manywarnings: enable nicer gcc warning messages

With gcc 4.3.4, -Wdisabled-optimization is noisy unless you also
use -funit-at-a-time.

With gcc 4.4.7, there is no indication which warning option
triggered a particular message unless you also use
-fdiagnostics-show-option.

Both of these options are default in newer gcc (such as 4.8.1);
but including them in the list of possible warnings makes the
experience nicer on older platforms.

* m4/manywarnings.m4 (gl_MANYWARN_ALL_GCC): Older gcc requires
some -f options for optimal warnings.

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

diff --git a/ChangeLog b/ChangeLog
index 4b6cbdc..211d296 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2013-09-24  Eric Blake  <eblake@redhat.com>
+
+       manywarnings: enable nicer gcc warning messages
+       * m4/manywarnings.m4 (gl_MANYWARN_ALL_GCC): Older gcc requires
+       some -f options for optimal warnings.
+
 2013-09-21  Jim Meyering  <meyering@fb.com>
 
        timespec: use the new TIMESPEC_RESOLUTION in a few more places

diff --git a/m4/manywarnings.m4 b/m4/manywarnings.m4
index be6d4c9..80b2476 100644 (file)
--- a/m4/manywarnings.m4
+++ b/m4/manywarnings.m4
@@ -1,4 +1,4 @@
-# manywarnings.m4 serial 5
+# manywarnings.m4 serial 6
 dnl Copyright (C) 2008-2013 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -204,6 +204,8 @@ AC_DEFUN([gl_MANYWARN_ALL_GCC],
     -Wvla \
     -Wvolatile-register-var \
     -Wwrite-strings \
+    -fdiagnostics-show-option \
+    -funit-at-a-time \
     \
     ; do
     gl_manywarn_set="$gl_manywarn_set $gl_manywarn_item"