improved narrowing of generics #745

DetachHead · 2024-10-06T09:11:51Z

use a generic's bound when narrowing with isinstance if it's covariant, Never if it's contravariant
creates a union of all possible combinations if it has constraints

fixes #674

packages/pyright-internal/src/tests/samples/typeNarrowingIsinstance6.py

beauxq · 2024-11-06T14:47:20Z

Thanks for working on this. I tried working on it for a while, but I got stuck on trying to understand the code.
I think this would be one of the most valuable features of basedpyright.

DetachHead · 2024-11-06T21:49:13Z

i ran into a difficult to solve edge case that led to me abandoning this change for now (see the failing test case) but i may give it another go in the future

packages/pyright-internal/src/analyzer/typeUtils.ts

beauxq · 2024-11-17T17:13:40Z

#885

You should pull from main here before looking at the diff there.

DetachHead · 2024-11-18T13:00:19Z

the primer identified this issue with constrained typevars:

from typing import Literal


class Foo[T: (int, str)]:
    ...

def asdf(value: object):
    if isinstance(value, Foo):
        reveal_type(value) # `Foo[object]`, should be `Foo[int] | Foo[str]`

…ant, or `Never` if it's contravariant

…`/Unknown

…hether to use variance to specialize type vars when narrowing

docs/configuration.md

…by the primer

…ew functionality

… ages to build

…en the value being narrowed is a union

… options

beauxq

I looked over all the code. Didn't see any problems.

docs/configuration.md

github-actions · 2024-11-23T02:48:32Z

Diff from mypy_primer, showing the effect of this PR on open source code:

