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Detect Clang masquerading as GCC. 

Autoconf detects the Clang compiler as GNU GCC (clang sets defines like
__GNUC__ etc) but Clang is *not* completely compatible. If we detect
Clang we set ac_vc_c_compiler_gnu to 'no'.
This commit is contained in:
Erik de Castro Lopo 2013-11-22 18:13:36 +11:00
parent 8e2eea6322
commit a6a4b6f205
3 changed files with 66 additions and 0 deletions
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3
configure.ac
View File

@ -35,6 +35,8 @@ m4_ifdef([AM_PROG_AR], [AM_PROG_AR])
LT_INIT([win32-dll disable-static pic-only])
AM_PROG_AS
AC_PROG_CXX
XIPH_C_COMPILER_IS_CLANG
XIPH_GCC_REALLY_IS_GCC
AC_PROG_MAKE_SET
AC_SYS_LARGEFILE
@ -521,6 +523,7 @@ AC_MSG_RESULT([
if test x$ac_cv_c_compiler_gnu = xyes ; then
echo " GCC version : ......................... ${GCC_VERSION}"
fi
echo " Compiler is Clang : ................... ${xiph_cv_c_compiler_clang}"
echo " Asm optimizations : ................... ${asm_optimisation}"
echo " Ogg/FLAC support : .................... ${have_ogg}"
echo

31
m4/clang.m4 Normal file
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@ -0,0 +1,31 @@
dnl @synopsis XIPH_C_COMPILER_IS_CLANG
dnl
dnl Find out if a compiler claiming to be gcc really is gcc (clang lies).
dnl @version 1.0 Oct 31 2013
dnl @author Erik de Castro Lopo <erikd AT mega-nerd DOT com>
dnl
dnl Permission to use, copy, modify, distribute, and sell this file for any
dnl purpose is hereby granted without fee, provided that the above copyright
dnl and this permission notice appear in all copies. No representations are
dnl made about the suitability of this software for any purpose. It is
dnl provided "as is" without express or implied warranty.
dnl
AC_DEFUN([XIPH_C_COMPILER_IS_CLANG],
[AC_CACHE_CHECK(whether we are using the CLANG C compiler,
xiph_cv_c_compiler_clang,
[ AC_LANG_ASSERT(C)
AC_TRY_LINK([
#include <stdio.h>
],
[
#ifndef __clang__
This is not clang!
#endif
],
xiph_cv_c_compiler_clang=yes,
xiph_cv_c_compiler_clang=no
])
)]
)

32
m4/really_gcc.m4 Normal file
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@ -0,0 +1,32 @@
dnl @synopsis XIPH_GCC_REALLY_IS_GCC
dnl
dnl Find out if a compiler claiming to be gcc really is gcc (clang lies).
dnl @version 1.0 Oct 31 2013
dnl @author Erik de Castro Lopo <erikd AT mega-nerd DOT com>
dnl
dnl Permission to use, copy, modify, distribute, and sell this file for any
dnl purpose is hereby granted without fee, provided that the above copyright
dnl and this permission notice appear in all copies. No representations are
dnl made about the suitability of this software for any purpose. It is
dnl provided "as is" without express or implied warranty.
dnl
# If the configure script has already detected GNU GCC, then make sure it
# isn't CLANG masquerading as GCC.
AC_DEFUN([XIPH_GCC_REALLY_IS_GCC],
[ AC_LANG_ASSERT(C)
if test "x$ac_cv_c_compiler_gnu" = "xyes" ; then
AC_TRY_LINK([
#include <stdio.h>
],
[
#ifdef __clang__
This is clang!
#endif
],
ac_cv_c_compiler_gnu=yes,
ac_cv_c_compiler_gnu=no
)
fi
])