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Copy pathsubtypes.py
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1811 lines (1616 loc) · 76 KB
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from __future__ import annotations
from contextlib import contextmanager
from typing import Any, Callable, Iterator, List, TypeVar, cast
from typing_extensions import Final, TypeAlias as _TypeAlias
import mypy.applytype
import mypy.constraints
import mypy.typeops
from mypy.erasetype import erase_type
from mypy.expandtype import expand_self_type, expand_type_by_instance
from mypy.maptype import map_instance_to_supertype
# Circular import; done in the function instead.
# import mypy.solve
from mypy.nodes import (
ARG_STAR,
ARG_STAR2,
CONTRAVARIANT,
COVARIANT,
Decorator,
FuncBase,
OverloadedFuncDef,
TypeInfo,
Var,
)
from mypy.options import Options
from mypy.state import state
from mypy.types import (
TUPLE_LIKE_INSTANCE_NAMES,
TYPED_NAMEDTUPLE_NAMES,
AnyType,
CallableType,
DeletedType,
ErasedType,
FormalArgument,
FunctionLike,
Instance,
LiteralType,
NoneType,
NormalizedCallableType,
Overloaded,
Parameters,
ParamSpecType,
PartialType,
ProperType,
TupleType,
Type,
TypeAliasType,
TypedDictType,
TypeOfAny,
TypeType,
TypeVarTupleType,
TypeVarType,
TypeVisitor,
UnboundType,
UninhabitedType,
UnionType,
UnpackType,
_flattened,
get_proper_type,
is_named_instance,
)
from mypy.typestate import SubtypeKind, type_state
from mypy.typevars import fill_typevars_with_any
from mypy.typevartuples import extract_unpack, fully_split_with_mapped_and_template
# Flags for detected protocol members
IS_SETTABLE: Final = 1
IS_CLASSVAR: Final = 2
IS_CLASS_OR_STATIC: Final = 3
IS_VAR: Final = 4
TypeParameterChecker: _TypeAlias = Callable[[Type, Type, int, bool, "SubtypeContext"], bool]
class SubtypeContext:
def __init__(
self,
*,
# Non-proper subtype flags
ignore_type_params: bool = False,
ignore_pos_arg_names: bool = False,
ignore_declared_variance: bool = False,
# Supported for both proper and non-proper
ignore_promotions: bool = False,
ignore_uninhabited: bool = False,
# Proper subtype flags
erase_instances: bool = False,
keep_erased_types: bool = False,
options: Options | None = None,
) -> None:
self.ignore_type_params = ignore_type_params
self.ignore_pos_arg_names = ignore_pos_arg_names
self.ignore_declared_variance = ignore_declared_variance
self.ignore_promotions = ignore_promotions
self.ignore_uninhabited = ignore_uninhabited
self.erase_instances = erase_instances
self.keep_erased_types = keep_erased_types
self.options = options
def check_context(self, proper_subtype: bool) -> None:
# Historically proper and non-proper subtypes were defined using different helpers
# and different visitors. Check if flag values are such that we definitely support.
if proper_subtype:
assert (
not self.ignore_pos_arg_names
and not self.ignore_declared_variance
)
else:
assert not self.erase_instances and not self.keep_erased_types
def is_subtype(
left: Type,
right: Type,
*,
subtype_context: SubtypeContext | None = None,
ignore_type_params: bool = False,
ignore_pos_arg_names: bool = False,
ignore_declared_variance: bool = False,
ignore_promotions: bool = False,
ignore_uninhabited: bool = False,
options: Options | None = None,
) -> bool:
"""Is 'left' subtype of 'right'?
Also consider Any to be a subtype of any type, and vice versa. This
recursively applies to components of composite types (List[int] is subtype
of List[Any], for example).
type_parameter_checker is used to check the type parameters (for example,
A with B in is_subtype(C[A], C[B]). The default checks for subtype relation
between the type arguments (e.g., A and B), taking the variance of the
type var into account.
