[Bug c++/20118] missing template<> causes weird errors

["manu at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #7 from manu at gcc dot gnu dot org  2008-08-09 23:24 -------
Testing the following patch. Not as good as ICC's diagnostic but close.

Index: gcc/testsuite/g++.dg/parse/pr20118.C
===================================================================
--- gcc/testsuite/g++.dg/parse/pr20118.C        (revision 0)
+++ gcc/testsuite/g++.dg/parse/pr20118.C        (revision 0)
@@ -0,0 +1,9 @@
+// { dg-do compile }
+// { dg-options "-fshow-column" }
+template<typename t>struct foo {
+  static const int i; };
+
+const int foo<bool>::i = 5; // { dg-error ":11: error: specializing member
?foo<bool>::?i?? requires ?template<>? syntax" }
+
+int main() { return 0; }
+
Index: gcc/cp/parser.c
===================================================================
--- gcc/cp/parser.c     (revision 138906)
+++ gcc/cp/parser.c     (working copy)
@@ -1905,11 +1905,11 @@ static tree cp_parser_lookup_name_simple
 static tree cp_parser_maybe_treat_template_as_class
   (tree, bool);
 static bool cp_parser_check_declarator_template_parameters
   (cp_parser *, cp_declarator *, location_t);
 static bool cp_parser_check_template_parameters
-  (cp_parser *, unsigned, location_t);
+  (cp_parser *, unsigned, location_t, cp_declarator *);
 static tree cp_parser_simple_cast_expression
   (cp_parser *);
 static tree cp_parser_global_scope_opt
   (cp_parser *, bool);
 static bool cp_parser_constructor_declarator_p
@@ -11591,11 +11591,12 @@ cp_parser_elaborated_type_specifier (cp_
                 || cp_lexer_next_token_is (parser->lexer, CPP_SEMICOLON)));
          /* An unqualified name was used to reference this type, so
             there were no qualifying templates.  */
          if (!cp_parser_check_template_parameters (parser,
                                                    /*num_templates=*/0,
-                                                   token->location))
+                                                   token->location,
+                                                   /*declarator=*/NULL))
            return error_mark_node;
          type = xref_tag (tag_type, identifier, ts, template_p);
        }
     }

@@ -15049,11 +15050,12 @@ cp_parser_class_head (cp_parser* parser,
      end of this function; set "type "to the correct return value and
      use "goto done;" to return.  */
   /* Make sure that the right number of template parameters were
      present.  */
   if (!cp_parser_check_template_parameters (parser, num_templates,
-                                           type_start_token->location))
+                                           type_start_token->location,
+                                           /*declarator=*/NULL))
     {
       /* If something went wrong, there is no point in even trying to
         process the class-definition.  */
       type = NULL_TREE;
       goto done;
@@ -16946,13 +16948,13 @@ cp_parser_check_declarator_template_para
               == TEMPLATE_ID_EXPR)
        /* If the DECLARATOR has the form `X<y>' then it uses one
           additional level of template parameters.  */
        ++num_templates;

-      return cp_parser_check_template_parameters (parser,
-                                                 num_templates,
-                                                 declarator_location);
+      return cp_parser_check_template_parameters
+       (parser, num_templates, declarator_location, declarator);
+

     case cdk_function:
     case cdk_array:
     case cdk_pointer:
     case cdk_reference:
@@ -16969,34 +16971,42 @@ cp_parser_check_declarator_template_para
   return false;
 }

 /* NUM_TEMPLATES were used in the current declaration.  If that is
    invalid, return FALSE and issue an error messages.  Otherwise,
-   return TRUE.  */
+   return TRUE.  If DECLARATOR is non-NULL, then we are checking a
+   declarator and we can print more accurate diagnostics.  */

 static bool
 cp_parser_check_template_parameters (cp_parser* parser,
                                     unsigned num_templates,
-                                    location_t location)
+                                    location_t location,
+                                    cp_declarator *declarator)
 {
+  /* If there are the same number of template classes and parameter
+     lists, that's OK.  */
+  if (parser->num_template_parameter_lists == num_templates)
+    return true;
+  /* If there are more, but only one more, then we are referring to a
+     member template.  That's OK too.  */
+  if (parser->num_template_parameter_lists == num_templates + 1)
+    return true;
   /* If there are more template classes than parameter lists, we have
      something like:

        template <class T> void S<T>::R<T>::f ();  */
   if (parser->num_template_parameter_lists < num_templates)
     {
-      error ("%Htoo few template-parameter-lists", &location);
+      if (declarator)
+       error_at (location, "specializing member %<%T::%qE%> "
+                 "requires %<template<>%> syntax",
+                 declarator->u.id.qualifying_scope,
+                 declarator->u.id.unqualified_name);
+      else
+       error_at (location, "too few template-parameter-lists");
       return false;
     }
-  /* If there are the same number of template classes and parameter
-     lists, that's OK.  */
-  if (parser->num_template_parameter_lists == num_templates)
-    return true;
-  /* If there are more, but only one more, then we are referring to a
-     member template.  That's OK too.  */
-  if (parser->num_template_parameter_lists == num_templates + 1)
-      return true;
   /* Otherwise, there are too many template parameter lists.  We have
      something like:

      template <class T> template <class U> void S::f();  */
   error ("%Htoo many template-parameter-lists", &location);


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20118