pt.c (redeclare_class_template): Merge default template arguments in both directions.

	* pt.c (redeclare_class_template): Merge default template
	arguments in both directions.

	* typeck.c (common_type): Undo 1999-08-18 change.  Remove
	compiler_error message.

From-SVN: r28774

gcc/cp/ChangeLog

+1999-08-19  Mark Mitchell  <mark@codesourcery.com>
+
+	* pt.c (redeclare_class_template): Merge default template
+	arguments in both directions.
+
+	* typeck.c (common_type): Undo 1999-08-18 change.  Remove
+	compiler_error message.
+
 1999-08-19  Jason Merrill  <jason@yorick.cygnus.com>
 
 	* cp-tree.h: Declare flag_use_repository.

gcc/cp/pt.c

@@ -2666,6 +2666,10 @@ redeclare_class_template (type, parms)
 	/* Update the previous template parameters (which are the ones
 	   that will really count) with the new default value.  */
 	TREE_PURPOSE (TREE_VEC_ELT (tmpl_parms, i)) = parm_default;
+      else if (tmpl_default != NULL_TREE)
+	/* Update the new parameters, too; they'll be used as the
+	   parameters for any members.  */
+	TREE_PURPOSE (TREE_VEC_ELT (parms, i)) = tmpl_default;
     }
 }
 

gcc/cp/typeck.c

@@ -698,13 +698,8 @@ common_type (t1, t2)
 	tt1 = TYPE_MAIN_VARIANT (tt1);
 	tt2 = TYPE_MAIN_VARIANT (tt2);
 
-	if (same_type_p (tt1, tt2))
+	if (tt1 == tt2)
 	  target = tt1;
-	else if (b1)
-	  {
-	    compiler_error ("common_type called with uncommon member types");
-	    target = tt1;
-	  }
 	else if (tt1 == void_type_node || tt2 == void_type_node)
 	  target = void_type_node;
 	else if (tt1 == unknown_type_node)

gcc/testsuite/g++.old-deja/g++.pt/decl3.C

+// Build don't link:
+// Origin: Jason Merrill <jason@cygnus.com>
+
+template <class T, class U = int> struct A;
+template <class T = int, class U> struct A { };