[PATCH] build: exclude M4 with buggy strstr

[Eric Blake]

From: Ralf Wildenhues <address@hidden>

* m4/m4.m4 (AC_PROG_GNU_M4): When searching PATH, do not accept
an m4 that has either the gnulib strstr bug, or the glibc/gnulib
strstr bug.

Signed-off-by: Eric Blake <address@hidden>
---

I tweaked it slightly, and pushed this.  Thanks again for starting it.

 ChangeLog |    8 ++++++++
 m4/m4.m4  |   14 ++++++++++++--
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index bb6cd46..45ee69a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,4 +1,12 @@
 2011-03-05  Ralf Wildenhues  <address@hidden>
+       and Eric Blake  <address@hidden>
+
+       build: exclude M4 with buggy strstr
+       * m4/m4.m4 (AC_PROG_GNU_M4): When searching PATH, do not accept
+       an m4 that has either the gnulib strstr bug, or the glibc/gnulib
+       strstr bug.
+
+2011-03-05  Ralf Wildenhues  <address@hidden>

        docs: fix description of AC_F77_IMPLICIT_NONE.
        * doc/autoconf.texi (Fortran Compiler) [AC_F77_IMPLICIT_NONE]:
diff --git a/m4/m4.m4 b/m4/m4.m4
index a11fe0d..dfc2c12 100644
--- a/m4/m4.m4
+++ b/m4/m4.m4
@@ -1,4 +1,4 @@
-# m4.m4 serial 11
+# m4.m4 serial 12

 # Copyright (C) 2000, 2006-2011 Free Software Foundation, Inc.

@@ -15,6 +15,7 @@
 # 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.])
@@ -25,15 +26,24 @@ 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; 1.4.14 is recommended])])])
+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],
-- 
1.7.4