Fix false positive reportUnnecessaryComparison for bytes-like types - #11547
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Fix false positive reportUnnecessaryComparison for bytes-like types#11547pctablet505 wants to merge 1 commit into
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The reportUnnecessaryComparison check assumed that any two disjoint built-in class instances could never compare equal, which is true for most types but not for "bytes", "bytearray" and "memoryview". These types are otherwise unrelated for assignability purposes, but their "__eq__" implementations do support cross-type content comparisons, so "bytearray(4) == bytes(4)" is valid and can be True. Fixes microsoft#11433
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Fixes #11433
reportUnnecessaryComparisontreats two disjoint built-in class instances as never comparable with==/!=. That's a reasonable default, but it doesn't hold forbytes,bytearrayandmemoryview: they're unrelated for assignability purposes, yet their__eq__implementations do support cross-type content comparisons (bytearray(4) == bytes(4)isTrueat runtime).This adds a narrow carve-out in
isTypeComparablefor this specific group of types, reusing the existingtypePromotionstable that already models the relationship elsewhere (it's the same list consulted for thebytes/bytearray/memoryviewassignability promotion). Comparability isn't gated behinddisableBytesTypePromotions, since that setting is about assignment compatibility, not about whether__eq__can returnTrue.Added test cases to
comparison1.pycoveringbytearray/bytes, abytearray-vs-literal-bytes comparison, and all pairings ofbytes/bytearray/memoryview, alongside a couple of genuinely-disjoint builtin cases (int/str,list/dict) to confirm the general diagnostic still fires where it should.