[Issue 20033] alias this does not support `deprecated` attribute

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=20033

Mathias LANG <pro.mathias.lang at gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|Deprecation not triggered   |alias this does not support
                   |with foreach + alias this   |`deprecated` attribute

--- Comment #3 from Mathias LANG <pro.mathias.lang at gmail.com> ---
Actually, after looking at the code, it simply does not support `deprecated`.

E.g. adding the following line to `main` does not trigger any deprecation:
```
    auto i = Test.init.front();
```

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