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# =============================================================================
# https://www.gnu.org/software/autoconf-archive/ax_compiler_flags_cflags.html
# =============================================================================
#
# SYNOPSIS
#
# AX_COMPILER_FLAGS_CFLAGS([VARIABLE], [IS-RELEASE], [EXTRA-BASE-FLAGS], [EXTRA-YES-FLAGS])
#
# DESCRIPTION
#
# Add warning flags for the C compiler to VARIABLE, which defaults to
# WARN_CFLAGS. VARIABLE is AC_SUBST-ed by this macro, but must be
# manually added to the CFLAGS variable for each target in the code base.
#
# This macro depends on the environment set up by AX_COMPILER_FLAGS.
# Specifically, it uses the value of $ax_enable_compile_warnings to decide
# which flags to enable.
#
# LICENSE
#
# Copyright (c) 2014, 2015 Philip Withnall <philip@tecnocode.co.uk>
# Copyright (c) 2017, 2018 Reini Urban <rurban@cpan.org>
#
# Copying and distribution of this file, with or without modification, are
# permitted in any medium without royalty provided the copyright notice
# and this notice are preserved. This file is offered as-is, without any
# warranty.
#serial 16
AC_DEFUN([AX_COMPILER_FLAGS_CFLAGS],[
AC_REQUIRE([AC_PROG_SED])
AX_REQUIRE_DEFINED([AX_APPEND_COMPILE_FLAGS])
AX_REQUIRE_DEFINED([AX_APPEND_FLAG])
AX_REQUIRE_DEFINED([AX_CHECK_COMPILE_FLAG])
# Variable names
m4_define([ax_warn_cflags_variable],
[m4_normalize(ifelse([$1],,[WARN_CFLAGS],[$1]))])
AC_LANG_PUSH([C])
AC_COMPILE_IFELSE([AC_LANG_PROGRAM([
[#ifndef __cplusplus
#error "no C++"
#endif]])],
[ax_compiler_cxx=yes;],
[ax_compiler_cxx=no;])
# Always pass -Werror=unknown-warning-option to get Clang to fail on bad
# flags, otherwise they are always appended to the warn_cflags variable, and
# Clang warns on them for every compilation unit.
# If this is passed to GCC, it will explode, so the flag must be enabled
# conditionally.
AX_CHECK_COMPILE_FLAG([-Werror=unknown-warning-option],[
ax_compiler_flags_test="-Werror=unknown-warning-option"
],[
ax_compiler_flags_test=""
])
# Check that -Wno-suggest-attribute=format is supported
AX_CHECK_COMPILE_FLAG([-Wno-suggest-attribute=format],[
ax_compiler_no_suggest_attribute_flags="-Wno-suggest-attribute=format"
],[
ax_compiler_no_suggest_attribute_flags=""
])
# Base flags
AX_APPEND_COMPILE_FLAGS([ dnl
-fno-strict-aliasing dnl
$3 dnl
],ax_warn_cflags_variable,[$ax_compiler_flags_test])
AS_IF([test "$ax_enable_compile_warnings" != "no"],[
# "yes" flags
AX_APPEND_COMPILE_FLAGS([ dnl
-Wall dnl
-Wextra dnl
-Wundef dnl
-Wwrite-strings dnl
-Wpointer-arith dnl
-Wmissing-declarations dnl
-Wredundant-decls dnl
-Wno-unused-parameter dnl
-Wno-missing-field-initializers dnl
-Wformat=2 dnl
-Wcast-align dnl
-Wformat-nonliteral dnl
-Wformat-security dnl
-Wsign-compare dnl
-Wstrict-aliasing dnl
-Wshadow dnl
-Winline dnl
-Wpacked dnl
-Wmissing-format-attribute dnl
-Wmissing-noreturn dnl
-Winit-self dnl
-Wredundant-decls dnl
-Wmissing-include-dirs dnl
-Wunused-but-set-variable dnl
-Warray-bounds dnl
-Wreturn-type dnl
-Wswitch-enum dnl
-Wswitch-default dnl
-Wduplicated-cond dnl
-Wduplicated-branches dnl
-Wlogical-op dnl
-Wrestrict dnl
-Wnull-dereference dnl
-Wdouble-promotion dnl
$4 dnl
$5 dnl
$6 dnl
$7 dnl
],ax_warn_cflags_variable,[$ax_compiler_flags_test])
if test "$ax_compiler_cxx" = "no" ; then
# C-only flags. Warn in C++
AX_APPEND_COMPILE_FLAGS([ dnl
-Wnested-externs dnl
-Wmissing-prototypes dnl
-Wstrict-prototypes dnl
-Wdeclaration-after-statement dnl
-Wimplicit-function-declaration dnl
-Wold-style-definition dnl
-Wjump-misses-init dnl
],ax_warn_cflags_variable,[$ax_compiler_flags_test])
fi
])
AS_IF([test "$ax_enable_compile_warnings" = "error"],[
# "error" flags; -Werror has to be appended unconditionally because
# it's not possible to test for
#
# suggest-attribute=format is disabled because it gives too many false
# positives
AX_APPEND_FLAG([-Werror],ax_warn_cflags_variable)
AX_APPEND_COMPILE_FLAGS([ dnl
[$ax_compiler_no_suggest_attribute_flags] dnl
],ax_warn_cflags_variable,[$ax_compiler_flags_test])
])
# In the flags below, when disabling specific flags, always add *both*
# -Wno-foo and -Wno-error=foo. This fixes the situation where (for example)
# we enable -Werror, disable a flag, and a build bot passes CFLAGS=-Wall,
# which effectively turns that flag back on again as an error.
for flag in $ax_warn_cflags_variable; do
AS_CASE([$flag],
[-Wno-*=*],[],
[-Wno-*],[
AX_APPEND_COMPILE_FLAGS([-Wno-error=$(AS_ECHO([$flag]) | $SED 's/^-Wno-//')],
ax_warn_cflags_variable,
[$ax_compiler_flags_test])
])
done
AC_LANG_POP([C])
# Substitute the variables
AC_SUBST(ax_warn_cflags_variable)
])dnl AX_COMPILER_FLAGS
|
