version 3.6.3

* NEWS: Record release date.

.prev-version

@@ -1 +1 @@
-3.5.94
+3.6.2

.travis.yml

@@ -46,7 +46,7 @@ jobs:
         - ./bootstrap
         - ./configure --enable-gcc-warnings || { cat config.log && false; }
         - make -j2
-        - make -j2 dist
+        - make -j2 dist-xz
         # Can help understanding why we get "dirty" tarballs.
         - git status
         - dist=$(echo bison*.xz)
@@ -69,53 +69,53 @@ jobs:
 
     # Start with three completely different environments, to get errors asap.
 
-    - name: "GCC 9 -O3"
+    - name: "GCC 10 -O3"
       stage: check
       os: linux
       dist: bionic
-      addons: &gcc9
+      addons: &gcc10
         apt:
           sources:
             # See https://github.com/travis-ci/apt-source-safelist/issues/410.
             - sourceline: 'ppa:ubuntu-toolchain-r/test'
-          packages: g++-9
+          packages: g++-10
       env:
-        - CC=gcc-9
-        - CXX=g++-9
+        - CC=gcc-10
+        - CXX=g++-10
         - CONFIGUREFLAGS='CPPFLAGS=-DNDEBUG CFLAGS=-O3 CXXFLAGS=-O3'
 
     # ASAN is time consuming, and we timeout the 50min granted by
     # Travis if we run all the tests in one go.  Run in two parts.
-    - name: "Clang 9 libc++ and ASAN part 1"
+    - name: "Clang 10 libc++ and ASAN part 1"
       stage: check
       os: linux
       dist: bionic
-      addons: &clang9
+      addons: &clang10
         apt:
           sources:
             # See https://github.com/travis-ci/apt-source-safelist/issues/410.
             - sourceline: 'ppa:ubuntu-toolchain-r/test'
-            - sourceline: 'deb http://apt.llvm.org/bionic/ llvm-toolchain-bionic-9 main'
+            - sourceline: 'deb http://apt.llvm.org/bionic/ llvm-toolchain-bionic-10 main'
               key_url: 'https://apt.llvm.org/llvm-snapshot.gpg.key'
           packages:
-            - clang-9
-            - libc++-9-dev
-            - libc++abi-9-dev
+            - clang-10
+            - libc++-10-dev
+            - libc++abi-10-dev
       env:
         # Do not use ASAN with ubuntu's libc++: https://bugs.llvm.org/show_bug.cgi?id=17379
-        - CC='clang-9 -fsanitize=address'
-        - CXX='clang++-9 -fsanitize=address -stdlib=libc++'
+        - CC='clang-10 -fsanitize=address'
+        - CXX='clang++-10 -fsanitize=address -stdlib=libc++'
         - PART=1
 
-    - name: "Clang 9 libc++ and ASAN part 2"
+    - name: "Clang 10 libc++ and ASAN part 2"
       stage: check
       os: linux
       dist: bionic
-      addons: *clang9
+      addons: *clang10
       env:
         # Do not use ASAN with ubuntu's libc++: https://bugs.llvm.org/show_bug.cgi?id=17379
-        - CC='clang-9 -fsanitize=address'
-        - CXX='clang++-9 -fsanitize=address -stdlib=libc++'
+        - CC='clang-10 -fsanitize=address'
+        - CXX='clang++-10 -fsanitize=address -stdlib=libc++'
         - PART=2
 
     - name: "ICC"
@@ -135,46 +135,41 @@ jobs:
           packages:
           - intel-oneapi-icc
 
-    ## ------- ##
-    ## First.  ##
-    ## ------- ##
-
-    # Start with three completely different environments, to get
-    # errors asap.
-
-    - name: "ARM64: GCC 9 -O3 part 1"
+    - name: "ARM64: GCC 10 -O3 part 1"
       stage: check
       os: linux
       arch: arm64
       dist: bionic
-      addons: *gcc9
+      addons: *gcc10
       env:
-        - CC=gcc-9
-        - CXX=g++-9
+        - CC=gcc-10
+        - CXX=g++-10
         - CONFIGUREFLAGS='CPPFLAGS=-DNDEBUG CFLAGS=-O3 CXXFLAGS=-O3'
         - PART=1
 
+    # GCC10 on PPC seems to be buggy.
+    # E.g., https://travis-ci.org/github/akimd/bison/jobs/687812428.
     - name: "PPC64le: GCC 9 part 1"
       stage: check
       os: linux
       arch: ppc64le
       dist: bionic
-      addons: *gcc9
+      addons: *gcc10
       env:
         - CC=gcc-9
         - CXX=g++-9
         - CONFIGUREFLAGS='CFLAGS=-O3 CXXFLAGS=-O3'
         - PART=1
 
-    - name: "s390x: GCC 9 part 1"
+    - name: "s390x: GCC 10 part 1"
       stage: check
       os: linux
       arch: s390x
       dist: bionic
-      addons: *gcc9
+      addons: *gcc10
       env:
-        - CC=gcc-9
-        - CXX=g++-9
+        - CC=gcc-10
+        - CXX=g++-10
         - CONFIGUREFLAGS='CFLAGS=-O3 CXXFLAGS=-O3'
         - PART=1
 
@@ -182,15 +177,19 @@ jobs:
     ## GCC.  ##
     ## ----- ##
 
-    - name: "GCC 8 with sanitizers part 1"
+    - name: "GCC 9 with sanitizers part 1"
+      stage: check
       os: linux
       dist: bionic
       addons:
         apt:
-          packages: g++-8
+          sources:
+            # See https://github.com/travis-ci/apt-source-safelist/issues/410.
+            - sourceline: 'ppa:ubuntu-toolchain-r/test'
+          packages: g++-9
       env:
-        - CC='gcc-8 -fsanitize=undefined,address -fno-omit-frame-pointer'
-        - CXX='g++-8 -fsanitize=undefined,address -fno-omit-frame-pointer'
+        - CC='gcc-9 -fsanitize=undefined,address -fno-omit-frame-pointer'
+        - CXX='g++-9 -fsanitize=undefined,address -fno-omit-frame-pointer'
         - CONFIGUREFLAGS='CFLAGS=-O1 CXXFLAGS=-O1'
         - PART=1
 
@@ -292,7 +291,27 @@ jobs:
     ## Clang.  ##
     ## ------- ##
 
-    - name: "Clang 8 -O3"
+    - name: "Clang 9 -O3"
+      stage: check
+      os: linux
+      dist: bionic
+      addons:
+        apt:
+          sources:
+            # See https://github.com/travis-ci/apt-source-safelist/issues/410.
+            - sourceline: 'ppa:ubuntu-toolchain-r/test'
+            - sourceline: 'deb http://apt.llvm.org/bionic/ llvm-toolchain-bionic-9 main'
+              key_url: 'https://apt.llvm.org/llvm-snapshot.gpg.key'
+          packages:
+            - clang-9
+            - libc++-9-dev
+            - libc++abi-9-dev
+      env:
+        - CC='clang-9'
+        - CXX='clang++-9 -stdlib=libc++'
+        - CONFIGUREFLAGS='CPPFLAGS=-DNDEBUG CFLAGS=-O3 CXXFLAGS=-O3'
+
+    - name: "Clang 8"
       stage: check
       os: linux
       dist: bionic
@@ -305,7 +324,6 @@ jobs:
       env:
         - CC=clang-8
         - CXX='clang++-8 -stdlib=libc++'
-        - CONFIGUREFLAGS='CPPFLAGS=-DNDEBUG CFLAGS=-O3 CXXFLAGS=-O3'
 
