Rework Match.group handling #5557
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Standardize group(), groups(), groupdict(), and __getattr__() to return Any instead of AnyStr. Also special case group(0) and __getattr__(0) to always return AnyStr. Use PEP 604 for unions in changed lines.
Akuli
reviewed
May 30, 2021
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I'm arfaid this will cause dead code warnings in mypy, if you do something like this: Having type checkers say "this is a string" has caused confusion before. See #5269 (comment) for example. |
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Maybe we should just use |
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Seems like it would also be better for mypyc (it's just one tool that uses typeshed, but an important tool): #5269 (comment) |
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Akuli
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May 30, 2021
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1 similar comment
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Diff from mypy_primer, showing the effect of this PR on open source code: sphinx (https://github.com/sphinx-doc/sphinx.git)
+ sphinx/ext/autodoc/__init__.py: note: In member "parse_name" of class "Documenter":
+ sphinx/ext/autodoc/__init__.py:405:23: error: Need type annotation for "parents"
pydantic (https://github.com/samuelcolvin/pydantic.git)
+ pydantic/networks.py:267: error: Item "None" of "Optional[Match[str]]" has no attribute "group" [union-attr]
werkzeug (https://github.com/pallets/werkzeug.git)
+ src/werkzeug/http.py:456: error: Unsupported operand types for + ("str" and "None")
+ src/werkzeug/http.py:456: note: Right operand is of type "Optional[str]"
+ src/werkzeug/http.py:458: error: Incompatible types in assignment (expression has type "Optional[str]", target has type "str")
aiohttp (https://github.com/aio-libs/aiohttp.git)
+ aiohttp/client_reqrep.py:809: error: unused "type: ignore" comment
+ aiohttp/client_reqrep.py:813: error: Argument 1 to "add" of "MultiDict" has incompatible type "Union[str, Any, URL]"; expected "Union[str, istr]" [arg-type]
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The primer output looks tolerable in my opinion, but we should wait to merge this to after the next mypy release, though, to minimize disruption. |
Akuli
added
the
status: deferred
srittau
removed
the
status: deferred
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Now that mypy has released, I'd consider this ready for merge. |
This was referenced Jun 8, 2021
JukkaL
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Jul 28, 2021
When trying to match `list[T]` and `list[str] | Any`, previously we gave up, because the union items caused conflicting inferred values for `T` (`str` and `Any`). Work around the issue by dropping `Any` constraints if there are multiple sets of contraints, since we prefer more precise types. This fixes false positives resulting from python/typeshed#5557, which changed some return types to contain unions with `Any` items. See mypy primer results in #10881 for a real-world example of this in sphinx.
JukkaL
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Jul 28, 2021
) When trying to match `list[T]` and `list[str] | Any`, previously we gave up, because the union items caused conflicting inferred values for `T` (`str` and `Any`). Work around the issue by dropping `Any` constraints if there are multiple sets of contraints, since we prefer more precise types. This fixes false positives resulting from python/typeshed#5557, which changed some return types to contain unions with `Any` items. See mypy primer results in #10881 for a real-world example of this in sphinx.
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Standardize
group(),groups(),groupdict(), and__getattr__()to returnAnyStr | Anyinstead ofAnyStr. Also special casegroup(0)and__getattr__(0)to always returnAnyStr. Correctly handle defaults. Use PEP 604 for unions in changed lines.Edited to include changes after review below.
Fixes #3902