"""
if subtype_context is None:
subtype_context = SubtypeContext(
ignore_type_params=ignore_type_params,
ignore_pos_arg_names=ignore_pos_arg_names,
ignore_declared_variance=ignore_declared_variance,
ignore_promotions=ignore_promotions,
ignore_uninhabited=ignore_uninhabited,
options=options,
)
else:
assert not any(
{
ignore_type_params,
ignore_pos_arg_names,
ignore_declared_variance,
ignore_promotions,
ignore_uninhabited,
options,
}
), "Don't pass both context and individual flags"
if type_state.is_assumed_subtype(left, right):
return True
if mypy.typeops.is_recursive_pair(left, right):
# This case requires special care because it may cause infinite recursion.
# Our view on recursive types is known under a fancy name of iso-recursive mu-types.
# Roughly this means that a recursive type is defined as an alias where right hand side
# can refer to the type as a whole, for example:
# A = Union[int, Tuple[A, ...]]
# and an alias unrolled once represents the *same type*, in our case all these represent
# the same type:
# A
# Union[int, Tuple[A, ...]]
# Union[int, Tuple[Union[int, Tuple[A, ...]], ...]]
# The algorithm for subtyping is then essentially under the assumption that left <: right,
# check that get_proper_type(left) <: get_proper_type(right). On the example above,
# If we start with:
# A = Union[int, Tuple[A, ...]]
# B = Union[int, Tuple[B, ...]]
# When checking if A <: B we push pair (A, B) onto 'assuming' stack, then when after few
# steps we come back to initial call is_subtype(A, B) and immediately return True.
with pop_on_exit(type_state.get_assumptions(is_proper=False), left, right):
return _is_subtype(left, right, subtype_context, proper_subtype=False)
return _is_subtype(left, right, subtype_context, proper_subtype=False)
def is_proper_subtype(
left: Type,
right: Type,
*,
subtype_context: SubtypeContext | None = None,
ignore_promotions: bool = False,
ignore_uninhabited: bool = False,
erase_instances: bool = False,
keep_erased_types: bool = False,
) -> bool:
"""Is left a proper subtype of right?
For proper subtypes, there's no need to rely on compatibility due to
Any types. Every usable type is a proper subtype of itself.
If erase_instances is True, erase left instance *after* mapping it to supertype
(this is useful for runtime isinstance() checks). If keep_erased_types is True,
do not consider ErasedType a subtype of all types (used by type inference against unions).
"""
if subtype_context is None:
subtype_context = SubtypeContext(
ignore_promotions=ignore_promotions,
ignore_uninhabited=ignore_uninhabited,
erase_instances=erase_instances,
keep_erased_types=keep_erased_types,
)
else:
assert not any(
{
ignore_promotions,
ignore_uninhabited,
erase_instances,
keep_erased_types,
ignore_uninhabited,
}
), "Don't pass both context and individual flags"
if type_state.is_assumed_proper_subtype(left, right):
return True
if mypy.typeops.is_recursive_pair(left, right):
# Same as for non-proper subtype, see detailed comment there for explanation.
with pop_on_exit(type_state.get_assumptions(is_proper=True), left, right):
return _is_subtype(left, right, subtype_context, proper_subtype=True)
return _is_subtype(left, right, subtype_context, proper_subtype=True)
def is_equivalent(
a: Type,
b: Type,
*,
ignore_type_params: bool = False,
ignore_pos_arg_names: bool = False,
options: Options | None = None,
subtype_context: SubtypeContext | None = None,
) -> bool:
return is_subtype(
a,
b,
ignore_type_params=ignore_type_params,
ignore_pos_arg_names=ignore_pos_arg_names,
options=options,
subtype_context=subtype_context,
) and is_subtype(
b,
a,
ignore_type_params=ignore_type_params,
ignore_pos_arg_names=ignore_pos_arg_names,
options=options,
subtype_context=subtype_context,
)
def is_same_type(
a: Type, b: Type, ignore_promotions: bool = True, subtype_context: SubtypeContext | None = None
) -> bool:
"""Are these types proper subtypes of each other?
This means types may have different representation (e.g. an alias, or
a non-simplified union) but are semantically exchangeable in all contexts.