more-itertools (https://github.com/more-itertools/more-itertools)
-   /tmp/mypy_primer/projects/more-itertools/more_itertools/more.py:224:5 - warning: Return type is unknown (reportUnknownParameterType)
+   /tmp/mypy_primer/projects/more-itertools/more_itertools/more.py:224:5 - warning: Return type, "object | Unknown", is partially unknown (reportUnknownParameterType)
-   /tmp/mypy_primer/projects/more-itertools/more_itertools/more.py:238:20 - warning: Return type is unknown (reportUnknownVariableType)
-   /tmp/mypy_primer/projects/more-itertools/more_itertools/more.py:253:5 - warning: Return type is unknown (reportUnknownParameterType)
+   /tmp/mypy_primer/projects/more-itertools/more_itertools/more.py:253:5 - warning: Return type, "object | Unknown", is partially unknown (reportUnknownParameterType)
-   /tmp/mypy_primer/projects/more-itertools/more_itertools/more.py:267:12 - warning: Return type is unknown (reportUnknownVariableType)
+   /tmp/mypy_primer/projects/more-itertools/more_itertools/more.py:267:12 - warning: Return type, "object | Unknown", is partially unknown (reportUnknownVariableType)
-   /tmp/mypy_primer/projects/more-itertools/more_itertools/more.py:2217:34 - warning: Type of "step" is unknown (reportUnknownMemberType)
-   /tmp/mypy_primer/projects/more-itertools/more_itertools/more.py:2217:56 - warning: Type of "step" is unknown (reportUnknownMemberType)
+   /tmp/mypy_primer/projects/more-itertools/more_itertools/more.py:2219:37 - error: Operator "<=" not supported for types "object" and "int" (reportOperatorIssue)
-   /tmp/mypy_primer/projects/more-itertools/more_itertools/more.py:2219:16 - warning: Type of "start" is unknown (reportUnknownMemberType)
-   /tmp/mypy_primer/projects/more-itertools/more_itertools/more.py:2219:37 - warning: Type of "start" is unknown (reportUnknownMemberType)
-   /tmp/mypy_primer/projects/more-itertools/more_itertools/more.py:2221:18 - warning: Type of "start" is unknown (reportUnknownMemberType)
+   /tmp/mypy_primer/projects/more-itertools/more_itertools/more.py:2221:18 - error: Operator ">=" not supported for types "object" and "int" (reportOperatorIssue)
-   /tmp/mypy_primer/projects/more-itertools/more_itertools/more.py:2224:17 - warning: Type of "start" is unknown (reportUnknownVariableType)
+   /tmp/mypy_primer/projects/more-itertools/more_itertools/more.py:2224:17 - warning: Type of "start" is partially unknown
+     Type of "start" is "Unknown | Any" (reportUnknownVariableType)
+   /tmp/mypy_primer/projects/more-itertools/more_itertools/more.py:2226:36 - error: Operator ">=" not supported for types "object" and "int" (reportOperatorIssue)
-   /tmp/mypy_primer/projects/more-itertools/more_itertools/more.py:2224:44 - warning: Type of "start" is unknown (reportUnknownMemberType)
-   /tmp/mypy_primer/projects/more-itertools/more_itertools/more.py:2224:44 - warning: Argument type is unknown
-     Argument corresponds to parameter "i" in function "_get_by_index" (reportUnknownArgumentType)
-   /tmp/mypy_primer/projects/more-itertools/more_itertools/more.py:2226:16 - warning: Type of "stop" is unknown (reportUnknownMemberType)
-   /tmp/mypy_primer/projects/more-itertools/more_itertools/more.py:2226:36 - warning: Type of "stop" is unknown (reportUnknownMemberType)
-   /tmp/mypy_primer/projects/more-itertools/more_itertools/more.py:2228:18 - warning: Type of "stop" is unknown (reportUnknownMemberType)
+   /tmp/mypy_primer/projects/more-itertools/more_itertools/more.py:2228:18 - error: Operator "<=" not supported for types "object" and "int" (reportOperatorIssue)
-   /tmp/mypy_primer/projects/more-itertools/more_itertools/more.py:2231:17 - warning: Type of "stop" is unknown (reportUnknownVariableType)
+   /tmp/mypy_primer/projects/more-itertools/more_itertools/more.py:2231:17 - warning: Type of "stop" is partially unknown
+     Type of "stop" is "Unknown | Any" (reportUnknownVariableType)
-   /tmp/mypy_primer/projects/more-itertools/more_itertools/more.py:2231:43 - warning: Type of "stop" is unknown (reportUnknownMemberType)
-   /tmp/mypy_primer/projects/more-itertools/more_itertools/more.py:2231:43 - warning: Argument type is unknown
-     Argument corresponds to parameter "i" in function "_get_by_index" (reportUnknownArgumentType)
-   /tmp/mypy_primer/projects/more-itertools/more_itertools/more.py:2773:9 - warning: Type of "_target" is partially unknown
-     Type of "_target" is "Sequence[Unknown]" (reportUnknownMemberType)
-   /tmp/mypy_primer/projects/more-itertools/more_itertools/more.py:2775:9 - warning: Return type is unknown (reportUnknownParameterType)
+   /tmp/mypy_primer/projects/more-itertools/more_itertools/more.py:2775:9 - error: Method "__getitem__" overrides class "Sequence" in an incompatible manner
+     Return type mismatch: base method returns type "Sequence[Unknown]", override returns type "object"
+       "object" is not assignable to "Sequence[Unknown]" (reportIncompatibleMethodOverride)
-   /tmp/mypy_primer/projects/more-itertools/more_itertools/more.py:2776:16 - warning: Type of "_target" is partially unknown
-     Type of "_target" is "Sequence[Unknown]" (reportUnknownMemberType)
-   /tmp/mypy_primer/projects/more-itertools/more_itertools/more.py:2776:16 - warning: Return type is unknown (reportUnknownVariableType)
-   /tmp/mypy_primer/projects/more-itertools/more_itertools/more.py:2779:20 - warning: Type of "_target" is partially unknown
-     Type of "_target" is "Sequence[Unknown]" (reportUnknownMemberType)
-   /tmp/mypy_primer/projects/more-itertools/more_itertools/more.py:2779:20 - warning: Argument type is partially unknown
-     Argument corresponds to parameter "obj" in function "len"
-     Argument type is "Sequence[Unknown]" (reportUnknownArgumentType)
-   /tmp/mypy_primer/projects/more-itertools/more_itertools/more.py:2782:62 - warning: Type of "_target" is partially unknown
-     Type of "_target" is "Sequence[Unknown]" (reportUnknownMemberType)
-   /tmp/mypy_primer/projects/more-itertools/more_itertools/more.py:2782:62 - warning: Argument type is partially unknown
-     Argument corresponds to parameter "obj" in function "repr"
-     Argument type is "Sequence[Unknown]" (reportUnknownArgumentType)
+   /tmp/mypy_primer/projects/more-itertools/more_itertools/more.py:4251:12 - error: "object" is not iterable
+     "__iter__" method not defined (reportGeneralTypeIssues)
- 24 errors, 2742 warnings, 0 notes
+ 30 errors, 2721 warnings, 0 notes

