[ty] Do not carry the generic context of Protocol or Generic in the ClassBase enum (#17989)
## Summary It doesn't seem to be necessary for our generics implementation to carry the `GenericContext` in the `ClassBase` variants. Removing it simplifies the code, fixes many TODOs about `Generic` or `Protocol` appearing multiple times in MROs when each should only appear at most once, and allows us to more accurately detect runtime errors that occur due to `Generic` or `Protocol` appearing multiple times in a class's bases. In order to remove the `GenericContext` from the `ClassBase` variant, it turns out to be necessary to emulate `typing._GenericAlias.__mro_entries__`, or we end up with a large number of false-positive `inconsistent-mro` errors. This PR therefore also does that. Lastly, this PR fixes the inferred MROs of PEP-695 generic classes, which implicitly inherit from `Generic` even if they have no explicit bases. ## Test Plan mdtests
This commit is contained in:
Alex Waygood
@@ -81,23 +81,22 @@ import typing
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class ListSubclass(typing.List): ...
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# revealed: tuple[<class 'ListSubclass'>, <class 'list[Unknown]'>, <class 'MutableSequence[Unknown]'>, <class 'Sequence[Unknown]'>, <class 'Reversible[Unknown]'>, <class 'Collection[Unknown]'>, <class 'Iterable[Unknown]'>, <class 'Container[Unknown]'>, typing.Protocol[_T_co], typing.Generic[_T_co], <class 'object'>]
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# revealed: tuple[<class 'ListSubclass'>, <class 'list[Unknown]'>, <class 'MutableSequence[Unknown]'>, <class 'Sequence[Unknown]'>, <class 'Reversible[Unknown]'>, <class 'Collection[Unknown]'>, <class 'Iterable[Unknown]'>, <class 'Container[Unknown]'>, typing.Protocol, typing.Generic, <class 'object'>]
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reveal_type(ListSubclass.__mro__)
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class DictSubclass(typing.Dict): ...
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# TODO: should not have multiple `Generic[]` elements
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# revealed: tuple[<class 'DictSubclass'>, <class 'dict[Unknown, Unknown]'>, <class 'MutableMapping[Unknown, Unknown]'>, <class 'Mapping[Unknown, Unknown]'>, <class 'Collection[Unknown]'>, <class 'Iterable[Unknown]'>, <class 'Container[Unknown]'>, typing.Protocol[_T_co], typing.Generic[_T_co], typing.Generic[_KT, _VT_co], <class 'object'>]
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# revealed: tuple[<class 'DictSubclass'>, <class 'dict[Unknown, Unknown]'>, <class 'MutableMapping[Unknown, Unknown]'>, <class 'Mapping[Unknown, Unknown]'>, <class 'Collection[Unknown]'>, <class 'Iterable[Unknown]'>, <class 'Container[Unknown]'>, typing.Protocol, typing.Generic, <class 'object'>]
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reveal_type(DictSubclass.__mro__)
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class SetSubclass(typing.Set): ...
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# revealed: tuple[<class 'SetSubclass'>, <class 'set[Unknown]'>, <class 'MutableSet[Unknown]'>, <class 'AbstractSet[Unknown]'>, <class 'Collection[Unknown]'>, <class 'Iterable[Unknown]'>, <class 'Container[Unknown]'>, typing.Protocol[_T_co], typing.Generic[_T_co], <class 'object'>]
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# revealed: tuple[<class 'SetSubclass'>, <class 'set[Unknown]'>, <class 'MutableSet[Unknown]'>, <class 'AbstractSet[Unknown]'>, <class 'Collection[Unknown]'>, <class 'Iterable[Unknown]'>, <class 'Container[Unknown]'>, typing.Protocol, typing.Generic, <class 'object'>]
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reveal_type(SetSubclass.__mro__)
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class FrozenSetSubclass(typing.FrozenSet): ...
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# revealed: tuple[<class 'FrozenSetSubclass'>, <class 'frozenset[Unknown]'>, <class 'AbstractSet[Unknown]'>, <class 'Collection[Unknown]'>, <class 'Iterable[Unknown]'>, <class 'Container[Unknown]'>, typing.Protocol[_T_co], typing.Generic[_T_co], <class 'object'>]
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# revealed: tuple[<class 'FrozenSetSubclass'>, <class 'frozenset[Unknown]'>, <class 'AbstractSet[Unknown]'>, <class 'Collection[Unknown]'>, <class 'Iterable[Unknown]'>, <class 'Container[Unknown]'>, typing.Protocol, typing.Generic, <class 'object'>]
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reveal_type(FrozenSetSubclass.__mro__)
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####################
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@@ -106,30 +105,26 @@ reveal_type(FrozenSetSubclass.__mro__)
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class ChainMapSubclass(typing.ChainMap): ...
