The following code runs correctly when compiled with ldc (1.4.0) but
fails with an assert error when compiled with dmd (2.076 and ldc 1.2.0)
```
class A
{
}
class B
{
T opCast(T)()
{
return this;
}
}
void main()
{
A a = null;
B b = null;
auto c = cast(Object)a;
auto d = cast(Object)b; // Fails with:
core.exception.AssertError@test.d(8): null this
}
```
How would you write an opCast that would handle this case correctly?
Testing if this is null at the start of the opCast doesn't help since
the assert is thrown before that happens.
Making the opCast static leaves us without access to this, which would
be needed in my use case.
We can't relay on ufcs since the rewrite to opCast doesn't happen when
it's not a member function.
--
Mike Wey
