1# ============================================================================ 2# http://www.gnu.org/software/autoconf-archive/ax_compiler_flags_cflags.html 3# ============================================================================ 4# 5# SYNOPSIS 6# 7# AX_COMPILER_FLAGS_CFLAGS([VARIABLE], [IS-RELEASE], [EXTRA-BASE-FLAGS], [EXTRA-YES-FLAGS]) 8# 9# DESCRIPTION 10# 11# Add warning flags for the C compiler to VARIABLE, which defaults to 12# WARN_CFLAGS. VARIABLE is AC_SUBST-ed by this macro, but must be 13# manually added to the CFLAGS variable for each target in the code base. 14# 15# This macro depends on the environment set up by AX_COMPILER_FLAGS. 16# Specifically, it uses the value of $ax_enable_compile_warnings to decide 17# which flags to enable. 18# 19# LICENSE 20# 21# Copyright (c) 2014, 2015 Philip Withnall <philip@tecnocode.co.uk> 22# 23# Copying and distribution of this file, with or without modification, are 24# permitted in any medium without royalty provided the copyright notice 25# and this notice are preserved. This file is offered as-is, without any 26# warranty. 27 28#serial 11 29 30AC_DEFUN([AX_COMPILER_FLAGS_CFLAGS],[ 31 AC_REQUIRE([AC_PROG_SED]) 32 AX_REQUIRE_DEFINED([AX_APPEND_COMPILE_FLAGS]) 33 AX_REQUIRE_DEFINED([AX_APPEND_FLAG]) 34 AX_REQUIRE_DEFINED([AX_CHECK_COMPILE_FLAG]) 35 36 # Variable names 37 m4_define(ax_warn_cflags_variable, 38 [m4_normalize(ifelse([$1],,[WARN_CFLAGS],[$1]))]) 39 40 AC_LANG_PUSH([C]) 41 42 # Always pass -Werror=unknown-warning-option to get Clang to fail on bad 43 # flags, otherwise they are always appended to the warn_cflags variable, and 44 # Clang warns on them for every compilation unit. 45 # If this is passed to GCC, it will explode, so the flag must be enabled 46 # conditionally. 47 AX_CHECK_COMPILE_FLAG([-Werror=unknown-warning-option],[ 48 ax_compiler_flags_test="-Werror=unknown-warning-option" 49 ],[ 50 ax_compiler_flags_test="" 51 ]) 52 53 # Base flags 54 AX_APPEND_COMPILE_FLAGS([ dnl 55 -fno-strict-aliasing dnl 56 $3 dnl 57 ],ax_warn_cflags_variable,[$ax_compiler_flags_test]) 58 59 AS_IF([test "$ax_enable_compile_warnings" != "no"],[ 60 # "yes" flags 61 AX_APPEND_COMPILE_FLAGS([ dnl 62 -Wall dnl 63 -Wextra dnl 64 -Wundef dnl 65 -Wnested-externs dnl 66 -Wwrite-strings dnl 67 -Wpointer-arith dnl 68 -Wmissing-declarations dnl 69 -Wmissing-prototypes dnl 70 -Wstrict-prototypes dnl 71 -Wredundant-decls dnl 72 -Wno-unused-parameter dnl 73 -Wno-missing-field-initializers dnl 74 -Wdeclaration-after-statement dnl 75 -Wformat=2 dnl 76 -Wold-style-definition dnl 77 -Wcast-align dnl 78 -Wformat-nonliteral dnl 79 -Wformat-security dnl 80 -Wsign-compare dnl 81 -Wstrict-aliasing dnl 82 -Wshadow dnl 83 -Winline dnl 84 -Wpacked dnl 85 -Wmissing-format-attribute dnl 86 -Wmissing-noreturn dnl 87 -Winit-self dnl 88 -Wredundant-decls dnl 89 -Wmissing-include-dirs dnl 90 -Wunused-but-set-variable dnl 91 -Warray-bounds dnl 92 -Wimplicit-function-declaration dnl 93 -Wreturn-type dnl 94 -Wswitch-enum dnl 95 -Wswitch-default dnl 96 $4 dnl 97 $5 dnl 98 $6 dnl 99 $7 dnl 100 ],ax_warn_cflags_variable,[$ax_compiler_flags_test]) 101 ]) 102 AS_IF([test "$ax_enable_compile_warnings" = "error"],[ 103 # "error" flags; -Werror has to be appended unconditionally because 104 # it's not possible to test for 105 # 106 # suggest-attribute=format is disabled because it gives too many false 107 # positives 108 AX_APPEND_FLAG([-Werror],ax_warn_cflags_variable) 109 110 AX_APPEND_COMPILE_FLAGS([ dnl 111 -Wno-suggest-attribute=format dnl 112 ],ax_warn_cflags_variable,[$ax_compiler_flags_test]) 113 ]) 114 115 # In the flags below, when disabling specific flags, always add *both* 116 # -Wno-foo and -Wno-error=foo. This fixes the situation where (for example) 117 # we enable -Werror, disable a flag, and a build bot passes CFLAGS=-Wall, 118 # which effectively turns that flag back on again as an error. 119 for flag in $ax_warn_cflags_variable; do 120 AS_CASE([$flag], 121 [-Wno-*=*],[], 122 [-Wno-*],[ 123 AX_APPEND_COMPILE_FLAGS([-Wno-error=$(AS_ECHO([$flag]) | $SED 's/^-Wno-//')], 124 ax_warn_cflags_variable, 125 [$ax_compiler_flags_test]) 126 ]) 127 done 128 129 AC_LANG_POP([C]) 130 131 # Substitute the variables 132 AC_SUBST(ax_warn_cflags_variable) 133])dnl AX_COMPILER_FLAGS 134