strndup: fix m4 usage error

Autoconf guarantees that AC_CHECK_DECLS_ONCE always defines the
corresponding HAVE_DECL_*, so checking #ifndef HAVE_DECL_* is bogus.
https://lists.gnu.org/archive/html/coreutils/2012-06/msg00037.html

* m4/strndup.m4 (gl_FUNC_STRNDUP): HAVE_DECL_STRNDUP is always
defined, to either 0 or 1.
Reported by Karel Zak.

Signed-off-by: Eric Blake <eblake@redhat.com>

diff --git a/ChangeLog b/ChangeLog
index 097c90d..a35ea2f 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2012-07-13  Eric Blake  <eblake@redhat.com>
+
+       strndup: fix m4 usage error
+       * m4/strndup.m4 (gl_FUNC_STRNDUP): HAVE_DECL_STRNDUP is always
+       defined, to either 0 or 1.
+       Reported by Karel Zak.
+
 2012-07-11  Jim Meyering  <meyering@redhat.com>
 
        maint: enable the sc_avoid_if_before_free syntax-check rule

diff --git a/m4/strndup.m4 b/m4/strndup.m4
index bdde5fe..cef6889 100644 (file)
--- a/m4/strndup.m4
+++ b/m4/strndup.m4
@@ -1,4 +1,4 @@
-# strndup.m4 serial 20
+# strndup.m4 serial 21
 dnl Copyright (C) 2002-2003, 2005-2012 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -24,7 +24,7 @@ AC_DEFUN([gl_FUNC_STRNDUP],
       [AC_RUN_IFELSE([
          AC_LANG_PROGRAM([[#include <string.h>
                            #include <stdlib.h>]], [[
-#ifndef HAVE_DECL_STRNDUP
+#if !HAVE_DECL_STRNDUP
   extern
   #ifdef __cplusplus
   "C"