Allow typing.Mapping to form type aliases
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fangyi-zhou
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typing.Mapping to form recursive aliasestyping.Mapping to form type aliases
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stroxler
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Jan 10, 2026
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This looks good to me, but I think there's a rebase conflict preventing me from importing. Could you try rebasing on main, and ping me when you're done so I can rerun the import?
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- Add `typing.Mapping` as a special export - Recongnise that subscript in `typing.Mapping` to be a type alias This fix is targeted to the failing conformance test suite. I think we need a longer term solution since there are other related "special exports" (e.g. `collections.abc.Mapping`, `typing.MutableMapping`, `typing.Sequence`).
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Regenerated the conformance test results, should be good now @stroxler |
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Diff from mypy_primer, showing the effect of this PR on open source code: scikit-build-core (https://github.com/scikit-build/scikit-build-core)
- ERROR src/scikit_build_core/_logging.py:19:31-38: Expected a type form, got instance of `Literal['Style']` [not-a-type]
- ::error file=src/scikit_build_core/_logging.py,line=19,col=31,endLine=19,endColumn=38,title=Pyrefly not-a-type::Expected a type form, got instance of `Literal['Style']`
discord.py (https://github.com/Rapptz/discord.py)
- ERROR discord/http.py:801:44-52: Unpacked keyword argument `str` is not assignable to parameter `cookies` with type `BaseCookie[str] | Iterable[tuple[str, str | Unknown]] | Mapping[str, str | Unknown] | None` in function `aiohttp.client.ClientSession.get` [bad-argument-type]
+ ERROR discord/http.py:801:44-52: Unpacked keyword argument `str` is not assignable to parameter `cookies` with type `BaseCookie[str] | Iterable[tuple[str, str | Unknown]] | Mapping[str, BaseCookie[str] | Morsel[Any] | str] | None` in function `aiohttp.client.ClientSession.get` [bad-argument-type]
- ::error file=discord/http.py,line=801,col=44,endLine=801,endColumn=52,title=Pyrefly bad-argument-type::Unpacked keyword argument `str` is not assignable to parameter `cookies` with type `BaseCookie[str] | Iterable[tuple[str, str | Unknown]] | Mapping[str, str | Unknown] | None` in function `aiohttp.client.ClientSession.get`
+ ::error file=discord/http.py,line=801,col=44,endLine=801,endColumn=52,title=Pyrefly bad-argument-type::Unpacked keyword argument `str` is not assignable to parameter `cookies` with type `BaseCookie[str] | Iterable[tuple[str, str | Unknown]] | Mapping[str, BaseCookie[str] | Morsel[Any] | str] | None` in function `aiohttp.client.ClientSession.get`
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yangdanny97
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Jan 13, 2026
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Summary
typing.Mappingas a special exporttyping.Mappingto be a type aliasThis fix is targeted to the failing conformance test suite (although I guess recursive aliases are still not working since recursive types are not supported afaik). Nonetheless, I think we need a longer term solution since there are other related "special exports" (e.g.
collections.abc.Mapping,typing.MutableMapping,typing.Sequence).Test Plan
python test.py