# m4.m4 serial 12

# Copyright (C) 2000, 2006-2012 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 1.4.6 (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.

# Also avoid versions of m4 that trigger strstr bugs.

AC_DEFUN([AC_PROG_GNU_M4],

  [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 1.4.5, as well as non-GNU m4 that ignore -t, -F.

      # Root out GNU M4 1.4.15 with buggy false negative replacement strstr.

      # Root out Glibc 2.9 - 2.12 and GNU M4 1.4.11 - 1.4.15 with buggy

      # false positive strstr.

      ac_snippet=change'quote(<,>)in''dir(<if''def>,mac,bug)'

      ac_snippet=${ac_snippet}pat'subst(a,\(b\)\|\(a\),\1)d'nl

      ac_snippet=${ac_snippet}${as_nl}if'else(in''dex(..wi.d.,.d.),-1,bug)'

      ac_snippet=${ac_snippet}${as_nl}if'else(in''dex(dnl

;:11-:12-:12-:12-:12-:12-:12-:12-:12.:12.:12.:12.:12.:12.:12.:12.:12-,dnl

:12-:12-:12-:12-:12-:12-:12-:12-),-1,,strstr-bug2)'

      test -z "`$ac_path_M4 -F conftest.m4f </dev/null 2>&1`" \

      && test -z "`AS_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 1.4.6 or later is required; 1.4.16 or newer is recommended.

GNU M4 1.4.15 uses a buggy replacement strstr on some systems.

Glibc 2.9 - 2.12 and GNU M4 1.4.11 - 1.4.15 have another strstr bug.])])])

  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 ;;

      *) ac_cv_prog_gnu_m4_debugfile=--error-output ;;

    esac])

  AC_SUBST([M4_DEBUGFILE], [$ac_cv_prog_gnu_m4_debugfile])

])

# Compatibility for bootstrapping with Autoconf 2.61.

dnl FIXME - replace this with AC_PREREQ([2.62]) after the release.

# AC_PATH_PROGS_FEATURE_CHECK was added the same time the slightly broken,

# undocumented _AC_PATH_PROG_FEATURE_CHECK was deleted.

m4_ifndef([AC_PATH_PROGS_FEATURE_CHECK],

  [m4_define([AC_PATH_PROGS_FEATURE_CHECK],

    [_AC_PATH_PROG_FEATURE_CHECK([$1], [$2], [$3], [$5])

])])