re PR c++/50224 ([C++0x] bogus unused parameter warning (it is referenced in lambda))

	PR c++/50224
	* semantics.c (finish_id_expression): Mark captured variables used.

From-SVN: r178277

gcc/cp/ChangeLog

+2011-08-29  Jason Merrill  <jason@redhat.com>
+
+	PR c++/50224
+	* semantics.c (finish_id_expression): Mark captured variables used.
+
 2011-08-29  Jakub Jelinek  <jakub@redhat.com>
 	    Jason Merrill  <jason@redhat.com>
 

gcc/cp/semantics.c

@@ -2949,6 +2949,9 @@ finish_id_expression (tree id_expression,
 	  tree lambda_expr = NULL_TREE;
 	  tree initializer = convert_from_reference (decl);
 
+	  /* Mark it as used now even if the use is ill-formed.  */
+	  mark_used (decl);
+
 	  /* Core issue 696: "[At the July 2009 meeting] the CWG expressed
 	     support for an approach in which a reference to a local
 	     [constant] automatic variable in a nested class or lambda body

gcc/testsuite/ChangeLog

+2011-08-29  Jason Merrill  <jason@redhat.com>
+
+	PR c++/50224
+	* g++.dg/cpp0x/lambda/lambda-use2.C: New.
+
 2011-08-29  Jakub Jelinek  <jakub@redhat.com>
 	    Jason Merrill  <jason@redhat.com>
 

gcc/testsuite/g++.dg/cpp0x/lambda/lambda-use2.C

+// PR c++/50224
+// { dg-options "-std=c++0x -Wunused-parameter" }
+
+struct T;
+
+void m(T& t) // ERROR here
+{
+  [&]{
+    t; // ``t`` is referenced here
+  };
+}