Skip to content

Fix dict.get issue for typeshed update #18806

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
hauntsaninja merged 1 commit into from
Mar 16, 2025
Merged

Fix dict.get issue for typeshed update #18806

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
5 changes: 3 additions & 2 deletions mypy/partially_defined.py
View file
Open in desktop
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):

@JelleZijlstra JelleZijlstra Mar 16, 2025

Copy link
Copy Markdown
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Can this be tested?

@JelleZijlstra JelleZijlstra Mar 16, 2025

Copy link
Copy Markdown
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

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.

@cdce8p cdce8p Mar 16, 2025

Copy link
Copy Markdown
Collaborator Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

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