re PR c/68907 (bogus warning: right-hand operand of comma expression has no…

re PR c/68907 (bogus warning: right-hand operand of comma expression has no effect on an atomic_int preincrement)

	PR c/68907
	* c-typeck.c (build_atomic_assign): Set TREE_NO_WARNING on an
	artificial decl.

	* gcc.dg/pr68907.c: New test.

From-SVN: r231656

gcc/c/ChangeLog

+2015-12-15  Marek Polacek  <polacek@redhat.com>
+
+	PR c/68907
+	* c-typeck.c (build_atomic_assign): Set TREE_NO_WARNING on an
+	artificial decl.
+
 2015-12-08  David Malcolm  <dmalcolm@redhat.com>
 
 	* c-parser.c (c_parser_alignof_expression): Capture location of

gcc/c/c-typeck.c

@@ -3814,6 +3814,7 @@ build_atomic_assign (location_t loc, tree lhs, enum tree_code modifycode,
   newval = create_tmp_var_raw (nonatomic_lhs_type);
   newval_addr = build_unary_op (loc, ADDR_EXPR, newval, 0);
   TREE_ADDRESSABLE (newval) = 1;
+  TREE_NO_WARNING (newval) = 1;
 
   loop_decl = create_artificial_label (loc);
   loop_label = build1 (LABEL_EXPR, void_type_node, loop_decl);

gcc/testsuite/ChangeLog

+2015-12-15  Marek Polacek  <polacek@redhat.com>
+
+	PR c/68907
+	* gcc.dg/pr68907.c: New test.
+
 2015-12-15  Alessandro Fanfarillo  <fanfarillo.gcc@gmail.com>
 
 	* gfortran.dg/coarray_critical_1.f90: New.

gcc/testsuite/gcc.dg/pr68907.c

+/* PR c/60195 */
+/* { dg-do compile } */
+/* { dg-options "-std=c11 -Wpedantic -Wall" } */
+
+_Atomic int a;
+
+void
+fn (void)
+{
+  ++a;
+  a++;
+  --a;
+  a--;
+}