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Fix dict.get issue for typeshed update #18806

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merged 1 commit into from
Mar 16, 2025
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Fix dict.get issue for typeshed update #18806

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5 changes: 3 additions & 2 deletions mypy/partially_defined.py
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Original file line number Diff line number Diff line change
Expand Up @@ -45,7 +45,7 @@
from mypy.patterns import AsPattern, StarredPattern
from mypy.reachability import ALWAYS_TRUE, infer_pattern_value
from mypy.traverser import ExtendedTraverserVisitor
from mypy.types import Type, UninhabitedType
from mypy.types import Type, UninhabitedType, get_proper_type


class BranchState:
Expand Down Expand Up @@ -507,7 +507,8 @@ def visit_break_stmt(self, o: BreakStmt) -> None:
self.tracker.skip_branch()

def visit_expression_stmt(self, o: ExpressionStmt) -> None:
if isinstance(self.type_map.get(o.expr, None), (UninhabitedType, type(None))):
typ = self.type_map.get(o.expr)
if typ is None or isinstance(get_proper_type(typ), UninhabitedType):
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Can this be tested?

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I.e., can there be a test that would have failed without this change but now passes? It seems like that would have to require a non-"proper" type that resolves to UninhabitedType.

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Can this be tested?

Probably not. The way I understand it, UninhabitedType is a synthetic type created by mypy itself to represent a true bottom type / never. Thus I guess it won't be part of a type alias.

The mypy plugin for get_proper_type doesn't seem to take that into account. Although I'm not sure it needs to. In these cases it's just a no-op. Easier to check it's always called on unexpanded types before isinstance checks.

self.tracker.skip_branch()
super().visit_expression_stmt(o)

Expand Down