     - name: "Clang 7"
       stage: check

Makefile.am

@@ -127,3 +127,7 @@ gen-ChangeLog:
 	    --since=$(gen_start_date) > $$cl.tmp &&	\
 	  mv -f $$cl.tmp $$cl;				\
 	fi
+
+# Useful to debug.
+.c.i:
+	$(CC) $(AM_CPPFLAGS) $(CPPFLAGS) $(AM_CFLAGS) $(CFLAGS) -o $@ -E $<

NEWS

@@ -1,5 +1,41 @@
 GNU Bison NEWS
 
+* Noteworthy changes in release 3.6.3 (2020-06-03) [stable]
+
+** Bug fixes
+
+  Incorrect comments in the generated parsers.
+
+  Warnings in push parsers (yacc.c).
+
+  Incorrect display of gotos in LAC traces (lalr1.cc).
+
+* Noteworthy changes in release 3.6.2 (2020-05-17) [stable]
+
+** Bug fixes
+
+  Some tests were fixed.
+
+  When token aliases contain comment delimiters:
+
+    %token FOO "/* foo */"
+
+  bison used to emit "nested" comments, which is invalid C.
+
+* Noteworthy changes in release 3.6.1 (2020-05-10) [stable]
+
+** Bug fixes
+
+  Restored ANSI-C compliance in yacc.c.
+
+  GNU readline portability issues.
+
+  In C++, yy::parser::symbol_name is now a public member, as was intended.
+
+** New features
+
+  In C++, yy::parser::symbol_type now has a public name() member function.
+
 * Noteworthy changes in release 3.6 (2020-05-08) [stable]
 
 ** Backward incompatible changes

THANKS

@@ -162,6 +162,7 @@ Quoc Peyrot               [email protected]
 R Blake                   [email protected]
 Raja R Harinath           [email protected]
 Ralf Wildenhues           [email protected]
+Ryan                      [email protected]
 Rich Wilson               [email protected]
 Richard Stallman          [email protected]
 Rici Lake                 [email protected]

TODO

@@ -1,4 +1,12 @@
-* Bison 3.6
+* Bison 3.7
+** Bistromathic
+- Hitting tab on a line with a syntax error is ugly
+
+- Be robust to existing ~/.inputrc
+
+- How about not evaluating incomplete lines when the text is not finished
+  (as shells do).
+
 ** Doc
 *** api.header.include
 
@@ -31,7 +39,6 @@ enough.
 *** calc.at
 Stop hard-coding "Calc".  Adjust local.at (look for FIXME).
 
-* Bison 3.7
 ** Counter example generation
 See https://github.com/akimd/bison/pull/15.
 
@@ -121,6 +128,25 @@ Rici:
 > At a minimum, the fact that yyclearin does not invoke the %destructor
 > should be highlighted in the documentation, since it is not at all obvious.
 
+** Issues in i18n
+
+Les catégories d'avertissements incluent :
+  conflicts-sr      conflits S/R (activé par défaut)
+  conflicts-rr      conflits R/R (activé par défaut)
+  dangling-alias    l'alias chaîne n'est pas attaché à un symbole
+  deprecated        construction obsolète
+  empty-rule        règle vide sans %empty
+  midrule-values    valeurs de règle intermédiaire non définies ou inutilisées
+  precedence        priorité et associativité inutiles
+  yacc              incompatibilités avec POSIX Yacc
+  other             tous les autres avertissements (activé par défaut)
+  all               tous les avertissements sauf « dangling-alias » et « yacc »
+  no-CATEGORY       désactiver les avertissements dans CATEGORIE
+  none              désactiver tous les avertissements
+  error[=CATEGORY]  traiter les avertissements comme des erreurs
+
+Line -1 and -3 should mention CATEGORIE, not CATEGORY.
+
 * Bison 3.8
 ** Unit rules / Injection rules (Akim Demaille)
 Maybe we could expand unit rules (or "injections", see

build-aux/update-test

@@ -73,6 +73,11 @@ def diff_to_re(match):
             is_diff = True
             to.append(l)
     if is_diff:
+        # Do not run s//SOMETHING/g (with an emty pattern), that won't
+        # work well...
+        if frm == []:
+            trace("no from for", match.group(1))
+            return
         frm = "\n".join(frm)
         to = "\n".join(to)
         subst[frm] = to
@@ -112,4 +117,6 @@ def process(logfile):
 
 for logfile in args.logs:
     trace("FILE:", logfile)
+    if os.path.isdir(logfile):
+        logfile = os.path.join(logfile, 'testsuite.log')
     process(logfile)

cfg.mk

@@ -51,7 +51,7 @@ gnulib_dir = $(srcdir)/gnulib
 bootstrap-tools = autoconf,automake,flex,gettext,gnulib
 
 announcement_Cc_ = \
-  [email protected], [email protected], bison-patches@gnu.org, \
+  [email protected], bison-announce@gnu.org, \
   [email protected]
 
 update-copyright: update-b4-copyright update-package-copyright-year

configure.ac

@@ -36,10 +36,8 @@ AC_DEFINE_UNQUOTED([PACKAGE_COPYRIGHT_YEAR], [$PACKAGE_COPYRIGHT_YEAR],
 AC_CONFIG_AUX_DIR([build-aux])
 AC_CONFIG_MACRO_DIR([m4])
 
-# We use Automake 1.14's %D% and %C%.
-#
 # When we move to Automake 1.16, simplify examples/c/reccalc/local.mk.
-# Our CI runs on Xenial, which has only Automake 1.15.
+# Our CI build the packages on Bionic, which has only Automake 1.15.
 #
 # We want gnits strictness only when rolling a stable release.  For
 # release candidates, we use version strings like 2.4.3_rc1, but gnits
@@ -47,7 +45,7 @@ AC_CONFIG_MACRO_DIR([m4])
 # releases, we want to be able run make dist without being required to
 # add a bogus NEWS entry.  In that case, the version string
 # automatically contains a dash, which we also let disable gnits.
-AM_INIT_AUTOMAKE([1.14 dist-xz nostdinc
+AM_INIT_AUTOMAKE([1.15 dist-lzip dist-xz nostdinc
                  color-tests parallel-tests
                  silent-rules]
                  m4_bmatch(m4_defn([AC_PACKAGE_VERSION]), [[-_]],
@@ -137,7 +135,9 @@ if test "$enable_gcc_warnings" = yes; then
     -Wpointer-arith -Wshadow
     -Wwrite-strings
     -wr188 -wr2259 -wr3179'
-  warn_c='-Wbad-function-cast -Wstrict-prototypes'
+  warn_c='-Wbad-function-cast
+    -Wmissing-prototypes
+    -Wstrict-prototypes'
   warn_cxx='-Wextra-semi -Wnoexcept -Wold-style-cast -Wundefined-func-template
     -Wweak-vtables'
   # Warnings for the test suite only.

