re PR c++/48424 (C++0x parameter packs expansion problem)

	PR c++/48424
	* decl.c (grokparms): Function parameter packs don't need to
	go at the end.
	* pt.c (type_unification_real): But they aren't deduced otherwise.

From-SVN: r174285

gcc/cp/ChangeLog

+2011-05-26  Jason Merrill  <jason@redhat.com>
+
+	PR c++/48424
+	* decl.c (grokparms): Function parameter packs don't need to
+	go at the end.
+	* pt.c (type_unification_real): But they aren't deduced otherwise.
+
 2011-05-25  Jason Merrill  <jason@redhat.com>
 
 	PR c++/48536

gcc/cp/decl.c

@@ -10551,12 +10551,6 @@ grokparms (tree parmlist, tree *parms)
 	    init = check_default_argument (decl, init);
 	}
 
-      if (TREE_CODE (decl) == PARM_DECL
-          && FUNCTION_PARAMETER_PACK_P (decl)
-          && TREE_CHAIN (parm)
-          && TREE_CHAIN (parm) != void_list_node)
-        error ("parameter packs must be at the end of the parameter list");
-
       DECL_CHAIN (decl) = decls;
       decls = decl;
       result = tree_cons (init, type, result);

gcc/cp/pt.c

@@ -14262,11 +14262,24 @@ type_unification_real (tree tparms,
   while (parms && parms != void_list_node
 	 && ia < nargs)
     {
-      if (TREE_CODE (TREE_VALUE (parms)) == TYPE_PACK_EXPANSION)
-        break;
-
       parm = TREE_VALUE (parms);
+
+      if (TREE_CODE (parm) == TYPE_PACK_EXPANSION
+	  && (!TREE_CHAIN (parms) || TREE_CHAIN (parms) == void_list_node))
+	/* For a function parameter pack that occurs at the end of the
+	   parameter-declaration-list, the type A of each remaining
+	   argument of the call is compared with the type P of the
+	   declarator-id of the function parameter pack.  */
+	break;
+
       parms = TREE_CHAIN (parms);
+
+      if (TREE_CODE (parm) == TYPE_PACK_EXPANSION)
+	/* For a function parameter pack that does not occur at the
+	   end of the parameter-declaration-list, the type of the
+	   parameter pack is a non-deduced context.  */
+	continue;
+
       arg = args[ia];
       ++ia;
       arg_expr = NULL;

gcc/testsuite/ChangeLog

+2011-05-26  Jason Merrill  <jason@redhat.com>
+
+	* g++.dg/cpp0x/variadic111.C: New.
+	* g++.dg/cpp0x/variadic41.C: Adjust.
+
 2011-05-26  Richard Guenther  <rguenther@suse.de>
 
 	PR tree-optimization/48702

gcc/testsuite/g++.dg/cpp0x/variadic111.C

+// PR c++/48424
+// { dg-options -std=c++0x }
+
+template<typename... Args1>
+struct S
+{
+  template<typename... Args2>
+    void f(Args1... args1, Args2&&... args2)
+    {
+    }
+};
+
+int main()
+{
+  S<int, double> s;
+  s.f(1,2.0,false,'a');
+}
+
+// { dg-final { scan-assembler "_ZN1SIIidEE1fIIbcEEEvidDpOT_" } }

gcc/testsuite/g++.dg/cpp0x/variadic41.C

+// A function parameter pack is only deduced if it's at the end
 // { dg-options "-std=gnu++0x" }
 template<typename... Args>
-void f(const Args&... args, int oops); // { dg-error "end" }
+void f(const Args&... args, int oops);
+
+int main()
+{
+  f<>(1);
+  f(1);
+  f<int>(1,2);
+  f(1,2);			// { dg-error "no match" }
+}
+
+// { dg-prune-output "note" }