1From c0f075bdee5edabf8f19b68e0880fbd249a89653 Mon Sep 17 00:00:00 2001 2From: Thomas Petazzoni <thomas.petazzoni@free-electrons.com> 3Date: Sat, 3 Jan 2015 15:09:59 +0100 4Subject: [PATCH] Add test for -Wunused-but-set-variable 5 6The -Wunused-but-set-variable option does not exist in some old gcc 7versions (gcc 4.5.x), so using it unconditionally breaks the build 8with such compilers. 9 10This commit introduces the AX_CHECK_COMPILE_FLAG m4 macro taken from 11the autoconf-archive 12(http://git.savannah.gnu.org/gitweb/?p=autoconf-archive.git;a=blob_plain;f=m4/ax_check_compile_flag.m4), 13and uses it to detect if the -Wunused-but-set-variable option is 14supported, and only uses it in this case. 15 16Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com> 17(rebased against v0.1.0) 18Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de> 19(rebased against v0.6.3) 20Signed-off-by: Adam Duskett <Aduskett@gmail.com> 21[rebased against v1.0.3) 22Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com> 23[Upstream status: rejected 24(https://github.com/meetecho/janus-gateway/pull/1789)] 25--- 26 Makefile.am | 1 + 27 configure.ac | 6 ++- 28 m4/ax_check_compile_flag.m4 | 74 +++++++++++++++++++++++++++++++++++++ 29 3 files changed, 79 insertions(+), 2 deletions(-) 30 create mode 100644 m4/ax_check_compile_flag.m4 31 32diff --git a/src/Makefile.am b/src/Makefile.am 33index f961fdb..3ddbe59 100644 34--- a/src/Makefile.am 35+++ b/src/Makefile.am 36@@ -151,6 +151,7 @@ janus_CFLAGS = \ 37 -DEVENTDIR=\"$(eventdir)\" \ 38 -DLOGGERDIR=\"$(loggerdir)\" \ 39 -DCONFDIR=\"$(confdir)\" \ 40+ @GCC_WARN_UNUSED_BUT_SET@ \ 41 $(BORINGSSL_CFLAGS) \ 42 $(NULL) 43 44diff --git a/configure.ac b/configure.ac 45index ca17a29..beef91a 100644 46--- a/configure.ac 47+++ b/configure.ac 48@@ -13,6 +13,9 @@ AM_SILENT_RULES([yes]) 49 AC_USE_SYSTEM_EXTENSIONS 50 51 AC_PROG_CC 52+AX_CHECK_COMPILE_FLAG([-Wunused-but-set-variable], 53+ [GCC_WARN_UNUSED_BUT_SET=-Wunused-but-set-variable]) 54+AC_SUBST(GCC_WARN_UNUSED_BUT_SET) 55 56 LT_PREREQ([2.2]) 57 LT_INIT 58@@ -64,8 +67,7 @@ clang*) 59 CFLAGS="$CFLAGS \ 60 -Wcast-align \ 61 -Wno-override-init \ 62- -Wunsafe-loop-optimizations \ 63- -Wunused-but-set-variable" 64+ -Wunsafe-loop-optimizations" 65 esac 66 67 JANUS_VERSION=103 68diff --git a/m4/ax_check_compile_flag.m4 b/m4/ax_check_compile_flag.m4 69new file mode 100644 70index 0000000..51df0c0 71--- /dev/null 72+++ b/m4/ax_check_compile_flag.m4 73@@ -0,0 +1,74 @@ 74+# =========================================================================== 75+# http://www.gnu.org/software/autoconf-archive/ax_check_compile_flag.html 76+# =========================================================================== 77+# 78+# SYNOPSIS 79+# 80+# AX_CHECK_COMPILE_FLAG(FLAG, [ACTION-SUCCESS], [ACTION-FAILURE], [EXTRA-FLAGS], [INPUT]) 81+# 82+# DESCRIPTION 83+# 84+# Check whether the given FLAG works with the current language's compiler 85+# or gives an error. (Warnings, however, are ignored) 86+# 87+# ACTION-SUCCESS/ACTION-FAILURE are shell commands to execute on 88+# success/failure. 89+# 90+# If EXTRA-FLAGS is defined, it is added to the current language's default 91+# flags (e.g. CFLAGS) when the check is done. The check is thus made with 92+# the flags: "CFLAGS EXTRA-FLAGS FLAG". This can for example be used to 93+# force the compiler to issue an error when a bad flag is given. 94+# 95+# INPUT gives an alternative input source to AC_COMPILE_IFELSE. 96+# 97+# NOTE: Implementation based on AX_CFLAGS_GCC_OPTION. Please keep this 98+# macro in sync with AX_CHECK_{PREPROC,LINK}_FLAG. 99+# 100+# LICENSE 101+# 102+# Copyright (c) 2008 Guido U. Draheim <guidod@gmx.de> 103+# Copyright (c) 2011 Maarten Bosmans <mkbosmans@gmail.com> 104+# 105+# This program is free software: you can redistribute it and/or modify it 106+# under the terms of the GNU General Public License as published by the 107+# Free Software Foundation, either version 3 of the License, or (at your 108+# option) any later version. 109+# 110+# This program is distributed in the hope that it will be useful, but 111+# WITHOUT ANY WARRANTY; without even the implied warranty of 112+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General 113+# Public License for more details. 114+# 115+# You should have received a copy of the GNU General Public License along 116+# with this program. If not, see <http://www.gnu.org/licenses/>. 117+# 118+# As a special exception, the respective Autoconf Macro's copyright owner 119+# gives unlimited permission to copy, distribute and modify the configure 120+# scripts that are the output of Autoconf when processing the Macro. You 121+# need not follow the terms of the GNU General Public License when using 122+# or distributing such scripts, even though portions of the text of the 123+# Macro appear in them. The GNU General Public License (GPL) does govern 124+# all other use of the material that constitutes the Autoconf Macro. 125+# 126+# This special exception to the GPL applies to versions of the Autoconf 127+# Macro released by the Autoconf Archive. When you make and distribute a 128+# modified version of the Autoconf Macro, you may extend this special 129+# exception to the GPL to apply to your modified version as well. 130+ 131+#serial 3 132+ 133+AC_DEFUN([AX_CHECK_COMPILE_FLAG], 134+[AC_PREREQ(2.59)dnl for _AC_LANG_PREFIX 135+AS_VAR_PUSHDEF([CACHEVAR],[ax_cv_check_[]_AC_LANG_ABBREV[]flags_$4_$1])dnl 136+AC_CACHE_CHECK([whether _AC_LANG compiler accepts $1], CACHEVAR, [ 137+ ax_check_save_flags=$[]_AC_LANG_PREFIX[]FLAGS 138+ _AC_LANG_PREFIX[]FLAGS="$[]_AC_LANG_PREFIX[]FLAGS $4 $1" 139+ AC_COMPILE_IFELSE([m4_default([$5],[AC_LANG_PROGRAM()])], 140+ [AS_VAR_SET(CACHEVAR,[yes])], 141+ [AS_VAR_SET(CACHEVAR,[no])]) 142+ _AC_LANG_PREFIX[]FLAGS=$ax_check_save_flags]) 143+AS_IF([test x"AS_VAR_GET(CACHEVAR)" = xyes], 144+ [m4_default([$2], :)], 145+ [m4_default([$3], :)]) 146+AS_VAR_POPDEF([CACHEVAR])dnl 147+])dnl AX_CHECK_COMPILE_FLAGS 148-- 1492.20.1 150 151