data/local.mk

@@ -34,6 +34,7 @@ dist_skeletons_DATA =                           \
   data/skeletons/lalr1.java                     \
   data/skeletons/location.cc                    \
   data/skeletons/stack.hh                       \
+  data/skeletons/traceon.m4                     \
   data/skeletons/variant.hh                     \
   data/skeletons/yacc.c
 

data/skeletons/bison.m4

@@ -19,6 +19,27 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 
+
+# m4_gsub(STRING, RE1, SUBST1, RE2, SUBST2, ...)
+# ----------------------------------------------
+# m4 equivalent of
+#
+#   $_ = STRING;
+#   s/RE1/SUBST1/g;
+#   s/RE2/SUBST2/g;
+#   ...
+#
+# Really similar to m4_bpatsubsts, but behaves properly with quotes.
+# See m4.at's "Generating Comments".  Super inelegant, but so far, I
+# did not find any better solution.
+m4_define([b4_gsub],
+[m4_bpatsubst(m4_bpatsubst(m4_bpatsubst([[[[$1]]]],
+                                        [$2], [$3]),
+                           [$4], [$5]),
+              [$6], [$7])])
+
+
+
 ## ---------------- ##
 ## Identification.  ##
 ## ---------------- ##

data/skeletons/c++.m4

@@ -357,6 +357,29 @@ m4_define([b4_symbol_type_define],
         Base::clear ();
       }
 
+]b4_parse_error_bmatch(
+[custom\|detailed],
+[[      /// The user-facing name of this symbol.
+      const char *name () const YY_NOEXCEPT
+      {
+        return ]b4_parser_class[::symbol_name (this->kind ());
+      }]],
+[simple],
+[[#if ]b4_api_PREFIX[DEBUG || ]b4_token_table_flag[
+      /// The user-facing name of this symbol.
+      const char *name () const YY_NOEXCEPT
+      {
+        return ]b4_parser_class[::symbol_name (this->kind ());
+      }
+#endif // #if ]b4_api_PREFIX[DEBUG || ]b4_token_table_flag[
+]],
+[verbose],
+[[      /// The user-facing name of this symbol.
+      std::string name () const YY_NOEXCEPT
+      {
+        return ]b4_parser_class[::symbol_name (this->kind ());
+      }]])[
+
       /// Backward compatibility (Bison 3.6).
       symbol_kind_type type_get () const YY_NOEXCEPT;
 

data/skeletons/c-like.m4

@@ -17,15 +17,21 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+
 # _b4_comment(TEXT, OPEN, CONTINUE, END)
 # --------------------------------------
 # Put TEXT in comment.  Avoid trailing spaces: don't indent empty lines.
 # Avoid adding indentation to the first line, as the indentation comes
 # from OPEN.  That's why we don't patsubst([$1], [^\(.\)], [   \1]).
+# Turn "*/" in TEXT into "* /" so that we don't unexpectedly close
+# the comments before its end.
 #
 # Prefix all the output lines with PREFIX.
 m4_define([_b4_comment],
-[$2[]m4_bpatsubst(m4_expand([[$1]]), [
+[$2[]b4_gsub(m4_expand([$1]),
+            [[*]/], [*\\/],
+            [/[*]], [/\\*],
+            [
 \(.\)], [
 $3\1])$4])
 

data/skeletons/lalr1.cc

@@ -241,6 +241,23 @@ m4_define([b4_shared_declarations],
     /// Report a syntax error.
     void error (const syntax_error& err);
 
+]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);]],
+[simple],
+[[#if ]b4_api_PREFIX[DEBUG || ]b4_token_table_flag[
+    /// The user-facing name of the symbol whose (internal) number is
+    /// YYSYMBOL.  No bounds checking.
+    static const char *symbol_name (symbol_kind_type yysymbol);
+#endif // #if ]b4_api_PREFIX[DEBUG || ]b4_token_table_flag[
+]],
+[verbose],
+[[    /// The user-facing name of the symbol whose (internal) number is
+    /// YYSYMBOL.  No bounds checking.
+    static std::string symbol_name (symbol_kind_type yysymbol);]])[
+
 ]b4_token_constructor_define[
 ]b4_parse_error_bmatch([custom\|detailed\|verbose], [[
     class context
@@ -317,26 +334,14 @@ m4_define([b4_shared_declarations],
     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);]],
 [simple],
 [[#if ]b4_api_PREFIX[DEBUG || ]b4_token_table_flag[
-    /// The user-facing name of the symbol whose (internal) number is
-    /// YYSYMBOL.  No bounds checking.
-    static const char *symbol_name (symbol_kind_type yysymbol);
-
     /// For a symbol, its name in clear.
     static const char* const yytname_[];
 #endif // #if ]b4_api_PREFIX[DEBUG || ]b4_token_table_flag[
 ]],
 [verbose],
-[[    /// The user-facing name of the symbol whose (internal) number is
-    /// YYSYMBOL.  No bounds checking.
-    static std::string symbol_name (symbol_kind_type yysymbol);
-
-    /// Convert the symbol name \a n to a form suitable for a diagnostic.
+[[    /// Convert the symbol name \a n to a form suitable for a diagnostic.
     static std::string yytnamerr_ (const char *yystr);
 
     /// For a symbol, its name in clear.
@@ -474,6 +479,7 @@ m4_define([b4_shared_declarations],
     };
 
 ]b4_parse_param_vars[
+]b4_percent_code_get([[yy_bison_internal_hook]])[
   };
 
 ]b4_token_ctor_if([b4_yytranslate_define([$1])[
@@ -607,83 +613,6 @@ m4_if(b4_prefix, [yy], [],
 #define YYRECOVERING()  (!!yyerrstatus_)
 
 ]b4_namespace_open[
-]b4_parse_error_bmatch([custom\|detailed],
-[[  const char *
-  ]b4_parser_class[::symbol_name (symbol_kind_type yysymbol)
-  {
-    static const char *const yy_sname[] =
-    {
-    ]b4_symbol_names[
-    };]b4_has_translations_if([[
-    /* YYTRANSLATABLE[SYMBOL-NUM] -- Whether YY_SNAME[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];]])[
-  }
-]],
-[simple],
-[[#if ]b4_api_PREFIX[DEBUG || ]b4_token_table_flag[
-  const char *
-  ]b4_parser_class[::symbol_name (symbol_kind_type yysymbol)
-  {
-    return yytname_[yysymbol];
-  }
-#endif // #if ]b4_api_PREFIX[DEBUG || ]b4_token_table_flag[
-]],
-[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.  */
-  std::string
-  ]b4_parser_class[::yytnamerr_ (const char *yystr)
-  {
-    if (*yystr == '"')
-      {
-        std::string yyr;
-        char const *yyp = yystr;
-
-        for (;;)
-          switch (*++yyp)
-            {
-            case '\'':
-            case ',':
-              goto do_not_strip_quotes;
-
-            case '\\':
-              if (*++yyp != '\\')
-                goto do_not_strip_quotes;
-              else
-                goto append;
-
-            append:
-            default:
-              yyr += *yyp;
-              break;
-
-            case '"':
-              return yyr;
-            }
-      do_not_strip_quotes: ;
-      }
-
-    return yystr;
-  }
-
-  std::string
-  ]b4_parser_class[::symbol_name (symbol_kind_type yysymbol)
-  {
-    return yytnamerr_ (yytname_[yysymbol]);
-  }
-]])[
-
   /// Build a parser object.
   ]b4_parser_class::b4_parser_class[ (]b4_parse_param_decl[)
 #if ]b4_api_PREFIX[DEBUG
@@ -815,7 +744,7 @@ m4_if(b4_prefix, [yy], [],
       {
         symbol_kind_type yykind = yysym.kind ();
         yyo << (yykind < YYNTOKENS ? "token" : "nterm")
-            << ' ' << symbol_name (yykind) << " ("]b4_locations_if([
+            << ' ' << yysym.name () << " ("]b4_locations_if([
             << yysym.location << ": "])[;
         ]b4_symbol_actions([printer])[
         yyo << ')';
@@ -1267,8 +1196,86 @@ b4_dollar_popdef])[]dnl
   {
     error (]b4_join(b4_locations_if([yyexc.location]),
                     [[yyexc.what ()]])[);
-  }]b4_parse_error_bmatch([custom\|detailed\|verbose], [[
+  }
 
