Fix 0.750 regression: union (non-)simplification should not affect inference #8077
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JelleZijlstra
approved these changes
Dec 4, 2019
mypy/constraints.py
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| @@ -108,6 +108,12 @@ def _infer_constraints(template: Type, actual: Type, | |||
| template = get_proper_type(template) | |||
| actual = get_proper_type(actual) | |||
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| # Type inference shouldn't be affected by whether union types have bee simplified. | |||
| @@ -3646,7 +3646,7 @@ def test_narrow_none() -> None: | |||
| a: Optional[int] | |||
| if int(): | |||
| a = narrow_none(a) | |||
| reveal_type(a) # N: Revealed type is 'Union[builtins.int, None]' | |||
| reveal_type(a) # N: Revealed type is 'builtins.int' | |||
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This is a nice improvement too.
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Fixes #8051
The fix is as discussed in the issue. I didn't find a test case for the union
actual, but I think it makes sense to simplify it as well. Note: I add thepythonevaltest just as a regression test, if you think it is not worth it, I can remove it.