From 28ba44ad9ca14153e96c94a9100423ea224c1af3 Mon Sep 17 00:00:00 2001 From: Simon Marchi Date: Tue, 18 Feb 2020 13:14:22 -0500 Subject: [PATCH] configure: simplify warning flags detection We currently use the AX_COMPILER_FLAGS macro to detect the warning flags that the current compiler supports. It works, but is quite invasive. It unconditionally enables a bunch of warnings we don't want, which forces us to disable them with many -Wno-foo switches. Instead of using AX_COMPILER_FLAGS, we can use the slightly lower lever macro AX_APPEND_COMPILE_FLAGS to achieve our goal of detecting which warning flags are supported. This is what we ended up using in lttng-tools (a completely unrelated project, but that has a suspiciously high ratio of contributors in common with Babeltrace). I looked in our git history to see which warning flags were mentioned in commit messages. I have added the flags that did find actual problems and are not enabled by default to the AX_APPEND_COMPILE_FLAGS invocation. I have also added the flags that AX_COMPILER_FLAGS did provide, which we didn't need to disable. The --{enable,disable}-Werror flag is added using an explicit AC_ARG_ENABLE. In lttng-tools, it was decided to _not_ have -Werror by default, so I suggest we do the same in Babeltrace, for consistency (although it saddens me very much). Developers who want to build with -Werror will need to pass --enable-Werror. Note that with this patch, we lose the following configure switch, that is provided by AX_COMPILER_FLAGS: --enable-compile-warnings=[no/yes/error] Change-Id: If968f7385a7f5c48d27f402c76bc26241a8f505a Signed-off-by: Simon Marchi Reviewed-on: https://review.lttng.org/c/babeltrace/+/3209 Tested-by: jenkins Reviewed-by: Michael Jeanson [Retrieved from: https://github.com/efficios/babeltrace/commit/28ba44ad9ca14153e96c94a9100423ea224c1af3] Signed-off-by: Fabrice Fontaine --- configure.ac | 74 +++++++++------ m4/ax_compiler_flags.m4 | 158 ------------------------------- m4/ax_compiler_flags_cflags.m4 | 161 -------------------------------- m4/ax_compiler_flags_gir.m4 | 60 ------------ m4/ax_compiler_flags_ldflags.m4 | 111 ---------------------- 5 files changed, 46 insertions(+), 518 deletions(-) delete mode 100644 m4/ax_compiler_flags.m4 delete mode 100644 m4/ax_compiler_flags_cflags.m4 delete mode 100644 m4/ax_compiler_flags_gir.m4 delete mode 100644 m4/ax_compiler_flags_ldflags.m4 diff --git a/configure.ac b/configure.ac index 055fba101..7ebcf2ad4 100644 --- a/configure.ac +++ b/configure.ac @@ -660,25 +660,35 @@ target. CFLAGS=${save_CFLAGS} # Detect C and LD warning flags supported by the compiler. -AX_COMPILER_FLAGS( - [WARN_CFLAGS], dnl CFLAGS variable name - [WARN_LDFLAGS], dnl LDFLAGS variable name (unused for now) - [], dnl is-release - [], dnl Extra base CFLAGS - [ dnl Extra "yes" CFLAGS - dnl Disable these flags, either because we don't want them - dnl or because we want them but are not ready to enable them - dnl yet. - -Wno-sign-compare dnl - -Wno-inline dnl - -Wno-declaration-after-statement dnl - -Wno-switch-enum dnl - -Wno-switch-default dnl - -Wno-packed dnl - -Wno-pointer-arith dnl + +# Detect warning flags supported by the compiler, append them to WARN_CFLAGS. +# +# Pass -Werror as an extra flag during the test: this is needed to make the +# -Wunknown-warning-option diagnostic fatal with clang. +AX_APPEND_COMPILE_FLAGS([ dnl + -Wall dnl + -Wextra dnl + -Wstrict-prototypes dnl + -Wmissing-prototypes dnl + -Wmissing-declarations dnl + -Wnull-dereference dnl + -Wundef dnl + -Wredundant-decls dnl + -Wshadow dnl + -Wjump-misses-init dnl + -Wtautological-constant-out-of-range-compare dnl + -Wnested-externs dnl + -Wwrite-strings dnl + -Wformat=2 dnl -Wno-format-nonliteral