starlette (https://github.com/encode/starlette)
-     Type of "exceptions" is "tuple[Unknown | BaseExceptionGroup[Unknown], ...]" (reportUnknownMemberType)
+     Type of "exceptions" is "tuple[Unknown | BaseExceptionGroup[Unknown], ...] | tuple[BaseException | BaseExceptionGroup[BaseException], ...]" (reportUnknownMemberType)
-     Argument type is "tuple[Unknown | BaseExceptionGroup[Unknown], ...]" (reportUnknownArgumentType)
+     Argument type is "tuple[Unknown | BaseExceptionGroup[Unknown], ...] | tuple[BaseException | BaseExceptionGroup[BaseException], ...]" (reportUnknownArgumentType)
-     Type of "exc" is "Unknown | BaseExceptionGroup[Unknown]" (reportUnknownVariableType)
+     Type of "exc" is "Unknown | BaseExceptionGroup[Unknown] | BaseException | BaseExceptionGroup[BaseException]" (reportUnknownVariableType)
-     Type of "exceptions" is "tuple[Unknown | BaseExceptionGroup[Unknown]]" (reportUnknownMemberType)
+     Type of "exceptions" is "tuple[Unknown | BaseExceptionGroup[Unknown]] | tuple[BaseException | BaseExceptionGroup[BaseException]]" (reportUnknownMemberType)
+   /tmp/mypy_primer/projects/starlette/starlette/testclient.py:336:39 - error: Argument of type "None" cannot be assigned to parameter "arg" of type "Never" in function "send"
+     Type "None" is not assignable to type "Never" (reportArgumentType)
-   /tmp/mypy_primer/projects/starlette/starlette/testclient.py:336:21 - warning: Type of "chunk" is unknown (reportUnknownVariableType)
-   /tmp/mypy_primer/projects/starlette/starlette/testclient.py:336:29 - warning: Type of "send" is partially unknown
-     Type of "send" is "(arg: Unknown, /) -> Unknown" (reportUnknownMemberType)
- 206 errors, 4252 warnings, 0 notes
+ 207 errors, 4250 warnings, 0 notes

pytest (https://github.com/pytest-dev/pytest)
-   /tmp/mypy_primer/projects/pytest/src/_pytest/python.py:978:34 - warning: Type of "pattern" is unknown (reportUnknownMemberType)
-   /tmp/mypy_primer/projects/pytest/src/_pytest/python.py:978:34 - warning: Argument type is unknown
-     Argument corresponds to parameter "val" in function "ascii_escaped" (reportUnknownArgumentType)
-   /tmp/mypy_primer/projects/pytest/src/_pytest/reports.py:205:50 - warning: Argument type is partially unknown
-     Argument corresponds to parameter "obj" in function "len"
-     Argument type is "Sequence[Unknown]" (reportUnknownArgumentType)
-   /tmp/mypy_primer/projects/pytest/src/_pytest/reports.py:206:13 - warning: Type of "word" is unknown (reportUnknownVariableType)
-   /tmp/mypy_primer/projects/pytest/src/_pytest/reports.py:206:19 - warning: Type of "markup" is unknown (reportUnknownVariableType)
-   /tmp/mypy_primer/projects/pytest/src/_pytest/reports.py:208:24 - warning: Return type, "tuple[str, Mapping[Unknown, Unknown]]", is partially unknown (reportUnknownVariableType)
+   /tmp/mypy_primer/projects/pytest/src/_pytest/reports.py:208:24 - warning: Return type, "tuple[str, Mapping[Unknown, object]]", is partially unknown (reportUnknownVariableType)
+   /tmp/mypy_primer/projects/pytest/src/_pytest/reports.py:208:30 - error: Type "tuple[str, Mapping[Unknown, object]]" is not assignable to return type "tuple[str, Mapping[str, bool]]"
+     "Mapping[Unknown, object]" is not assignable to "Mapping[str, bool]"
+       Type parameter "_VT_co@Mapping" is covariant, but "object" is not a subtype of "bool"
+         "object" is not assignable to "bool" (reportReturnType)
-     Argument type is "Mapping[Unknown, Unknown]" (reportUnknownArgumentType)
+     Argument type is "Mapping[Unknown, object]" (reportUnknownArgumentType)
-   /tmp/mypy_primer/projects/pytest/src/_pytest/_code/code.py:789:37 - warning: Type of "value" is partially unknown
-     Type of "value" is "BaseExceptionGroup[Unknown]*" (reportUnknownMemberType)
-   /tmp/mypy_primer/projects/pytest/src/_pytest/_code/code.py:789:37 - warning: Argument type is partially unknown
-     Argument corresponds to parameter "exc_group" in function "_group_contains"
-     Argument type is "BaseExceptionGroup[Unknown]*" (reportUnknownArgumentType)
-   /tmp/mypy_primer/projects/pytest/src/_pytest/config/__init__.py:1673:40 - warning: Argument type is partially unknown
-     Argument corresponds to parameter "args" in function "__init__"
-     Argument type is "PathLike[Unknown]" (reportUnknownArgumentType)
+   /tmp/mypy_primer/projects/pytest/src/_pytest/config/__init__.py:1673:40 - error: Argument of type "PathLike[str] | PathLike[bytes]" cannot be assigned to parameter "args" of type "StrPath" in function "__new__"
+     Type "PathLike[str] | PathLike[bytes]" is not assignable to type "StrPath"
+       Type "PathLike[bytes]" is not assignable to type "StrPath"
+         "PathLike[bytes]" is not assignable to "str"
+         "PathLike[bytes]" is not assignable to "PathLike[str]"
+           Type parameter "AnyStr_co@PathLike" is covariant, but "bytes" is not a subtype of "str"
+             "bytes" is not assignable to "str" (reportArgumentType)
+   /tmp/mypy_primer/projects/pytest/src/_pytest/config/__init__.py:1673:40 - error: Argument of type "PathLike[str] | PathLike[bytes]" cannot be assigned to parameter "args" of type "StrPath" in function "__init__"
+     Type "PathLike[str] | PathLike[bytes]" is not assignable to type "StrPath"
+       Type "PathLike[bytes]" is not assignable to type "StrPath"
+         "PathLike[bytes]" is not assignable to "str"
+         "PathLike[bytes]" is not assignable to "PathLike[str]"
+           Type parameter "AnyStr_co@PathLike" is covariant, but "bytes" is not a subtype of "str"
+             "bytes" is not assignable to "str" (reportArgumentType)
- 1162 errors, 17372 warnings, 0 notes
+ 1165 errors, 17364 warnings, 0 notes

