assert module and --enable-assert

[Eric Blake]

William Pursell astutely noticed that autoconf's AC_HEADER_ASSERT (added in 
2.60) treats --enable-assert as a synonym for --disable-assert.  It is now 
fixed in autoconf.git, so I'm applying the same fix to gnulib (we have to 
continue using m4/assert.m4 until such time as all gnulib projects assume 
autoconf 2.64 or newer).

From: William Pursell <address@hidden>
Date: Mon, 8 Dec 2008 14:24:04 -0700
Subject: [PATCH] assert: honor --enable-assert

* m4/assert.m4 (gl_ASSERT): Synchronize with autoconf 2.64, in
order to honor --enable-assert, rather than treating it as a
synonym for --disable-assert.

Signed-off-by: Eric Blake <address@hidden>
---
 ChangeLog    |    8 ++++++++
 m4/assert.m4 |   24 ++++++++++++++----------
 2 files changed, 22 insertions(+), 10 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 05a3ad5..30f98ac 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2008-12-08  William Pursell  <address@hidden>  (tiny change)
+       and Eric Blake  <address@hidden>
+
+       assert: honor --enable-assert
+       * m4/assert.m4 (gl_ASSERT): Synchronize with autoconf 2.64, in
+       order to honor --enable-assert, rather than treating it as a
+       synonym for --disable-assert.
+
 2008-12-07  Bruno Haible  <address@hidden>
 
        * tests/test-lock.c (test_lock, test_rwlock, test_recursive_lock,
diff --git a/m4/assert.m4 b/m4/assert.m4
index bfdc00f..72cc0dc 100644
--- a/m4/assert.m4
+++ b/m4/assert.m4
@@ -1,19 +1,23 @@
-#serial 5
+#serial 6
 
-# Copyright (C) 1998, 1999, 2001, 2004 Free Software Foundation, Inc.
+# Copyright (C) 1998, 1999, 2001, 2004, 2008 Free Software Foundation, Inc.
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
 # with or without modifications, as long as this notice is preserved.
 
 dnl based on code from Eleftherios Gkioulekas
-
+dnl Autoconf 2.60 provides AC_HEADER_ASSERT for the same purpose, but
+dnl it has broken semantics for --enable-assert until 2.64.
 AC_DEFUN([gl_ASSERT],
 [
-  AC_MSG_CHECKING(whether to enable assertions)
-  AC_ARG_ENABLE(assert,
-       [  --disable-assert        turn off assertions],
-       [ AC_MSG_RESULT(no)
-         AC_DEFINE(NDEBUG,1,[Define to 1 if assertions should be disabled.]) ],
-       [ AC_MSG_RESULT(yes) ]
-               )
+  AC_MSG_CHECKING([whether to enable assertions])
+  AC_ARG_ENABLE([assert],
+    [AS_HELP_STRING([--disable-assert], [turn off assertions])],
+    [AS_IF([test "x$enableval" = xno],
+      [AC_DEFINE([NDEBUG], [1],
+       [Define to 1 if assertions should be disabled.])],
+      [test "x$enableval" != xyes],
+      [AC_MSG_WARN([invalid argument supplied to --enable-assert])
+      enable_assert=no])])
+  AC_MSG_RESULT([$enable_assert])
 ])
-- 
1.6.0.4