dnl - -Wno-double-promotion dnl - -Wno-cast-align dnl + -Wstrict-aliasing dnl + -Wmissing-noreturn dnl + -Winit-self dnl + -Wduplicated-cond dnl + -Wduplicated-branches dnl + -Wlogical-op dnl + -Wno-unused-parameter dnl + -Wno-sign-compare dnl dnl dnl Some versions of SWIG (like 3.0.12) generate code that produces dnl -Wcast-function-type warnings. This warning is present in gcc >= 8. This @@ -692,24 +702,32 @@ AX_COMPILER_FLAGS( dnl dnl Ref: https://github.com/swig/swig/issues/1259 -Wno-cast-function-type dnl - ]) - -# CFLAGS from AX_COMPILER_FLAGS. -AM_CFLAGS="${AM_CFLAGS} ${WARN_CFLAGS}" + -Wno-missing-field-initializers dnl + ], + [WARN_CFLAGS], + [-Werror]) + +# When given, add -Werror to WARN_CFLAGS. +AC_ARG_ENABLE([Werror], + [AS_HELP_STRING([--enable-Werror], [Treat compiler warnings as errors.])] +) +AS_IF([test "x$enable_Werror" = "xyes"], + [WARN_CFLAGS="${WARN_CFLAGS} -Werror"] +) -# The test used in AX_COMPILER_FLAGS, generated using AC_LANG_PROGRAM, is +# The test used in AX_APPEND_COMPILE_FLAGS, generated using AC_LANG_PROGRAM, is # written in such a way that it triggers a -Wold-style-definition warning. So -# if the user has -Werror in their CFLAGS, that warning flag will end up -# disabled, because the test program will not build. +# this warning always ends up disabled if we put it there, because the test +# program does not build. # # Enable it here unconditionally. It is supported by GCC >= 4.8 and by Clang # (it is accepted for compatibility although it has no effect), and there is # not reason to not want it. -AM_CFLAGS="${AM_CFLAGS} -Wold-style-definition" +WARN_CFLAGS="${WARN_CFLAGS} -Wold-style-definition" -# We want this one to always be an error. -AM_CFLAGS="${AM_CFLAGS} -Werror=implicit-function-declaration" +# CFLAGS from AX_APPEND_COMPILE_FLAGS. +AM_CFLAGS="${AM_CFLAGS} ${WARN_CFLAGS}" # Done for AM_CFLAGS. AC_SUBST(AM_CFLAGS) diff --git a/m4/ax_compiler_flags.m4 b/m4/ax_compiler_flags.m4 deleted file mode 100644 index ddb0456c4..000000000 --- a/m4/ax_compiler_flags.m4 +++ /dev/null @@ -1,158 +0,0 @@ -# =========================================================================== -# https://www.gnu.org/software/autoconf-archive/ax_compiler_flags.html -# =========================================================================== -# -# SYNOPSIS -# -# AX_COMPILER_FLAGS([CFLAGS-VARIABLE], [LDFLAGS-VARIABLE], [IS-RELEASE], [EXTRA-BASE-CFLAGS], [EXTRA-YES-CFLAGS], [UNUSED], [UNUSED], [UNUSED], [EXTRA-BASE-LDFLAGS], [EXTRA-YES-LDFLAGS], [UNUSED], [UNUSED], [UNUSED]) -# -# DESCRIPTION -# -# Check for the presence of an --enable-compile-warnings option to -# configure, defaulting to "error" in normal operation, or "yes" if -# IS-RELEASE is equal to "yes". Return the value in the variable -# $ax_enable_compile_warnings. -# -# Depending on the value of --enable-compile-warnings, different compiler -# warnings are checked to see if they work with the current compiler and, -# if so, are appended to CFLAGS-VARIABLE and LDFLAGS-VARIABLE. This -# allows a consistent set of baseline compiler warnings to be used across -# a code base, irrespective of any warnings enabled locally by individual -# developers. By standardising the warnings used by all developers of a -# project, the project can commit to a zero-warnings policy, using -Werror -# to prevent compilation if new warnings are introduced. This makes -# catching bugs which are flagged by warnings a lot easier. -# -# By providing a consistent --enable-compile-warnings argument across all -# projects using this macro, continuous integration systems can easily be -# configured the same for all projects. Automated systems or build -# systems aimed at beginners may want to pass the --disable-Werror -# argument to unconditionally prevent warnings being fatal. -# -# --enable-compile-warnings can take the values: -# -# * no: Base compiler warnings only; not even -Wall. -# * yes: The above, plus a broad range of useful warnings. -# * error: The above, plus -Werror so that all warnings are fatal. -# Use --disable-Werror to override this and disable fatal -# warnings. -# -# The set of base and enabled flags can be augmented using the -# EXTRA-*-CFLAGS and EXTRA-*-LDFLAGS variables, which are tested and -# appended to the output variable if --enable-compile-warnings is not -# "no". Flags should not be disabled using these arguments, as the entire -# point of AX_COMPILER_FLAGS is to enforce a consistent set of useful -# compiler warnings on code, using warnings which have been chosen for low -# false positive rates. If a compiler emits false positives for a -# warning, a #pragma should be used in the code to disable the warning -# locally. See: -# -# https://gcc.gnu.org/onlinedocs/gcc-4.9.2/gcc/Diagnostic-Pragmas.html#Diagnostic-Pragmas -# -# The EXTRA-* variables should only be used to supply extra warning flags, -# and not general purpose compiler flags, as they are controlled by -# configure options such as --disable-Werror. -# -# IS-RELEASE can be used to disable -Werror when making a release, which -# is useful for those hairy moments when you just want to get the release -# done as quickly as possible. Set it to "yes" to disable -Werror. By -# default, it uses the value of $ax_is_release, so if you are using the -# AX_IS_RELEASE macro, there is no need to pass this parameter. For -# example: -# -# AX_IS_RELEASE([git-directory]) -# AX_COMPILER_FLAGS() -# -# CFLAGS-VARIABLE defaults to WARN_CFLAGS, and LDFLAGS-VARIABLE defaults -# to WARN_LDFLAGS. Both variables are AC_SUBST-ed by this macro, but must -# be manually added to the CFLAGS and LDFLAGS variables for each target in -# the code base. -# -# If C++ language support is enabled with AC_PROG_CXX, which must occur -# before this macro in configure.ac, warning flags for the C++ compiler -# are AC_SUBST-ed as WARN_CXXFLAGS, and must be manually added to the -# CXXFLAGS variables for each target in the code base. EXTRA-*-CFLAGS can -# be used to augment the base and enabled flags. -# -# Warning flags for g-ir-scanner (from GObject Introspection) are -# AC_SUBST-ed as WARN_SCANNERFLAGS. This variable must be manually added -# to the SCANNERFLAGS variable for each GIR target in the code base. If -# extra g-ir-scanner flags need to be enabled, the AX_COMPILER_FLAGS_GIR -# macro must be invoked manually. -# -# AX_COMPILER_FLAGS may add support for other tools in future, in addition -# to the compiler and linker. No extra EXTRA-* variables will be added -# for those tools, and all extra support will still use the single -# --enable-compile-warnings configure option. For finer grained control -# over the flags for individual tools, use AX_COMPILER_FLAGS_CFLAGS, -# AX_COMPILER_FLAGS_LDFLAGS and AX_COMPILER_FLAGS_* for new tools. -# -# The UNUSED variables date from a previous version of this macro, and are -# automatically appended to the preceding non-UNUSED variable. They should -# be left empty in new uses of the macro. -# -# LICENSE -# -# Copyright (c) 2014, 2015 Philip Withnall -# Copyright (c) 2015 David King -# -# 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 14 - -# _AX_COMPILER_FLAGS_LANG([LANGNAME]) -m4_defun([_AX_COMPILER_FLAGS_LANG], -[m4_ifdef([_AX_COMPILER_FLAGS_LANG_]$1[_enabled], [], - [m4_define([_AX_COMPILER_FLAGS_LANG_]$1[_enabled], [])dnl - AX_REQUIRE_DEFINED([AX_COMPILER_FLAGS_]$1[FLAGS])])dnl -]) - -AC_DEFUN([AX_COMPILER_FLAGS],[ - # C support is enabled by