Introduce a helper function to map types to protocols + fix for dict kwargs false positive #20419
+102
−32
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This comment has been minimized.
This comment has been minimized.
randolf-scholz
commented
Dec 16, 2025
Comment on lines
+29
to
+30
| from mypy.subtypes import is_subtype | ||
| from mypy.typeops import get_all_type_vars |
Contributor
Author
There was a problem hiding this comment.
had to put these there due to circular import issues
randolf-scholz
commented
Dec 16, 2025
Comment on lines
+45
to
+47
| # need to manually include these because solve_constraints ignores them | ||
| # apparently | ||
| constraints.append(Constraint(tvar, SUBTYPE_OF, tvar.upper_bound)) |
Contributor
Author
There was a problem hiding this comment.
Is it intentional that solve_constraints ignores the upper bounds of the tvars it solves for?
Contributor
|
According to mypy_primer, this change doesn't affect type check results on a corpus of open source code. ✅ |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Fixes: #20424
Following my comments in #20416, this PR introduces a new helper function
as_typethat can be used to determine whether a type can be matched to a certain protocol or not.As an example application, I fix a bug in
is_valid_keyword_var_argthat stems from checkingkwargs <: SupportsKeyAndGetItem[str, Any]This check is too eager, because
SupportsKeyAndGetItemis invariant in the key type, it will produce a false positive whenkwargsis for instancedict[Literal["foo", "bar"], int]. The correct test is:Does there exist
T <: strso thatkwargs <: SupportsKeyAndGetItem[T, Any]which can be checked with the new helper function.
Updated tests
I updated
testLiteralKwargsto test:dictargumentMappingargumentSupportsKeyAndGetitemargument