[ty] Use the top materialization of classes for if type(x) is y narrowing#22553
Merged
AlexWaygood merged 2 commits intomainfrom Jan 13, 2026
Merged
[ty] Use the top materialization of classes for if type(x) is y narrowing#22553AlexWaygood merged 2 commits intomainfrom
if type(x) is y narrowing#22553AlexWaygood merged 2 commits intomainfrom
Conversation
AlexWaygood
requested review from
carljm,
dcreager and
sharkdp
as code owners
AlexWaygood
added
bug
Diagnostic diff on typing conformance testsNo changes detected when running ty on typing conformance tests ✅ |
|
AlexWaygood
force-pushed
the
alex/type-narrow-top-materialize
branch
from
d06805b to
bdbb990
Compare
|
| Lint rule | Added | Removed | Changed |
|---|---|---|---|
invalid-assignment |
5 | 0 | 5 |
invalid-return-type |
1 | 0 | 7 |
invalid-argument-type |
2 | 2 | 3 |
possibly-unresolved-reference |
6 | 0 | 0 |
unused-ignore-comment |
2 | 3 | 0 |
possibly-missing-attribute |
0 | 3 | 1 |
invalid-await |
0 | 2 | 0 |
unresolved-attribute |
0 | 0 | 2 |
redundant-cast |
1 | 0 | 0 |
unsupported-operator |
1 | 0 | 0 |
| Total | 18 | 10 | 18 |
Member
Author
|
Okay, so the first homeassistant hit looks like this: def get_events_json(self):
"""Return a batch of events formatted for writing."""
queue_seconds = QUEUE_BACKLOG_SECONDS + self.max_tries * RETRY_DELAY
count = 0
json = []
dropped = 0
with suppress(queue.Empty):
while len(json) < BATCH_BUFFER_SIZE and not self.shutdown:
timeout = None if count == 0 else self.batch_timeout()
item = self.queue.get(timeout=timeout)
count += 1
if item is None:
self.shutdown = True
elif type(item) is tuple:
timestamp, event = item
age = time.monotonic() - timestampand we're now emitting a diagnostic on the last line where we didn't before. Adding some reveal_type calls in there shows this with the Screenshot
and this on my PR branch: Screenshot
So this is basically a textbook case of astral-sh/ty#1578. This PR makes our I'm guessing the other new ecosystem diagnostics are like this too. I still think the answer here is probably better explanatory diagnostics that tell the user why we've unexpectedly inferred |
carljm
approved these changes
Jan 13, 2026
| place, | ||
| NarrowingConstraint::regular( | ||
| Type::instance(self.db, rhs_class.unknown_specialization(self.db)) | ||
| Type::instance(self.db, rhs_class.top_materialization(self.db)) |
Contributor
There was a problem hiding this comment.
So hard to review these massive diffs...
AlexWaygood
added a commit
that referenced
this pull request
Jan 14, 2026
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
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
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.
Summary
This is consistent with our
isinstance()/issubclass()narrowing, fixes some open TODOs in our mdtests, and leads to clearly better results.Test Plan
Added mdtests that fail on
main, and updated existing mdtests that had TODOs.