Recognize plain aliases of an existing sentinel as sentinel declarations - #21972
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edgarrmondragon wants to merge 3 commits into
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Recognize plain aliases of an existing sentinel as sentinel declarations#21972edgarrmondragon wants to merge 3 commits into
edgarrmondragon wants to merge 3 commits into
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Currently `is_sentinel_declaration` only recognizes the exact `NAME = Sentinel("NAME")` call shape, so a re-export like `ALIAS = NAME` (same module or via `import mod; ALIAS = mod.NAME`) silently loses is_sentinel, and ALIAS becomes invalid in type position.
This is exactly the pattern pydantic 2.14 uses to re-export MISSING from pydantic_core: `MISSING = pydantic_core.MISSING`.
Extend is_sentinel_declaration/setup_sentinel_var to also accept a `RefExpr` rvalue (`NameExpr` or `MemberExpr`) that resolves to a Var already flagged `is_sentinel`, reusing its already-computed `LiteralType` rather than requiring a fresh `Sentinel(...)` call.
Signed-off-by: Edgar Ramírez Mondragón <edgarrm358@gmail.com>
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…signment does not result in a special form Signed-off-by: Edgar Ramírez Mondragón <edgarrm358@gmail.com>
Signed-off-by: Edgar Ramírez Mondragón <edgarrm358@gmail.com>
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According to mypy_primer, this change doesn't affect type check results on a corpus of open source code. ✅ |
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Currently
is_sentinel_declarationonly recognizes the exactNAME = Sentinel("NAME")call shape, so a re-export likeALIAS = NAME(same module or viaimport mod; ALIAS = mod.NAME) silently losesis_sentinel, andALIASbecomes invalid in type position.This is exactly the pattern pydantic 2.14 uses to re-export
MISSINGfrom pydantic_core:MISSING = pydantic_core.MISSING.Extend
is_sentinel_declaration/setup_sentinel_varto also accept aRefExprrvalue (NameExprorMemberExpr) that resolves to a Var already flaggedis_sentinel, reusing its already-computedLiteralTyperather than requiring a freshSentinel(...)call.FWIW the spec1 doesn't say anything about re-assignment, so this seems valid.
Closes #21971
Footnotes
https://typing.python.org/en/latest/spec/special-types.html#sentinels ↩