+]b4_parse_error_bmatch([custom\|detailed],
+[[  const char *
+  ]b4_parser_class[::symbol_name (symbol_kind_type yysymbol)
+  {
+    static const char *const yy_sname[] =
+    {
+    ]b4_symbol_names[
+    };]b4_has_translations_if([[
+    /* YYTRANSLATABLE[SYMBOL-NUM] -- Whether YY_SNAME[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];]])[
+  }
+]],
+[simple],
+[[#if ]b4_api_PREFIX[DEBUG || ]b4_token_table_flag[
+  const char *
+  ]b4_parser_class[::symbol_name (symbol_kind_type yysymbol)
+  {
+    return yytname_[yysymbol];
+  }
+#endif // #if ]b4_api_PREFIX[DEBUG || ]b4_token_table_flag[
+]],
+[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.  */
+  std::string
+  ]b4_parser_class[::yytnamerr_ (const char *yystr)
+  {
+    if (*yystr == '"')
+      {
+        std::string yyr;
+        char const *yyp = yystr;
+
+        for (;;)
+          switch (*++yyp)
+            {
+            case '\'':
+            case ',':
+              goto do_not_strip_quotes;
+
+            case '\\':
+              if (*++yyp != '\\')
+                goto do_not_strip_quotes;
+              else
+                goto append;
+
+            append:
+            default:
+              yyr += *yyp;
+              break;
+
+            case '"':
+              return yyr;
+            }
+      do_not_strip_quotes: ;
+      }
+
+    return yystr;
+  }
+
+  std::string
+  ]b4_parser_class[::symbol_name (symbol_kind_type yysymbol)
+  {
+    return yytnamerr_ (yytname_[yysymbol]);
+  }
+]])[
+
+]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)
@@ -1404,7 +1411,7 @@ b4_dollar_popdef])[]dnl
                      : yylac_stack_.back ());
         // Push the resulting state of the reduction.
         state_type state = yy_lr_goto_state_ (top_state, yyr1_[yyrule]);
-        YYCDEBUG << " G" << state;
+        YYCDEBUG << " G" << int (state);
         yylac_stack_.push_back (state);
       }
   }

data/skeletons/traceon.m4

@@ -0,0 +1,2 @@
+dnl GNU M4 treats -dV in a position-independent manner.
+m4_debugmode(V)m4_traceon()dnl

data/skeletons/yacc.c

@@ -1480,7 +1480,7 @@ yypull_parse (yypstate *yyps]b4_user_formals[)
 ]b4_parse_state_variable_macros([b4_pstate_macro_define])[
 
 /* Initialize the parser data structure.  */
-void
+static void
 yypstate_clear (yypstate *yyps)
 {
 ]b4_initialize_parser_state_variables[
@@ -1979,7 +1979,7 @@ yyerrorlab:
 yyerrlab1:
   yyerrstatus = 3;      /* Each real token shifted decrements this.  */
 
-  // Pop stack until we find a state that shifts the error token.
+  /* Pop stack until we find a state that shifts the error token.  */
   for (;;)
     {
       yyn = yypact[yystate];

doc/bison.texi

@@ -1879,6 +1879,7 @@ Here is the code for the lexical analyzer:
    and tabs, and returns 0 for end-of-input. */
 
 #include <ctype.h>
+#include <stdlib.h>
 @end group
 
 @group
@@ -1895,7 +1896,8 @@ yylex (void)
   if (c == '.' || isdigit (c))
     @{
       ungetc (c, stdin);
-      scanf ("%lf", &yylval);
+      if (scanf ("%lf", &yylval) != 1)
+        abort ();
       return NUM;
     @}
 @end group
@@ -2728,7 +2730,8 @@ yylex (void)
   if (c == '.' || isdigit (c))
     @{
       ungetc (c, stdin);
-      scanf ("%lf", &yylval.NUM);
+      if (scanf ("%lf", &yylval.NUM) != 1)
+        abort ();
       return NUM;
     @}
 @end group
@@ -2755,10 +2758,10 @@ Bison generated a definition of @code{YYSTYPE} with a member named
           if (bufsize <= i)
             @{
               bufsize = 2 * bufsize + 40;
-              symbuf = realloc (symbuf, bufsize);
+              symbuf = realloc (symbuf, (size_t) bufsize);
             @}
           /* Add this character to the buffer. */
-          symbuf[i++] = c;
+          symbuf[i++] = (char) c;
           /* Get another character. */
           c = getchar ();
         @}
@@ -10629,7 +10632,7 @@ when there were errors.  No file was generated (except the reports generated
 by @option{--verbose}, etc.).  In particular, the output files that possibly
 existed were not changed.
 
-@item 63 (mistmatch)
+@item 63 (mismatch)
 when @command{bison} does not meet the version requirements of the grammar
 file. @xref{Require Decl}.  No file was generated or changed.
 @end table
@@ -12154,6 +12157,8 @@ values, which is always less than @code{YYNTOKENS}.
 
 @deftypemethod {parser} {const char *} symbol_name (@code{symbol_kind_t} @var{symbol}) @code{const}
 The name of the symbol whose kind is @var{symbol}, possibly translated.
+
+Returns a @code{std::string} when @code{parse.error} is @code{verbose}.
 @end deftypemethod
 
 A custom syntax error function looks as follows.  This implementation is
@@ -12286,6 +12291,12 @@ applicable) location.
 The kind of this symbol.
 @end deftypemethod
 
+@deftypemethod {symbol_type} {const char *} name () @code{const}
+The name of the kind of this symbol.
+
+Returns a @code{std::string} when @code{parse.error} is @code{verbose}.
+@end deftypemethod
+
 @sp 1
 
 For each token kind, Bison generates named constructors as follows.
@@ -15261,6 +15272,7 @@ London, Department of Computer Science, TR-00-12 (December 2000).
 @c LocalWords: YYUNDEF SymbolKind yypcontext YYENOMEM TOKENMAX getBundle
 @c LocalWords: ResourceBundle myResources getString getName getToken
 @c LocalWords: getLocation getExpectedTokens reportSyntaxError bistromathic
+@c LocalWords: TokenKind
 
 @c Local Variables:
 @c ispell-dictionary: "american"

examples/c++/README.md

@@ -13,8 +13,8 @@ semantic value.
 
 Run as `./simple`.
 
-Extracted from the documentation: "A Simple C++ Example".
-https://www.gnu.org/software/bison/manual/html_node/A-Simple-C_002b_002b-Example.html
+Extracted from the documentation: [A Simple C++
+Example](https://www.gnu.org/software/bison/manual/html_node/A-Simple-C_002b_002b-Example.html).
 
 ## variant.yy - Self-contained example in C++98
 A variation of simple.yy, in C++98.
@@ -36,8 +36,8 @@ starting point for a clean parser in C++.  The previous examples are better
 introductory examples, and the C examples are also useful introductory
 examples.
 
-Extracted from the documentation: "A Complete C++ Example".
-https://www.gnu.org/software/bison/manual/html_node/A-Complete-C_002b_002b-Example.html
+Extracted from the documentation: [A Complete C++
+Example](https://www.gnu.org/software/bison/manual/html_node/A-Complete-C_002b_002b-Example.html).
 
 <!---
 

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

@@ -5,9 +5,9 @@ saw the traditional implementation in C, please first read
 examples/c/lexcalc, which can be seen as a C precursor of this example.
 
