Implement basic subtyping & inferrence for variadic classes. #13105
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| @@ -702,7 +753,7 @@ def visit_tuple_type(self, template: TupleType) -> List[Constraint]: | |||
| isinstance(actual, Instance) | |||
| and actual.type.fullname == "builtins.tuple" | |||
| ) | |||
| unpack_index = find_unpack_in_tuple(template) | |||
| unpack_index = find_unpack_in_list(template.items) | |||
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I wanted to migrate this to use the other helpers, but couldn't figure out how to cleanly do it.
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| Ts = TypeVarTuple("Ts") | ||
| T = TypeVar("T") | ||
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| class Variadic(Generic[T, Ts]): |
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This test fails if I add a suffix type variable, with a weird error Argument 1 to "foo" has incompatible type "Variadic[int, str, bool, float]"; expected "Variadic[int, str, bool, float]" (diff)
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I left a comment below about what seems to be going on.
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mypy/subtypes.py
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| assert unpack_index is not None | ||
| type_params = zip( | ||
| left_prefix + right_prefix, | ||
| left_suffix + right_suffix, |
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These are not correct. It should be left_prefix + left_suffix and right_prefix + right_suffix, I think.
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Ya that does seem like a bad problem.
mypy/constraints.py
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| template_unpack.type.fullname == "builtins.tuple" | ||
| ): | ||
| # TODO: check homogenous tuple case | ||
| assert NotImplementedError |
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Maybe add a TODO about fixed-length tuple here?
| ) | ||
| modified_actual = actual.copy_modified( | ||
| items=list(actual_items) | ||
| ) |
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Should we also infer constraints for the prefix and suffix? I guess they may contain regular type variable types?
mypy/expandtype.py
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| @@ -26,8 +27,27 @@ def expand_type_by_instance(typ: Type, instance: Instance) -> Type: | |||
| return typ | |||
| else: | |||
| variables: Dict[TypeVarId, Type] = {} | |||
| for binder, arg in zip(instance.type.defn.type_vars, instance.args): | |||
| if instance.type.has_type_var_tuple_type: | |||
| import mypy.constraints | |||
mypy/typevartuples.py
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| from mypy.types import Instance, UnpackType, ProperType, get_proper_type, Type | ||
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| """Helpers for interacting with type var tuples.""" |
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Style nit: move docstring to top of file.
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Diff from mypy_primer, showing the effect of this PR on open source code: dragonchain (https://github.com/dragonchain/dragonchain)
- dragonchain/lib/database/redis.py:399:36: error: Argument 2 to "zadd" of "SortedSetCommands" has incompatible type "Dict[str, int]"; expected "Mapping[Union[str, bytes], Union[bytes, float, int, str]]"
+ dragonchain/lib/database/redis.py:399:36: error: Argument 2 to "zadd" of "SortedSetCommands" has incompatible type "Dict[str, int]"; expected "Mapping[Union[str, bytes], Union[bytes, float, str]]"
- dragonchain/lib/database/redis_utest.py:218:9: error: "Callable[[Union[str, bytes], Mapping[Union[str, bytes], Union[bytes, float, int, str]], bool, bool, bool, bool, Optional[Any], Optional[Any]], int]" has no attribute "assert_called_once_with"
+ dragonchain/lib/database/redis_utest.py:218:9: error: "Callable[[Union[str, bytes], Mapping[Union[str, bytes], Union[bytes, float, str]], bool, bool, bool, bool, Optional[Any], Optional[Any]], int]" has no attribute "assert_called_once_with"
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| left_items = t.args[:right.type.type_var_tuple_prefix] | ||
| right_items = right.args[:right.type.type_var_tuple_prefix] | ||
| if right.type.type_var_tuple_suffix: | ||
| left_items += t.args[-right.type.type_var_tuple_suffix:] | ||
| right_items += right.args[-right.type.type_var_tuple_suffix:] |
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@jhance maybe I'm just totally missing something, but I think these aren't actually used anywhere? The slicing means we're not mutating the original t.args and right.args
This makes several basic testcases for using classes with variadic generics pass. Some pieces of this are left as TODOs to flesh out various edge cases to avoid the diff growing in complexity.