re PR c/64440 (-Wdiv-by-zero false negative on const variables)

	PR c/64440
	* c-common.c (c_fully_fold_internal): Warn for division and modulo
	if orig_op1 isn't INTEGER_CST, op1 is INTEGER_CST and is zero.

	* gcc.dg/pr64440.c: New test.
	* c-c++-common/pr56607.c: Don't limit dg-warnings to C++.

From-SVN: r219279

gcc/c-family/ChangeLog

+2015-01-07  Marek Polacek  <polacek@redhat.com>
+
+	PR c/64440
+	* c-common.c (c_fully_fold_internal): Warn for division and modulo
+	if orig_op1 isn't INTEGER_CST, op1 is INTEGER_CST and is zero.
+
 2015-01-05  Trevor Saunders  <tsaunders@mozilla.com>
 
 	PR c++/31397

gcc/c-family/c-common.c

@@ -1364,6 +1364,17 @@ c_fully_fold_internal (tree expr, bool in_init, bool *maybe_const_operands,
 				 ? G_("left shift count >= width of type")
 				 : G_("right shift count >= width of type")));
 	}
+      if ((code == TRUNC_DIV_EXPR
+	   || code == CEIL_DIV_EXPR
+	   || code == FLOOR_DIV_EXPR
+	   || code == EXACT_DIV_EXPR
+	   || code == TRUNC_MOD_EXPR)
+	  && TREE_CODE (orig_op1) != INTEGER_CST
+	  && TREE_CODE (op1) == INTEGER_CST
+	  && (TREE_CODE (TREE_TYPE (orig_op0)) == INTEGER_TYPE
+	      || TREE_CODE (TREE_TYPE (orig_op0)) == FIXED_POINT_TYPE)
+	  && TREE_CODE (TREE_TYPE (orig_op1)) == INTEGER_TYPE)
+	warn_for_div_by_zero (loc, op1);
       goto out;
 
     case INDIRECT_REF:

gcc/testsuite/ChangeLog

 2015-01-07  Marek Polacek  <polacek@redhat.com>
 
+	PR c/64440
+	* gcc.dg/pr64440.c: New test.
+	* c-c++-common/pr56607.c: Don't limit dg-warnings to C++.
+
+2015-01-07  Marek Polacek  <polacek@redhat.com>
+
 	PR c/64417
 	* gcc.c-torture/compile/pr28865.c: Add dg-errors.
 	* gcc.dg/pr64417.c: New test.

gcc/testsuite/c-c++-common/pr56607.c

@@ -12,7 +12,7 @@ int
 f2 (void)
 {
   const int x = sizeof (char) - 1;
-  return 1 / x;				/* { dg-warning "division by zero" "" { target c++ } } */
+  return 1 / x;				/* { dg-warning "division by zero" } */
 }
 
 int
@@ -25,5 +25,5 @@ int
 f4 (void)
 {
   const int x = sizeof (int) / 3 - 1;
-  return 1 / x;				/* { dg-warning "division by zero" "" { target c++ } } */
+  return 1 / x;				/* { dg-warning "division by zero" } */
 }

gcc/testsuite/gcc.dg/pr64440.c

+/* PR c/64440 */
+/* { dg-do compile } */
+/* { dg-options "-Wall -O2" } */
+
+int
+foo (int x)
+{
+  const int y = 0;
+  int r = 0;
+  r += x / y; /* { dg-warning "division by zero" } */
+  r += x / 0; /* { dg-warning "division by zero" } */
+  r += x % y; /* { dg-warning "division by zero" } */
+  r += x % 0; /* { dg-warning "division by zero" } */
+  return r;
+}