mkosi (https://github.com/systemd/mkosi)
-   /tmp/mypy_primer/projects/mkosi/mkosi/config.py:4924:20 - warning: Return type is unknown (reportUnknownVariableType)
-   /tmp/mypy_primer/projects/mkosi/mkosi/config.py:4924:30 - warning: Argument type is partially unknown
-     Argument corresponds to parameter "path" in function "fspath"
-     Argument type is "PathLike[Unknown]" (reportUnknownArgumentType)
- 25 errors, 1559 warnings, 0 notes
+ 25 errors, 1557 warnings, 0 notes

openlibrary (https://github.com/internetarchive/openlibrary)
-   /tmp/mypy_primer/projects/openlibrary/openlibrary/catalog/marc/tests/test_parse.py:119:28 - error: Argument of type "Iterable[Unknown]" cannot be assigned to parameter "obj" of type "Sized" in function "len"
+   /tmp/mypy_primer/projects/openlibrary/openlibrary/catalog/marc/tests/test_parse.py:119:28 - error: Argument of type "Iterable[object]" cannot be assigned to parameter "obj" of type "Sized" in function "len"
-     "Iterable[Unknown]" is incompatible with protocol "Sized"
+     "Iterable[object]" is incompatible with protocol "Sized"
-   /tmp/mypy_primer/projects/openlibrary/openlibrary/catalog/marc/tests/test_parse.py:148:28 - error: Argument of type "Iterable[Unknown]" cannot be assigned to parameter "obj" of type "Sized" in function "len"
+   /tmp/mypy_primer/projects/openlibrary/openlibrary/catalog/marc/tests/test_parse.py:148:28 - error: Argument of type "Iterable[object]" cannot be assigned to parameter "obj" of type "Sized" in function "len"
-     "Iterable[Unknown]" is incompatible with protocol "Sized"
+     "Iterable[object]" is incompatible with protocol "Sized"
-     Argument type is "set[Unknown]" (reportUnknownArgumentType)
+     Argument type is "set[Unknown] | set[object]" (reportUnknownArgumentType)
-   /tmp/mypy_primer/projects/openlibrary/openlibrary/solr/updater/abstract.py:53:68 - warning: Argument type is partially unknown
-     Argument corresponds to parameter "o" in function "__init__"
-     Argument type is "Any | Iterable[Unknown]" (reportUnknownArgumentType)
- 1920 errors, 33718 warnings, 0 notes
+ 1920 errors, 33717 warnings, 0 notes

yarl (https://github.com/aio-libs/yarl)
-   /tmp/mypy_primer/projects/yarl/yarl/_url.py:1232:14 - warning: Unnecessary isinstance call; "Never" is always an instance of "Sequence[Unknown]" (reportUnnecessaryIsInstance)
+   /tmp/mypy_primer/projects/yarl/yarl/_url.py:1232:14 - warning: Unnecessary isinstance call; "Never" is always an instance of "Sequence[object]" (reportUnnecessaryIsInstance)

