Require C11 for C++17 on Solaris

	* config/sol2.h (TARGET_OS_CPP_BUILTINS): Define __STDC_VERSION__
	to 201112L since C++17.

From-SVN: r244430

gcc/ChangeLog

+2017-01-13  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>
+
+	* config/sol2.h (TARGET_OS_CPP_BUILTINS): Define __STDC_VERSION__
+	to 201112L since C++17.
+
 2017-01-13  Maxim Ostapenko  <m.ostapenko@samsung.com>
 
 	PR sanitizer/78887

gcc/config/sol2.h

@@ -94,7 +94,22 @@ along with GCC; see the file COPYING3.  If not see
        library.  */					\
     if (c_dialect_cxx ())				\
       {							\
+	switch (cxx_dialect)				\
+	  {						\
+	  case cxx98:					\
+	  case cxx11:					\
+	  case cxx14:					\
+	    /* C++11 and C++14 are based on C99.	\
+	       libstdc++ makes use of C99 features	\
+	       even for C++98.  */			\
 	    builtin_define ("__STDC_VERSION__=199901L");\
+	    break;					\
+							\
+	  default:					\
+	    /* C++17 is based on C11.  */		\
+	    builtin_define ("__STDC_VERSION__=201112L");\
+	    break;					\
+	  }						\
 	builtin_define ("_XOPEN_SOURCE=600");		\
 	builtin_define ("_LARGEFILE_SOURCE=1");		\
 	builtin_define ("_LARGEFILE64_SOURCE=1");	\