3 # Copyright (C) 2000, 2006-2019, 2021-2024 Free Software Foundation,
6 # Copying and distribution of this file, with or without modification,
7 # are permitted in any medium without royalty provided the copyright
8 # notice and this notice are preserved. This file is offered as-is,
9 # without warranty of any kind.
13 # Check for GNU M4, at least 1.4.6 (all earlier versions had bugs in
14 # trace support and regexp support):
15 # http://lists.gnu.org/archive/html/bug-gnu-utils/2006-11/msg00096.html
16 # http://lists.gnu.org/archive/html/bug-autoconf/2009-07/msg00023.html
17 # Also, check whether --error-output (through 1.4.x) or --debugfile (2.0)
18 # is supported, and AC_SUBST M4_DEBUGFILE accordingly.
19 # Also avoid versions of m4 that trigger strstr bugs.
20 AC_DEFUN([AC_PROG_GNU_M4],
21 [AC_ARG_VAR([M4], [Location of GNU M4 1.4.6 or later. Defaults to the first
22 program of 'm4', 'gm4', or 'gnum4' on PATH that meets Autoconf needs.])
23 AC_CACHE_CHECK([for GNU M4 that supports accurate traces], [ac_cv_path_M4],
25 ac_had_posixly_correct=${POSIXLY_CORRECT:+yes}
26 AS_UNSET([POSIXLY_CORRECT])
27 AC_PATH_PROGS_FEATURE_CHECK([M4], [m4 gm4 gnum4],
28 [dnl Creative quoting here to avoid raw dnl and ifdef in configure.
29 # Root out GNU M4 1.4.5, as well as non-GNU m4 that ignore -t, -F.
30 # Root out GNU M4 1.4.15 with buggy false negative replacement strstr.
31 # Root out Glibc 2.9 - 2.12 and GNU M4 1.4.11 - 1.4.15 with buggy
32 # false positive strstr.
33 ac_snippet=change'quote(<,>)in''dir(<if''def>,mac,bug)'
34 ac_snippet=${ac_snippet}pat'subst(a,\(b\)\|\(a\),\1)d'nl
35 ac_snippet=$ac_snippet${as_nl}if'else(in''dex(..wi.d.,.d.),-1,bug)'
36 ac_snippet=$ac_snippet${as_nl}if'else(in''dex(dnl
37 ;:11-:12-:12-:12-:12-:12-:12-:12-:12.:12.:12.:12.:12.:12.:12.:12.:12-,dnl
38 :12-:12-:12-:12-:12-:12-:12-:12-),-1,,strstr-bug2)'
39 test -z "`$ac_path_M4 -F conftest.m4f </dev/null 2>&1`" \
40 && test -z "`AS_ECHO([$ac_snippet]) | $ac_path_M4 --trace=mac 2>&1`" \
41 && test -f conftest.m4f \
42 && ac_cv_path_M4=$ac_path_M4 ac_path_M4_found=:
44 [AC_MSG_ERROR([no acceptable m4 could be found in \$PATH.
45 GNU M4 1.4.6 or later is required; 1.4.16 or newer is recommended.
46 GNU M4 1.4.15 uses a buggy replacement strstr on some systems.
47 Glibc 2.9 - 2.12 and GNU M4 1.4.11 - 1.4.15 have another strstr bug.])])])
49 AC_CACHE_CHECK([whether $ac_cv_path_M4 accepts --gnu],
50 [ac_cv_prog_gnu_m4_gnu],
51 [case `$M4 --help < /dev/null 2>&1` in
52 *--gnu*) ac_cv_prog_gnu_m4_gnu=yes ;;
53 *) ac_cv_prog_gnu_m4_gnu=no ;;
55 if test yes = "$ac_cv_prog_gnu_m4_gnu"; then
61 if test yes = "$ac_had_posixly_correct"; then
63 if test no = $ac_cv_prog_gnu_m4_gnu; then
64 AC_MSG_WARN([the version of M4 that was found does not support -g])
65 AC_MSG_WARN([using it with POSIXLY_CORRECT set may cause problems])
68 AC_CACHE_CHECK([how m4 supports trace files], [ac_cv_prog_gnu_m4_debugfile],
69 [case `$M4 --help < /dev/null 2>&1` in
70 *debugfile*) ac_cv_prog_gnu_m4_debugfile=--debugfile ;;
71 *) ac_cv_prog_gnu_m4_debugfile=--error-output ;;
73 AC_SUBST([M4_DEBUGFILE], [$ac_cv_prog_gnu_m4_debugfile])
76 # Compatibility for bootstrapping with Autoconf 2.61.
77 dnl FIXME - replace this with AC_PREREQ([2.62]) after the release.
78 # AC_PATH_PROGS_FEATURE_CHECK was added the same time the slightly broken,
79 # undocumented _AC_PATH_PROG_FEATURE_CHECK was deleted.
80 m4_ifndef([AC_PATH_PROGS_FEATURE_CHECK],
81 [m4_define([AC_PATH_PROGS_FEATURE_CHECK],
82 [_AC_PATH_PROG_FEATURE_CHECK([$1], [$2], [$3], [$5])