Re: [C++ PATCH] Change order of tentative parsing in cp_parser_postfix_dot_deref_expression (PR c++/35138)

[Jakub Jelinek <jakub at redhat dot com>]

On Tue, Feb 12, 2008 at 02:41:30PM -0500, Jakub Jelinek wrote:
> If you mean something like attached patch, then that works too.
> To me it looks uglier though, because it repeats part of
> cp_parser_type_name/cp_parser_class_name to skip over tokens
> cp_parser_type_name would consume.

Or even following patch works too.  If cp_parser_type_name ->
cp_parser_class_name decides to call cp_parser_template_id,
then cp_parser_id_expression would call it too, so that's not a case
it needs to fear that an error would be immediately reported during
tentative parsing.  When cp_parser_type_name/cp_parser_class_name
don't call cp_parser_template_id, they consume just one CPP_NAME,
so we can check that even without going into yet another tentative
parse.

Regtested on x86_64-linux.

2008-02-12  Jakub Jelinek  <jakub@redhat.com>

	PR c++/35138
	* parser.c (cp_parser_pseudo_destructor_name): If next token
	is CPP_NAME, not followed by template argument list nor
	::~, return before calling cp_parser_type_name.

	* g++.dg/template/member8.C: New test.

--- gcc/cp/parser.c.jj	2008-02-12 14:49:55.000000000 +0100
+++ gcc/cp/parser.c	2008-02-12 20:47:09.000000000 +0100
@@ -5164,6 +5164,27 @@ cp_parser_pseudo_destructor_name (cp_par
      additional qualification.  */
   else if (cp_lexer_next_token_is_not (parser->lexer, CPP_COMPL))
     {
+      /* If postfix-expression before . or -> token was dependent,
+	 this might be actually a normal class access rather than
+	 pseudo destructor.  As cp_parser_type_name can report
+	 errors, first make sure the identifier is followed
+	 by `::~'.  */
+      cp_token *token = cp_lexer_peek_token (parser->lexer);
+      if (token->type != CPP_NAME && token->type != CPP_TEMPLATE_ID)
+	{
+	  cp_parser_error (parser, "expected class-name");
+	  return;
+	}
+
+      if (token->type == CPP_NAME
+	  && !cp_parser_nth_token_starts_template_argument_list_p (parser, 2)
+	  && (cp_lexer_peek_nth_token (parser->lexer, 2)->type != CPP_SCOPE
+	      || cp_lexer_peek_nth_token (parser->lexer, 3)->type != CPP_COMPL))
+	{
+	  cp_parser_error (parser, "not a pseudo destructor");
+	  return;
+	}
+
       /* Look for the type-name.  */
       *scope = TREE_TYPE (cp_parser_type_name (parser));
 
--- gcc/testsuite/g++.dg/template/member8.C.jj	2008-02-12 18:32:14.000000000 +0100
+++ gcc/testsuite/g++.dg/template/member8.C	2008-02-12 18:19:23.000000000 +0100
@@ -0,0 +1,25 @@
+// PR c++/35138
+// { dg-do compile }
+
+namespace N1 { struct A { }; }
+namespace N2 { struct A { }; }
+using namespace N1;
+using namespace N2;
+
+template <typename T> int
+foo (T const &t)
+{
+  return t.A;
+}
+
+struct B
+{
+  int A;
+};
+
+int
+main ()
+{
+  B b;
+  foo (b);
+}


	Jakub