re PR c++/13810 (ICE on invalid default templates)

	PR c++/13810
	* parser.c (cp_parser_type_parameter): When cp_parser_id_expression
	returns a TYPE_DECL. no further lookup is required.
	* semantics.c (check_template_template_default_arg): A TYPE_DECL
	is invalid. Rework to give better diagnostics.

From-SVN: r76593

3 files changed, 39 insertions, 11 deletions

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 9047381..5171c70 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,11 @@
+2004-01-25  Giovanni Bajo  <giovannibajo@gcc.gnu.org>
+
+	PR c++/13810
+	* parser.c (cp_parser_type_parameter): When cp_parser_id_expression 
+	returns a TYPE_DECL. no further lookup is required.
+	* semantics.c (check_template_template_default_arg): A TYPE_DECL
+	is invalid. Rework to give better diagnostics.
+
 2004-01-25  Kriang Lerdsuwanakij  <lerdsuwa@users.sourceforge.net>
 
 	PR c++/13797
diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index 4fde7b6..0ca1dca 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -7708,13 +7708,19 @@ cp_parser_type_parameter (cp_parser* parser)
 					 /*check_dependency_p=*/true,
 					 /*template_p=*/&is_template,
 					 /*declarator_p=*/false);
-	    /* Look up the name.  */
-	    default_argument 
-	      = cp_parser_lookup_name (parser, default_argument,
-				       /*is_type=*/false,
-				       /*is_template=*/is_template,
-				       /*is_namespace=*/false,
-				       /*check_dependency=*/true);
+	    if (TREE_CODE (default_argument) == TYPE_DECL)
+	      /* If the id-expression was a template-id that refers to
+		 a template-class, we already have the declaration here,
+		 so no further lookup is needed.  */
+		 ;
+	    else
+	      /* Look up the name.  */
+	      default_argument 
+		= cp_parser_lookup_name (parser, default_argument,
+					/*is_type=*/false,
+					/*is_template=*/is_template,
+					/*is_namespace=*/false,
+					/*check_dependency=*/true);
 	    /* See if the default argument is valid.  */
 	    default_argument
 	      = check_template_template_default_arg (default_argument);
@@ -12705,8 +12711,8 @@ cp_parser_base_specifier (cp_parser* parser)
 	  break;
 	}
     }
-  /* It is not uncommon to see programs mechanically, errouneously, use

-     the 'typename' keyword to denote (dependent) qualified types

+  /* It is not uncommon to see programs mechanically, errouneously, use
+     the 'typename' keyword to denote (dependent) qualified types
      as base classes.  */
   if (cp_lexer_next_token_is_keyword (parser->lexer, RID_TYPENAME))
     {
diff --git a/gcc/cp/semantics.c b/gcc/cp/semantics.c
index 059ed15..3cf4e08 100644
--- a/gcc/cp/semantics.c
+++ b/gcc/cp/semantics.c
@@ -1942,10 +1942,24 @@ check_template_template_default_arg (tree argument)
 {
   if (TREE_CODE (argument) != TEMPLATE_DECL
       && TREE_CODE (argument) != TEMPLATE_TEMPLATE_PARM
-      && TREE_CODE (argument) != TYPE_DECL
       && TREE_CODE (argument) != UNBOUND_CLASS_TEMPLATE)
     {
-      error ("invalid default template argument");
+      if (TREE_CODE (argument) == TYPE_DECL)
+	{
+	  tree t = TREE_TYPE (argument);
+
+	  /* Try to emit a slightly smarter error message if we detect
+	     that the user is using a template instantiation.  */
+	  if (CLASSTYPE_TEMPLATE_INFO (t) 
+	      && CLASSTYPE_TEMPLATE_INSTANTIATION (t))
+	    error ("invalid use of type `%T' as a default value for a "
+	           "template template-parameter", t);
+	  else
+	    error ("invalid use of `%D' as a default value for a template "
+	           "template-parameter", argument);
+	}
+      else
+	error ("invalid default argument for a template template parameter");
       return error_mark_node;
     }