Issue 21398 - Name clash between import and method triggers a segfault

[BorisCarvajal]

Problem was here:
d = cast(Declaration)mostVisibleOverload(fd, sc._module);

The function mostVisibleOverload() can return many kinds of objects, most are derived from Declaration except for TemplateDeclaration so we need to handle that case as well.

[dlang-bot]

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Bugzilla references

Auto-close	Bugzilla	Severity	Description
✓	21398	normal	Name clash between import and method triggers a segfault

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 "stable + dmd#11972"

[thewilsonator]

Please make sure the commit message says "Fix issue 21398: ..." so the bot picks it up.

[BorisCarvajal]

Wow I forgot the "Fix ..." part.