Fix Issue 20840 - No deprecation for template from deprecated selecti…

[MoonlightSentinel]

…ve import

Selective imports are lowered to an AliasDeclarations which were discarded when
resolving the actual TemplateDeclaration. So make sure to check the AD as well.

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Bugzilla references

Auto-close	Bugzilla	Severity	Description
✓	20840	normal	No deprecation when using template from deprecated selective import

Testing this PR locally

If you don't have a local development environment setup, you can use Digger to test this PR:

dub run digger -- build "master + dmd#11158"

[schveiguy]

With this, can you deprecate a template? The test case doesn't include a template that is directly deprecated. This does look like it should provide a way forward though for the problem at hand.

[MoonlightSentinel]

You mean a template declaration or an instance?

[schveiguy]

My original plan was to put in a deprecated AliasSeq in std.math, but even deprecating a template declaration doesn't do anything!

e.g.:

deprecated alias AliasSeq(V...) = V;

alias x = AliasSeq!(1, 2, 3); // no message

[MoonlightSentinel]

I see. That issue needs to be fixed as well but is unrelated to the current bug.

EDIT:
Because this concerns non-deprecated template declarations.

[wilzbach]

Nice!

[MoonlightSentinel]

Changed to only check AliasDeclarations because the eager check print's a wrong error message for some deprecated templates (WIP)

[Geod24]

Does it also work with __traits(isDeprecated) ? Asking because https://issues.dlang.org/show_bug.cgi?id=20221

[MoonlightSentinel]

No, but it probably will once that bug is fixed.