re PR c++/41920 ([C++0x] Invalid 'unused parameter' warning for parameters used in lambdas)

	PR c++/41920
	* semantics.c (build_lambda_object): Call mark_used on captured
	variables.

From-SVN: r156085

gcc/cp/ChangeLog

 2010-01-20  Jason Merrill  <jason@redhat.com>
 
+	PR c++/41920
+	* semantics.c (build_lambda_object): Call mark_used on captured
+	variables.
+
 	PR c++/40750
 	* decl.c (grokdeclarator): Clear type_quals for a member function
 	declared using a typedef.  Don't complain about adding cv-quals

gcc/cp/semantics.c

@@ -5408,6 +5408,9 @@ build_lambda_object (tree lambda_expr)
       tree field = TREE_PURPOSE (node);
       tree val = TREE_VALUE (node);
 
+      if (DECL_P (val))
+	mark_used (val);
+
       /* Mere mortals can't copy arrays with aggregate initialization, so
 	 do some magic to make it work here.  */
       if (TREE_CODE (TREE_TYPE (field)) == ARRAY_TYPE)

gcc/testsuite/ChangeLog

 2010-01-20  Jason Merrill  <jason@redhat.com>
 
+	PR c++/41920
+	* g++.dg/cpp0x/lambda/lambda-warn1.C: New.
+
 	PR c++/40750
 	* g++.dg/parse/fn-typedef1.C: New.
 	* g++.dg/other/cv_quals.C: Adjust.

gcc/testsuite/g++.dg/cpp0x/lambda/lambda-warn1.C

+// PR c++/41920
+// { dg-options "-std=c++0x -Wall -Wextra" }
+
+int foo(int i)
+{
+    auto bar = [=](){ return i; };
+    return bar();
+}