Fix wunused false positive on CanEqual #18641
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| * Ignore CanEqual imports | ||
| */ | ||
| private def isImportIgnored(imp: tpd.Import, sel: ImportSelector)(using Context): Boolean = | ||
| (sel.isWildcard && imp.expr.tpe.allMembers.exists(p => p.symbol.typeRef.baseClasses.exists(_.derivesFrom(defn.CanEqualClass)))) || |
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I think this is problematic because perhaps it only imports CanEqual's that are not even used. Perhaps it makes more sense to record the CanEqual usages in the typer?
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Also this should check if its also a "given" import, rather than "*"
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Unfortunately, after a lengthy discussion with Martin and the team and making some PoCs, we decided that extracting that information from Typer is unfeasible without making the Typer and Implicit resolution slower / more complex. So we want to emulate it or fix false positives. But I will address the second comment 👍
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Emulating the feature will require summoning the exact same implicit again wont it? seems like even more work
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Yes, and this logic could get even more complex I suppose given that it is a type param, and the resolution is pre typer vs the emulation would be post typer. Not a good idea
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Im not sure how it works, but might it produce more accurate warnings if you only ignore warnings generated by the import selector when the specific unused symbol derives from CanEqual?
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It's pretty much what we are doing here
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Backports #18641 to the LTS branch. PR submitted by the release tooling. [skip ci]
Backports #18641 to the LTS branch. PR submitted by the release tooling. [skip ci]
Fixes #17762