"""
# Note that using ignore_promotions=True (default) makes types like int and int64
# considered not the same type (which is the case at runtime).
# Also Union[bool, int] (if it wasn't simplified before) will be different
# from plain int, etc.
return is_proper_subtype(
a, b, ignore_promotions=ignore_promotions, subtype_context=subtype_context
) and is_proper_subtype(
b, a, ignore_promotions=ignore_promotions, subtype_context=subtype_context
)
# This is a common entry point for subtyping checks (both proper and non-proper).
# Never call this private function directly, use the public versions.
def _is_subtype(
left: Type, right: Type, subtype_context: SubtypeContext, proper_subtype: bool
) -> bool:
subtype_context.check_context(proper_subtype)
orig_right = right
orig_left = left
left = get_proper_type(left)
right = get_proper_type(right)
if not proper_subtype and (
isinstance(right, AnyType)
or isinstance(right, UnboundType)
or isinstance(right, ErasedType)
):
# TODO: should we consider all types proper subtypes of UnboundType and/or
# ErasedType as we do for non-proper subtyping.
return True
if isinstance(right, UnionType) and not isinstance(left, UnionType):
# Normally, when 'left' is not itself a union, the only way
# 'left' can be a subtype of the union 'right' is if it is a
# subtype of one of the items making up the union.
if proper_subtype:
is_subtype_of_item = any(
is_proper_subtype(orig_left, item, subtype_context=subtype_context)
for item in right.items
)
else:
is_subtype_of_item = any(
is_subtype(orig_left, item, subtype_context=subtype_context)
for item in right.items
)
# Recombine rhs literal types, to make an enum type a subtype
# of a union of all enum items as literal types. Only do it if
# the previous check didn't succeed, since recombining can be
# expensive.
# `bool` is a special case, because `bool` is `Literal[True, False]`.
if (
not is_subtype_of_item
and isinstance(left, Instance)
and (left.type.is_enum or left.type.fullname == "builtins.bool")
):
right = UnionType(mypy.typeops.try_contracting_literals_in_union(right.items))
if proper_subtype:
is_subtype_of_item = any(
is_proper_subtype(orig_left, item, subtype_context=subtype_context)
for item in right.items
)
else:
is_subtype_of_item = any(
is_subtype(orig_left, item, subtype_context=subtype_context)
for item in right.items
)
# However, if 'left' is a type variable T, T might also have
# an upper bound which is itself a union. This case will be
# handled below by the SubtypeVisitor. We have to check both
# possibilities, to handle both cases like T <: Union[T, U]
# and cases like T <: B where B is the upper bound of T and is
# a union. (See #2314.)
if not isinstance(left, TypeVarType):
return is_subtype_of_item
elif is_subtype_of_item:
return True
# otherwise, fall through
return left.accept(SubtypeVisitor(orig_right, subtype_context, proper_subtype))
def check_type_parameter(
left: Type, right: Type, variance: int, proper_subtype: bool, subtype_context: SubtypeContext
) -> bool:
if variance == COVARIANT:
if proper_subtype:
return is_proper_subtype(left, right, subtype_context=subtype_context)
else:
return is_subtype(left, right, subtype_context=subtype_context)
elif variance == CONTRAVARIANT:
if proper_subtype:
return is_proper_subtype(right, left, subtype_context=subtype_context)
else:
return is_subtype(right, left, subtype_context=subtype_context)
else:
if proper_subtype:
# We pass ignore_promotions=False because it is a default for subtype checks.
# The actual value will be taken from the subtype_context, and it is whatever
# the original caller passed.
return is_same_type(
left, right, ignore_promotions=False, subtype_context=subtype_context
)
else:
return is_equivalent(left, right, subtype_context=subtype_context)
class SubtypeVisitor(TypeVisitor[bool]):
def __init__(self, right: Type, subtype_context: SubtypeContext, proper_subtype: bool) -> None:
self.right = get_proper_type(right)
self.orig_right = right
self.proper_subtype = proper_subtype
self.subtype_context = subtype_context
self.options = subtype_context.options
self._subtype_kind = SubtypeVisitor.build_subtype_kind(subtype_context, proper_subtype)
@staticmethod
def build_subtype_kind(subtype_context: SubtypeContext, proper_subtype: bool) -> SubtypeKind:
return (
state.strict_optional,
proper_subtype,
subtype_context.ignore_type_params,
subtype_context.ignore_pos_arg_names,
subtype_context.ignore_declared_variance,
subtype_context.ignore_promotions,
subtype_context.erase_instances,
subtype_context.keep_erased_types,
)
def _is_subtype(self, left: Type, right: Type) -> bool:
if self.proper_subtype:
return is_proper_subtype(left, right, subtype_context=self.subtype_context)
return is_subtype(left, right, subtype_context=self.subtype_context)
