@@ -63,7 +63,6 @@ ABSTOPDIR = $(shell pwd)
TOPDIR := .
# Common build flags
-CSTD = -std=gnu90
CFLAGS = $(SUBST_CFLAGS) \
$(CSTD) \
-include config.h \
@@ -4,6 +4,7 @@
export
CC = @CC@
+CSTD = @BTRFS_CSTD_FLAGS@
LN_S = @LN_S@
AR = @AR@
RM = @RM@
@@ -26,6 +26,7 @@ AC_CONFIG_SRCDIR([btrfs.c])
AC_PREFIX_DEFAULT([/usr/local])
AC_PROG_CC
+BTRFS_DETECT_CSTD
AC_CANONICAL_HOST
AC_C_CONST
AC_C_VOLATILE
new file mode 100644
@@ -0,0 +1,74 @@
+# ===========================================================================
+# 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 <guidod@gmx.de>
+# 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 <https://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.
+
+#serial 5
+
+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
new file mode 100644
@@ -0,0 +1,37 @@
+dnl @synopsis AX_GCC_VERSION(MAJOR, MINOR, PATCHLEVEL, [ACTION-SUCCESS], [ACTION-FAILURE])
+dnl @summary check wither gcc is at least version MAJOR.MINOR.PATCHLEVEL
+dnl @category InstalledPackages
+dnl
+dnl Check whether we are using gcc and, if so, whether its version
+dnl is at least MAJOR.MINOR.PATCHLEVEL
+dnl
+dnl ACTION-SUCCESS/ACTION-FAILURE are shell commands to execute on
+dnl success/failure.
+dnl
+dnl @version 2005-05-30
+dnl @license GPLWithACException
+dnl @author Steven G. Johnson <stevenj@alum.mit.edu> and Matteo Frigo.
+AC_DEFUN([AX_GCC_VERSION],
+[
+AC_REQUIRE([AC_PROG_CC])
+AC_CACHE_CHECK(whether we are using gcc $1.$2.$3 or later, ax_cv_gcc_$1_$2_$3,
+[
+ax_cv_gcc_$1_$2_$3=no
+if test "$GCC" = "yes"; then
+dnl The semicolon after "yes" below is to pacify NeXT's syntax-checking cpp.
+AC_EGREP_CPP(yes, [
+#ifdef __GNUC__
+# if (__GNUC__ > $1) || (__GNUC__ == $1 && __GNUC_MINOR__ > $2) \
+ || (__GNUC__ == $1 && __GNUC_MINOR__ == $2 && __GNUC_PATCHLEVEL__ >= $3)
+ yes;
+# endif
+#endif
+], [ax_cv_gcc_$1_$2_$3=yes])
+fi
+])
+if test "$ax_cv_gcc_$1_$2_$3" = yes; then
+ m4_default([$4], :)
+else
+ m4_default([$5], :)
+fi
+])
new file mode 100644
@@ -0,0 +1,20 @@
+dnl We prefer -std=gnu90 but gcc versions prior to 4.5.0 don't support
+dnl it. AX_CHECK_COMPILE_FLAG is the right way to determine whether a
+dnl particular version of gcc supports a flag, but it requires autoconf
+dnl 2.64. Since (for now) we still want to support older releases
+dnl that ship with autoconf 2.63, we the also-deprecated AX_GCC_VERSION
+dnl macro there.
+AC_DEFUN([BTRFS_DETECT_CSTD],
+[
+ m4_version_prereq([2.64], [
+ AX_CHECK_COMPILE_FLAG([-std=gnu90],
+ [BTRFS_CSTD_FLAGS=-std=gnu90],
+ [BTRFS_CSTD_FLAGS=-std=gnu89])
+ ], [
+ AX_GCC_VERSION([4], [5], [0],
+ [BTRFS_CSTD_FLAGS=-std=gnu90],
+ [BTRFS_CSTD_FLAGS=-std=gnu89])
+ ])
+ AC_SUBST([BTRFS_CSTD_FLAGS])
+]) dnl BTRFS_DETECT_CSTD
+