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configure: Test compiler flags

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When AC_PROG_CC detects GCC, Make.mk adds a bunch of flags to CFLAGS.
Works only for flags that any version of gcc in use accepts.

Instead, make configure add the flags that actually work to CFLAGS.
This will let us add flags that work only for some compilers.

The new autoconf macros are from autoconf-archive v2015.02.24.

Unfortunately, AX_APPEND_COMPILE_FLAGS doesn't work reliably for
-Wno-*: gcc complains about unknown -Wno-foo only when other
diagnostics are being produced.  Test -Wfoo instead of -Wno-foo, and
rename to MY_APPEND_COMPILE_FLAGS.

Signed-off-by: Markus Armbruster <armbru@pond.sub.org>
This commit is contained in:
Markus Armbruster 2015-06-06 15:53:00 +02:00
parent 35f34581be
commit 23373d01d9
7 changed files with 269 additions and 9 deletions
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67
m4/my_append_compile_flags.m4 Normal file
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# SYNOPSIS
#
# MY_APPEND_COMPILE_FLAGS([FLAG1 FLAG2 ...], [FLAGS-VARIABLE], [EXTRA-FLAGS])
#
# DESCRIPTION
#
# For every FLAG1, FLAG2 it is checked whether the compiler works with the
# flag. If it does, the flag is added FLAGS-VARIABLE
#
# Works just like AX_APPEND_COMPILE_FLAGS, except when testing
# -Wno-foo, run the compiler with -Wfoo, because gcc complains about
# unknown -Wno-foo only when other diagnostics are being produced.
#
# 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.
#
# NOTE: This macro depends on the AX_APPEND_FLAG and
# AX_CHECK_COMPILE_FLAG. Please keep this macro in sync with
# MY_APPEND_LINK_FLAGS.
#
# Derived from AX_APPEND_COMPILE_FLAGS, covered by the following
# copyright and permission notice:
#
# LICENSE
#
# Copyright (c) 2011 Maarten Bosmans <mkbosmans@gmail.com>
#
# This program is free software: you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by the
# Free Software Foundation, either version 3 of the License, or (at your
# option) any later version.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
# Public License for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program. If not, see <http://www.gnu.org/licenses/>.
#
# As a special exception, the respective Autoconf Macro's copyright owner
# gives unlimited permission to copy, distribute and modify the configure
# scripts that are the output of Autoconf when processing the Macro. You
# need not follow the terms of the GNU General Public License when using
# or distributing such scripts, even though portions of the text of the
# Macro appear in them. The GNU General Public License (GPL) does govern
# all other use of the material that constitutes the Autoconf Macro.
#
# This special exception to the GPL applies to versions of the Autoconf
# Macro released by the Autoconf Archive. When you make and distribute a
# modified version of the Autoconf Macro, you may extend this special
# exception to the GPL to apply to your modified version as well.
AC_DEFUN([MY_APPEND_COMPILE_FLAGS],
[AX_REQUIRE_DEFINED([AX_CHECK_COMPILE_FLAG])
AX_REQUIRE_DEFINED([AX_APPEND_FLAG])
for flag in $1; do
tflag=`echo "$flag" | sed 's/^-Wno-/-W/'`
AX_CHECK_COMPILE_FLAG([$tflag], [AX_APPEND_FLAG([$flag], [$2])], [], [$3])
done
])dnl MY_APPEND_COMPILE_FLAGS