
-
-<<EOF>>  return TOK_EOF;
+<<EOF>>  return TOK_YYEOF;
 %%
 /* Epilogue (C code). */

examples/c/local.mk

@@ -1,4 +1,4 @@
-## Copyright (C) 2018-2019 Free Software Foundation, Inc.
+## Copyright (C) 2018-2020 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
@@ -16,8 +16,10 @@
 cdir = $(docdir)/%D%
 dist_c_DATA = %D%/README.md
 
+include %D%/bistromathic/local.mk
 include %D%/calc/local.mk
 include %D%/lexcalc/local.mk
 include %D%/mfcalc/local.mk
+include %D%/pushcalc/local.mk
 include %D%/reccalc/local.mk
 include %D%/rpcalc/local.mk

examples/c/mfcalc/local.mk

@@ -1,4 +1,4 @@
-## Copyright (C) 2005-2006, 2008-2015, 2018-2019 Free Software
+## Copyright (C) 2005-2006, 2008-2015, 2018-2020 Free Software
 ## Foundation, Inc.
 ##
 ## This program is free software: you can redistribute it and/or modify

examples/c/mfcalc/mfcalc.test

@@ -1,6 +1,6 @@
 #! /bin/sh
 
-# Copyright (C) 2005-2015, 2018-2019 Free Software Foundation, Inc.
+# Copyright (C) 2005-2015, 2018-2020 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
@@ -25,3 +25,15 @@ cat >input <<EOF
 EOF
 run 0 9
 run -noerr 0 9 -p
+
+cat >input <<EOF
+a = 256
+sqrt (a)
+EOF
+run 0 '256
+16'
+
+cat >input <<EOF
+16 == 12
+EOF
+run 0 'err: syntax error'

examples/c/pushcalc/Makefile

@@ -0,0 +1,28 @@
+# This Makefile is designed to be simple and readable.  It does not
+# aim at portability.  It requires GNU Make.
+
+BASE = calc
+BISON = bison
+XSLTPROC = xsltproc
+
+all: $(BASE)
+
+%.c %.h %.xml %.gv: %.y
+	$(BISON) $(BISONFLAGS) --defines --xml --graph=$*.gv -o $*.c $<
+
+$(BASE): $(BASE).o
+	$(CC) $(CFLAGS) -o $@ $^
+
+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
+
+clean:
+	rm -f $(CLEANFILES)

examples/c/pushcalc/README.md

@@ -0,0 +1,32 @@
+# pushcalc - push parser with Bison
+
+This directory contains pushcalc, the traditional calculator, implemented as
+a push parser.
+
+Traditionally Bison is used to create so called "pull parsers": the user
+invokes the parser once, which repeatedly calls (pulls) the scanner until
+the input is drained.
+
+This example demonstrates the "push parsers": the user calls scanner to
+fetch the next token, passes (pushes) it to the parser, and repeats the
+operation until the input is drained.
+
+This example is a straightforward conversion of the 'calc' example to the
+push-parser model.
+
+<!---
+Local Variables:
+fill-column: 76
+ispell-dictionary: "american"
+End:
+
+Copyright (C) 2020 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
+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/pushcalc/calc.test

@@ -0,0 +1,42 @@
+#! /bin/sh
+
+# Copyright (C) 2020 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 <http://www.gnu.org/licenses/>.
+
+cat >input <<EOF
+1+2*3
+EOF
+run 0 7
+
+cat >input <<EOF
+1 - 2 - 3
+EOF
+run 0 -4
+
+cat >input <<EOF
+8 / 2 / 2
+EOF
+run 0 2
+
+cat >input <<EOF
+(1+2) * 3
+EOF
+run 0 9
+run -noerr 0 9 -p
+
+cat >input <<EOF
+1++2
+EOF
+run 0 "err: syntax error, unexpected '+', expecting number or '('"

examples/c/pushcalc/calc.y

@@ -0,0 +1,114 @@
+%code top {
+  #include <ctype.h>  /* isdigit. */
+  #include <stdbool.h>
+  #include <stdio.h>  /* For printf, etc. */
+  #include <string.h> /* strcmp. */
+}
+
+%code {
+  int yylex (YYSTYPE *yylval);
+  void yyerror (char const *);
+}
+
+%define api.header.include {"calc.h"}
+
+/* Generate YYSTYPE from the types used in %token and %type.  */
+%define api.value.type union
+%token <double> NUM "number"
+%type  <double> expr term fact
+
+/* Don't share global variables between the scanner and the parser.  */
+%define api.pure full
+/* Generate a push parser.  */
+%define api.push-pull push
+
+/* Nice error messages with details. */
+%define parse.error detailed
+
+/* Generate the parser description file (calc.output).  */
+%verbose
+
+ /* Enable run-time traces (yydebug).  */
+%define parse.trace
+
+/* Formatting semantic values in debug traces.  */
+%printer { fprintf (yyo, "%g", $$); } <double>;
+
+%% /* The grammar follows.  */
+input:
+  %empty
+| input line
+;
+
+line:
+  '\n'
+| expr '\n'  { printf ("%.10g\n", $1); }
+| error '\n' { yyerrok; }
+;
+
+expr:
+  expr '+' term { $$ = $1 + $3; }
+| expr '-' term { $$ = $1 - $3; }
+| term
+;
+
+term:
+  term '*' fact { $$ = $1 * $3; }
+| term '/' fact { $$ = $1 / $3; }
+| fact
+;
+
+fact:
+  "number"
+| '(' expr ')' { $$ = $expr; }
+;
+
+%%
+
+int
+yylex (YYSTYPE *yylval)
+{
+  int c;
+
+  /* Ignore white space, get first nonwhite character.  */
+  while ((c = getchar ()) == ' ' || c == '\t')
+    continue;
+
+  if (c == EOF)
+    return 0;
+
+  /* Char starts a number => parse the number.         */
+  if (c == '.' || isdigit (c))
+    {
+      ungetc (c, stdin);
+      scanf ("%lf", &yylval->NUM);
+      return NUM;
+    }
+
+  /* Any other character is a token by itself.        */
+  return c;
+}
+
+/* Called by yyparse on error.  */
+void
+yyerror (char const *s)
+{
+  fprintf (stderr, "%s\n", s);
+}
+
+int
+main (int argc, char const* argv[])
+{
+  /* Enable parse traces on option -p.  */
+  for (int i = 1; i < argc; ++i)
+    if (!strcmp (argv[i], "-p"))
+      yydebug = 1;
+  int status;
+  yypstate *ps = yypstate_new ();
+  do {
+    YYSTYPE lval;
+    status = yypush_parse (ps, yylex (&lval), &lval);
+  } while (status == YYPUSH_MORE);
+  yypstate_delete (ps);
+  return status;
+}

