Improvements to Clang's diagnostics
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+- We now generate a diagnostic for signed integer overflow due to unary minus
+ in a non-constant expression context. This fixes
+ `Issue 31643 <https://github.com/llvm/llvm-project/issues/31643>`_
Non-comprehensive list of changes in this release
-------------------------------------------------
return false;
if (!Result.isInt()) return Error(E);
const APSInt &Value = Result.getInt();
- if (Value.isSigned() && Value.isMinSignedValue() && E->canOverflow() &&
- !HandleOverflow(Info, E, -Value.extend(Value.getBitWidth() + 1),
- E->getType()))
- return false;
+ if (Value.isSigned() && Value.isMinSignedValue() && E->canOverflow()) {
+ if (Info.checkingForUndefinedBehavior())
+ Info.Ctx.getDiagnostics().Report(E->getExprLoc(),
+ diag::warn_integer_constant_overflow)
+ << toString(Value, 10) << E->getType();
+
+ if (!HandleOverflow(Info, E, -Value.extend(Value.getBitWidth() + 1),
+ E->getType()))
+ return false;
+ }
return Success(-Value, E);
}
case UO_Not: {
Expr *OriginalE = Exprs.pop_back_val();
Expr *E = OriginalE->IgnoreParenCasts();
- if (isa<BinaryOperator>(E)) {
+ if (isa<BinaryOperator, UnaryOperator>(E)) {
E->EvaluateForOverflow(Context);
continue;
}
constexpr int int_min = ~0x7fffffff;
constexpr int minus_int_min = -int_min; // expected-error {{constant expression}} expected-note {{value 2147483648 is outside the range}}
+ constexpr int minus_int_min_from_shift = -(1<<31); // expected-error {{constant expression}} expected-note {{value 2147483648 is outside the range}}
constexpr int div0 = 3 / 0; // expected-error {{constant expression}} expected-note {{division by zero}}
constexpr int mod0 = 3 % 0; // expected-error {{constant expression}} expected-note {{division by zero}}
constexpr int int_min_div_minus_1 = int_min / -1; // expected-error {{constant expression}} expected-note {{value 2147483648 is outside the range}}
}
}
}
+
+namespace GH31643 {
+void f() {
+ int a = -(1<<31); // expected-warning {{overflow in expression; result is -2147483648 with type 'int'}}
+}
+}
Frontend
| EvaluateAsRValue (<test.cc:8:21>)
| EvaluateForOverflow (<test.cc:8:21, col:25>)
+| EvaluateForOverflow (<test.cc:8:30, col:32>)
| EvaluateAsRValue (<test.cc:9:14>)
| EvaluateForOverflow (<test.cc:9:9, col:14>)
| isPotentialConstantExpr (slow_namespace::slow_func)