[ty] Ignore generic specialization in layout compatibility checks#25178
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Typing conformance resultsNo changes detected ✅Current numbersThe percentage of diagnostics emitted that were expected errors held steady at 89.36%. The percentage of expected errors that received a diagnostic held steady at 85.49%. The number of fully passing files held steady at 88/134. |
Memory usage reportMemory usage unchanged ✅ |
|
| Lint rule | Added | Removed | Changed |
|---|---|---|---|
invalid-argument-type |
2 | 0 | 0 |
instance-layout-conflict |
0 | 1 | 0 |
unresolved-attribute |
0 | 0 | 1 |
| Total | 2 | 1 | 1 |
Raw diff:
beartype (https://github.com/beartype/beartype)
- beartype/claw/_ast/_kind/clawastimport.py:698:40 error[unresolved-attribute] Attribute `get` is not defined on `None` in union `None | (Iota & BeartypeDecorPlaceTrieABC) | (Unknown & BeartypeDecorPlaceTrieABC)`
+ beartype/claw/_ast/_kind/clawastimport.py:698:40 error[unresolved-attribute] Attribute `get` is not defined on `None` in union `None | (dict[str, dict[str, Divergent] | None] & BeartypeDecorPlaceTrieABC) | (Iota & BeartypeDecorPlaceTrieABC) | (Unknown & BeartypeDecorPlaceTrieABC)`
core (https://github.com/home-assistant/core)
+ homeassistant/core.py:633:43 error[invalid-argument-type] Argument to bound method `HomeAssistant.async_create_task` is incorrect: Expected `Coroutine[Any, Any, _R@async_add_job]`, found `(((...) -> Coroutine[Any, Any, _R@async_add_job] | _R@async_add_job) & Coroutine[object, Never, object]) | Coroutine[Any, Any, _R@async_add_job]`
+ homeassistant/core.py:960:43 error[invalid-argument-type] Argument to bound method `HomeAssistant.async_create_task` is incorrect: Expected `Coroutine[Any, Any, _R@async_run_job]`, found `(((...) -> Coroutine[Any, Any, _R@async_run_job] | _R@async_run_job) & Coroutine[object, Never, object]) | Coroutine[Any, Any, _R@async_run_job]`
pyodide (https://github.com/pyodide/pyodide)
- src/py/pyodide/webloop.py:169:7 error[instance-layout-conflict] Class will raise `TypeError` at runtime due to incompatible bases: Bases `Task` and `PyodideFuture` cannot be combined in multiple inheritance
dcreager
approved these changes
May 18, 2026
thejchap
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to thejchap/ruff
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May 23, 2026
…tral-sh#25178) ## Summary Every time someone tries to touch this code, it gets rejected, so I don't have high hopes here. Anyway... Previously, a generic disjoint base and a subclass of that base could be marked as incompatible if the type arguments didn't line up. But at runtime, CPython's instance layout check isn't affected by type arguments. A concrete example is: ```python import asyncio class Future(asyncio.Future): ... class Task(asyncio.Task): ... class SubClass(Task, Future): ... ``` `asyncio.Task` is a subclass of `asyncio.Future`, so these bases can coexist in the same MRO. But before, we ended up doing a comparison like `Task[Unknown] <: Future[Unknown]`, which I believe ends up failing because `Unknown <: Unknown` is false under subtyping?
anishgirianish
pushed a commit
to anishgirianish/ruff
that referenced
this pull request
May 28, 2026
…tral-sh#25178) ## Summary Every time someone tries to touch this code, it gets rejected, so I don't have high hopes here. Anyway... Previously, a generic disjoint base and a subclass of that base could be marked as incompatible if the type arguments didn't line up. But at runtime, CPython's instance layout check isn't affected by type arguments. A concrete example is: ```python import asyncio class Future(asyncio.Future): ... class Task(asyncio.Task): ... class SubClass(Task, Future): ... ``` `asyncio.Task` is a subclass of `asyncio.Future`, so these bases can coexist in the same MRO. But before, we ended up doing a comparison like `Task[Unknown] <: Future[Unknown]`, which I believe ends up failing because `Unknown <: Unknown` is false under subtyping?
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Summary
Every time someone tries to touch this code, it gets rejected, so I don't have high hopes here. Anyway...
Previously, a generic disjoint base and a subclass of that base could be marked as incompatible if the type arguments didn't line up. But at runtime, CPython's instance layout check isn't affected by type arguments. A concrete example is:
asyncio.Taskis a subclass ofasyncio.Future, so these bases can coexist in the same MRO. But before, we ended up doing a comparison likeTask[Unknown] <: Future[Unknown], which I believe ends up failing becauseUnknown <: Unknownis false under subtyping?Closes astral-sh/ty#3466.