[PATCH] ignore-value: new module

[Jim Meyering]

I wanted to ignore some new warnings in coreutils,
but a "(void)" cast no longer does the job with the latest gcc
and libc headers.

Here's the proposed module:

>From 179c0e32f86c8b0013111d343f17d27730391e63 Mon Sep 17 00:00:00 2001
From: Jim Meyering <address@hidden>
Date: Thu, 16 Oct 2008 23:20:44 +0200
Subject: [PATCH] ignore-value: new module

* modules/ignore-value: New file.
* lib/ignore-value.h: New file.
* MODULES.html.sh (Compiler warning management): New section,
just for this module.  More to come.
---
 MODULES.html.sh      |   10 ++++++++++
 lib/ignore-value.h   |   45 +++++++++++++++++++++++++++++++++++++++++++++
 modules/ignore-value |   22 ++++++++++++++++++++++
 3 files changed, 77 insertions(+), 0 deletions(-)
 create mode 100644 lib/ignore-value.h
 create mode 100644 modules/ignore-value

diff --git a/MODULES.html.sh b/MODULES.html.sh
index 9597f09..9680163 100755
--- a/MODULES.html.sh
+++ b/MODULES.html.sh
@@ -1830,6 +1830,16 @@ func_all_modules ()
   func_module crypto/gc-sha1
   func_end_table

+  element="Compiler warning management"
+  element=`printf "%s" "$element" | sed -e "$sed_lt" -e "$sed_gt"`
+  func_section_wrap ansic_ext_misc
+  func_wrap H3
+  func_echo "$element"
+
+  func_begin_table
+  func_module ignore-value
+  func_end_table
+
   element="Misc"
   element=`printf "%s" "$element" | sed -e "$sed_lt" -e "$sed_gt"`
   func_section_wrap ansic_ext_misc
diff --git a/lib/ignore-value.h b/lib/ignore-value.h
new file mode 100644
index 0000000..5f97c91
--- /dev/null
+++ b/lib/ignore-value.h
@@ -0,0 +1,45 @@
+/* ignore a value to quiet a compiler warning
+
+   Copyright (C) 2008 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+/* Written by Jim Meyering.  */
+
+#ifndef __attribute__
+# if __GNUC__ < 2 || (__GNUC__ == 2 && __GNUC_MINOR__ < 8)
+#  define __attribute__(x)
+# endif
+#endif
+
+/* Use this function to avoid a warning when using a function declared with
+   gcc's warn_unused_result attribute, but for which you really do want to
+   ignore the result.  Traditionally, people have used a "(void)" cast to
+   indicate that a function's return value is deliberately unused.  However,
+   if the function is declared with __attribute__((warn_unused_result)),
+   gcc issues a warning even with the cast.
+
+   Caution: most of the time, you really should heed gcc's warning, and
+   check the return value.  However, in those exceptional cases in which
+   you're sure you know what you're doing, use this function.
+
+   For the record, here's one of the ignorable warnings:
+   "copy.c:233: warning: ignoring return value of 'fchown',
+   declared with attribute warn_unused_result".  */
+
+static inline void
+ignore_value (int i __attribute__ ((__unused__)))
+{
+  /* empty */
+}
diff --git a/modules/ignore-value b/modules/ignore-value
new file mode 100644
index 0000000..32991ab
--- /dev/null
+++ b/modules/ignore-value
@@ -0,0 +1,22 @@
+Description:
+ignore a value to quiet a compiler warning
+
+Files:
+lib/ignore-value.h
+
+Depends-on:
+inline
+
+configure.ac:
+
+Makefile.am:
+lib_SOURCES += ignore-value.h
+
+Include:
+#include <ignore-value.h>
+
+License:
+LGPL
+
+Maintainer:
+Jim Meyering
--
1.6.0.2.532.g84ed4c