[C PATCH] Make -Wno-shift-count-negative -Wno-shift-count-overflow work for const ints (PR c/65830)

[Marek Polacek]

A trivial patch to use OPT_* where they belong.

Bootstrapped/regtested on x86_64-linux, ok for trunk?

2015-04-21  Marek Polacek  <pola...@redhat.com>

        PR c/65830
        * c-common.c (c_fully_fold_internal): Use OPT_Wshift_count_negative
        and OPT_Wshift_count_overflow.

        * c-c++-common/pr65830.c: New test.

diff --git gcc/c-family/c-common.c gcc/c-family/c-common.c
index 7fe7fa6..64fc95f 100644
--- gcc/c-family/c-common.c
+++ gcc/c-family/c-common.c
@@ -1370,15 +1370,17 @@ c_fully_fold_internal (tree expr, bool in_init, bool 
*maybe_const_operands,
          && c_inhibit_evaluation_warnings == 0)
        {
          if (tree_int_cst_sgn (op1) < 0)
-           warning_at (loc, 0, (code == LSHIFT_EXPR
-                                ? G_("left shift count is negative")
-                                : G_("right shift count is negative")));
+           warning_at (loc, OPT_Wshift_count_negative,
+                       (code == LSHIFT_EXPR
+                        ? G_("left shift count is negative")
+                        : G_("right shift count is negative")));
          else if (compare_tree_int (op1,
                                     TYPE_PRECISION (TREE_TYPE (orig_op0)))
                   >= 0)
-           warning_at (loc, 0, (code == LSHIFT_EXPR
-                                ? G_("left shift count >= width of type")
-                                : G_("right shift count >= width of type")));
+           warning_at (loc, OPT_Wshift_count_overflow,
+                       (code == LSHIFT_EXPR
+                        ? G_("left shift count >= width of type")
+                        : G_("right shift count >= width of type")));
        }
       if ((code == TRUNC_DIV_EXPR
           || code == CEIL_DIV_EXPR
diff --git gcc/testsuite/c-c++-common/pr65830.c 
gcc/testsuite/c-c++-common/pr65830.c
index e69de29..e115f18 100644
--- gcc/testsuite/c-c++-common/pr65830.c
+++ gcc/testsuite/c-c++-common/pr65830.c
@@ -0,0 +1,16 @@
+/* PR c/65830 */
+/* { dg-do compile } */
+/* { dg-options "-O -Wno-shift-count-negative -Wno-shift-count-overflow" } */
+
+int
+foo (int x)
+{
+  const int a = sizeof (int) * __CHAR_BIT__;
+  const int b = -7;
+  int c = 0;
+  c += x << a; /* { dg-bogus "left shift count >= width of type" } */
+  c += x << b; /* { dg-bogus "left shift count is negative" } */
+  c += x >> a; /* { dg-bogus "right shift count >= width of type" } */
+  c += x >> b;  /* { dg-bogus "right shift count is negative" } */
+  return c;
+}

        Marek