# visit_x(left) means: is left (which is an instance of X) a subtype of
# right?
def visit_unbound_type(self, left: UnboundType) -> bool:
# This can be called if there is a bad type annotation. The result probably
# doesn't matter much but by returning True we simplify these bad types away
# from unions, which could filter out some bogus messages.
return True
def visit_any(self, left: AnyType) -> bool:
return isinstance(self.right, AnyType) if self.proper_subtype else True
def visit_none_type(self, left: NoneType) -> bool:
if state.strict_optional:
if isinstance(self.right, NoneType) or is_named_instance(
self.right, "builtins.object"
):
return True
if isinstance(self.right, Instance) and self.right.type.is_protocol:
members = self.right.type.protocol_members
# None is compatible with Hashable (and other similar protocols). This is
# slightly sloppy since we don't check the signature of "__hash__".
# None is also compatible with `SupportsStr` protocol.
return not members or all(member in ("__hash__", "__str__") for member in members)
return False
else:
return True
def visit_uninhabited_type(self, left: UninhabitedType) -> bool:
# We ignore this for unsafe overload checks, so that and empty list and
# a list of int will be considered non-overlapping.
if isinstance(self.right, UninhabitedType):
return True
return not self.subtype_context.ignore_uninhabited
def visit_erased_type(self, left: ErasedType) -> bool:
# This may be encountered during type inference. The result probably doesn't
# matter much.
# TODO: it actually does matter, figure out more principled logic about this.
return not self.subtype_context.keep_erased_types
def visit_deleted_type(self, left: DeletedType) -> bool:
return True
def visit_instance(self, left: Instance) -> bool:
if left.type.fallback_to_any and not self.proper_subtype:
# NOTE: `None` is a *non-subclassable* singleton, therefore no class
# can by a subtype of it, even with an `Any` fallback.
# This special case is needed to treat descriptors in classes with
# dynamic base classes correctly, see #5456.
return not isinstance(self.right, NoneType)
right = self.right
if isinstance(right, TupleType) and mypy.typeops.tuple_fallback(right).type.is_enum:
return self._is_subtype(left, mypy.typeops.tuple_fallback(right))
if isinstance(right, Instance):
if type_state.is_cached_subtype_check(self._subtype_kind, left, right):
return True
if not self.subtype_context.ignore_promotions:
for base in left.type.mro:
if base._promote and any(
self._is_subtype(p, self.right) for p in base._promote
):
type_state.record_subtype_cache_entry(self._subtype_kind, left, right)
return True
# Special case: Low-level integer types are compatible with 'int'. We can't
# use promotions, since 'int' is already promoted to low-level integer types,
# and we can't have circular promotions.
if left.type.alt_promote is right.type:
return True
rname = right.type.fullname
# Always try a nominal check if possible,
# there might be errors that a user wants to silence *once*.
# NamedTuples are a special case, because `NamedTuple` is not listed
# in `TypeInfo.mro`, so when `(a: NamedTuple) -> None` is used,
# we need to check for `is_named_tuple` property
if (
left.type.has_base(rname)
or rname == "builtins.object"
or (
rname in TYPED_NAMEDTUPLE_NAMES
and any(l.is_named_tuple for l in left.type.mro)
)
) and not self.subtype_context.ignore_declared_variance:
# Map left type to corresponding right instances.
t = map_instance_to_supertype(left, right.type)
if self.subtype_context.erase_instances:
erased = erase_type(t)
assert isinstance(erased, Instance)
t = erased
nominal = True
if right.type.has_type_var_tuple_type:
split_result = fully_split_with_mapped_and_template(left, right)
if split_result is None:
return False
(
left_prefix,
left_mprefix,
left_middle,
left_msuffix,
left_suffix,
right_prefix,
right_mprefix,
right_middle,
right_msuffix,
right_suffix,
) = split_result
left_unpacked = extract_unpack(left_middle)
right_unpacked = extract_unpack(right_middle)
# Helper for case 2 below so we can treat them the same.
def check_mixed(
unpacked_type: ProperType, compare_to: tuple[Type, ...]
