cvt.c (convert_to_void): Only warn about COND_EXPR if neither the second nor…

cvt.c (convert_to_void): Only warn about COND_EXPR if neither the second nor third operand has side effects.

cp/:
	* cvt.c (convert_to_void): Only warn about COND_EXPR if neither
	the second nor third operand has side effects.
testsuite/:
	* g++.dg/warn/Wunused-16.C: New testcase.

From-SVN: r148950

gcc/cp/ChangeLog

 2009-06-25  Ian Lance Taylor  <iant@google.com>
 
+	* cvt.c (convert_to_void): Only warn about COND_EXPR if neither
+	the second nor third operand has side effects.
+
+2009-06-25  Ian Lance Taylor  <iant@google.com>
+
 	* parser.c (cp_parser_binary_expression): Increment
 	c_inhibit_evaluation_warnings while parsing the right hand side of
 	"true || x" or "false && x".

gcc/cp/cvt.c

@@ -828,11 +828,12 @@ convert_to_void (tree expr, const char *implicit, tsubst_flags_t complain)
 	/* The two parts of a cond expr might be separate lvalues.  */
 	tree op1 = TREE_OPERAND (expr,1);
 	tree op2 = TREE_OPERAND (expr,2);
+	bool side_effects = TREE_SIDE_EFFECTS (op1) || TREE_SIDE_EFFECTS (op2);
 	tree new_op1 = convert_to_void
-	  (op1, (implicit && !TREE_SIDE_EFFECTS (op2)
+	  (op1, (implicit && !side_effects
 		 ? "second operand of conditional" : NULL), complain);
 	tree new_op2 = convert_to_void
-	  (op2, (implicit && !TREE_SIDE_EFFECTS (op1)
+	  (op2, (implicit && !side_effects
 		 ? "third operand of conditional" : NULL), complain);
 
 	expr = build3 (COND_EXPR, TREE_TYPE (new_op1),

gcc/testsuite/ChangeLog

 2009-06-25  Ian Lance Taylor  <iant@google.com>
 
+	* g++.dg/warn/Wunused-16.C: New testcase.
+
+2009-06-25  Ian Lance Taylor  <iant@google.com>
+
 	* g++.dg/warn/skip-2.C: New testcase.
 
 2009-06-25  Steve Ellcey  <sje@cup.hp.com>

gcc/testsuite/g++.dg/warn/Wunused-16.C

+// { dg-do compile }
+// { dg-options "-Wunused-value" }
+
+extern void f1();
+void
+f(bool b)
+{
+  b ? f1(), 0 : 0;	// { dg-bogus "has no effect" }
+}