 Read the corresponding chapter in the documentation: "A Complete C++
-Example".  It is also available on line (maybe with a different version of
-Bison):
-https://www.gnu.org/software/bison/manual/html_node/A-Complete-C_002b_002b-Example.html
+Example".  It is also available [on
+line](https://www.gnu.org/software/bison/manual/html_node/A-Complete-C_002b_002b-Example.html)
+(maybe with a different version of Bison).
 
 To use it, copy this directory into some work directory, and run `make` to
 compile the executable, and try it.  It is a simple calculator which accepts

examples/c/README.md

@@ -10,8 +10,8 @@ The first example is that of a simple double-precision Reverse Polish
 Notation calculator (a calculator using postfix operators). This example
 provides a good starting point, since operator precedence is not an issue.
 
-Extracted from the documentation: "Reverse Polish Notation Calculator"
-https://www.gnu.org/software/bison/manual/html_node/RPN-Calc.html
+Extracted from the documentation: [Reverse Polish Notation
+Calculator](https://www.gnu.org/software/bison/manual/html_node/RPN-Calc.html).
 
 ## calc - Simple Calculator
 This example is slightly more complex than rpcalc: it features infix
@@ -24,18 +24,18 @@ A more complete C example: a multi-function calculator.  More complex than
 the previous example.  Using precedence directives to support infix
 operators.
 
-Extracted from the documentation: "Multi-Function Calculator: mfcalc".
-https://www.gnu.org/software/bison/manual/html_node/Multi_002dfunction-Calc.html
+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 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.
-Such parsers can be called concurrently in different threads, or even
-recursively.  To demonstrate this feature, expressions in parentheses are
-tokenized as strings, and then recursively parsed from the parser.  So
+This example builds on top of the previous one to provide a reentrant
+parser.  Such parsers can be called concurrently in different threads, or
+even 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

examples/c/bistromathic/README.md

@@ -14,6 +14,9 @@ This example demonstrates best practices when using Bison.
 - It supports debug traces with semantic values.
 - It uses named references instead of the traditional $1, $2, etc.
 
+To customize the interaction with bistromathic, see the GNU Readline user
+manual (see `info rluserman`).
+
 <!---
 Local Variables:
 fill-column: 76

examples/c/bistromathic/bistromathic.test

@@ -15,6 +15,10 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+# Users may customize the behavior of readline, which might break our
+# expected results.
+INPUTRC=/dev/null
+export INPUTRC
 
 # Beware of portability issues of readline when not feeding it from a
 # terminal.
@@ -41,7 +45,7 @@ echo >perfect '> 0
 echo >ok '0'
 echo '0' | prog >effective
 
-echo "checking for readline output"
+echo "checking for readline output..."
 if diff perfect effective; then
     # Alles ist gut.
     strip_prompt=false
@@ -265,8 +269,8 @@ fi
 # On Windows10/MSYS2 the ^G coming from <tab> completion is not
 # emitted the same way
 # (https://lists.gnu.org/r/bug-bison/2020-05/msg00076.html).
-echo "checking for kernel name"
-case `uname -s` in
+echo "checking for kernel name... $(uname -s)"
+case $(uname -s) in
   (MSYS*)
     echo "SKIP: this is Windows/MSYS"
     exit $status

examples/c/bistromathic/local.mk

@@ -31,6 +31,7 @@ if ENABLE_BISTROMATHIC
     -DBISON_LOCALEDIR='"$(localdir)"'		\
     -DLOCALEDIR='"$(localdir)"'			\
     -I$(top_srcdir)/%D% -I$(top_builddir)/%D%
+  %C%_bistromathic_CFLAGS = $(TEST_CFLAGS)
   %C%_bistromathic_LDADD = -lm $(LIBREADLINE) $(LIBINTL)
 endif
 

examples/c/bistromathic/parse.y

@@ -1,7 +1,6 @@
 %require "3.6"
 
 %code top {
-  #include <assert.h>
   #include <ctype.h>  // isdigit
   #include <locale.h> // LC_ALL
   #include <math.h>   // cos, sin, etc.
@@ -218,7 +217,7 @@ getsym (char const *name)
 }
 
 // How many symbols are registered.
-int
+static int
 symbol_count (void)
 {
   int res = 0;
@@ -312,7 +311,7 @@ yylex (const char **line, YYSTYPE *yylval, YYLTYPE *yylloc)
 `---------*/
 
 
-const char *
+static const char *
 error_format_string (int argc)
 {
   switch (argc)
@@ -407,7 +406,8 @@ xstrndup (const char *string, size_t n)
   const char *end = memchr (string, '\0', n);
   size_t len = end ? (size_t) (end - string) : n;
   char *new = malloc (len + 1);
-  assert (new);
+  if (!new)
+    abort ();
   new[len] = '\0';
   return memcpy (new, string, len);
 }
@@ -418,7 +418,8 @@ xstrndup (const char *string, size_t n)
 `-----------*/
 
 // Parse (and execute) this line.
-int process_line (YYLTYPE *lloc, const char *line)
+static int
+process_line (YYLTYPE *lloc, const char *line)
 {
   yypstate *ps = yypstate_new ();
   int status = 0;
@@ -433,7 +434,8 @@ int process_line (YYLTYPE *lloc, const char *line)
 }
 
 // Get the list of possible tokens after INPUT was read.
-int
+// Returns a nonnegative.
+static int
 expected_tokens (const char *input,
                  int *tokens, int ntokens)
 {
@@ -454,6 +456,8 @@ expected_tokens (const char *input,
 
   // Then query for the accepted tokens at this point.
   int res = yypstate_expected_tokens (ps, tokens, ntokens);
+  if (res < 0)
+    abort ();
   yypstate_delete (ps);
   return res;
 }
@@ -463,7 +467,7 @@ expected_tokens (const char *input,
 // 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 **
+static char **
 completion (const char *text, int start, int end)
 {
   YYDPRINTF ((stderr, "completion (\"%.*s[%.*s]%s\")\n",
@@ -473,14 +477,17 @@ completion (const char *text, int start, int end)
 
   // Get list of token numbers.
   int tokens[YYNTOKENS];
-  char *line = xstrndup (rl_line_buffer, start);
+  char *line = xstrndup (rl_line_buffer, (size_t) start);
   int ntokens = expected_tokens (line, tokens, YYNTOKENS);
   free (line);
 
   // Build MATCHES, the list of possible completions.
-  const int len = strlen (text);
+  const size_t len = strlen (text);
   // Need initial prefix and final NULL.
-  char **matches = calloc (ntokens + symbol_count () + 2, sizeof *matches);
+  char **matches
+    = calloc ((size_t) ntokens + (size_t) symbol_count () + 2, sizeof *matches);
+  if (!matches)
+    abort ();
   int match = 1;
   for (int i = 0; i < ntokens; ++i)
     switch (tokens[i])
@@ -510,9 +517,9 @@ completion (const char *text, int start, int end)
     matches[0] = strdup (text);
   else
     {
-      int lcplen = strlen (matches[1]);
+      size_t lcplen = strlen (matches[1]);
       for (int i = 2; i < match && lcplen; ++i)
-        for (int j = 0; j < lcplen; ++j)
+        for (size_t j = 0; j < lcplen; ++j)
           if (matches[1][j] != matches[i][j])
             lcplen = j;
       matches[0] = xstrndup (matches[1], lcplen);
@@ -536,7 +543,8 @@ completion (const char *text, int start, int end)
   return matches;
 }
 
