re PR c++/44361 (-Wunused-but-set-variable vs. explicit void cast)

	PR c++/44361
	* c-typeck.c (mark_exp_read): Handle C_MAYBE_CONST_EXPR.
	* c-parser.c (c_parser_postfix_expression): Call mark_exp_read on
	statement expression.

	* c-c++-common/Wunused-var-9.c: New test.

From-SVN: r160317

gcc/ChangeLog

+2010-06-05  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/44361
+	* c-typeck.c (mark_exp_read): Handle C_MAYBE_CONST_EXPR.
+	* c-parser.c (c_parser_postfix_expression): Call mark_exp_read on
+	statement expression.
+
 2010-06-05  Jan Hubicka  <jh@suse.cz>
 
 	* df-problems.c (seen_in_block, seen_in_insn): Convert to bitmap_head.

gcc/c-parser.c

@@ -5601,6 +5601,7 @@ c_parser_postfix_expression (c_parser *parser)
 	  pedwarn (loc, OPT_pedantic,
 		   "ISO C forbids braced-groups within expressions");
 	  expr.value = c_finish_stmt_expr (brace_loc, stmt);
+	  mark_exp_read (expr.value);
 	}
       else if (c_token_starts_typename (c_parser_peek_2nd_token (parser)))
 	{

gcc/c-typeck.c

@@ -1841,6 +1841,7 @@ mark_exp_read (tree exp)
       mark_exp_read (TREE_OPERAND (exp, 0));
       break;
     case COMPOUND_EXPR:
+    case C_MAYBE_CONST_EXPR:
       mark_exp_read (TREE_OPERAND (exp, 1));
       break;
     default:

gcc/testsuite/ChangeLog

+2010-06-05  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/44361
+	* c-c++-common/Wunused-var-9.c: New test.
+
 2010-06-05  Jason Merrill  <jason@redhat.com>
 
 	* g++.dg/cpp0x/noexcept06.C: Call set_unexpected.