| blob | 14acae55755a33a78d6cbe4d54a6a6773de0394d |
1 From c0f075bdee5edabf8f19b68e0880fbd249a89653 Mon Sep 17 00:00:00 2001
2 From: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
3 Date: Sat, 3 Jan 2015 15:09:59 +0100
4 Subject: [PATCH] Add test for -Wunused-but-set-variable
6 The -Wunused-but-set-variable option does not exist in some old gcc
7 versions (gcc 4.5.x), so using it unconditionally breaks the build
8 with such compilers.
10 This commit introduces the AX_CHECK_COMPILE_FLAG m4 macro taken from
11 the autoconf-archive
12 (http://git.savannah.gnu.org/gitweb/?p=autoconf-archive.git;a=blob_plain;f=m4/ax_check_compile_flag.m4),
13 and uses it to detect if the -Wunused-but-set-variable option is
14 supported, and only uses it in this case.
16 Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
17 ---
18 Makefile.am | 2 +-
19 configure.ac | 3 ++
20 m4/ax_check_compile_flag.m4 | 74 +++++++++++++++++++++++++++++++++++++++++++++
21 3 files changed, 78 insertions(+), 1 deletion(-)
22 create mode 100644 m4/ax_check_compile_flag.m4
24 diff --git a/Makefile.am b/Makefile.am
25 index 5d23e0b..0f51f6a 100644
26 --- a/Makefile.am
27 +++ b/Makefile.am
28 @@ -6,7 +6,7 @@ AM_CFLAGS = \
29 -Wnested-externs -Wstrict-prototypes -Wunsafe-loop-optimizations \
30 -Wwrite-strings -Wno-missing-field-initializers -Wno-unused-parameter \
31 -Wcast-align -Wformat-nonliteral -Wformat-security -Wswitch-default \
32 - -Wmissing-include-dirs -Waggregate-return -Wunused-but-set-variable \
33 + -Wmissing-include-dirs -Waggregate-return @GCC_WARN_UNUSED_BUT_SET@ \
34 -Warray-bounds -Wold-style-definition -Wsign-compare -Wlarger-than=65537
35 AM_CFLAGS += -Wno-undef # sophiasip is not -Wundef--safe
36 AM_CFLAGS += -Wredundant-decls # sophiasip also contains redundant declarations
37 diff --git a/configure.ac b/configure.ac
38 index 17870a7..f9bb1e4 100644
39 --- a/configure.ac
40 +++ b/configure.ac
41 @@ -7,6 +7,9 @@ AM_SILENT_RULES([yes])
42 AC_GNU_SOURCE
44 AC_PROG_CC
45 +AX_CHECK_COMPILE_FLAG([-Wunused-but-set-variable],
46 + [GCC_WARN_UNUSED_BUT_SET=-Wunused-but-set-variable])
47 +AC_SUBST(GCC_WARN_UNUSED_BUT_SET)
49 LT_PREREQ([2.2])
50 LT_INIT
51 diff --git a/m4/ax_check_compile_flag.m4 b/m4/ax_check_compile_flag.m4
52 new file mode 100644
53 index 0000000..51df0c0
54 --- /dev/null
55 +++ b/m4/ax_check_compile_flag.m4
56 @@ -0,0 +1,74 @@
57 +# ===========================================================================
58 +# http://www.gnu.org/software/autoconf-archive/ax_check_compile_flag.html
59 +# ===========================================================================
60 +#
61 +# SYNOPSIS
62 +#
63 +# AX_CHECK_COMPILE_FLAG(FLAG, [ACTION-SUCCESS], [ACTION-FAILURE], [EXTRA-FLAGS], [INPUT])
64 +#
65 +# DESCRIPTION
66 +#
67 +# Check whether the given FLAG works with the current language's compiler
68 +# or gives an error. (Warnings, however, are ignored)
69 +#
70 +# ACTION-SUCCESS/ACTION-FAILURE are shell commands to execute on
71 +# success/failure.
72 +#
73 +# If EXTRA-FLAGS is defined, it is added to the current language's default
74 +# flags (e.g. CFLAGS) when the check is done. The check is thus made with
75 +# the flags: "CFLAGS EXTRA-FLAGS FLAG". This can for example be used to
76 +# force the compiler to issue an error when a bad flag is given.
77 +#
78 +# INPUT gives an alternative input source to AC_COMPILE_IFELSE.
79 +#
80 +# NOTE: Implementation based on AX_CFLAGS_GCC_OPTION. Please keep this
81 +# macro in sync with AX_CHECK_{PREPROC,LINK}_FLAG.
82 +#
83 +# LICENSE
84 +#
85 +# Copyright (c) 2008 Guido U. Draheim <guidod@gmx.de>
86 +# Copyright (c) 2011 Maarten Bosmans <mkbosmans@gmail.com>
87 +#
88 +# This program is free software: you can redistribute it and/or modify it
89 +# under the terms of the GNU General Public License as published by the
90 +# Free Software Foundation, either version 3 of the License, or (at your
91 +# option) any later version.
92 +#
93 +# This program is distributed in the hope that it will be useful, but
94 +# WITHOUT ANY WARRANTY; without even the implied warranty of
95 +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
96 +# Public License for more details.
97 +#
98 +# You should have received a copy of the GNU General Public License along
99 +# with this program. If not, see <http://www.gnu.org/licenses/>.
100 +#
101 +# As a special exception, the respective Autoconf Macro's copyright owner
102 +# gives unlimited permission to copy, distribute and modify the configure
103 +# scripts that are the output of Autoconf when processing the Macro. You
104 +# need not follow the terms of the GNU General Public License when using
105 +# or distributing such scripts, even though portions of the text of the
106 +# Macro appear in them. The GNU General Public License (GPL) does govern
107 +# all other use of the material that constitutes the Autoconf Macro.
108 +#
109 +# This special exception to the GPL applies to versions of the Autoconf
110 +# Macro released by the Autoconf Archive. When you make and distribute a
111 +# modified version of the Autoconf Macro, you may extend this special
112 +# exception to the GPL to apply to your modified version as well.
113 +
114 +#serial 3
115 +
116 +AC_DEFUN([AX_CHECK_COMPILE_FLAG],
117 +[AC_PREREQ(2.59)dnl for _AC_LANG_PREFIX
118 +AS_VAR_PUSHDEF([CACHEVAR],[ax_cv_check_[]_AC_LANG_ABBREV[]flags_$4_$1])dnl
119 +AC_CACHE_CHECK([whether _AC_LANG compiler accepts $1], CACHEVAR, [
120 + ax_check_save_flags=$[]_AC_LANG_PREFIX[]FLAGS
121 + _AC_LANG_PREFIX[]FLAGS="$[]_AC_LANG_PREFIX[]FLAGS $4 $1"
122 + AC_COMPILE_IFELSE([m4_default([$5],[AC_LANG_PROGRAM()])],
123 + [AS_VAR_SET(CACHEVAR,[yes])],
124 + [AS_VAR_SET(CACHEVAR,[no])])
125 + _AC_LANG_PREFIX[]FLAGS=$ax_check_save_flags])
126 +AS_IF([test x"AS_VAR_GET(CACHEVAR)" = xyes],
127 + [m4_default([$2], :)],
128 + [m4_default([$3], :)])
129 +AS_VAR_POPDEF([CACHEVAR])dnl
130 +])dnl AX_CHECK_COMPILE_FLAGS
131 --
132 2.1.0