re PR c++/49251 ([C++0x][parameter pack expanding] unused parameter warning with…

re PR c++/49251 ([C++0x][parameter pack expanding] unused parameter warning with unpacking empty tuples)

	PR c++/49251
	* semantics.c (finish_id_expression): Mark even dependent
	variables as used.

From-SVN: r175119

gcc/cp/ChangeLog

 2011-06-16  Jason Merrill  <jason@redhat.com>
 
+	PR c++/49251
+	* semantics.c (finish_id_expression): Mark even dependent
+	variables as used.
+
 	PR c++/49420
 	* error.c (dump_template_argument): Don't try to omit default
 	template args from an argument pack.

gcc/cp/semantics.c

@@ -3196,7 +3196,10 @@ finish_id_expression (tree id_expression,
 	     (or an instantiation thereof).  */
 	  if (TREE_CODE (decl) == VAR_DECL
 	      || TREE_CODE (decl) == PARM_DECL)
-	    return convert_from_reference (decl);
+	    {
+	      mark_used (decl);
+	      return convert_from_reference (decl);
+	    }
 	  /* The same is true for FIELD_DECL, but we also need to
 	     make sure that the syntax is correct.  */
 	  else if (TREE_CODE (decl) == FIELD_DECL)

gcc/testsuite/ChangeLog

 2011-06-16  Jason Merrill  <jason@redhat.com>
 
+	PR c++/49251
+	* g++.dg/cpp0x/variadic113.C: New.
+
 	PR c++/49420
 	* g++.dg/cpp0x/variadic112.C: New.
 

gcc/testsuite/g++.dg/cpp0x/variadic113.C

+// PR c++/49251
+// { dg-options "-std=c++0x -Wunused-parameter" }
+
+struct A {};
+template <int> int f(A);
+
+template< int... Indices >
+struct indices {};
+
+template< class... Args >
+void sink( Args&&... ) {}
+
+template< class T, int... Indices >
+void unpack_test( T && t, indices<Indices...> ) {
+  sink( f<Indices>(t)... );
+}
+
+int main() {
+  unpack_test( A(), indices<>() );
+}