Import M4 detection fix from Autoconf.

[bison.git] / m4 / m4.m4

diff --git a/m4/m4.m4 b/m4/m4.m4
index 3ef7908492fccf35ea2157feeb5724aaa8cb31e2..c6b64b08c8fc77d880a20265d3704487a5d1a954 100644 (file)
--- a/m4/m4.m4
+++ b/m4/m4.m4
@@ -1,14 +1,73 @@
-# serial 1
-
-# BISON_AC_PROG_GNU_M4
-# --------------------
-# Check for GNU m4, at least 1.3 (supports frozen files).
-AC_DEFUN([BISON_AC_PROG_GNU_M4],
-[AC_PATH_PROGS(M4, gm4 gnum4 m4, m4)
-AC_CACHE_CHECK(whether m4 supports frozen files, ac_cv_prog_gnu_m4,
-[ac_cv_prog_gnu_m4=no
-if test x"$M4" != x; then
-  case `$M4 --help < /dev/null 2>&1` in
-    *reload-state*) ac_cv_prog_gnu_m4=yes ;;
-  esac
-fi])])
+# m4.m4 serial 10
+
+# 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 1.4.6 (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 1.4.6 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=${POSIXLY_CORRECT:+yes}
+AS_UNSET([POSIXLY_CORRECT])
+AC_PATH_PROGS_FEATURE_CHECK([M4], [m4 gm4 gnum4],
+      [dnl Creative quoting here to avoid raw dnl and ifdef in configure.
+      # Root out GNU M4 1.4.5, as well as non-GNU m4 that ignore -t, -F.
+      ac_snippet=change'quote(<,>)in''dir(<if''def>,mac,bug)'
+      ac_snippet=${ac_snippet}pat'subst(a,\(b\)\|\(a\),\1)d'nl
+      test -z "`$ac_path_M4 -F conftest.m4f </dev/null 2>&1`" \
+      && test -z "`AS_ECHO([$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; 1.4.13 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 ;;
+      *) 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])
+])])