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# TODO: should not have multiple `Generic[]` elements
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# revealed: tuple[<class 'ChainMapSubclass'>, <class 'ChainMap[Unknown, Unknown]'>, <class 'MutableMapping[Unknown, Unknown]'>, <class 'Mapping[Unknown, Unknown]'>, <class 'Collection[Unknown]'>, <class 'Iterable[Unknown]'>, <class 'Container[Unknown]'>, typing.Protocol[_T_co], typing.Generic[_T_co], typing.Generic[_KT, _VT_co], <class 'object'>]
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# revealed: tuple[<class 'ChainMapSubclass'>, <class 'ChainMap[Unknown, Unknown]'>, <class 'MutableMapping[Unknown, Unknown]'>, <class 'Mapping[Unknown, Unknown]'>, <class 'Collection[Unknown]'>, <class 'Iterable[Unknown]'>, <class 'Container[Unknown]'>, typing.Protocol, typing.Generic, <class 'object'>]
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reveal_type(ChainMapSubclass.__mro__)
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class CounterSubclass(typing.Counter): ...
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# TODO: Should have one `Generic[]` element, not three(!)
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# revealed: tuple[<class 'CounterSubclass'>, <class 'Counter[Unknown]'>, <class 'dict[Unknown, int]'>, <class 'MutableMapping[Unknown, int]'>, <class 'Mapping[Unknown, int]'>, <class 'Collection[Unknown]'>, <class 'Iterable[Unknown]'>, <class 'Container[Unknown]'>, typing.Protocol[_T_co], typing.Generic[_T_co], typing.Generic[_KT, _VT_co], typing.Generic[_T], <class 'object'>]
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# revealed: tuple[<class 'CounterSubclass'>, <class 'Counter[Unknown]'>, <class 'dict[Unknown, int]'>, <class 'MutableMapping[Unknown, int]'>, <class 'Mapping[Unknown, int]'>, <class 'Collection[Unknown]'>, <class 'Iterable[Unknown]'>, <class 'Container[Unknown]'>, typing.Protocol, typing.Generic, <class 'object'>]
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reveal_type(CounterSubclass.__mro__)
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class DefaultDictSubclass(typing.DefaultDict): ...
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# TODO: Should not have multiple `Generic[]` elements
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# revealed: tuple[<class 'DefaultDictSubclass'>, <class 'defaultdict[Unknown, Unknown]'>, <class 'dict[Unknown, Unknown]'>, <class 'MutableMapping[Unknown, Unknown]'>, <class 'Mapping[Unknown, Unknown]'>, <class 'Collection[Unknown]'>, <class 'Iterable[Unknown]'>, <class 'Container[Unknown]'>, typing.Protocol[_T_co], typing.Generic[_T_co], typing.Generic[_KT, _VT_co], <class 'object'>]
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# revealed: tuple[<class 'DefaultDictSubclass'>, <class 'defaultdict[Unknown, Unknown]'>, <class 'dict[Unknown, Unknown]'>, <class 'MutableMapping[Unknown, Unknown]'>, <class 'Mapping[Unknown, Unknown]'>, <class 'Collection[Unknown]'>, <class 'Iterable[Unknown]'>, <class 'Container[Unknown]'>, typing.Protocol, typing.Generic, <class 'object'>]
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reveal_type(DefaultDictSubclass.__mro__)
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class DequeSubclass(typing.Deque): ...
