[Issue 23552] Function `x` does not override any function, but it actually does

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=23552

--- Comment #1 from Grim Maple <grimmaple95 at gmail.com> ---
Similar issue happens with below code:
```
import std;

class Base
{
    final void foo() { }
}

class Derived : Base
{
    override void foo() { writeln("foo"); }
    int data() { return 0; }
}

class DerivedX : Derived
{
    override int data() { return 1; }
}
```
Error output:
```
onlineapp.d(10): Error: function `onlineapp.Derived.foo` cannot override
`final` function `onlineapp.Base.foo`
onlineapp.d(10): Error: function `void onlineapp.Derived.foo()` does not
override any function, did you mean to override `void onlineapp.Base.foo()`?
onlineapp.d(16): Error: function `onlineapp.DerivedX.data` does not override
any function
```

--