ibis (https://github.com/ibis-project/ibis)
-   /tmp/mypy_primer/projects/ibis/ibis/util.py:650:13 - warning: Type of "hashable_obj" is partially unknown
-     Type of "hashable_obj" is "tuple[Unknown, ...]*" (reportUnknownVariableType)
-   /tmp/mypy_primer/projects/ibis/ibis/util.py:650:34 - warning: Argument type is partially unknown
-     Argument corresponds to parameter "iterable" in function "__new__"
-     Argument type is "Sequence[Unknown]*" (reportUnknownArgumentType)
-     Type of "hashable_obj" is "tuple[tuple[Unknown, Unknown], ...]" (reportUnknownVariableType)
+     Type of "hashable_obj" is "tuple[tuple[Unknown, object], ...]" (reportUnknownVariableType)
-     Argument type is "ItemsView[Unknown, Unknown]" (reportUnknownArgumentType)
+     Argument type is "ItemsView[Unknown, object]" (reportUnknownArgumentType)
-   /tmp/mypy_primer/projects/ibis/ibis/util.py:654:13 - warning: Type of "hashable_obj" is partially unknown
-     Type of "hashable_obj" is "frozenset[Unknown]*" (reportUnknownVariableType)
-   /tmp/mypy_primer/projects/ibis/ibis/util.py:654:38 - warning: Argument type is partially unknown
-     Argument corresponds to parameter "iterable" in function "__new__"
-     Argument type is "AbstractSet[Unknown]*" (reportUnknownArgumentType)
-     Argument type is "tuple[type[Sequence[Unknown]]* | type[Mapping[Unknown, Unknown]]* | type[AbstractSet[Unknown]]* | type[object]*, tuple[Unknown, ...]* | tuple[tuple[Unknown, Unknown], ...] | frozenset[Unknown]* | int*]" (reportUnknownArgumentType)
+     Argument type is "tuple[type[Sequence[object]]* | type[Mapping[Unknown, object]]* | type[AbstractSet[object]]* | type[object]*, tuple[object, ...]* | tuple[tuple[Unknown, object], ...] | frozenset[object]* | int*]" (reportUnknownArgumentType)
-     Argument type is "Sequence[Unknown]* | Mapping[Unknown, Unknown]* | AbstractSet[Unknown]* | object*" (reportUnknownArgumentType)
+     Argument type is "Sequence[object]* | Mapping[Unknown, object]* | AbstractSet[object]* | object*" (reportUnknownArgumentType)
-   /tmp/mypy_primer/projects/ibis/ibis/backends/polars/__init__.py:443:9 - warning: Return type, "tuple[type[Value[Unknown, Unknown]], ...]", is partially unknown (reportUnknownParameterType)
-   /tmp/mypy_primer/projects/ibis/ibis/backends/polars/__init__.py:444:16 - warning: Return type, "tuple[type[Value[Unknown, Unknown]], ...]", is partially unknown (reportUnknownVariableType)
-   /tmp/mypy_primer/projects/ibis/ibis/backends/polars/__init__.py:444:22 - warning: Argument type is partially unknown
-     Argument corresponds to parameter "iterable" in function "__new__"
-     Argument type is "Generator[type[Value[Unknown, Unknown]], None, None]" (reportUnknownArgumentType)
-   /tmp/mypy_primer/projects/ibis/ibis/backends/polars/__init__.py:455:9 - warning: Type of "op_classes" is partially unknown
-     Type of "op_classes" is "tuple[type[Value[Unknown, Unknown]], ...]" (reportUnknownVariableType)
-   /tmp/mypy_primer/projects/ibis/ibis/backends/polars/__init__.py:455:22 - warning: Type of "_get_operations" is partially unknown
-     Type of "_get_operations" is "_lru_cache_wrapper[tuple[type[Value[Unknown, Unknown]], ...]]" (reportUnknownMemberType)
-   /tmp/mypy_primer/projects/ibis/ibis/backends/polars/compiler.py:379:13 - warning: Type of "repl" is partially unknown
-     Type of "repl" is "Unknown | None" (reportUnknownVariableType)
-     Type of "get" is "Overload[(key: Unknown, /) -> (Unknown | None), (key: Unknown, /, default: Unknown | _T@get) -> (Unknown | _T@get)]" (reportUnknownMemberType)
+     Type of "get" is "Overload[(key: Unknown, /) -> (object | None), (key: Unknown, /, default: object | _T@get) -> (object | _T@get)]" (reportUnknownMemberType)
+   /tmp/mypy_primer/projects/ibis/ibis/backends/polars/compiler.py:381:29 - error: Cannot access attribute "value" for class "object"
+     Attribute "value" is unknown (reportAttributeAccessIssue)
-   /tmp/mypy_primer/projects/ibis/ibis/backends/polars/compiler.py:891:8 - warning: Type of "dtype" is unknown (reportUnknownMemberType)
+   /tmp/mypy_primer/projects/ibis/ibis/backends/polars/compiler.py:891:17 - error: Cannot access attribute "unit" for class "DataType"
+     Attribute "unit" is unknown (reportAttributeAccessIssue)
-   /tmp/mypy_primer/projects/ibis/ibis/backends/polars/compiler.py:894:18 - warning: Type of "dtype" is unknown (reportUnknownMemberType)
+   /tmp/mypy_primer/projects/ibis/ibis/backends/polars/compiler.py:894:27 - error: Cannot access attribute "unit" for class "DataType"
+     Attribute "unit" is unknown (reportAttributeAccessIssue)
-   /tmp/mypy_primer/projects/ibis/ibis/backends/polars/compiler.py:1391:12 - warning: Type of "step" is partially unknown
-     Type of "step" is "Literal[Unknown]" (reportUnknownMemberType)
-   /tmp/mypy_primer/projects/ibis/ibis/backends/polars/compiler.py:1410:12 - warning: Type of "step" is partially unknown