examples/c/pushcalc/local.mk

@@ -0,0 +1,33 @@
+## Copyright (C) 2020 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 <http://www.gnu.org/licenses/>.
+
+pushcalcdir = $(docdir)/%D%
+
+## ------ ##
+## Calc.  ##
+## ------ ##
+
+check_PROGRAMS += %D%/calc
+TESTS += %D%/calc.test
+EXTRA_DIST += %D%/calc.test
+nodist_%C%_calc_SOURCES = %D%/calc.y
+%D%/calc.c: $(dependencies)
+
+# Don't use gnulib's system headers.
+%C%_calc_CPPFLAGS = -I$(top_srcdir)/%D% -I$(top_builddir)/%D%
+
+dist_pushcalc_DATA = %D%/calc.y %D%/Makefile %D%/README.md
+CLEANFILES += %D%/calc.[ch] %D%/calc.output
+CLEANDIRS += %D%/*.dSYM

examples/c/reccalc/README.md

@@ -26,20 +26,13 @@ fill-column: 76
 ispell-dictionary: "american"
 End:
 
-Copyright (C) 2018-2019 Free Software Foundation, Inc.
+Copyright (C) 2018-2020 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.
 
-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 <http://www.gnu.org/licenses/>.
 --->

examples/c/reccalc/local.mk

@@ -1,4 +1,4 @@
-## Copyright (C) 2019 Free Software Foundation, Inc.
+## Copyright (C) 2019-2020 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

examples/c/reccalc/parse.y

@@ -4,7 +4,11 @@
 // Emitted in the header file, before the definition of YYSTYPE.
 %code requires
 {
+  #ifndef YY_TYPEDEF_YY_SCANNER_T
+  # define YY_TYPEDEF_YY_SCANNER_T
   typedef void* yyscan_t;
+  #endif
+
   typedef struct
   {
     // Whether to print the intermediate results.
@@ -22,7 +26,7 @@
   // Tell Flex the expected prototype of yylex.
   // The scanner argument must be named yyscanner.
 #define YY_DECL                                                         \
-  enum yytokentype yylex (YYSTYPE* yylval, yyscan_t yyscanner, result *res)
+  yytoken_kind_t yylex (YYSTYPE* yylval, yyscan_t yyscanner, result *res)
   YY_DECL;
 
   void yyerror (yyscan_t scanner, result *res, const char *msg, ...);
@@ -132,7 +136,6 @@ exp:
 
 %%
 // Epilogue (C code).
-
 #include "scan.h"
 
 result

examples/c/reccalc/reccalc.test

@@ -1,6 +1,6 @@
 #! /bin/sh
 
-# Copyright (C) 2018-2019 Free Software Foundation, Inc.
+# Copyright (C) 2018-2020 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
@@ -15,6 +15,8 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+seq 0 >/dev/null || exit 77
+
 cat >input <<EOF
 1+2*3
 EOF

examples/c/reccalc/scan.l

@@ -1,4 +1,4 @@
-/* Prologue (directives).   -*- C++ -*- */
+/* Prologue (directives).   -*- C -*- */
 
 /* Disable Flex features we don't need, to avoid warnings. */
 %option nodefault noinput nounput noyywrap
@@ -17,10 +17,14 @@
 
 %%
 %{
+  // Number of opened parentheses.
   int nesting = 0;
+  // A buffer storing the text inside the outer parentheses.
   char *str = NULL;
-  int size = 0;
+  // Its allocated size.
   int capacity = 0;
+  // Its used size.
+  int size = 0;
 #define STR_APPEND()                                    \
   do {                                                  \
     if (capacity < size + yyleng + 1)                   \

examples/c/rpcalc/local.mk

@@ -1,4 +1,4 @@
-## Copyright (C) 2005-2006, 2008-2015, 2018-2019 Free Software
+## Copyright (C) 2005-2006, 2008-2015, 2018-2020 Free Software
 ## Foundation, Inc.
 ##
 ## This program is free software: you can redistribute it and/or modify

examples/c/rpcalc/rpcalc.test

@@ -1,6 +1,6 @@
 #! /bin/sh
 
-# Copyright (C) 2005-2015, 2018-2019 Free Software Foundation, Inc.
+# Copyright (C) 2005-2015, 2018-2020 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

examples/d/README.md

@@ -15,7 +15,7 @@ fill-column: 76
 ispell-dictionary: "american"
 End:
 
-Copyright (C) 2018-2019 Free Software Foundation, Inc.
+Copyright (C) 2018-2020 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/d/calc.test

@@ -1,6 +1,6 @@
 #! /bin/sh
 
-# Copyright (C) 2018-2019 Free Software Foundation, Inc.
+# Copyright (C) 2018-2020 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