) -> bool:
if (
isinstance(unpacked_type, Instance)
and unpacked_type.type.fullname == "builtins.tuple"
):
return all(is_equivalent(l, unpacked_type.args[0]) for l in compare_to)
if isinstance(unpacked_type, TypeVarTupleType):
return False
if isinstance(unpacked_type, AnyType):
return True
if isinstance(unpacked_type, TupleType):
if len(unpacked_type.items) != len(compare_to):
return False
for t1, t2 in zip(unpacked_type.items, compare_to):
if not is_equivalent(t1, t2):
return False
return True
return False
# Case 1: Both are unpacks, in this case we check what is being
# unpacked is the same.
if left_unpacked is not None and right_unpacked is not None:
if not is_equivalent(left_unpacked, right_unpacked):
return False
# Case 2: Only one of the types is an unpack. The equivalence
# case is mostly the same but we check some additional
# things when unpacking on the right.
elif left_unpacked is not None and right_unpacked is None:
if not check_mixed(left_unpacked, right_middle):
return False
elif left_unpacked is None and right_unpacked is not None:
if not check_mixed(right_unpacked, left_middle):
return False
# Case 3: Neither type is an unpack. In this case we just compare
# the items themselves.
else:
if len(left_middle) != len(right_middle):
return False
for left_t, right_t in zip(left_middle, right_middle):
if not is_equivalent(left_t, right_t):
return False
assert len(left_mprefix) == len(right_mprefix)
assert len(left_msuffix) == len(right_msuffix)
for left_item, right_item in zip(
left_mprefix + left_msuffix, right_mprefix + right_msuffix
):
if not is_equivalent(left_item, right_item):
return False
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 :]
unpack_index = right.type.type_var_tuple_prefix
assert unpack_index is not None
type_params = zip(
left_prefix + left_suffix,
right_prefix + right_suffix,
right.type.defn.type_vars[:unpack_index]
+ right.type.defn.type_vars[unpack_index + 1 :],
)
else:
type_params = zip(t.args, right.args, right.type.defn.type_vars)
if not self.subtype_context.ignore_type_params:
for lefta, righta, tvar in type_params:
if isinstance(tvar, TypeVarType):
if not check_type_parameter(
lefta,
righta,
tvar.variance,
self.proper_subtype,
self.subtype_context,
):
nominal = False
else:
if not check_type_parameter(
lefta, righta, COVARIANT, self.proper_subtype, self.subtype_context
):
nominal = False
if nominal:
type_state.record_subtype_cache_entry(self._subtype_kind, left, right)
return nominal
if right.type.is_protocol and is_protocol_implementation(
left, right, proper_subtype=self.proper_subtype
):
return True
return False
if isinstance(right, TypeType):
item = right.item
if isinstance(item, TupleType):
item = mypy.typeops.tuple_fallback(item)
# TODO: this is a bit arbitrary, we should only skip Any-related cases.
if not self.proper_subtype:
if is_named_instance(left, "builtins.type"):
return self._is_subtype(TypeType(AnyType(TypeOfAny.special_form)), right)
if left.type.is_metaclass():
if isinstance(item, AnyType):
return True
if isinstance(item, Instance):
return is_named_instance(item, "builtins.object")
if isinstance(right, LiteralType) and left.last_known_value is not None:
return self._is_subtype(left.last_known_value, right)
if isinstance(right, CallableType):
