PR c++/88373 - wrong parse error with ~.

	* parser.c (cp_parser_template_name): Check tag_type for
	none_type.

	* g++.dg/cpp2a/fn-template19.C: New test.

From-SVN: r266865

gcc/cp/ChangeLog

+2018-12-06  Marek Polacek  <polacek@redhat.com>
+
+	PR c++/88373 - wrong parse error with ~.
+	* parser.c (cp_parser_template_name): Check tag_type for
+	none_type.
+
 2018-12-06  Segher Boessenkool  <segher@kernel.crashing.org>
 
 	* cp-tree.h (finish_asm_stmt): Update declaration.

gcc/cp/parser.c

@@ -16579,7 +16579,8 @@ cp_parser_template_name (cp_parser* parser,
       if (!found
 	  && (cxx_dialect > cxx17)
 	  && !scoped_p
-	  && cp_lexer_next_token_is (parser->lexer, CPP_LESS))
+	  && cp_lexer_next_token_is (parser->lexer, CPP_LESS)
+	  && tag_type == none_type)
 	{
 	  /* [temp.names] says "A name is also considered to refer to a template
 	     if it is an unqualified-id followed by a < and name lookup finds

gcc/testsuite/ChangeLog

+2018-12-06  Marek Polacek  <polacek@redhat.com>
+
+	PR c++/88373 - wrong parse error with ~.
+	* g++.dg/cpp2a/fn-template19.C: New test.
+
 2018-12-06  Richard Sandiford  <richard.sandiford@arm.com>
 
 	* gcc.dg/vect/vect-over-widen-23.c: Remove unwanted line.

gcc/testsuite/g++.dg/cpp2a/fn-template19.C

+// PR c++/88373
+// { dg-do compile }
+// { dg-options "-std=c++2a" }
+
+template <class T>
+constexpr T value = T {};
+
+template <class T, T t>
+struct S {};
+
+using U = S <int, ~value <int>>;