flac/m4/gcc_version.m4
sezero d4a1b345dd configure.ac: allow several compiler flags for clang
The flac configury marked clang as 'not being gcc' and excluded
a lot of compiler switches, most importantly the visibility flags,
from being used with it. This was done possibly after a problem
reported at: https://github.com/erikd/libsndfile/issues/49 .

This patch does the following:

- m4/gcc_version.m4 (XIPH_GCC_VERSION): set GCC_MAJOR_VERSION and
  GCC_MINOR_VERSION to 0 for non-gcc. Previously, they were left
  unset.

- configure: the gcc version checks are, naturally, against non-
  zero values, so, allow many compiler switches to be used with
  clang without affecting real-gcc cases.

- configure: When setting CFLAGS="-O3 -funroll-loops", also set
  CXXFLAGS="-O3".  Prevents g++ warnings with _FORTIFY_SOURCE, i.e.:
 '_FORTIFY_SOURCE requires compiling with optimization (-O)'

Tested compilation using gcc-7.3.1 and clang-5.0.2 on x86_64-linux,
and gcc-4.4.7 and clang-3.4.2 on an i686-linux.  Also tested cross-
compiling for Mac OS X using clang-5.0.2.
2019-10-10 18:31:26 +11:00

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dnl @synopsis XIPH_GCC_VERSION
dnl
dnl Find the version of gcc.
dnl @version 1.0 Nov 05 2007
dnl @version 1.1 Mar 10 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_GCC_VERSION],
[
if test "x$ac_cv_c_compiler_gnu" = "xyes" ; then
AC_MSG_CHECKING([for version of $CC])
GCC_VERSION=`$CC -dumpversion`
AC_MSG_RESULT($GCC_VERSION)
GCC_MAJOR_VERSION=`echo $GCC_VERSION | cut -d. -f 1`
GCC_MINOR_VERSION=`echo $GCC_VERSION | cut -d. -f 2`
else
GCC_MAJOR_VERSION=0
GCC_MINOR_VERSION=0
fi
AC_SUBST(GCC_VERSION)
AC_SUBST(GCC_MAJOR_VERSION)
AC_SUBST(GCC_MINOR_VERSION)
])# XIPH_GCC_VERSION