Replace BISON_PROG_GNU_M4 with Autoconf's AC_PROG_GNU_M4.

[bison.git] / m4 / m4.m4

diff --git a/m4/m4.m4 b/m4/m4.m4
index be0140f06a9fb1426adf1dfff04c4b91339a47be..f27d8c052013489d7d842c3f12a294569b11d868 100644 (file)
--- a/m4/m4.m4
+++ b/m4/m4.m4
@@ -1,27 +1,46 @@
-# Copyright 2000 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/>.
+# m4.m4 serial 5
+dnl Copyright (C) 2000, 2006, 2007, 2008 Free Software Foundation, 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.
 
-# BISON_PROG_GNU_M4
-# -----------------
-# Check for GNU m4, at least 1.3 (supports frozen files).
-AC_DEFUN([BISON_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])])
+# 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)
+# 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
+    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_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
+      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])])])
+  M4=$ac_cv_path_M4
+  AC_CACHE_CHECK([how m4 supports trace files], [ac_cv_prog_gnu_m4_debugfile],
+    [case `$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])
+])])