| blob | 13bc21ea42c17aae25d088059b55d66cc04c6a20 |
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 (rebased against v0.1.0)
18 Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
19 ---
20 Makefile.am | 2 +-
21 configure.ac | 3 ++
22 m4/ax_check_compile_flag.m4 | 74 +++++++++++++++++++++++++++++++++++++++++++++
23 3 files changed, 78 insertions(+), 1 deletion(-)
24 create mode 100644 m4/ax_check_compile_flag.m4
26 diff --git a/Makefile.am b/Makefile.am
27 index 5d23e0b..0f51f6a 100644
28 --- a/Makefile.am
29 +++ b/Makefile.am
30 @@ -6,7 +6,7 @@ AM_CFLAGS = \
31 -Wnested-externs -Wstrict-prototypes -Wunsafe-loop-optimizations \
32 -Wwrite-strings -Wno-missing-field-initializers -Wno-unused-parameter \
33 -Wcast-align -Wformat-nonliteral -Wformat-security -Wswitch-default \
34 - -Wmissing-include-dirs -Wno-aggregate-return -Wunused-but-set-variable \
35 + -Wmissing-include-dirs -Wno-aggregate-return @GCC_WARN_UNUSED_BUT_SET@ \
36 -Warray-bounds -Wold-style-definition -Wsign-compare -Wlarger-than=65537
37 AM_CFLAGS += -Wno-undef # sophiasip is not -Wundef--safe
38 AM_CFLAGS += -Wno-redundant-decls # sophiasip also contains redundant declarations
39 diff --git a/configure.ac b/configure.ac
40 index 17870a7..f9bb1e4 100644
41 --- a/configure.ac
42 +++ b/configure.ac
43 @@ -7,6 +7,9 @@ AM_SILENT_RULES([yes])
44 AC_GNU_SOURCE
46 AC_PROG_CC
47 +AX_CHECK_COMPILE_FLAG([-Wunused-but-set-variable],
48 + [GCC_WARN_UNUSED_BUT_SET=-Wunused-but-set-variable])
49 +AC_SUBST(GCC_WARN_UNUSED_BUT_SET)
51 LT_PREREQ([2.2])
52 LT_INIT
53 diff --git a/m4/ax_check_compile_flag.m4 b/m4/ax_check_compile_flag.m4
54 new file mode 100644
55 index 0000000..51df0c0
56 --- /dev/null
57 +++ b/m4/ax_check_compile_flag.m4
58 @@ -0,0 +1,74 @@
59 +# ===========================================================================
60 +# http://www.gnu.org/software/autoconf-archive/ax_check_compile_flag.html
61 +# ===========================================================================
62 +#
63 +# SYNOPSIS
64 +#
65 +# AX_CHECK_COMPILE_FLAG(FLAG, [ACTION-SUCCESS], [ACTION-FAILURE], [EXTRA-FLAGS], [INPUT])
66 +#
67 +# DESCRIPTION
68 +#
69 +# Check whether the given FLAG works with the current language's compiler
70 +# or gives an error. (Warnings, however, are ignored)
71 +#
72 +# ACTION-SUCCESS/ACTION-FAILURE are shell commands to execute on
73 +# success/failure.
74 +#
75 +# If EXTRA-FLAGS is defined, it is added to the current language's default
76 +# flags (e.g. CFLAGS) when the check is done. The check is thus made with
77 +# the flags: "CFLAGS EXTRA-FLAGS FLAG". This can for example be used to
78 +# force the compiler to issue an error when a bad flag is given.
79 +#
80 +# INPUT gives an alternative input source to AC_COMPILE_IFELSE.
81 +#
82 +# NOTE: Implementation based on AX_CFLAGS_GCC_OPTION. Please keep this
83 +# macro in sync with AX_CHECK_{PREPROC,LINK}_FLAG.
84 +#
85 +# LICENSE
86 +#
87 +# Copyright (c) 2008 Guido U. Draheim <guidod@gmx.de>
88 +# Copyright (c) 2011 Maarten Bosmans <mkbosmans@gmail.com>
89 +#
90 +# This program is free software: you can redistribute it and/or modify it
91 +# under the terms of the GNU General Public License as published by the
92 +# Free Software Foundation, either version 3 of the License, or (at your
93 +# option) any later version.
94 +#
95 +# This program is distributed in the hope that it will be useful, but
96 +# WITHOUT ANY WARRANTY; without even the implied warranty of
97 +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
98 +# Public License for more details.
99 +#
100 +# You should have received a copy of the GNU General Public License along
101 +# with this program. If not, see <http://www.gnu.org/licenses/>.
102 +#
103 +# As a special exception, the respective Autoconf Macro's copyright owner
104 +# gives unlimited permission to copy, distribute and modify the configure
105 +# scripts that are the output of Autoconf when processing the Macro. You
106 +# need not follow the terms of the GNU General Public License when using
107 +# or distributing such scripts, even though portions of the text of the
108 +# Macro appear in them. The GNU General Public License (GPL) does govern
109 +# all other use of the material that constitutes the Autoconf Macro.
110 +#
111 +# This special exception to the GPL applies to versions of the Autoconf
112 +# Macro released by the Autoconf Archive. When you make and distribute a
113 +# modified version of the Autoconf Macro, you may extend this special
114 +# exception to the GPL to apply to your modified version as well.
115 +
116 +#serial 3
117 +
118 +AC_DEFUN([AX_CHECK_COMPILE_FLAG],
119 +[AC_PREREQ(2.59)dnl for _AC_LANG_PREFIX
120 +AS_VAR_PUSHDEF([CACHEVAR],[ax_cv_check_[]_AC_LANG_ABBREV[]flags_$4_$1])dnl
121 +AC_CACHE_CHECK([whether _AC_LANG compiler accepts $1], CACHEVAR, [
122 + ax_check_save_flags=$[]_AC_LANG_PREFIX[]FLAGS
123 + _AC_LANG_PREFIX[]FLAGS="$[]_AC_LANG_PREFIX[]FLAGS $4 $1"
124 + AC_COMPILE_IFELSE([m4_default([$5],[AC_LANG_PROGRAM()])],
125 + [AS_VAR_SET(CACHEVAR,[yes])],
126 + [AS_VAR_SET(CACHEVAR,[no])])
127 + _AC_LANG_PREFIX[]FLAGS=$ax_check_save_flags])
128 +AS_IF([test x"AS_VAR_GET(CACHEVAR)" = xyes],
129 + [m4_default([$2], :)],
130 + [m4_default([$3], :)])
131 +AS_VAR_POPDEF([CACHEVAR])dnl
132 +])dnl AX_CHECK_COMPILE_FLAGS
133 --
134 2.1.0