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# revealed: tuple[<class 'DequeSubclass'>, <class 'deque[Unknown]'>, <class 'MutableSequence[Unknown]'>, <class 'Sequence[Unknown]'>, <class 'Reversible[Unknown]'>, <class 'Collection[Unknown]'>, <class 'Iterable[Unknown]'>, <class 'Container[Unknown]'>, typing.Protocol[_T_co], typing.Generic[_T_co], <class 'object'>]
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# revealed: tuple[<class 'DequeSubclass'>, <class 'deque[Unknown]'>, <class 'MutableSequence[Unknown]'>, <class 'Sequence[Unknown]'>, <class 'Reversible[Unknown]'>, <class 'Collection[Unknown]'>, <class 'Iterable[Unknown]'>, <class 'Container[Unknown]'>, typing.Protocol, typing.Generic, <class 'object'>]
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reveal_type(DequeSubclass.__mro__)
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class OrderedDictSubclass(typing.OrderedDict): ...
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# TODO: Should not have multiple `Generic[]` elements
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# revealed: tuple[<class 'OrderedDictSubclass'>, <class 'OrderedDict[Unknown, Unknown]'>, <class 'dict[Unknown, Unknown]'>, <class 'MutableMapping[Unknown, Unknown]'>, <class 'Mapping[Unknown, Unknown]'>, <class 'Collection[Unknown]'>, <class 'Iterable[Unknown]'>, <class 'Container[Unknown]'>, typing.Protocol[_T_co], typing.Generic[_T_co], typing.Generic[_KT, _VT_co], <class 'object'>]
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# revealed: tuple[<class 'OrderedDictSubclass'>, <class 'OrderedDict[Unknown, Unknown]'>, <class 'dict[Unknown, Unknown]'>, <class 'MutableMapping[Unknown, Unknown]'>, <class 'Mapping[Unknown, Unknown]'>, <class 'Collection[Unknown]'>, <class 'Iterable[Unknown]'>, <class 'Container[Unknown]'>, typing.Protocol, typing.Generic, <class 'object'>]
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reveal_type(OrderedDictSubclass.__mro__)
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```
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@@ -24,9 +24,7 @@ class:
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```py
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class Bad(Generic[T], Generic[T]): ... # error: [duplicate-base]
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# TODO: should emit an error (fails at runtime)
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class AlsoBad(Generic[T], Generic[S]): ...
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class AlsoBad(Generic[T], Generic[S]): ... # error: [duplicate-base]
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```
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You cannot use the same typevar more than once.
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@@ -527,6 +527,45 @@ reveal_type(unknown_object) # revealed: Unknown
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reveal_type(unknown_object.__mro__) # revealed: Unknown
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```
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## MROs of classes that use multiple inheritance with generic aliases and subscripted `Generic`
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```py
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from typing import Generic, TypeVar, Iterator
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T = TypeVar("T")
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class peekable(Generic[T], Iterator[T]): ...
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# revealed: tuple[<class 'peekable[Unknown]'>, <class 'Iterator[T]'>, <class 'Iterable[T]'>, typing.Protocol, typing.Generic, <class 'object'>]
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reveal_type(peekable.__mro__)
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class peekable2(Iterator[T], Generic[T]): ...
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# revealed: tuple[<class 'peekable2[Unknown]'>, <class 'Iterator[T]'>, <class 'Iterable[T]'>, typing.Protocol, typing.Generic, <class 'object'>]
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reveal_type(peekable2.__mro__)
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class Base: ...
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class Intermediate(Base, Generic[T]): ...
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class Sub(Intermediate[T], Base): ...
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# revealed: tuple[<class 'Sub[Unknown]'>, <class 'Intermediate[T]'>, <class 'Base'>, typing.Generic, <class 'object'>]
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reveal_type(Sub.__mro__)
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```
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## Unresolvable MROs involving generics have the original bases reported in the error message, not the resolved bases
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<!-- snapshot-diagnostics -->
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```py
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from typing_extensions import Protocol, TypeVar, Generic
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T = TypeVar("T")
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class Foo(Protocol): ...
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class Bar(Protocol[T]): ...
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class Baz(Protocol[T], Foo, Bar[T]): ... # error: [inconsistent-mro]
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```
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## Classes that inherit from themselves
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These are invalid, but we need to be able to handle them gracefully without panicking.
