c++: Don't show constructor internal name in error message [PR105483]

We mention 'X::__ct' instead of 'X::X' in the "names the constructor,
not the type" error for this invalid code:

=== cut here ===
struct X {};
void g () {
  X::X x;
}
=== cut here ===

The problem is that we use %<%T::%D%> to build the error message, while
%qE does exactly what we need since we have DECL_CONSTRUCTOR_P. This is
what this patch does.

It also skips until the end of the statement and returns error_mark_node
for this and the preceding if block, to avoid emitting extra (useless)
errors.

	PR c++/105483

gcc/cp/ChangeLog:

	* parser.cc (cp_parser_expression_statement): Use %qE instead of
	incorrect %<%T::%D%>. Skip to end of statement and return
	error_mark_node in case of error.

gcc/testsuite/ChangeLog:

	* g++.dg/parse/error36.C: Adjust test expectation.
	* g++.dg/tc1/dr147.C: Likewise.
	* g++.old-deja/g++.other/typename1.C: Likewise.
	* g++.dg/diagnostic/pr105483.C: New test.

1 files changed, 9 insertions, 5 deletions

diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc
index 28ebf2b..a722641 100644
--- a/gcc/cp/parser.cc
+++ b/gcc/cp/parser.cc
@@ -13232,18 +13232,22 @@ cp_parser_expression_statement (cp_parser* parser, tree in_statement_expr)
   if (cp_lexer_next_token_is_not (parser->lexer, CPP_SEMICOLON)
       && !cp_parser_uncommitted_to_tentative_parse_p (parser))
     {
+      bool has_errored = true;
       if (TREE_CODE (statement) == SCOPE_REF)
 	error_at (token->location, "need %<typename%> before %qE because "
 		  "%qT is a dependent scope",
 		  statement, TREE_OPERAND (statement, 0));
       else if (is_overloaded_fn (statement)
 	       && DECL_CONSTRUCTOR_P (get_first_fn (statement)))
+	/* A::A a; */
+	error_at (token->location, "%qE names the constructor, not the type",
+		  get_first_fn (statement));
+      else
+	has_errored = false;
+      if (has_errored)
 	{
-	  /* A::A a; */
-	  tree fn = get_first_fn (statement);
-	  error_at (token->location,
-		    "%<%T::%D%> names the constructor, not the type",
-		    DECL_CONTEXT (fn), DECL_NAME (fn));
+	  cp_parser_skip_to_end_of_statement (parser);
+	  return error_mark_node;
 	}
     }