[Issue 12615] Warn against, and then deprecate old alias syntax

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=12615

--- Comment #2 from bearophile_h...@eml.cc ---
(In reply to Mike from comment #1)
> A prerequisite to this would be to replace all occurrences of the old syntax
> in DRuntime and Phobos with the new syntax.

Right. And the warning will help find all those occurrences.

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