-void init_readline (void)
+static void
+init_readline (void)
 {
   // Allow conditional parsing of the ~/.inputrc file.
   rl_readline_name = "bistromathic";
@@ -555,7 +563,8 @@ void init_readline (void)
 | Main.  |
 `-------*/
 
-int main (int argc, char const* argv[])
+int
+main (int argc, char const* argv[])
 {
 #if defined ENABLE_NLS && ENABLE_NLS
   // Set up internationalization.

examples/c/calc/calc.y

@@ -1,6 +1,7 @@
 %code top {
   #include <ctype.h>  /* isdigit. */
-  #include <stdio.h>  /* For printf, etc. */
+  #include <stdio.h>  /* printf. */
+  #include <stdlib.h> /* abort. */
   #include <string.h> /* strcmp. */
 
   int yylex (void);
@@ -73,7 +74,8 @@ yylex (void)
   if (c == '.' || isdigit (c))
     {
       ungetc (c, stdin);
-      scanf ("%lf", &yylval.NUM);
+      if (scanf ("%lf", &yylval.NUM) != 1)
+        abort ();
       return NUM;
     }
 

examples/c/calc/local.mk

@@ -27,6 +27,7 @@ nodist_%C%_calc_SOURCES = %D%/calc.y
 
 # Don't use gnulib's system headers.
 %C%_calc_CPPFLAGS = -I$(top_srcdir)/%D% -I$(top_builddir)/%D%
+%C%_calc_CFLAGS = $(TEST_CFLAGS)
 
 dist_calc_DATA = %D%/calc.y %D%/Makefile %D%/README.md
 CLEANFILES += %D%/calc.[ch] %D%/calc.output %D%/scan.c

examples/c/lexcalc/local.mk

@@ -25,6 +25,8 @@ if FLEX_WORKS
   nodist_%C%_lexcalc_SOURCES = %D%/parse.y %D%/parse.h %D%/scan.l
   # Don't use gnulib's system headers.
   %C%_lexcalc_CPPFLAGS = -I$(top_srcdir)/%D% -I$(top_builddir)/%D%
+  # Fighting warnings triggered by Flex is just too painful.
+  # %C%_lexcalc_CFLAGS = $(TEST_CFLAGS)
 endif FLEX_WORKS
 
 %D%/parse.c: $(dependencies)

examples/c/lexcalc/scan.l

@@ -4,7 +4,7 @@
 %option nodefault noinput nounput noyywrap
 
 %{
-#include <errno.h> /* errno, ERANGE */
+#include <errno.h>  /* errno, ERANGE */
 #include <limits.h> /* INT_MIN */
 #include <stdlib.h> /* strtol */
 
@@ -12,7 +12,7 @@
 
   // Each time a rule is matched, advance the end cursor/position.
 #define YY_USER_ACTION                          \
-  yylloc->last_column += yyleng;
+  yylloc->last_column += (int) yyleng;
 
   // Move the first position onto the last.
 #define LOCATION_STEP()                         \

examples/c/mfcalc/local.mk

@@ -31,6 +31,7 @@ nodist_%C%_mfcalc_SOURCES = $(mfcalc_sources)
 %D%/mfcalc.c: $(dependencies)
 # Don't use gnulib's system headers.
 %C%_mfcalc_CPPFLAGS = -I$(top_srcdir)/%D% -I$(top_builddir)/%D%
+%C%_mfcalc_CFLAGS = $(TEST_CFLAGS)
 %C%_mfcalc_LDADD = -lm
 
 dist_TESTS += %D%/mfcalc.test

examples/c/pushcalc/calc.y

@@ -1,7 +1,7 @@
 %code top {
   #include <ctype.h>  /* isdigit. */
-  #include <stdbool.h>
-  #include <stdio.h>  /* For printf, etc. */
+  #include <stdio.h>  /* printf. */
+  #include <stdlib.h> /* abort. */
   #include <string.h> /* strcmp. */
 }
 
@@ -81,7 +81,8 @@ yylex (YYSTYPE *yylval)
   if (c == '.' || isdigit (c))
     {
       ungetc (c, stdin);
-      scanf ("%lf", &yylval->NUM);
+      if (scanf ("%lf", &yylval->NUM) != 1)
+        abort ();
       return NUM;
     }
 

examples/c/pushcalc/local.mk

@@ -27,6 +27,7 @@ nodist_%C%_calc_SOURCES = %D%/calc.y
 
 # Don't use gnulib's system headers.
 %C%_calc_CPPFLAGS = -I$(top_srcdir)/%D% -I$(top_builddir)/%D%
+%C%_calc_CFLAGS = $(TEST_CFLAGS)
 
 dist_pushcalc_DATA = %D%/calc.y %D%/Makefile %D%/README.md
 CLEANFILES += %D%/calc.[ch] %D%/calc.output

examples/c/reccalc/local.mk

@@ -26,6 +26,8 @@ if FLEX_WORKS
   BUILT_SOURCES += $(nodist_%C%_reccalc_SOURCES)
   # Don't use gnulib's system headers.
   %C%_reccalc_CPPFLAGS = -I$(top_srcdir)/%D% -I$(top_builddir)/%D%
+  # Fighting warnings triggered by Flex is just too painful.
+  # %C%_reccalc_CFLAGS = $(TEST_CFLAGS)
 endif FLEX_WORKS
 
 %D%/parse.c: $(dependencies)

examples/c/reccalc/scan.l

@@ -32,9 +32,9 @@
         do                                              \
           capacity = capacity ? 2 * capacity : 128;     \
         while (capacity < size + yyleng + 1);           \
-        str = realloc (str, capacity);                  \
+        str = realloc (str, (size_t) capacity);         \
       }                                                 \
-    memcpy (str + size, yytext, yyleng);                \
+    memcpy (str + size, yytext, (size_t) yyleng);       \
     size += yyleng;                                     \
     assert (size < capacity);                           \
   } while (0)

examples/c/rpcalc/local.mk

@@ -31,6 +31,7 @@ nodist_%C%_rpcalc_SOURCES = $(rpcalc_sources)
 %D%/rpcalc.c: $(dependencies)
 # Don't use gnulib's system headers.
 %C%_rpcalc_CPPFLAGS = -I$(top_builddir)/%D%
+%C%_rpcalc_CFLAGS = $(TEST_CFLAGS)
 %C%_rpcalc_LDADD = -lm
 
 dist_TESTS += %D%/rpcalc.test

examples/local.mk

@@ -35,6 +35,9 @@
 dist_noinst_SCRIPTS = %D%/extexi %D%/test
 TEST_LOG_COMPILER = $(SHELL) $(top_srcdir)/%D%/test
 
+TEST_CFLAGS =						\
+  $(WARN_CFLAGS) $(WARN_CFLAGS_TEST) $(WERROR_CFLAGS)
+
 AM_CXXFLAGS =							\
   $(WARN_CXXFLAGS) $(WARN_CXXFLAGS_TEST) $(WERROR_CXXFLAGS)
 

examples/test

@@ -36,10 +36,11 @@ strip_prompt=false
 
 # If diff supports --strip-trailing-cr, use it, to avoid EOL issues
 # when testing Java programs on Windows.
-echo "checking for diff --strip-trailing-cr"
+echo "checking for diff --strip-trailing-cr..."
 if diff --strip-trailing-cr "$1" "$1"; then
   diff_opts=--strip-trailing-cr
 fi
+echo "checking for diff --strip-trailing-cr... $diff_opts"
 
