Improve type inference special case that involves union with Any #10887
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When trying to match `list[T]` and `list[str] | Any`, previously we gave up, because the union items caused conflicting inferred values for `T` (`str` and `Any`). Work around the issue by dropping `Any` constraints if there are multiple sets of contraints, since we prefer more precise types. This fixes false positives resulting from python/typeshed#5557, which changed some return types to contain unions with `Any` items. See mypy primer results in #10881 for a real-world example of this in sphinx.
ilevkivskyi
approved these changes
Jul 28, 2021
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When trying to match
list[T]andlist[str] | Any, previously wegave up, because the union items caused conflicting inferred values
for
T(strandAny). Work around the issue by droppingAnyconstraints if there are multiple sets of contraints, since we
prefer more precise types.
This fixes false positives resulting from python/typeshed#5557,
which changed some return types to contain unions with
Anyitems.See mypy primer results in #10881 for a real-world example of this
in sphinx.