-     Type of "step" is "Literal[Unknown]" (reportUnknownMemberType)
-   /tmp/mypy_primer/projects/ibis/ibis/backends/polars/compiler.py:1411:12 - warning: Type of "step" is partially unknown
-     Type of "step" is "Literal[Unknown]" (reportUnknownMemberType)
-   /tmp/mypy_primer/projects/ibis/ibis/backends/polars/compiler.py:1411:12 - warning: Type of "dtype" is unknown (reportUnknownMemberType)
+   /tmp/mypy_primer/projects/ibis/ibis/backends/polars/compiler.py:1411:26 - error: Cannot access attribute "unit" for class "DataType"
+     Attribute "unit" is unknown (reportAttributeAccessIssue)
-     Type of "mapping" is "Mapping[Unknown, Unknown]" (reportUnknownVariableType)
+     Type of "mapping" is "Mapping[Unknown, object]" (reportUnknownVariableType)
-     Type of "replacements" is "Mapping[Unknown, Unknown]" (reportUnknownMemberType)
+     Type of "replacements" is "Mapping[Unknown, object]" (reportUnknownMemberType)
-     Type of "value" is "Unknown | None" (reportUnknownVariableType)
+     Type of "value" is "Unknown | object | None" (reportUnknownVariableType)
-     Type of "get" is "Overload[(key: Unknown, /) -> (Unknown | None), (key: Unknown, /, default: Unknown | _T@get) -> (Unknown | _T@get)] | Overload[(key: Unknown, /) -> (Unknown | None), (key: Unknown, default: Unknown, /) -> Unknown, (key: Unknown, default: _T@get, /) -> (Unknown | _T@get)]" (reportUnknownMemberType)
+     Type of "get" is "Overload[(key: Unknown, /) -> (object | None), (key: Unknown, /, default: object | _T@get) -> (object | _T@get)] | Overload[(key: Unknown, /) -> (Unknown | None), (key: Unknown, default: Unknown, /) -> Unknown, (key: Unknown, default: _T@get, /) -> (Unknown | _T@get)]" (reportUnknownMemberType)
+   /tmp/mypy_primer/projects/ibis/ibis/backends/sql/rewrites.py:168:38 - error: Argument of type "tuple[Field, Unknown | object]" cannot be assigned to parameter "arg" of type "VarTuple[Value[Unknown, Any]]" in function "__init__"
+     Type "Unknown | object" is not assignable to type "Value[Unknown, Any]"
+       "object" is not assignable to "Value[Unknown, Any]" (reportArgumentType)
-   /tmp/mypy_primer/projects/ibis/ibis/backends/sql/rewrites.py:481:27 - warning: Type of "nth" is partially unknown
-     Type of "nth" is "Literal[Unknown]" (reportUnknownMemberType)
-   /tmp/mypy_primer/projects/ibis/ibis/backends/sql/rewrites.py:481:50 - warning: Type of "nth" is partially unknown
-     Type of "nth" is "Literal[Unknown]" (reportUnknownMemberType)
-   /tmp/mypy_primer/projects/ibis/ibis/backends/sql/rewrites.py:481:50 - warning: Type of "dtype" is unknown (reportUnknownMemberType)
-   /tmp/mypy_primer/projects/ibis/ibis/backends/sql/rewrites.py:481:50 - warning: Argument type is unknown
-     Argument corresponds to parameter "dtype" in function "__init__" (reportUnknownArgumentType)
-   /tmp/mypy_primer/projects/ibis/ibis/backends/sql/compilers/base.py:1000:61 - warning: Type of "length" is partially unknown
-     Type of "length" is "Literal[Unknown]" (reportUnknownMemberType)
-   /tmp/mypy_primer/projects/ibis/ibis/backends/sql/compilers/clickhouse.py:707:22 - warning: Type of "step" is partially unknown
-     Type of "step" is "Literal[Unknown]" (reportUnknownMemberType)
-   /tmp/mypy_primer/projects/ibis/ibis/backends/sql/compilers/duckdb.py:188:21 - warning: Type of "start" is partially unknown
-     Type of "start" is "Literal[Unknown]" (reportUnknownMemberType)
-   /tmp/mypy_primer/projects/ibis/ibis/backends/sql/compilers/duckdb.py:196:24 - warning: Type of "stop" is partially unknown
-     Type of "stop" is "Literal[Unknown]" (reportUnknownMemberType)
-   /tmp/mypy_primer/projects/ibis/ibis/backends/sql/compilers/flink.py:342:9 - warning: Type of "idx" is partially unknown
-     Type of "idx" is "Literal[Unknown]" (reportUnknownVariableType)
-   /tmp/mypy_primer/projects/ibis/ibis/backends/sql/compilers/flink.py:342:15 - warning: Type of "index" is partially unknown
-     Type of "index" is "Literal[Unknown]" (reportUnknownMemberType)
-   /tmp/mypy_primer/projects/ibis/ibis/backends/sql/compilers/flink.py:344:12 - warning: Type of "dtype" is unknown (reportUnknownMemberType)
-   /tmp/mypy_primer/projects/ibis/ibis/backends/sql/compilers/flink.py:344:12 - warning: Type of "is_integer" is unknown (reportUnknownMemberType)
-   /tmp/mypy_primer/projects/ibis/ibis/backends/sql/compilers/flink.py:347:20 - warning: Type of "dtype" is unknown (reportUnknownMemberType)
-   /tmp/mypy_primer/projects/ibis/ibis/backends/sql/compilers/flink.py:347:20 - warning: Type of "is_string" is unknown (reportUnknownMemberType)
-   /tmp/mypy_primer/projects/ibis/ibis/backends/sql/compilers/flink.py:347:43 - warning: Type of "dtype" is unknown (reportUnknownMemberType)
-   /tmp/mypy_primer/projects/ibis/ibis/backends/sql/compilers/impala.py:240:13 - warning: Type of "format_str" is partially unknown
-     Type of "format_str" is "Literal[Unknown]" (reportUnknownMemberType)