 # The exercised program.
 abs_medir=$cwd/examples/$medir

src/getargs.c

@@ -257,7 +257,8 @@ static const argmatch_trace_doc argmatch_trace_docs[] =
   { "sets",       "grammar sets: firsts, nullable etc." },
   { "muscles",    "m4 definitions passed to the skeleton" },
   { "tools",      "m4 invocation" },
-  { "m4",         "m4 traces" },
+  { "m4-early",   "m4 traces starting from the start" },
+  { "m4",         "m4 traces starting from the skeleton evaluation" },
   { "skeleton",   "skeleton postprocessing" },
   { "time",       "time consumption" },
   { "ielr",       "IELR conversion" },
@@ -279,6 +280,7 @@ static const argmatch_trace_arg argmatch_trace_args[] =
   { "sets",      trace_sets },
   { "muscles",   trace_muscles },
   { "tools",     trace_tools },
+  { "m4-early",  trace_m4_early },
   { "m4",        trace_m4 },
   { "skeleton",  trace_skeleton },
   { "time",      trace_time },

src/getargs.h

@@ -100,11 +100,12 @@ enum trace
     trace_grammar   = 1 << 7,  /**< Reading, reducing the grammar. */
     trace_time      = 1 << 8,  /**< Time consumption. */
     trace_skeleton  = 1 << 9,  /**< Skeleton postprocessing. */
-    trace_m4        = 1 << 10, /**< M4 traces. */
-    trace_muscles   = 1 << 11, /**< M4 definitions of the muscles. */
-    trace_ielr      = 1 << 12, /**< IELR conversion. */
-    trace_closure   = 1 << 13, /**< Input/output of closure(). */
-    trace_locations = 1 << 14, /**< Full display of locations. */
+    trace_m4_early  = 1 << 10, /**< M4 early traces. */
+    trace_m4        = 1 << 11, /**< M4 traces. */
+    trace_muscles   = 1 << 12, /**< M4 definitions of the muscles. */
+    trace_ielr      = 1 << 13, /**< IELR conversion. */
+    trace_closure   = 1 << 14, /**< Input/output of closure(). */
+    trace_locations = 1 << 15, /**< Full display of locations. */
     trace_all       = ~0       /**< All of the above.  */
   };
 /** What debug items bison displays during its run.  */

src/output.c

@@ -687,6 +687,7 @@ output_skeleton (void)
   char *skeldir = xpath_join (datadir, "skeletons");
   char *m4sugar = xpath_join (datadir, "m4sugar/m4sugar.m4");
   char *m4bison = xpath_join (skeldir, "bison.m4");
+  char *traceon = xpath_join (skeldir, "traceon.m4");
   char *skel = (IS_PATH_WITH_DIR (skeleton)
                 ? xstrdup (skeleton)
                 : xpath_join (skeldir, skeleton));
@@ -698,21 +699,10 @@ output_skeleton (void)
 
   /* Create an m4 subprocess connected to us via two pipes.  */
 
-  if (trace_flag & trace_tools)
-    fprintf (stderr, "running: %s %s - %s %s\n",
-             m4, m4sugar, m4bison, skel);
-
-  /* Some future version of GNU M4 (most likely 1.6) may treat the -dV in a
-     position-dependent manner.  Keep it as the first argument so that all
-     files are traced.
-
-     See the thread starting at
-     <http://lists.gnu.org/archive/html/bug-bison/2008-07/msg00000.html>
-     for details.  */
   int filter_fd[2];
   pid_t pid;
   {
-    char const *argv[10];
+    char const *argv[11];
     int i = 0;
     argv[i++] = m4;
 
@@ -730,15 +720,29 @@ output_skeleton (void)
 
     argv[i++] = "-I";
     argv[i++] = datadir;
-    if (trace_flag & trace_m4)
+    /* Some future version of GNU M4 (most likely 1.6) may treat the
+       -dV in a position-dependent manner.  See the thread starting at
+       <http://lists.gnu.org/archive/html/bug-bison/2008-07/msg00000.html>
+       for details.  */
+    if (trace_flag & trace_m4_early)
       argv[i++] = "-dV";
     argv[i++] = m4sugar;
     argv[i++] = "-";
     argv[i++] = m4bison;
+    if (trace_flag & trace_m4)
+      argv[i++] = traceon;
     argv[i++] = skel;
     argv[i++] = NULL;
     aver (i <= ARRAY_CARDINALITY (argv));
 
+    if (trace_flag & trace_tools)
+      {
+        fputs ("running:", stderr);
+        for (int j = 0; argv[j]; ++j)
+          fprintf (stderr, " %s", argv[j]);
+        fputc ('\n', stderr);
+      }
+
     /* The ugly cast is because gnulib gets the const-ness wrong.  */
     pid = create_pipe_bidi ("m4", m4, (char **)(void*)argv, false, true,
                             true, filter_fd);
@@ -747,6 +751,7 @@ output_skeleton (void)
   free (skeldir);
   free (m4sugar);
   free (m4bison);
+  free (traceon);
   free (skel);
 
   if (trace_flag & trace_muscles)

src/parse-gram.c

@@ -2705,7 +2705,7 @@ yyerrorlab:
 yyerrlab1:
   yyerrstatus = 3;      /* Each real token shifted decrements this.  */
 
-  // Pop stack until we find a state that shifts the error token.
+  /* Pop stack until we find a state that shifts the error token.  */
   for (;;)
     {
       yyn = yypact[yystate];

tests/c++.at

@@ -109,11 +109,6 @@ AT_DATA_GRAMMAR([list.yy],
 %define parse.assert
 %debug
 
-%code top
-{
-  // Get access to stack_symbol_type for the tests.
-# define private public
-}
 %code provides
 {
   ]AT_YYLEX_DECLARE[
@@ -136,6 +131,14 @@ AT_DATA_GRAMMAR([list.yy],
 %code requires { #include <vector> }
 %code { int yylex (yy::parser::semantic_type* lvalp); }
 
+// A hack which relies on internal hooks to check stack_symbol_type,
+// which is private.
+%code yy_bison_internal_hook {
+  public:
+    typedef stack_symbol_type yy_stack_symbol_type;
+    typedef stack_type yy_stack_type;
+}
+
 %%
 exp: "int" { $$.push_back ($1); }
 %%
@@ -157,6 +160,9 @@ int main()
   // symbol_type: construction, accessor.
   {
     parser::symbol_type s = parser::make_INT (12);
+    assert_eq (s.kind (), parser::symbol_kind::S_INT);
+    assert_eq (parser::symbol_name (s.kind ()), std::string ("\"int\""));
+    assert_eq (s.name (), std::string ("\"int\""));
     assert_eq (s.value.as<int> (), 12);
   }
 
@@ -180,12 +186,13 @@ int main()
   }
 
   // stack_symbol_type: construction, accessor.
+  typedef parser::yy_stack_symbol_type stack_symbol_type;
   {
 #if 201103L <= YY_CPLUSPLUS
-    auto ss = parser::stack_symbol_type(1, parser::make_INT(123));
+    auto ss = stack_symbol_type (1, parser::make_INT(123));
 #else
     parser::symbol_type s = parser::make_INT (123);
-    parser::stack_symbol_type ss(1, s);
+    stack_symbol_type ss(1, s);
 #endif
     assert_eq (ss.value.as<int> (), 123);
   }
@@ -194,17 +201,17 @@ int main()
   // Sufficiently many so that it will be resized.
   // Probably 3 times (starting at 200).
   {
-    parser::stack_type st;
+    parser::yy_stack_type st;
     const int mucho = 1700;
     const int int_reduction_state = 1; // Read list.output to find it.
     for (int i = 0; i < mucho; ++i)
       {
 #if 201103L <= YY_CPLUSPLUS
-        st.push(parser::stack_symbol_type{int_reduction_state,
-                                          parser::make_INT (i)});
+        st.push(stack_symbol_type{int_reduction_state,
+                                  parser::make_INT (i)});
 #else
         parser::symbol_type s = parser::make_INT (i);
-        parser::stack_symbol_type ss (int_reduction_state, s);
+        stack_symbol_type ss (int_reduction_state, s);
         st.push (ss);
 #endif
       }

tests/input.at

@@ -1352,8 +1352,20 @@ AT_BISON_CHECK([-fcaret  input.y], [1], [],
 ]])
 
