re PR c++/45278 (-Wextra doesn't warn about (pointer < 0 ).)

/cp
2011-09-28  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/45278
	* typeck.c (cp_build_binary_op): With -Wextra, warn for ordered
	comparison of pointer with zero.

/testsuite
2011-09-28  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/45278
	* g++.dg/warn/Wextra-3.C: New.

From-SVN: r179321

gcc/cp/ChangeLog

+2011-09-28  Paolo Carlini  <paolo.carlini@oracle.com>
+
+	PR c++/45278
+	* typeck.c (cp_build_binary_op): With -Wextra, warn for ordered
+	comparison of pointer with zero.
+
 2011-09-27  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	PR c++/31489

gcc/cp/typeck.c

@@ -4189,9 +4189,19 @@ cp_build_binary_op (location_t location,
 	result_type = composite_pointer_type (type0, type1, op0, op1,
 					      CPO_COMPARISON, complain);
       else if (code0 == POINTER_TYPE && null_ptr_cst_p (op1))
-	result_type = type0;
+	{
+	  result_type = type0;
+	  if (extra_warnings && (complain & tf_warning))
+	    warning (OPT_Wextra,
+		     "ordered comparison of pointer with integer zero");
+	}
       else if (code1 == POINTER_TYPE && null_ptr_cst_p (op0))
-	result_type = type1;
+	{
+	  result_type = type1;
+	  if (extra_warnings && (complain & tf_warning))
+	    warning (OPT_Wextra,
+		     "ordered comparison of pointer with integer zero");
+	}
       else if (null_ptr_cst_p (op0) && null_ptr_cst_p (op1))
 	/* One of the operands must be of nullptr_t type.  */
         result_type = TREE_TYPE (nullptr_node);

gcc/testsuite/ChangeLog

+2011-09-28  Paolo Carlini  <paolo.carlini@oracle.com>
+
+	PR c++/45278
+	* g++.dg/warn/Wextra-3.C: New.
+
 2011-09-28  Oleg Endo  <oleg.endo@t-online.de>
 
 	PR target/49486

gcc/testsuite/g++.dg/warn/Wextra-3.C

+// PR c++/45278
+// { dg-options "-Wextra" } 
+
+extern void* p;
+
+int f1() { return ( p <  0 ? 1 : 0 ); } // { dg-warning "ordered comparison" }
+int f2() { return ( p <= 0 ? 1 : 0 ); } // { dg-warning "ordered comparison" }
+int f3() { return ( p >  0 ? 1 : 0 ); } // { dg-warning "ordered comparison" }
+int f4() { return ( p >= 0 ? 1 : 0 ); } // { dg-warning "ordered comparison" }