... (truncated 133 lines) ...

sympy (https://github.com/sympy/sympy)
-   /tmp/mypy_primer/projects/sympy/sympy/combinatorics/permutations.py:1662:20 - error: Argument of type "Iterable[Unknown]" cannot be assigned to parameter "obj" of type "Sized" in function "len"
+   /tmp/mypy_primer/projects/sympy/sympy/combinatorics/permutations.py:1662:20 - error: Argument of type "Iterable[object]" cannot be assigned to parameter "obj" of type "Sized" in function "len"
-     "Iterable[Unknown]" is incompatible with protocol "Sized"
+     "Iterable[object]" is incompatible with protocol "Sized"
-   /tmp/mypy_primer/projects/sympy/sympy/combinatorics/permutations.py:1664:60 - warning: Argument type is partially unknown
-     Argument corresponds to parameter "args" in function "format"
-     Argument type is "Iterable[Unknown]" (reportUnknownArgumentType)
-   /tmp/mypy_primer/projects/sympy/sympy/combinatorics/permutations.py:1665:21 - error: "__getitem__" method not defined on type "Iterable[Unknown]" (reportIndexIssue)
+   /tmp/mypy_primer/projects/sympy/sympy/combinatorics/permutations.py:1665:21 - error: "__getitem__" method not defined on type "Iterable[object]" (reportIndexIssue)
-   /tmp/mypy_primer/projects/sympy/sympy/core/basic.py:412:18 - warning: Unnecessary isinstance call; "Never" is always an instance of "frozenset[Unknown]" (reportUnnecessaryIsInstance)
+   /tmp/mypy_primer/projects/sympy/sympy/core/basic.py:412:18 - warning: Unnecessary isinstance call; "Never" is always an instance of "frozenset[object]" (reportUnnecessaryIsInstance)
-   /tmp/mypy_primer/projects/sympy/sympy/core/basic.py:413:34 - warning: Unnecessary isinstance call; "Never" is always an instance of "frozenset[Unknown]" (reportUnnecessaryIsInstance)
+   /tmp/mypy_primer/projects/sympy/sympy/core/basic.py:413:34 - warning: Unnecessary isinstance call; "Never" is always an instance of "frozenset[object]" (reportUnnecessaryIsInstance)
-   /tmp/mypy_primer/projects/sympy/sympy/core/basic.py:414:28 - warning: Argument type is unknown
-     Argument corresponds to parameter "args" in function "__new__" (reportUnknownArgumentType)
-     Type of "sequence" is "ItemsView[Unknown, Unknown] | dict_items[Basic, Basic]" (reportUnknownVariableType)
+     Type of "sequence" is "ItemsView[Unknown, object] | dict_items[Basic, Basic]" (reportUnknownVariableType)
-     Type of "s2" is "Unknown | Basic" (reportUnknownVariableType)
+     Type of "s2" is "Unknown | object | Basic" (reportUnknownVariableType)
-     Type of "sequence" is "ItemsView[Unknown, Unknown] | dict_items[Basic, Basic]" (reportUnknownVariableType)
+     Type of "sequence" is "ItemsView[Unknown, object] | dict_items[Basic, Basic]" (reportUnknownVariableType)
-     Type of "new" is "Unknown | Basic" (reportUnknownVariableType)
+     Type of "new" is "object | Basic | Unknown" (reportUnknownVariableType)
-     Argument type is "ItemsView[Unknown, Unknown] | dict_items[Basic, Basic] | Unknown | list[tuple[Unknown, Unknown]]" (reportUnknownArgumentType)
+     Argument type is "ItemsView[Unknown, object] | dict_items[Basic, Basic] | Unknown | list[tuple[Unknown, Unknown]]" (reportUnknownArgumentType)
-     Type of "__str__" is "((self: list[Unknown]) -> str) | ((self: tuple[Unknown, ...]) -> str) | ((self: set[Unknown]) -> str) | ((self: frozenset[Unknown]) -> str)" (reportUnknownMemberType)
+     Type of "__str__" is "((self: list[Unknown]) -> str) | ((self: tuple[Unknown, ...]) -> str) | ((self: set[Unknown]) -> str) | ((self: frozenset[object]) -> str)" (reportUnknownMemberType)
-     Argument type is "list[Unknown] | tuple[Unknown, ...] | set[Unknown] | frozenset[Unknown]" (reportUnknownArgumentType)
+     Argument type is "list[Unknown] | tuple[Unknown, ...] | set[Unknown] | frozenset[object]" (reportUnknownArgumentType)
-     Type of "__repr__" is "((self: list[Unknown]) -> str) | ((self: tuple[Unknown, ...]) -> str) | ((self: set[Unknown]) -> str) | ((self: frozenset[Unknown]) -> str)" (reportUnknownMemberType)
+     Type of "__repr__" is "((self: list[Unknown]) -> str) | ((self: tuple[Unknown, ...]) -> str) | ((self: set[Unknown]) -> str) | ((self: frozenset[object]) -> str)" (reportUnknownMemberType)
-     Argument type is "list[Unknown] | tuple[Unknown, ...] | set[Unknown] | frozenset[Unknown]" (reportUnknownArgumentType)
+     Argument type is "list[Unknown] | tuple[Unknown, ...] | set[Unknown] | frozenset[object]" (reportUnknownArgumentType)
-   /tmp/mypy_primer/projects/sympy/sympy/interactive/printing.py:149:39 - warning: Argument type is unknown
+   /tmp/mypy_primer/projects/sympy/sympy/interactive/printing.py:149:46 - warning: Type of "i" is partially unknown
+     Type of "i" is "Unknown | object" (reportUnknownVariableType)
-     Argument corresponds to parameter "o" in function "_can_print" (reportUnknownArgumentType)
-   /tmp/mypy_primer/projects/sympy/sympy/interactive/printing.py:149:46 - warning: Type of "i" is unknown (reportUnknownVariableType)
-   /tmp/mypy_primer/projects/sympy/sympy/matrices/common.py:2293:62 - warning: Argument type is partially unknown
-     Argument corresponds to parameter "iterable" in function "__init__"
-     Argument type is "Permutation | Iterable[Unknown]" (reportUnknownArgumentType)

