[ty] Retain recursively-defined state in binary expressions#25277
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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 ✅ |
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thejchap
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May 23, 2026
…h#25277) ## Summary Prior to this change, a recursive implicit attribute like: ```python from __future__ import annotations from typing import Final class ScopeChain: def __init__(self, parent: ScopeChain | None = None) -> None: self.depth: Final = 1 if parent is None else parent.depth + 1 ``` ...could fail to converge during type inference. We now preserve the recursive-definition marker when literal binary operations produce a new literal result, so recursive literal unions continue through the existing widening path instead of accumulating results indefinitely. Note: in the above snippet, the bare `Final` exposes the issue because we infer the RHS to get the type, as opposed to relying on the annotation, but in theory it needn't be specific to `Final`... Codex believes this is the only way to trigger that panic as of now, though because it's the only site where we create a recursive attribute lookup _and_ retain the exact RHS literal type (e.g., the non-`Final` version, `self.depth = 1 if parent is None else parent.depth + 1`, promotes those literals). Closes astral-sh/ty#3499.
anishgirianish
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May 28, 2026
…h#25277) ## Summary Prior to this change, a recursive implicit attribute like: ```python from __future__ import annotations from typing import Final class ScopeChain: def __init__(self, parent: ScopeChain | None = None) -> None: self.depth: Final = 1 if parent is None else parent.depth + 1 ``` ...could fail to converge during type inference. We now preserve the recursive-definition marker when literal binary operations produce a new literal result, so recursive literal unions continue through the existing widening path instead of accumulating results indefinitely. Note: in the above snippet, the bare `Final` exposes the issue because we infer the RHS to get the type, as opposed to relying on the annotation, but in theory it needn't be specific to `Final`... Codex believes this is the only way to trigger that panic as of now, though because it's the only site where we create a recursive attribute lookup _and_ retain the exact RHS literal type (e.g., the non-`Final` version, `self.depth = 1 if parent is None else parent.depth + 1`, promotes those literals). Closes astral-sh/ty#3499.
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Summary
Prior to this change, a recursive implicit attribute like:
...could fail to converge during type inference. We now preserve the recursive-definition marker when literal binary operations produce a new literal result, so recursive literal unions continue through the existing widening path instead of accumulating results indefinitely.
Note: in the above snippet, the bare
Finalexposes the issue because we infer the RHS to get the type, as opposed to relying on the annotation, but in theory it needn't be specific toFinal... Codex believes this is the only way to trigger that panic as of now, though because it's the only site where we create a recursive attribute lookup and retain the exact RHS literal type (e.g., the non-Finalversion,self.depth = 1 if parent is None else parent.depth + 1, promotes those literals).Closes astral-sh/ty#3499.