[Issue 21458] missed oportunity to progapage final to its its aliased symbol

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=21458

--- Comment #1 from Basile-z <b2.temp at gmx.com> ---
sorry guys, first comment should be

    // final class B : A!Y {}  ???

suposing the alias create this

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