PR11604: don't allow floating-literal-to-integer casts in ICEs if the (truncated)
floating literal value does not fit into the destination type. Such casts have
undefined behavior at translation time; treating them as non-ICE matches the
behavior of modern gcc versions.
llvm-svn: 146842
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index 0d32ebf..88a0331 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -5252,9 +5252,23 @@
case Expr::CXXConstCastExprClass:
case Expr::ObjCBridgedCastExprClass: {
const Expr *SubExpr = cast<CastExpr>(E)->getSubExpr();
- if (isa<ExplicitCastExpr>(E) &&
- isa<FloatingLiteral>(SubExpr->IgnoreParenImpCasts()))
- return NoDiag();
+ if (isa<ExplicitCastExpr>(E)) {
+ if (const FloatingLiteral *FL
+ = dyn_cast<FloatingLiteral>(SubExpr->IgnoreParenImpCasts())) {
+ unsigned DestWidth = Ctx.getIntWidth(E->getType());
+ bool DestSigned = E->getType()->isSignedIntegerOrEnumerationType();
+ APSInt IgnoredVal(DestWidth, !DestSigned);
+ bool Ignored;
+ // If the value does not fit in the destination type, the behavior is
+ // undefined, so we are not required to treat it as a constant
+ // expression.
+ if (FL->getValue().convertToInteger(IgnoredVal,
+ llvm::APFloat::rmTowardZero,
+ &Ignored) & APFloat::opInvalidOp)
+ return ICEDiag(2, E->getLocStart());
+ return NoDiag();
+ }
+ }
switch (cast<CastExpr>(E)->getCastKind()) {
case CK_LValueToRValue:
case CK_NoOp: