Support for singleton types in unions with Enum #7693
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JukkaL
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JukkaL
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Thanks for the PR! Looks great.
(I'll give @Michael0x2a a chance to have a look before merging since he's our resident expert on literal types.)
mypy/checker.py
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| if typ.last_known_value: | ||
| return typ.last_known_value | ||
| elif typ.type.is_enum and len(typ.type.names) == 1: | ||
| key, = typ.type.names |
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I believe the names dict can also contain reference to methods, which shouldn't be counted as an enum values.
I'd try refactoring out the "get all enum values" check on lines ~4794 to ~4798 of this file into a separate helper function and call it here instead of using typ.type.names directly, and maybe also add a test case making sure mypy doesn't do anything weird if we have an single-value enum that also defines a method.
mypy/checker.py
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| # Also make this return True if the type corresponds to ... (ellipsis) or NotImplemented? | ||
| return isinstance(typ, NoneType) or (isinstance(typ, LiteralType) and typ.is_enum_literal()) | ||
| return (isinstance(typ, NoneType) or (isinstance(typ, LiteralType) and typ.is_enum_literal()) | ||
| or (isinstance(typ, Instance) and typ.type.is_enum and len(typ.type.names) == 1)) |
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See other comment about typ.type.names -- the same fix should be done here.
Michael0x2a
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Michael0x2a
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Looks good now, thanks!
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This PR adds supports for singleton types in unions using
Enums as described in PEP 484 (without usingFinal).As suggested by @Michael0x2a in the corresponding issue, adding another case to the
is_singleton_typeandcoerce_to_literalfunctions allows mypy to recognize anEnumwith 1 value as a singleton type.Fixes #7279