default. - _AX_COMPILER_FLAGS_LANG([C]) - # Only enable C++ support if AC_PROG_CXX is called. The redefinition of - # AC_PROG_CXX is so that a fatal error is emitted if this macro is called - # before AC_PROG_CXX, which would otherwise cause no C++ warnings to be - # checked. - AC_PROVIDE_IFELSE([AC_PROG_CXX], - [_AX_COMPILER_FLAGS_LANG([CXX])], - [m4_define([AC_PROG_CXX], defn([AC_PROG_CXX])[_AX_COMPILER_FLAGS_LANG([CXX])])]) - AX_REQUIRE_DEFINED([AX_COMPILER_FLAGS_LDFLAGS]) - - # Default value for IS-RELEASE is $ax_is_release - ax_compiler_flags_is_release=m4_tolower(m4_normalize(ifelse([$3],, - [$ax_is_release], - [$3]))) - - AC_ARG_ENABLE([compile-warnings], - AS_HELP_STRING([--enable-compile-warnings=@<:@no/yes/error@:>@], - [Enable compiler warnings and errors]),, - [AS_IF([test "$ax_compiler_flags_is_release" = "yes"], - [enable_compile_warnings="yes"], - [enable_compile_warnings="error"])]) - AC_ARG_ENABLE([Werror], - AS_HELP_STRING([--disable-Werror], - [Unconditionally make all compiler warnings non-fatal]),, - [enable_Werror=maybe]) - - # Return the user's chosen warning level - AS_IF([test "$enable_Werror" = "no" -a \ - "$enable_compile_warnings" = "error"],[ - enable_compile_warnings="yes" - ]) - - ax_enable_compile_warnings=$enable_compile_warnings - - AX_COMPILER_FLAGS_CFLAGS([$1],[$ax_compiler_flags_is_release], - [$4],[$5 $6 $7 $8]) - m4_ifdef([_AX_COMPILER_FLAGS_LANG_CXX_enabled], - [AX_COMPILER_FLAGS_CXXFLAGS([WARN_CXXFLAGS], - [$ax_compiler_flags_is_release], - [$4],[$5 $6 $7 $8])]) - AX_COMPILER_FLAGS_LDFLAGS([$2],[$ax_compiler_flags_is_release], - [$9],[$10 $11 $12 $13]) - AX_COMPILER_FLAGS_GIR([WARN_SCANNERFLAGS],[$ax_compiler_flags_is_release]) -])dnl AX_COMPILER_FLAGS diff --git a/m4/ax_compiler_flags_cflags.m4 b/m4/ax_compiler_flags_cflags.m4 deleted file mode 100644 index 916f91837..000000000 --- a/m4/ax_compiler_flags_cflags.m4 +++ /dev/null @@ -1,161 +0,0 @@ -# ============================================================================= -# 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 -# Copyright (c) 2017, 2018 Reini Urban -# -# 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 17 - -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 "$ax_enable_compile_warnings" != "no"],[ - if test "$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 - - # "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]) - ]) - 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 diff --git a/m4/ax_compiler_flags_gir.m4 b/m4/ax_compiler_flags_gir.m4 deleted file mode 100644 index 5b4924a20..000000000 --- a/m4/ax_compiler_flags_gir.m4 +++ /dev/null @@ -1,60 +0,0 @@ -# =========================================================================== -# https://www.gnu.org/software/autoconf-archive/ax_compiler_flags_gir.html -# =========================================================================== -# -# SYNOPSIS -# -# AX_COMPILER_FLAGS_GIR([VARIABLE], [IS-RELEASE], [EXTRA-BASE-FLAGS], [EXTRA-YES-FLAGS]) -# -# DESCRIPTION -# -# Add warning flags for the g-ir-scanner (from GObject Introspection) to -# VARIABLE, which defaults to WARN_SCANNERFLAGS. VARIABLE is AC_SUBST-ed -# by this macro, but must be manually added to the SCANNERFLAGS variable -# for each GIR 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) 2015 Philip Withnall -# -# 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 6 - -AC_DEFUN([AX_COMPILER_FLAGS_GIR],[ - AX_REQUIRE_DEFINED([AX_APPEND_FLAG]) - - # Variable names - m4_define([ax_warn_scannerflags_variable], - [m4_normalize(ifelse([$1],,[WARN_SCANNERFLAGS],[$1]))]) - - # Base flags - AX_APPEND_FLAG([$3],ax_warn_scannerflags_variable) - - AS_IF([test "$ax_enable_compile_warnings" != "no"],[ - # "yes" flags - AX_APPEND_FLAG([ dnl - --warn-all dnl - $4 dnl - $5 dnl - $6 dnl - $7 dnl - ],ax_warn_scannerflags_variable) - ]) - AS_IF([test "$ax_enable_compile_warnings" = "error"],[ - # "error" flags - AX_APPEND_FLAG([ dnl - --warn-error dnl - ],ax_warn_scannerflags_variable) - ]) - - # Substitute the variables - AC_SUBST(ax_warn_scannerflags_variable) -])dnl AX_COMPILER_FLAGS diff --git a/m4/ax_compiler_flags_ldflags.m4 b/m4/ax_compiler_flags_ldflags.m4 deleted file mode 100644 index 976d1198d..000000000 --- a/m4/ax_compiler_flags_ldflags.m4 +++ /dev/null @@ -1,111 +0,0 @@ -# ============================================================================== -# https://www.gnu.org/software/autoconf-archive/ax_compiler_flags_ldflags.html -# ============================================================================== -# -# SYNOPSIS -# -# AX_COMPILER_FLAGS_LDFLAGS([VARIABLE], [IS-RELEASE], [EXTRA-BASE-FLAGS], [EXTRA-YES-FLAGS]) -# -# DESCRIPTION -# -# Add warning flags for the linker to VARIABLE, which defaults to -# WARN_LDFLAGS. VARIABLE is AC_SUBST-ed by this macro, but must be -# manually added to the LDFLAGS 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 -# Copyright (c) 2017, 2018 Reini Urban -# -# 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 9 - -AC_DEFUN([AX_COMPILER_FLAGS_LDFLAGS],[ - AX_REQUIRE_DEFINED([AX_APPEND_LINK_FLAGS]) - AX_REQUIRE_DEFINED([AX_APPEND_FLAG]) - AX_REQUIRE_DEFINED([AX_CHECK_COMPILE_FLAG]) - AX_REQUIRE_DEFINED([AX_CHECK_LINK_FLAG]) - - # Variable names - m4_define([ax_warn_ldflags_variable], - [m4_normalize(ifelse([$1],,[WARN_LDFLAGS],[$1]))]) - - # Always pass -Werror=unknown-warning-option to get Clang to fail on bad - # flags, otherwise they are always appended to the warn_ldflags variable, - # and Clang warns on them for every compilation unit. - # If this is passed to GCC, it will explode, so the flag must be enabled - # conditionally. - AX_CHECK_COMPILE_FLAG([-Werror=unknown-warning-option],[ - ax_compiler_flags_test="-Werror=unknown-warning-option" - ],[ - ax_compiler_flags_test="" - ]) - - AX_CHECK_LINK_FLAG([-Wl,--as-needed], [ - AX_APPEND_LINK_FLAGS([-Wl,--as-needed], - [AM_LDFLAGS],[$ax_compiler_flags_test]) - ]) - AX_CHECK_LINK_FLAG([-Wl,-z,relro], [ - AX_APPEND_LINK_FLAGS([-Wl,-z,relro], - [AM_LDFLAGS],[$ax_compiler_flags_test]) - ]) - AX_CHECK_LINK_FLAG([-Wl,-z,now], [ - AX_APPEND_LINK_FLAGS([-Wl,-z,now], - [AM_LDFLAGS],[$ax_compiler_flags_test]) - ]) - AX_CHECK_LINK_FLAG([-Wl,-z,noexecstack], [ - AX_APPEND_LINK_FLAGS([-Wl,-z,noexecstack], - [AM_LDFLAGS],[$ax_compiler_flags_test]) - ]) - # textonly, retpolineplt not yet - - # macOS and cygwin linker do not have --as-needed - AX_CHECK_LINK_FLAG([-Wl,--no-as-needed], [ - ax_compiler_flags_as_needed_option="-Wl,--no-as-needed" - ], [ - ax_compiler_flags_as_needed_option="" - ]) - - # macOS linker speaks with a different accent - ax_compiler_flags_fatal_warnings_option="" - AX_CHECK_LINK_FLAG([-Wl,--fatal-warnings], [ - ax_compiler_flags_fatal_warnings_option="-Wl,--fatal-warnings" - ]) - AX_CHECK_LINK_FLAG([-Wl,-fatal_warnings], [ - ax_compiler_flags_fatal_warnings_option="-Wl,-fatal_warnings" - ]) - - # Base flags - AX_APPEND_LINK_FLAGS([ dnl - $ax_compiler_flags_as_needed_option dnl - $3 dnl - ],ax_warn_ldflags_variable,[$ax_compiler_flags_test]) - - AS_IF([test "$ax_enable_compile_warnings" != "no"],[ - # "yes" flags - AX_APPEND_LINK_FLAGS([$4 $5 $6 $7], - ax_warn_ldflags_variable, - [$ax_compiler_flags_test]) - ]) - 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_LINK_FLAGS([ dnl - $ax_compiler_flags_fatal_warnings_option dnl - ],ax_warn_ldflags_variable,[$ax_compiler_flags_test]) - ]) - - # Substitute the variables - AC_SUBST(ax_warn_ldflags_variable) -])dnl AX_COMPILER_FLAGS