From 7b71ff68c7027a1fa9329ad9167625b81ea3aab2 Mon Sep 17 00:00:00 2001 From: Jeff Mahoney Date: Fri, 27 Apr 2018 14:47:28 -0400 Subject: [PATCH 3/3 v2] btrfs-progs: build: detect whether -std=gnu90 is supported Patch-mainline: Submitted, linux-btrfs 30 Apr 2018 GCC releases prior to 4.5.0 don't support -std=gnu90 so btrfs-progs won't build at all on older distros. We can detect whether the compiler supports -std=gnu90 and fall back to -std=gnu89 if it doesn't. AX_CHECK_COMPILE_FLAG is the right way to do this, but it depends on autoconf 2.64. AX_GCC_VERSION has been deprecated, so we'll use that only for earlier autoconf versions so we can drop it when we drop support for older autoconf releases. Signed-off-by: Jeff Mahoney --- Makefile | 1 - Makefile.inc.in | 1 + configure.ac | 1 + m4/ax_check_compile_flag.m4 | 74 +++++++++++++++++++++++++++++++++++++++++++++ m4/ax_gcc_version.m4 | 37 +++++++++++++++++++++++ m4/btrfs_detect_cstd.m4 | 20 ++++++++++++ 6 files changed, 133 insertions(+), 1 deletion(-) create mode 100644 m4/ax_check_compile_flag.m4 create mode 100644 m4/ax_gcc_version.m4 create mode 100644 m4/btrfs_detect_cstd.m4 diff --git a/Makefile b/Makefile index 5ba76d2..c0eb3d6 100644 --- a/Makefile +++ b/Makefile @@ -63,7 +63,6 @@ ABSTOPDIR = $(shell pwd) TOPDIR := . # Common build flags -CSTD = -std=gnu90 CFLAGS = $(SUBST_CFLAGS) \ $(CSTD) \ -include config.h \ diff --git a/Makefile.inc.in b/Makefile.inc.in index 52410f6..fb32461 100644 --- a/Makefile.inc.in +++ b/Makefile.inc.in @@ -4,6 +4,7 @@ export CC = @CC@ +CSTD = @BTRFS_CSTD_FLAGS@ LN_S = @LN_S@ AR = @AR@ RM = @RM@ diff --git a/configure.ac b/configure.ac index 9e5603b..4f63bb6 100644 --- a/configure.ac +++ b/configure.ac @@ -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 diff --git a/m4/ax_check_compile_flag.m4 b/m4/ax_check_compile_flag.m4 new file mode 100644 index 0000000..dcabb92 --- /dev/null +++ b/m4/ax_check_compile_flag.m4 @@ -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 +# Copyright (c) 2011 Maarten Bosmans +# +# 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 . +# +# 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 diff --git a/m4/ax_gcc_version.m4 b/m4/ax_gcc_version.m4 new file mode 100644 index 0000000..63914d5 --- /dev/null +++ b/m4/ax_gcc_version.m4 @@ -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 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 +]) diff --git a/m4/btrfs_detect_cstd.m4 b/m4/btrfs_detect_cstd.m4 new file mode 100644 index 0000000..f0c45d9 --- /dev/null +++ b/m4/btrfs_detect_cstd.m4 @@ -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 + -- 1.7.12.4