configury: bail out early if GNU M4 is not on the path.

Now that libtoolize requires an installed GNU M4 to parse
configure.ac and aclocal.m4 sources for libltdl macros, let the
user know at configure time when it is missing.
* m4/m4.m4: New file for rejecting non-GNU and buggy GNU versions
of M4. Copied from GNU Autoconf m4.m4.
* Makefile.am (lt_aclocal_m4_deps): Add m4/m4.m4.
* configure.ac (AC_PROG_GNU_M4): Call it.
* NEWS: Update.
Reported by Michael Felt

Signed-off-by: Gary V. Vaughan <gary@gnu.org>

1 files changed, 82 insertions, 0 deletions

diff --git a/m4/m4.m4 b/m4/m4.m4
new file mode 100644
index 00000000..80bd42c2
--- /dev/null
+++ b/m4/m4.m4
@@ -0,0 +1,82 @@
+# m4.m4 serial 12
+
+# Copyright (C) 2000, 2006-2014 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])
+])])