# Special case: Instance can be a subtype of Callable.
call = find_member("__call__", left, left, is_operator=True)
if call:
return self._is_subtype(call, right)
return False
else:
return False
def visit_type_var(self, left: TypeVarType) -> bool:
right = self.right
if isinstance(right, TypeVarType) and left.id == right.id:
return True
if left.values and self._is_subtype(UnionType.make_union(left.values), right):
return True
return self._is_subtype(left.upper_bound, self.right)
def visit_param_spec(self, left: ParamSpecType) -> bool:
right = self.right
if (
isinstance(right, ParamSpecType)
and right.id == left.id
and right.flavor == left.flavor
):
return True
if isinstance(right, Parameters) and are_trivial_parameters(right):
return True
return self._is_subtype(left.upper_bound, self.right)
def visit_type_var_tuple(self, left: TypeVarTupleType) -> bool:
right = self.right
if isinstance(right, TypeVarTupleType) and right.id == left.id:
return True
return self._is_subtype(left.upper_bound, self.right)
def visit_unpack_type(self, left: UnpackType) -> bool:
if isinstance(self.right, UnpackType):
return self._is_subtype(left.type, self.right.type)
return False
def visit_parameters(self, left: Parameters) -> bool:
if isinstance(self.right, Parameters) or isinstance(self.right, CallableType):
right = self.right
if isinstance(right, CallableType):
right = right.with_unpacked_kwargs()
return are_parameters_compatible(
left,
right,
is_compat=self._is_subtype,
ignore_pos_arg_names=self.subtype_context.ignore_pos_arg_names,
)
else:
return False
def visit_callable_type(self, left: CallableType) -> bool:
right = self.right
if isinstance(right, CallableType):
if left.type_guard is not None and right.type_guard is not None:
if not self._is_subtype(left.type_guard, right.type_guard):
return False
elif right.type_guard is not None and left.type_guard is None:
# This means that one function has `TypeGuard` and other does not.
# They are not compatible. See https://github.com/python/mypy/issues/11307
return False
return is_callable_compatible(
left,
right,
is_compat=self._is_subtype,
ignore_pos_arg_names=self.subtype_context.ignore_pos_arg_names,
strict_concatenate=self.options.strict_concatenate if self.options else True,
)
elif isinstance(right, Overloaded):
return all(self._is_subtype(left, item) for item in right.items)
elif isinstance(right, Instance):
if right.type.is_protocol and "__call__" in right.type.protocol_members:
# OK, a callable can implement a protocol with a `__call__` member.
# TODO: we should probably explicitly exclude self-types in this case.
call = find_member("__call__", right, left, is_operator=True)
assert call is not None
if self._is_subtype(left, call):
if len(right.type.protocol_members) == 1:
return True
if is_protocol_implementation(left.fallback, right, skip=["__call__"]):
return True
if right.type.is_protocol and left.is_type_obj():
ret_type = get_proper_type(left.ret_type)
if isinstance(ret_type, TupleType):
ret_type = mypy.typeops.tuple_fallback(ret_type)
if isinstance(ret_type, Instance) and is_protocol_implementation(
ret_type, right, proper_subtype=self.proper_subtype, class_obj=True
):
return True
return self._is_subtype(left.fallback, right)
elif isinstance(right, TypeType):
# This is unsound, we don't check the __init__ signature.
return left.is_type_obj() and self._is_subtype(left.ret_type, right.item)
elif isinstance(right, Parameters):
# this doesn't check return types.... but is needed for is_equivalent
return are_parameters_compatible(
left.with_unpacked_kwargs(),
right,
is_compat=self._is_subtype,
ignore_pos_arg_names=self.subtype_context.ignore_pos_arg_names,
)
else:
return False
def visit_tuple_type(self, left: TupleType) -> bool:
right = self.right
if isinstance(right, Instance):
if is_named_instance(right, "typing.Sized"):
return True
elif is_named_instance(right, TUPLE_LIKE_INSTANCE_NAMES):
if right.args:
iter_type = right.args[0]
else:
if self.proper_subtype:
return False
iter_type = AnyType(TypeOfAny.special_form)
if is_named_instance(right, "builtins.tuple") and isinstance(
get_proper_type(iter_type), AnyType
):
# TODO: We shouldn't need this special case. This is currently needed
# for isinstance(x, tuple), though it's unclear why.
return True
return all(self._is_subtype(li, iter_type) for li in left.items)
elif self._is_subtype(mypy.typeops.tuple_fallback(left), right):
return True
return False
elif isinstance(right, TupleType):
if len(left.items) != len(right.items):
return False
if any(not self._is_subtype(l, r) for l, r in zip(left.items, right.items)):
return False
rfallback = mypy.typeops.tuple_fallback(right)
if is_named_instance(rfallback, "builtins.tuple"):
