1dnl Copyright 2010 The Kyua Authors. 2dnl All rights reserved. 3dnl 4dnl Redistribution and use in source and binary forms, with or without 5dnl modification, are permitted provided that the following conditions are 6dnl met: 7dnl 8dnl * Redistributions of source code must retain the above copyright 9dnl notice, this list of conditions and the following disclaimer. 10dnl * Redistributions in binary form must reproduce the above copyright 11dnl notice, this list of conditions and the following disclaimer in the 12dnl documentation and/or other materials provided with the distribution. 13dnl * Neither the name of Google Inc. nor the names of its contributors 14dnl may be used to endorse or promote products derived from this software 15dnl without specific prior written permission. 16dnl 17dnl THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 18dnl "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 19dnl LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 20dnl A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 21dnl OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 22dnl SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 23dnl LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 24dnl DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 25dnl THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 26dnl (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 27dnl OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 28 29dnl \file compiler-flags.m4 30dnl 31dnl Macros to check for the existence of compiler flags. The macros in this 32dnl file support both C and C++. 33dnl 34dnl Be aware that, in order to detect a flag accurately, we may need to enable 35dnl strict warning checking in the compiler (i.e. enable -Werror). Some 36dnl compilers, e.g. Clang, report unknown -W flags as warnings unless -Werror is 37dnl selected. This fact would confuse the flag checks below because we would 38dnl conclude that a flag is valid while in reality it is not. To resolve this, 39dnl the macros below will pass -Werror to the compiler along with any other flag 40dnl being checked. 41 42 43dnl Checks for a compiler flag and sets a result variable. 44dnl 45dnl This is an auxiliary macro for the implementation of _KYUA_FLAG. 46dnl 47dnl \param 1 The shell variable containing the compiler name. Used for 48dnl reporting purposes only. C or CXX. 49dnl \param 2 The shell variable containing the flags for the compiler. 50dnl CFLAGS or CXXFLAGS. 51dnl \param 3 The name of the compiler flag to check for. 52dnl \param 4 The shell variable to set with the result of the test. Will 53dnl be set to 'yes' if the flag is valid, 'no' otherwise. 54dnl \param 5 Additional, optional flags to pass to the C compiler while 55dnl looking for the flag in $3. We use this here to pass -Werror to the 56dnl flag checks (unless we are checking for -Werror already). 57AC_DEFUN([_KYUA_FLAG_AUX], [ 58 if test x"${$4-unset}" = xunset; then 59 AC_MSG_CHECKING(whether ${$1} supports $3) 60 saved_flags="${$2}" 61 $4=no 62 $2="${$2} $5 $3" 63 # The inclusion of a header file in the test program below is needed 64 # because some compiler flags that we test for may actually not be 65 # compatible with other flags, and such compatibility checks are 66 # performed within the system header files. 67 # 68 # As an example, if we are testing for -D_FORTIFY_SOURCE=2 and the 69 # compilation is being done with -O2, Linux's /usr/include/features.h 70 # will abort the compilation of our code later on. By including a 71 # generic header file here that pulls in features.h we ensure that 72 # this test is accurate for the build stage. 73 AC_LINK_IFELSE([AC_LANG_PROGRAM([#include <stdio.h>], [return 0;])], 74 AC_MSG_RESULT(yes) 75 $4=yes, 76 AC_MSG_RESULT(no)) 77 $2="${saved_flags}" 78 fi 79]) 80 81 82dnl Checks for a compiler flag and appends it to a result variable. 83dnl 84dnl \param 1 The shell variable containing the compiler name. Used for 85dnl reporting purposes only. CC or CXX. 86dnl \param 2 The shell variable containing the flags for the compiler. 87dnl CFLAGS or CXXFLAGS. 88dnl \param 3 The name of the compiler flag to check for. 89dnl \param 4 The shell variable to which to append $3 if the flag is valid. 90AC_DEFUN([_KYUA_FLAG], [ 91 _KYUA_FLAG_AUX([$1], [$2], [-Werror], [kyua_$1_has_werror]) 92 if test "$3" = "-Werror"; then 93 found=${kyua_$1_has_werror} 94 else 95 found=unset 96 if test ${kyua_$1_has_werror} = yes; then 97 _KYUA_FLAG_AUX([$1], [$2], [$3], [found], [-Werror]) 98 else 99 _KYUA_FLAG_AUX([$1], [$2], [$3], [found], []) 100 fi 101 fi 102 if test ${found} = yes; then 103 $4="${$4} $3" 104 fi 105]) 106 107 108dnl Checks for a C compiler flag and appends it to a variable. 109dnl 110dnl \pre The current language is C. 111dnl 112dnl \param 1 The name of the compiler flag to check for. 113dnl \param 2 The shell variable to which to append $1 if the flag is valid. 114AC_DEFUN([KYUA_CC_FLAG], [ 115 AC_LANG_ASSERT([C]) 116 _KYUA_FLAG([CC], [CFLAGS], [$1], [$2]) 117]) 118 119 120dnl Checks for a C++ compiler flag and appends it to a variable. 121dnl 122dnl \pre The current language is C++. 123dnl 124dnl \param 1 The name of the compiler flag to check for. 125dnl \param 2 The shell variable to which to append $1 if the flag is valid. 126AC_DEFUN([KYUA_CXX_FLAG], [ 127 AC_LANG_ASSERT([C++]) 128 _KYUA_FLAG([CXX], [CXXFLAGS], [$1], [$2]) 129]) 130 131 132dnl Checks for a set of C compiler flags and appends them to CFLAGS. 133dnl 134dnl The checks are performed independently and only when all the checks are 135dnl done, the output variable is modified. 136dnl 137dnl \param 1 Whitespace-separated list of C flags to check. 138AC_DEFUN([KYUA_CC_FLAGS], [ 139 AC_LANG_PUSH([C]) 140 valid_cflags= 141 for f in $1; do 142 KYUA_CC_FLAG(${f}, valid_cflags) 143 done 144 if test -n "${valid_cflags}"; then 145 CFLAGS="${CFLAGS} ${valid_cflags}" 146 fi 147 AC_LANG_POP([C]) 148]) 149 150 151dnl Checks for a set of C++ compiler flags and appends them to CXXFLAGS. 152dnl 153dnl The checks are performed independently and only when all the checks are 154dnl done, the output variable is modified. 155dnl 156dnl \pre The current language is C++. 157dnl 158dnl \param 1 Whitespace-separated list of C flags to check. 159AC_DEFUN([KYUA_CXX_FLAGS], [ 160 AC_LANG_PUSH([C++]) 161 valid_cxxflags= 162 for f in $1; do 163 KYUA_CXX_FLAG(${f}, valid_cxxflags) 164 done 165 if test -n "${valid_cxxflags}"; then 166 CXXFLAGS="${CXXFLAGS} ${valid_cxxflags}" 167 fi 168 AC_LANG_POP([C++]) 169]) 170