Improve diagnostic for redundant template arguments in declaration.

	* pt.c (check_explicit_specialization): If the declarator is a
	template-id, only check whether the arguments are dependent.

From-SVN: r268997

gcc/cp/ChangeLog

 2019-02-18  Jason Merrill  <jason@redhat.com>
 
+	* pt.c (check_explicit_specialization): If the declarator is a
+	template-id, only check whether the arguments are dependent.
+
 	Improve duplicate [[likely]] diagnostic.
 	* parser.c (cp_parser_statement): Make attrs_loc a range.  Pass it
 	to process_stmt_hotness_attribute.

gcc/cp/pt.c

@@ -2849,7 +2849,7 @@ check_explicit_specialization (tree declarator,
 	  /* This case handles bogus declarations like template <>
 	     template <class T> void f<int>(); */
 
-	  if (!uses_template_parms (declarator))
+	  if (!uses_template_parms (TREE_OPERAND (declarator, 1)))
 	    error ("template-id %qD in declaration of primary template",
 		   declarator);
 	  else if (variable_template_p (TREE_OPERAND (declarator, 0)))

gcc/testsuite/g++.old-deja/g++.robertl/eb82.C

@@ -2,7 +2,8 @@
 #include <stdio.h>
 
 template <int n1>
-double val <int> () // { dg-error "" } bogus code
+double val <int> () // { dg-error "expected" "" { target c++17_down } } bogus code
+// { dg-error "template-id .val<int>. in declaration of primary template" "" { target c++2a } .-1 }
 {                          
    return (double) n1;
 }