[PATCH] use m4 -g when available

[Paolo Bonzini]

M4sugar requires GNU m4 extensions to be enabled.  Override
POSIXLY_CORRECT using -g.

2009-07-12  Paolo Bonzini  <address@hidden>

        * m4/m4.m4: Test for -g.
        * bin/Makefile.am: Substitute @M4_GNU@ into generated files.
        * bin/autom4te.in: Pass @M4_GNU@ to m4.
---
 bin/Makefile.am |    1 +
 bin/autom4te.in |    2 +-
 m4/m4.m4        |   11 +++++++++++
 3 files changed, 13 insertions(+), 1 deletions(-)

diff --git a/bin/Makefile.am b/bin/Makefile.am
index ba88ab0..da65b85 100644
--- a/bin/Makefile.am
+++ b/bin/Makefile.am
@@ -46,6 +46,7 @@ edit = sed \
        -e 's|@address@hidden|'`echo autom4te | sed '$(transform)'`'|g' \
        -e 's|@address@hidden|$(M4)|g' \
        -e 's|@address@hidden|$(M4_DEBUGFILE)|g' \
+       -e 's|@address@hidden|$(M4_GNU)|g' \
        -e 's|@address@hidden|$(AWK)|g' \
        -e 's|@address@hidden|'$(RELEASE_YEAR)'|g' \
        -e 's|@address@hidden|$(VERSION)|g' \
diff --git a/bin/autom4te.in b/bin/autom4te.in
index cf425bb..1baf507 100644
--- a/bin/autom4te.in
+++ b/bin/autom4te.in
@@ -463,7 +463,7 @@ sub handle_m4 ($@)
   #
   # We don't output directly to the cache files, to avoid problems
   # when we are interrupted (that leaves corrupted files).
-  xsystem ("$m4"
+  xsystem ("$m4 @M4_GNU@"
           . join (' --include=', '', map { shell_quote ($_) } @include)
           . ' --debug=aflq'
           . (!exists $ENV{'AUTOM4TE_NO_FATAL'} ? ' --fatal-warning' : '')
diff --git a/m4/m4.m4 b/m4/m4.m4
index dd90cca..45e03fc 100644
--- a/m4/m4.m4
+++ b/m4/m4.m4
@@ -32,6 +32,17 @@ AC_PATH_PROGS_FEATURE_CHECK([M4], [m4 gm4 gnum4],
       [AC_MSG_ERROR([no acceptable m4 could be found in \$PATH.
 GNU M4 1.4.5 or later is required; 1.4.11 is recommended])])])
   M4=$ac_cv_path_M4
+  AC_CACHE_CHECK([whether $ac_cv_path_M4 accepts -g], [ac_cv_prog_gnu_m4_gnu],
+    [case `$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 "$ac_cv_prog_gnu_m4_gnu" = yes; then
+    M4_GNU=-g
+  else
+    M4_GNU=
+  fi
+  AC_SUBST([M4_GNU])
   AC_CACHE_CHECK([how m4 supports trace files], [ac_cv_prog_gnu_m4_debugfile],
     [case `$M4 --help < /dev/null 2>&1` in
       *debugfile*) ac_cv_prog_gnu_m4_debugfile=--debugfile ;;
-- 
1.6.2.5