Bug 18744 – Class l-values can be implicitly converted to `Object` l-values, even in safe code

--- @safe: class A { int* a; } class B { long b; } // Either of these shouldn't be allowed: void boom1(ref A a, B b) { (cast(Object)a) = b; } void boom2(ref A a, B b) { (true ? a : b) = b; } int main() { A a = new A; B b = new B; boom1(a, b); boom2(a, b); return *a.a; } --- compiles fine on DMD 2.079, but covariance in l-values can't be allowed. This is the same problem often illustrated using containers.

Using latest dmd master I get: test2.d(7): Error: `cast(Object)a` is not an lvalue and cannot be modified test2.d(8): Error: conditional expression `true ? cast(Object)a : cast(Object)b` is not a modifiable lvalue So this seems to have been fixed.