constexpr: Treat INT_MIN % -1 as undefined behavior in C++11. Technically, it

isn't, but this is just a (reported) defect in the wording.

llvm-svn: 149448

1 files changed, 4 insertions, 6 deletions

diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index 5a385e6eb47..15ab15ce3d6 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -4431,17 +4431,15 @@ bool IntExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
   case BO_Xor: return Success(LHS ^ RHS, E);
   case BO_Or:  return Success(LHS | RHS, E);
   case BO_Div:
+  case BO_Rem:
     if (RHS == 0)
       return Error(E, diag::note_expr_divide_by_zero);
-    // Check for overflow case: INT_MIN / -1.
+    // Check for overflow case: INT_MIN / -1 or INT_MIN % -1. The latter is not
+    // actually undefined behavior in C++11 due to a language defect.
     if (RHS.isNegative() && RHS.isAllOnesValue() &&
         LHS.isSigned() && LHS.isMinSignedValue())
       HandleOverflow(Info, E, -LHS.extend(LHS.getBitWidth() + 1), E->getType());
-    return Success(LHS / RHS, E);
-  case BO_Rem:
-    if (RHS == 0)
-      return Error(E, diag::note_expr_divide_by_zero);
-    return Success(LHS % RHS, E);
+    return Success(E->getOpcode() == BO_Rem ? LHS % RHS : LHS / RHS, E);
   case BO_Shl: {
     // During constant-folding, a negative shift is an opposite shift. Such a
     // shift is not a constant expression.