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@@ -67,12 +67,10 @@ It's an error to include both bare `Protocol` and subscripted `Protocol[]` in th
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simultaneously:
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```py
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# TODO: should emit a `[duplicate-bases]` error here:
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class DuplicateBases(Protocol, Protocol[T]):
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class DuplicateBases(Protocol, Protocol[T]): # error: [duplicate-base]
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x: T
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# TODO: should not have `Protocol` or `Generic` multiple times
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# revealed: tuple[<class 'DuplicateBases[Unknown]'>, typing.Protocol, typing.Generic, typing.Protocol[T], typing.Generic[T], <class 'object'>]
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# revealed: tuple[<class 'DuplicateBases[Unknown]'>, Unknown, <class 'object'>]
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reveal_type(DuplicateBases.__mro__)
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```
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@@ -0,0 +1,37 @@
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---
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source: crates/ty_test/src/lib.rs
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expression: snapshot
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---
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---
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mdtest name: mro.md - Method Resolution Order tests - Unresolvable MROs involving generics have the original bases reported in the error message, not the resolved bases
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mdtest path: crates/ty_python_semantic/resources/mdtest/mro.md
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---
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# Python source files
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## mdtest_snippet.py
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```
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1 | from typing_extensions import Protocol, TypeVar, Generic
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2 |
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3 | T = TypeVar("T")
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4 |
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5 | class Foo(Protocol): ...
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6 | class Bar(Protocol[T]): ...
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7 | class Baz(Protocol[T], Foo, Bar[T]): ... # error: [inconsistent-mro]
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```
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# Diagnostics
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```
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error[inconsistent-mro]: Cannot create a consistent method resolution order (MRO) for class `Baz` with bases list `[typing.Protocol[T], <class 'Foo'>, <class 'Bar[T]'>]`
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--> src/mdtest_snippet.py:7:1
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5 | class Foo(Protocol): ...
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6 | class Bar(Protocol[T]): ...
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7 | class Baz(Protocol[T], Foo, Bar[T]): ... # error: [inconsistent-mro]
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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info: rule `inconsistent-mro` is enabled by default
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```
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@@ -16,7 +16,7 @@ class Foo[T]: ...
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class Bar(Foo[Bar]): ...
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reveal_type(Bar) # revealed: <class 'Bar'>
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reveal_type(Bar.__mro__) # revealed: tuple[<class 'Bar'>, <class 'Foo[Bar]'>, <class 'object'>]
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reveal_type(Bar.__mro__) # revealed: tuple[<class 'Bar'>, <class 'Foo[Bar]'>, typing.Generic, <class 'object'>]
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```
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## Access to attributes declared in stubs
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@@ -83,7 +83,7 @@ python-version = "3.9"
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```py
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class A(tuple[int, str]): ...
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# revealed: tuple[<class 'A'>, <class 'tuple[@Todo(Generic tuple specializations), ...]'>, <class 'Sequence[@Todo(Generic tuple specializations)]'>, <class 'Reversible[@Todo(Generic tuple specializations)]'>, <class 'Collection[@Todo(Generic tuple specializations)]'>, <class 'Iterable[@Todo(Generic tuple specializations)]'>, <class 'Container[@Todo(Generic tuple specializations)]'>, typing.Protocol[_T_co], typing.Generic[_T_co], <class 'object'>]
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# revealed: tuple[<class 'A'>, <class 'tuple[@Todo(Generic tuple specializations), ...]'>, <class 'Sequence[@Todo(Generic tuple specializations)]'>, <class 'Reversible[@Todo(Generic tuple specializations)]'>, <class 'Collection[@Todo(Generic tuple specializations)]'>, <class 'Iterable[@Todo(Generic tuple specializations)]'>, <class 'Container[@Todo(Generic tuple specializations)]'>, typing.Protocol, typing.Generic, <class 'object'>]
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reveal_type(A.__mro__)
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```
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@@ -114,6 +114,6 @@ from typing import Tuple
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class C(Tuple): ...
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# revealed: tuple[<class 'C'>, <class 'tuple[Unknown, ...]'>, <class 'Sequence[Unknown]'>, <class 'Reversible[Unknown]'>, <class 'Collection[Unknown]'>, <class 'Iterable[Unknown]'>, <class 'Container[Unknown]'>, typing.Protocol[_T_co], typing.Generic[_T_co], <class 'object'>]
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# revealed: tuple[<class 'C'>, <class 'tuple[Unknown, ...]'>, <class 'Sequence[Unknown]'>, <class 'Reversible[Unknown]'>, <class 'Collection[Unknown]'>, <class 'Iterable[Unknown]'>, <class 'Container[Unknown]'>, typing.Protocol, typing.Generic, <class 'object'>]
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reveal_type(C.__mro__)
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```
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