+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
+])
+dnl ---------------------------------------------------------------------------