dnl CF_CLANG_COMPILER version: 1 updated: 2012/06/16 14:55:39
dnl -----------------
dnl Check if the given compiler is really clang.  clang's C driver defines
dnl __GNUC__ (fooling the configure script into setting $GCC to yes) but does
dnl not ignore some gcc options.
dnl
dnl This macro should be run "soon" after AC_PROG_CC or AC_PROG_CPLUSPLUS, to
dnl ensure that it is not mistaken for gcc/g++.  It is normally invoked from
dnl the wrappers for gcc and g++ warnings.
dnl
dnl $1 = GCC (default) or GXX
dnl $2 = INTEL_COMPILER (default) or INTEL_CPLUSPLUS
dnl $3 = CFLAGS (default) or CXXFLAGS
AC_DEFUN([CF_CLANG_COMPILER],[
ifelse([$2],,CLANG_COMPILER,[$2])=no

if test "$ifelse([$1],,[$1],GCC)" = yes ; then
	AC_MSG_CHECKING(if this is really Clang ifelse([$1],GXX,C++,C) compiler)
	cf_save_CFLAGS="$ifelse([$3],,CFLAGS,[$3])"
	ifelse([$3],,CFLAGS,[$3])="$ifelse([$3],,CFLAGS,[$3]) -Qunused-arguments"
	AC_TRY_COMPILE([],[
#ifdef __clang__
#else
make an error
#endif
],[ifelse([$2],,CLANG_COMPILER,[$2])=yes
cf_save_CFLAGS="$cf_save_CFLAGS -Qunused-arguments"
],[])
	ifelse([$3],,CFLAGS,[$3])="$cf_save_CFLAGS"
	AC_MSG_RESULT($ifelse([$2],,CLANG_COMPILER,[$2]))
fi
])
