re PR middle-end/49705 (-Wstrict-overflow should not diagnose unevaluated expressions)

gcc/c-family:
	PR middle-end/49705
	* c-common.c (c_disable_warnings): New static function.
	(c_enable_warnings): New static function.
	(c_fully_fold_internal): Change local unused_p to bool.  Call
	c_disable_warnings and c_enable_warnings rather than change
	c_inhibit_evaluation_warnings.
gcc/testsuite:
	PR middle-end/49705
	* gcc.dg/pr49705.c: New test.

From-SVN: r176591

2 files changed, 42 insertions, 7 deletions

diff --git a/gcc/c-family/ChangeLog b/gcc/c-family/ChangeLog
index c5f2306..8af431e 100644
--- a/gcc/c-family/ChangeLog
+++ b/gcc/c-family/ChangeLog
@@ -1,3 +1,12 @@
+2011-07-21  Ian Lance Taylor  <iant@google.com>
+
+	PR middle-end/49705
+	* c-common.c (c_disable_warnings): New static function.
+	(c_enable_warnings): New static function.
+	(c_fully_fold_internal): Change local unused_p to bool.  Call
+	c_disable_warnings and c_enable_warnings rather than change
+	c_inhibit_evaluation_warnings.
+
 2011-07-20  Jason Merrill  <jason@redhat.com>
 
 	PR c++/6709 (DR 743)
diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c
index 6078d94..96275ba 100644
--- a/gcc/c-family/c-common.c
+++ b/gcc/c-family/c-common.c
@@ -963,6 +963,32 @@ fix_string_type (tree value)
   return value;
 }
 
+/* If DISABLE is true, stop issuing warnings.  This is used when
+   parsing code that we know will not be executed.  This function may
+   be called multiple times, and works as a stack.  */
+
+static void
+c_disable_warnings (bool disable)
+{
+  if (disable)
+    {
+      ++c_inhibit_evaluation_warnings;
+      fold_defer_overflow_warnings ();
+    }
+}
+
+/* If ENABLE is true, reenable issuing warnings.  */
+
+static void
+c_enable_warnings (bool enable)
+{
+  if (enable)
+    {
+      --c_inhibit_evaluation_warnings;
+      fold_undefer_and_ignore_overflow_warnings ();
+    }
+}
+
 /* Fully fold EXPR, an expression that was not folded (beyond integer
    constant expressions and null pointer constants) when being built
    up.  If IN_INIT, this is in a static initializer and certain
@@ -1029,7 +1055,7 @@ c_fully_fold_internal (tree expr, bool in_init, bool *maybe_const_operands,
   bool op0_const = true, op1_const = true, op2_const = true;
   bool op0_const_self = true, op1_const_self = true, op2_const_self = true;
   bool nowarning = TREE_NO_WARNING (expr);
-  int unused_p;
+  bool unused_p;
 
   /* This function is not relevant to C++ because C++ folds while
      parsing, and may need changes to be correct for C++ when C++
@@ -1278,10 +1304,10 @@ c_fully_fold_internal (tree expr, bool in_init, bool *maybe_const_operands,
       unused_p = (op0 == (code == TRUTH_ANDIF_EXPR
 			  ? truthvalue_false_node
 			  : truthvalue_true_node));
-      c_inhibit_evaluation_warnings += unused_p;
+      c_disable_warnings (unused_p);
       op1 = c_fully_fold_internal (op1, in_init, &op1_const, &op1_const_self);
       STRIP_TYPE_NOPS (op1);
-      c_inhibit_evaluation_warnings -= unused_p;
+      c_enable_warnings (unused_p);
 
       if (op0 != orig_op0 || op1 != orig_op1 || in_init)
 	ret = in_init
@@ -1313,15 +1339,15 @@ c_fully_fold_internal (tree expr, bool in_init, bool *maybe_const_operands,
       op0 = c_fully_fold_internal (op0, in_init, &op0_const, &op0_const_self);
 
       STRIP_TYPE_NOPS (op0);
-      c_inhibit_evaluation_warnings += (op0 == truthvalue_false_node);
+      c_disable_warnings (op0 == truthvalue_false_node);
       op1 = c_fully_fold_internal (op1, in_init, &op1_const, &op1_const_self);
       STRIP_TYPE_NOPS (op1);
-      c_inhibit_evaluation_warnings -= (op0 == truthvalue_false_node);
+      c_enable_warnings (op0 == truthvalue_false_node);
 
-      c_inhibit_evaluation_warnings += (op0 == truthvalue_true_node);
+      c_disable_warnings (op0 == truthvalue_true_node);
       op2 = c_fully_fold_internal (op2, in_init, &op2_const, &op2_const_self);
       STRIP_TYPE_NOPS (op2);
-      c_inhibit_evaluation_warnings -= (op0 == truthvalue_true_node);
+      c_enable_warnings (op0 == truthvalue_true_node);
 
       if (op0 != orig_op0 || op1 != orig_op1 || op2 != orig_op2)
 	ret = fold_build3_loc (loc, code, TREE_TYPE (expr), op0, op1, op2);