Fix PR c++/77639 (ICE during error recovery)

gcc/cp/ChangeLog:

	PR c++/77639
	* parser.c (cp_parser_class_head): When
	processing_template_parmlist, don't assume that the
	class-head may start an explicit specialization.

gcc/testsuite/ChangeLog:

	PR c++/77639
	* g++.dg/template/error-recovery4.C: New test.

From-SVN: r240245

gcc/cp/ChangeLog

+2016-09-16  Patrick Palka  <ppalka@gcc.gnu.org>
+
+	PR c++/77639
+	* parser.c (cp_parser_class_head): When
+	processing_template_parmlist, don't assume that the
+	class-head may start an explicit specialization.
+
 2016-09-16  Jakub Jelinek  <jakub@redhat.com>
 
 	PR c++/77482

gcc/cp/parser.c

@@ -22025,6 +22025,7 @@ cp_parser_class_head (cp_parser* parser,
      it is not, try to recover gracefully.  */
   if (at_namespace_scope_p ()
       && parser->num_template_parameter_lists == 0
+      && !processing_template_parmlist
       && template_id_p)
     {
       /* Build a location of this form:

gcc/testsuite/ChangeLog

+2016-09-19  Patrick Palka  <ppalka@gcc.gnu.org>
+
+	PR c++/77639
+	* g++.dg/template/error-recovery4.C: New test.
+
 2016-09-19  Bin Cheng  <bin.cheng@arm.com>
 
 	* gcc.dg/vect/pr57558-1.c: Use unsigned int instead of unsigned long.

gcc/testsuite/g++.dg/template/error-recovery4.C

+// PR c++/77639
+
+template <class, int, class, int> struct B {};
+template <class T, int a, class U struct B<T, a, U, 1> {}; // { dg-error "" }
+B<int, 2, char, 1> i;