From: Simon Marchi Date: Fri, 31 Jan 2020 18:05:20 +0000 (-0500) Subject: configure: use AX_APPEND_COMPILE_FLAGS to detect supported warning flags X-Git-Tag: v2.13.0-rc1~753 X-Git-Url: https://git.lttng.org/?p=lttng-tools.git;a=commitdiff_plain;h=7f08cc82e68617aa423952b8f9cc7c74bc247f8d configure: use AX_APPEND_COMPILE_FLAGS to detect supported warning flags I would eventually like to enable some additional warnings by default when building lttng-tools. However, some warnings are compiler-specific or are not present in older versions of some compilers we need to support. We can therefore not add them unconditionally to CFLAGS. This patch uses the AX_APPEND_COMPILE_FLAGS macro to address that. This macro tests each individual flag we pass it with the current compiler. If it finds that the flag is supported (the compiler exits with status 0 when compiling a file with that flag), it appends it to the given variable, WARN_CFLAGS in our case). WARN_CFLAGS is then added to AM_CFLAGS. With time, we'll be able to throw any warning flag in there that we think is useful, even if just available in a recent version of one compiler. Signed-off-by: Simon Marchi Change-Id: Id2ae4b4e8882af788c835ce89a979544531370e9 Signed-off-by: Jérémie Galarneau --- diff --git a/configure.ac b/configure.ac index 852c61f0e..2bb30edb3 100644 --- a/configure.ac +++ b/configure.ac @@ -26,6 +26,16 @@ AC_PROG_CXX RW_PROG_CXX_WORKS AM_CONDITIONAL([CXX_WORKS], [test "x$rw_cv_prog_cxx_works" = "xyes"]) +# Detect warning flags supported by the compiler, append them to WARN_CFLAGS. +# +# Pass -Werror as an extra flag during the test: this is needed to make the +# -Wunknown-warning-option diagnostic fatal with clang. +AX_APPEND_COMPILE_FLAGS([ dnl + -Wall dnl + ], + [WARN_CFLAGS], + [-Werror]) + # Checks for programs. AC_PROG_GREP AC_PROG_MAKE_SET @@ -1038,7 +1048,7 @@ AM_CONDITIONAL([BUILD_LIB_SESSIOND_COMM], [test x$build_lib_sessiond_comm = xyes AM_CONDITIONAL([BUILD_LIB_TESTPOINT], [test x$build_lib_testpoint = xyes]) AM_CONDITIONAL([BUILD_LIB_UST_CONSUMER], [test x$build_lib_ust_consumer = xyes]) -AM_CFLAGS="-Wall -fno-strict-aliasing $PTHREAD_CFLAGS" +AM_CFLAGS="${WARN_CFLAGS} -fno-strict-aliasing $PTHREAD_CFLAGS" AC_SUBST(AM_CFLAGS) # The order in which the include folders are searched is important. diff --git a/m4/ax_append_compile_flags.m4 b/m4/ax_append_compile_flags.m4 new file mode 100644 index 000000000..9c856356c --- /dev/null +++ b/m4/ax_append_compile_flags.m4 @@ -0,0 +1,46 @@ +# ============================================================================ +# https://www.gnu.org/software/autoconf-archive/ax_append_compile_flags.html +# ============================================================================ +# +# SYNOPSIS +# +# AX_APPEND_COMPILE_FLAGS([FLAG1 FLAG2 ...], [FLAGS-VARIABLE], [EXTRA-FLAGS], [INPUT]) +# +# DESCRIPTION +# +# For every FLAG1, FLAG2 it is checked whether the compiler works with the +# flag. If it does, the flag is added FLAGS-VARIABLE +# +# If FLAGS-VARIABLE is not specified, the current language's flags (e.g. +# CFLAGS) is used. During the check the flag is always added to the +# current language's flags. +# +# If EXTRA-FLAGS is defined, it is added to the current language's default +# flags (e.g. CFLAGS) when the check is done. The check is thus made with +# the flags: "CFLAGS EXTRA-FLAGS FLAG". This can for example be used to +# force the compiler to issue an error when a bad flag is given. +# +# INPUT gives an alternative input source to AC_COMPILE_IFELSE. +# +# NOTE: This macro depends on the AX_APPEND_FLAG and +# AX_CHECK_COMPILE_FLAG. Please keep this macro in sync with +# AX_APPEND_LINK_FLAGS. +# +# LICENSE +# +# Copyright (c) 2011 Maarten Bosmans +# +# 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 7 + +AC_DEFUN([AX_APPEND_COMPILE_FLAGS], +[AX_REQUIRE_DEFINED([AX_CHECK_COMPILE_FLAG]) +AX_REQUIRE_DEFINED([AX_APPEND_FLAG]) +for flag in $1; do + AX_CHECK_COMPILE_FLAG([$flag], [AX_APPEND_FLAG([$flag], [$2])], [], [$3], [$4]) +done +])dnl AX_APPEND_COMPILE_FLAGS diff --git a/m4/ax_append_flag.m4 b/m4/ax_append_flag.m4 new file mode 100644 index 000000000..dd6d8b614 --- /dev/null +++ b/m4/ax_append_flag.m4 @@ -0,0 +1,50 @@ +# =========================================================================== +# https://www.gnu.org/software/autoconf-archive/ax_append_flag.html +# =========================================================================== +# +# SYNOPSIS +# +# AX_APPEND_FLAG(FLAG, [FLAGS-VARIABLE]) +# +# DESCRIPTION +# +# FLAG is appended to the FLAGS-VARIABLE shell variable, with a space +# added in between. +# +# If FLAGS-VARIABLE is not specified, the current language's flags (e.g. +# CFLAGS) is used. FLAGS-VARIABLE is not changed if it already contains +# FLAG. If FLAGS-VARIABLE is unset in the shell, it is set to exactly +# FLAG. +# +# NOTE: Implementation based on AX_CFLAGS_GCC_OPTION. +# +# LICENSE +# +# Copyright (c) 2008 Guido U. Draheim +# Copyright (c) 2011 Maarten Bosmans +# +# 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 8 + +AC_DEFUN([AX_APPEND_FLAG], +[dnl +AC_PREREQ(2.64)dnl for _AC_LANG_PREFIX and AS_VAR_SET_IF +AS_VAR_PUSHDEF([FLAGS], [m4_default($2,_AC_LANG_PREFIX[FLAGS])]) +AS_VAR_SET_IF(FLAGS,[ + AS_CASE([" AS_VAR_GET(FLAGS) "], + [*" $1 "*], [AC_RUN_LOG([: FLAGS already contains $1])], + [ + AS_VAR_APPEND(FLAGS,[" $1"]) + AC_RUN_LOG([: FLAGS="$FLAGS"]) + ]) + ], + [ + AS_VAR_SET(FLAGS,[$1]) + AC_RUN_LOG([: FLAGS="$FLAGS"]) + ]) +AS_VAR_POPDEF([FLAGS])dnl +])dnl AX_APPEND_FLAG diff --git a/m4/ax_check_compile_flag.m4 b/m4/ax_check_compile_flag.m4 new file mode 100644 index 000000000..bd753b34d --- /dev/null +++ b/m4/ax_check_compile_flag.m4 @@ -0,0 +1,53 @@ +# =========================================================================== +# https://www.gnu.org/software/autoconf-archive/ax_check_compile_flag.html +# =========================================================================== +# +# SYNOPSIS +# +# AX_CHECK_COMPILE_FLAG(FLAG, [ACTION-SUCCESS], [ACTION-FAILURE], [EXTRA-FLAGS], [INPUT]) +# +# DESCRIPTION +# +# Check whether the given FLAG works with the current language's compiler +# or gives an error. (Warnings, however, are ignored) +# +# ACTION-SUCCESS/ACTION-FAILURE are shell commands to execute on +# success/failure. +# +# If EXTRA-FLAGS is defined, it is added to the current language's default +# flags (e.g. CFLAGS) when the check is done. The check is thus made with +# the flags: "CFLAGS EXTRA-FLAGS FLAG". This can for example be used to +# force the compiler to issue an error when a bad flag is given. +# +# INPUT gives an alternative input source to AC_COMPILE_IFELSE. +# +# NOTE: Implementation based on AX_CFLAGS_GCC_OPTION. Please keep this +# macro in sync with AX_CHECK_{PREPROC,LINK}_FLAG. +# +# LICENSE +# +# Copyright (c) 2008 Guido U. Draheim +# Copyright (c) 2011 Maarten Bosmans +# +# 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_CHECK_COMPILE_FLAG], +[AC_PREREQ(2.64)dnl for _AC_LANG_PREFIX and AS_VAR_IF +AS_VAR_PUSHDEF([CACHEVAR],[ax_cv_check_[]_AC_LANG_ABBREV[]flags_$4_$1])dnl +AC_CACHE_CHECK([whether _AC_LANG compiler accepts $1], CACHEVAR, [ + ax_check_save_flags=$[]_AC_LANG_PREFIX[]FLAGS + _AC_LANG_PREFIX[]FLAGS="$[]_AC_LANG_PREFIX[]FLAGS $4 $1" + AC_COMPILE_IFELSE([m4_default([$5],[AC_LANG_PROGRAM()])], + [AS_VAR_SET(CACHEVAR,[yes])], + [AS_VAR_SET(CACHEVAR,[no])]) + _AC_LANG_PREFIX[]FLAGS=$ax_check_save_flags]) +AS_VAR_IF(CACHEVAR,yes, + [m4_default([$2], :)], + [m4_default([$3], :)]) +AS_VAR_POPDEF([CACHEVAR])dnl +])dnl AX_CHECK_COMPILE_FLAGS diff --git a/m4/ax_require_defined.m4 b/m4/ax_require_defined.m4 new file mode 100644 index 000000000..17c3eab7d --- /dev/null +++ b/m4/ax_require_defined.m4 @@ -0,0 +1,37 @@ +# =========================================================================== +# https://www.gnu.org/software/autoconf-archive/ax_require_defined.html +# =========================================================================== +# +# SYNOPSIS +# +# AX_REQUIRE_DEFINED(MACRO) +# +# DESCRIPTION +# +# AX_REQUIRE_DEFINED is a simple helper for making sure other macros have +# been defined and thus are available for use. This avoids random issues +# where a macro isn't expanded. Instead the configure script emits a +# non-fatal: +# +# ./configure: line 1673: AX_CFLAGS_WARN_ALL: command not found +# +# It's like AC_REQUIRE except it doesn't expand the required macro. +# +# Here's an example: +# +# AX_REQUIRE_DEFINED([AX_CHECK_LINK_FLAG]) +# +# LICENSE +# +# Copyright (c) 2014 Mike Frysinger +# +# 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 2 + +AC_DEFUN([AX_REQUIRE_DEFINED], [dnl + m4_ifndef([$1], [m4_fatal([macro ]$1[ is not defined; is a m4 file missing?])]) +])dnl AX_REQUIRE_DEFINED