 
+# Clang chokes on some of our comments, because it tries to "parse"
+# some documentation directives in the comments:
+#
+# input.c:166:50: error: '\a' command does not have a valid word argument [-Werror,-Wdocumentation]
+#     FAKE = 258                     /* "fake [] \a\b\f\n\r\t\v\"'?\\[\\ ??!??'??(??)??-??/??<??=??> \001\001"  */
+#                                                ~~^
 AT_DATA_GRAMMAR([input.y],
-[[%{
+[[%code requires {
+#if defined __clang__ && 10 <= __clang_major__
+# pragma clang diagnostic ignored "-Wdocumentation"
+#endif
+}
+
+%{
 /* This is seen in GCC: a %{ and %} in middle of a comment. */
 const char *foo = "So %{ and %} can be here too.";
 
@@ -1424,6 +1436,11 @@ char quote[] = "@:>@@:>@,";
 /* Exercise quotes in strings.  */
 %token FAKE "fake @<:@@:>@ \a\b\f\n\r\t\v\"\'\?\\\u005B\U0000005c ??!??'??(??)??-??/??<??=??> \x1\1"
 
+/* Beware of the generated comments that embed string aliases that
+   might close the comment.  */
+%token COMMENT_CLOSE "*/"
+%token COMMENT       "/* comment */"
+
 %%
 /* Exercise M4 quoting: '@:>@@:>@', @<:@, 1.  */
 exp: '@<:@' '\1' two '$' '@' '{' oline output.or.oline.opt

tests/local.at

@@ -500,7 +500,7 @@ m4_define([AT_DATA_SOURCE_PROLOGUE],
 # The prologue that should be included in any grammar whose parser is
 # meant to be compiled.
 m4_define([AT_DATA_GRAMMAR_PROLOGUE],
-[[%code top {
+[[%code top { /* -*- ]AT_LANG[ -*- */
 ]AT_DATA_SOURCE_PROLOGUE[]dnl
 [}
 ]])

tests/local.mk

@@ -56,6 +56,7 @@ TESTSUITE_AT =                                \
   %D%/java.at                                 \
   %D%/javapush.at                             \
   %D%/local.at                                \
+  %D%/m4.at                                   \
   %D%/named-refs.at                           \
   %D%/output.at                               \
   %D%/package.m4                              \

tests/m4.at

@@ -0,0 +1,72 @@
+# Basic m4 macros.                               -*- Autotest -*-
+
+# 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/>.
+
+AT_BANNER([[M4 Macros.]])
+
+
+AT_SETUP([Generating Comments])
+
+AT_DATA([input.y],
+[%%
+exp:
+])
+
+AT_DATA([input.m4],
+[[m4@&t@_include(b4_skeletonsdir/[c.m4])
+
+b4_output_begin([output.txt])
+
+b4_gsub([[abcd]],
+  [a], [b])
+b4_gsub([[abcd]],
+  [a], [b],
+  [b], [c],
+  [c], [d])
+
+_b4_comment([["/* () */"]])
+_b4_comment([["/* (  */"]])
+_b4_comment([["/*  ) */"]])
+_b4_comment([["/* [] */"]])
+
+b4_comment([["/* () */"]])
+b4_comment([["/* (  */"]])
+b4_comment([["/*  ) */"]])
+b4_comment([["/* [] */"]])
+
+b4_output_end([output.txt])
+]])
+
+AT_BISON_CHECK([-S ./input.m4 input.y])
+
+AT_CHECK([cat output.txt], [],
+[[
+[bbcd]
+[dddd]
+
+"/\* () *\/"
+"/\* (  *\/"
+"/\*  ) *\/"
+"/\* [] *\/"
+
+/* "/\* () *\/"  */
+/* "/\* (  *\/"  */
+/* "/\*  ) *\/"  */
+/* "/\* [] *\/"  */
+
+]])
+
+AT_CLEANUP

tests/regression.at

@@ -372,8 +372,19 @@ m4_pushdef([AT_TEST],
 
 AT_BISON_OPTION_PUSHDEFS([$1])
 
+
+# Clang chokes on some of our comments, because it tries to "parse"
+# some documentation directives in the comments:
+#
+# input.c:131:48: error: '\a' command does not have a valid word argument [-Werror,-Wdocumentation]
+#     SPECIAL = 261                  /* "\\'?\"\a\b\f\n\r\t\v\001\201\001\201??!"  */
+#                                              ~~^
 AT_DATA_GRAMMAR([input.y],
 [%{
+#if defined __clang__ && 10 <= __clang_major__
+# pragma clang diagnostic ignored "-Wdocumentation"
+#endif
+
 ]AT_YYERROR_DECLARE[
 ]AT_YYLEX_DECLARE[
 %}
@@ -398,14 +409,14 @@ exp: ]AT_ERROR_VERBOSE_IF(["\\\'\?\"\a\b\f\n\r\t\v\001\201\x001\x000081??!"], ["
 # C-string literal.  Also notice that unnecessary escaping, such as "\?", from
 # the user specification is eliminated.
 AT_BISON_CHECK([-fcaret -o input.c input.y], [[0]], [[]],
-[[input.y:22.8-14: warning: symbol SPECIAL redeclared [-Wother]
-   22 | %token SPECIAL "\\\'\?\"\a\b\f\n\r\t\v\001\201\x001\x000081??!"
+[[input.y:26.8-14: warning: symbol SPECIAL redeclared [-Wother]
+   26 | %token SPECIAL "\\\'\?\"\a\b\f\n\r\t\v\001\201\x001\x000081??!"
       |        ^~~~~~~
-input.y:21.8-14: note: previous declaration
-   21 | %token SPECIAL "\\\'\?\"\a\b\f\n\r\t\v\001\201\x001\x000081??!"
+input.y:25.8-14: note: previous declaration
+   25 | %token SPECIAL "\\\'\?\"\a\b\f\n\r\t\v\001\201\x001\x000081??!"
       |        ^~~~~~~
-input.y:22.16-63: warning: symbol "\\'?\"\a\b\f\n\r\t\v\001\201\001\201??!" used more than once as a literal string [-Wother]
-   22 | %token SPECIAL "\\\'\?\"\a\b\f\n\r\t\v\001\201\x001\x000081??!"
+input.y:26.16-63: warning: symbol "\\'?\"\a\b\f\n\r\t\v\001\201\001\201??!" used more than once as a literal string [-Wother]
+   26 | %token SPECIAL "\\\'\?\"\a\b\f\n\r\t\v\001\201\x001\x000081??!"
       |                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 ]])
 

tests/testsuite.at

@@ -16,6 +16,8 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+# Basic M4 macros.
+m4_include([m4.at])
 
 # Resistance to user bugs.
 m4_include([input.at])