... (truncated 1707 lines) ...```

jorenham · 2024-11-23T12:01:27Z

this is fantastic

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DetachHead force-pushed the isinstance-narrow-generics-to-bound branch from 13dd380 to 56f2fd5 Compare October 6, 2024 11:41

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DetachHead force-pushed the isinstance-narrow-generics-to-bound branch from 253fe90 to d5ef6a7 Compare October 7, 2024 04:52

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DetachHead marked this pull request as draft October 7, 2024 07:50

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beauxq reviewed Nov 6, 2024

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No bounds if type param present #885

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DetachHead marked this pull request as ready for review November 18, 2024 12:59

DetachHead added 5 commits November 20, 2024 19:02

use a generic's bound when narrowing with isinstance if it's covari…

f697aa1

…ant, or `Never` if it's contravariant

do the same with match statements

8b53acf

add tests for typevar narrowing changes

9bc70e9

don't do the variance narrowing thing if the type was originally `Any…

be80947

…`/Unknown

workaround for fake typevars in __init__ methods when determining w…

875c90b

…hether to use variance to specialize type vars when narrowing

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DetachHead and others added 10 commits November 23, 2024 01:02

add test for an issue with the new generic narrowing logic picked up …

bce38d8

…by the primer

don't use bounds for narrowing generics when type param is known

1a452ed

remove parentheses

4e893da

fix comment

4931ced

remove leading space from docstrings in tests

1695c7a

narrow constraints to a union of all possible conditions

d334e3e

add improvedGenericNarrowing option to allow users to disable the n…

468c396

…ew functionality

don't sync when running the docs npm script because the project takes…

a2265df

… ages to build

fix logic to determine whether to use generic bounds for narrowing wh…

b190ca2

…en the value being narrowed is a union

rename improvedGenericNarrowing to be consistent with other similar…

04e71ae

… options

DetachHead force-pushed the isinstance-narrow-generics-to-bound branch from cccd781 to 04e71ae Compare November 22, 2024 15:03

DetachHead changed the title ~~use a generic's bound when narrowing with isinstance if it's covariant, or Never if it's contravariant~~ improved narrowing of generics Nov 22, 2024

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DetachHead added 2 commits November 23, 2024 11:32

add documentation for strictGenericNarrowing

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add more info links to all the new settings

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DetachHead merged commit 0355baf into main Nov 23, 2024
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improved narrowing of generics #745

improved narrowing of generics #745

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edited

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jorenham commented Nov 23, 2024

improved narrowing of generics #745

improved narrowing of generics #745

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