-# m4.m4 serial 5
-dnl Copyright (C) 2000, 2006, 2007, 2008-2009 Free Software Foundation,
-dnl Inc.
-dnl This file is free software; the Free Software Foundation
-dnl gives unlimited permission to copy and/or distribute it,
-dnl with or without modifications, as long as this notice is preserved.
+# m4.m4 serial 9
+
+# Copyright (C) 2000, 2006, 2007, 2008, 2009 Free Software Foundation,
+# Inc.
+
+# Copying and distribution of this file, with or without modification,
+# are permitted in any medium without royalty provided the copyright
+# notice and this notice are preserved. This file is offered as-is,
+# without warranty of any kind.
# AC_PROG_GNU_M4
# --------------
-# Check for GNU M4, at least 1.4.5 (all earlier versions had a bug in
-# trace support:
-# http://lists.gnu.org/archive/html/bug-gnu-utils/2006-11/msg00096.html)
+# Check for GNU M4, at least 1.4.6 (all earlier versions had bugs in
+# trace support and regexp support):
+# http://lists.gnu.org/archive/html/bug-gnu-utils/2006-11/msg00096.html
+# http://lists.gnu.org/archive/html/bug-autoconf/2009-07/msg00023.html
# Also, check whether --error-output (through 1.4.x) or --debugfile (2.0)
# is supported, and AC_SUBST M4_DEBUGFILE accordingly.
AC_DEFUN([AC_PROG_GNU_M4],
- [AC_ARG_VAR([M4], [Location of GNU M4 1.4.5 or later. Defaults to the first
+ [AC_ARG_VAR([M4], [Location of GNU M4 1.4.6 or later. Defaults to the first
program of `m4', `gm4', or `gnum4' on PATH that meets Autoconf needs.])
AC_CACHE_CHECK([for GNU M4 that supports accurate traces], [ac_cv_path_M4],
[rm -f conftest.m4f
+ac_had_posixly_correct=${POSIXLY_CORRECT:+yes}
+AS_UNSET([POSIXLY_CORRECT])
AC_PATH_PROGS_FEATURE_CHECK([M4], [m4 gm4 gnum4],
[dnl Creative quoting here to avoid raw dnl and ifdef in configure.
- # Root out GNU M4 1.4.4, as well as non-GNU m4 that ignore -t, -F.
- ac_snippet=change'quote(<,>)in''dir(<if''def>,mac,bug)d'nl
+ # Root out GNU M4 1.4.5, as well as non-GNU m4 that ignore -t, -F.
+ ac_snippet=change'quote(<,>)in''dir(<if''def>,mac,bug)'
+ ac_snippet=${ac_snippet}pat'subst(a,\(b\)\|\(a\),\1)d'nl
test -z "`$ac_path_M4 -F conftest.m4f </dev/null 2>&1`" \
&& test -z "`echo $ac_snippet | $ac_path_M4 --trace=mac 2>&1`" \
&& test -f conftest.m4f \
&& ac_cv_path_M4=$ac_path_M4 ac_path_M4_found=:
rm -f conftest.m4f],
[AC_MSG_ERROR([no acceptable m4 could be found in \$PATH.
-GNU M4 1.4.5 or later is required; 1.4.11 is recommended])])])
+GNU M4 1.4.6 or later is required; 1.4.13 is recommended])])])
M4=$ac_cv_path_M4
+ AC_CACHE_CHECK([whether $ac_cv_path_M4 accepts --gnu],
+ [ac_cv_prog_gnu_m4_gnu],
+ [case `$M4 --help < /dev/null 2>&1` in
+ *--gnu*) ac_cv_prog_gnu_m4_gnu=yes ;;
+ *) ac_cv_prog_gnu_m4_gnu=no ;;
+ esac])
+ if test "$ac_cv_prog_gnu_m4_gnu" = yes; then
+ M4_GNU=--gnu
+ else
+ M4_GNU=
+ fi
+ AC_SUBST([M4_GNU])
+ if test x$ac_had_posixly_correct = xyes; then
+ POSIXLY_CORRECT=:
+ if test $ac_cv_prog_gnu_m4_gnu = no; then
+ AC_MSG_WARN([The version of M4 that was found does not support -g.])
+ AC_MSG_WARN([Using it with POSIXLY_CORRECT set may cause problems.])
+ fi
+ fi
AC_CACHE_CHECK([how m4 supports trace files], [ac_cv_prog_gnu_m4_debugfile],
[case `$M4 --help < /dev/null 2>&1` in
*debugfile*) ac_cv_prog_gnu_m4_debugfile=--debugfile ;;
FILE *in;
FILE *out;
int filter_fd[2];
- char const *argv[9];
+ char const *argv[10];
pid_t pid;
/* Compute the names of the package data dir and skeleton files. */
{
int i = 0;
argv[i++] = m4;
+
+ /* When POSIXLY_CORRECT is set, GNU M4 1.6 and later disable GNU
+ extensions, which Bison's skeletons depend on. With older M4,
+ it has no effect. M4 1.4.12 added a -g/--gnu command-line
+ option to make it explicit that a program wants GNU M4
+ extensions even when POSIXLY_CORRECT is set.
+
+ See the thread starting at
+ <http://lists.gnu.org/archive/html/bug-bison/2008-07/msg00000.html>
+ for details. */
+ if (*M4_GNU_OPTION)
+ argv[i++] = M4_GNU_OPTION;
+
argv[i++] = "-I";
argv[i++] = pkgdatadir;
if (trace_flag & trace_m4)
argv[i++] = full_skeleton;
argv[i++] = NULL;
}
- /* When POSIXLY_CORRECT is set, some future versions of GNU M4 (most likely
- 2.0) may drop some of the GNU extensions that Bison's skeletons depend
- upon. So that the next release of Bison is forward compatible with those
- future versions of GNU M4, we unset POSIXLY_CORRECT here.
-
- FIXME: A user might set POSIXLY_CORRECT to affect processes run from
- macros like m4_syscmd in a custom skeleton. For now, Bison makes no
- promises about the behavior of custom skeletons, so this scenario is not a
- concern. However, we eventually want to eliminate this shortcoming. The
- next release of GNU M4 (1.4.12 or 1.6) will accept the -g command-line
- option as a no-op, and later releases will accept it to indicate that
- POSIXLY_CORRECT should be ignored. Once the GNU M4 versions that accept
- -g are pervasive, Bison should use -g instead of unsetting
- POSIXLY_CORRECT.
- See the thread starting at
- <http://lists.gnu.org/archive/html/bug-bison/2008-07/msg00000.html>
- for details. */
- unsetenv ("POSIXLY_CORRECT");
init_subpipe ();
pid = create_subpipe (argv, filter_fd);
free (full_m4sugar);
projects / bison.git / commitdiff