# No need to verify fallback. This is useful since the calculated fallback
# may be inconsistent due to how we calculate joins between unions vs.
# non-unions. For example, join(int, str) == object, whereas
# join(Union[int, C], Union[str, C]) == Union[int, str, C].
return True
lfallback = mypy.typeops.tuple_fallback(left)
return self._is_subtype(lfallback, rfallback)
else:
return False
def visit_typeddict_type(self, left: TypedDictType) -> bool:
right = self.right
if isinstance(right, Instance):
return self._is_subtype(left.fallback, right)
elif isinstance(right, TypedDictType):
if not left.names_are_wider_than(right):
return False
for name, l, r in left.zip(right):
# TODO: should we pass on the full subtype_context here and below?
if self.proper_subtype:
check = is_same_type(l, r)
else:
check = is_equivalent(
l,
r,
ignore_type_params=self.subtype_context.ignore_type_params,
options=self.options,
)
if not check:
return False
# Non-required key is not compatible with a required key since
# indexing may fail unexpectedly if a required key is missing.
# Required key is not compatible with a non-required key since
# the prior doesn't support 'del' but the latter should support
# it.
#
# NOTE: 'del' support is currently not implemented (#3550). We
# don't want to have to change subtyping after 'del' support
# lands so here we are anticipating that change.
if (name in left.required_keys) != (name in right.required_keys):
return False
# (NOTE: Fallbacks don't matter.)
return True
else:
return False
def visit_literal_type(self, left: LiteralType) -> bool:
if isinstance(self.right, LiteralType):
return left == self.right
else:
return self._is_subtype(left.fallback, self.right)
def visit_overloaded(self, left: Overloaded) -> bool:
right = self.right
if isinstance(right, Instance):
if right.type.is_protocol and "__call__" in right.type.protocol_members:
# same as for CallableType
call = find_member("__call__", right, left, is_operator=True)
assert call is not None
if self._is_subtype(left, call):
if len(right.type.protocol_members) == 1:
return True
if is_protocol_implementation(left.fallback, right, skip=["__call__"]):
return True
return self._is_subtype(left.fallback, right)
elif isinstance(right, CallableType):
for item in left.items:
if self._is_subtype(item, right):
return True
return False
elif isinstance(right, Overloaded):
if left == self.right:
# When it is the same overload, then the types are equal.
return True
# Ensure each overload in the right side (the supertype) is accounted for.
previous_match_left_index = -1
matched_overloads = set()
for right_item in right.items:
found_match = False
for left_index, left_item in enumerate(left.items):
subtype_match = self._is_subtype(left_item, right_item)
# Order matters: we need to make sure that the index of
# this item is at least the index of the previous one.
if subtype_match and previous_match_left_index <= left_index:
previous_match_left_index = left_index
found_match = True
matched_overloads.add(left_index)
break
else:
# If this one overlaps with the supertype in any way, but it wasn't
# an exact match, then it's a potential error.
strict_concat = self.options.strict_concatenate if self.options else True
if left_index not in matched_overloads and (
is_callable_compatible(
left_item,
right_item,
is_compat=self._is_subtype,
ignore_return=True,
ignore_pos_arg_names=self.subtype_context.ignore_pos_arg_names,
strict_concatenate=strict_concat,
)
or is_callable_compatible(
right_item,
left_item,
is_compat=self._is_subtype,
ignore_return=True,
ignore_pos_arg_names=self.subtype_context.ignore_pos_arg_names,
strict_concatenate=strict_concat,
)
):
return False
if not found_match:
return False
return True
elif isinstance(right, UnboundType):
return True
elif isinstance(right, TypeType):
# All the items must have the same type object status, so
# it's sufficient to query only (any) one of them.
# This is unsound, we don't check all the __init__ signatures.
return left.is_type_obj() and self._is_subtype(left.items[0], right)
else:
return False
def visit_union_type(self, left: UnionType) -> bool:
if isinstance(self.right, Instance):
literal_types: set[Instance] = set()
# avoid redundant check for union of literals
for item in left.relevant_items():
p_item = get_proper_type(item)
lit_type = mypy.typeops.simple_literal_type(p_item)
if lit_type is not None:
if lit_type in literal_types:
continue
literal_types.add(lit_type)
item = lit_type
if not self._is_subtype(item, self.orig_right):
return False
return True
elif isinstance(self.right, UnionType):
# prune literals early to avoid nasty quadratic behavior which would otherwise arise when checking
# subtype relationships between slightly different narrowings of an Enum
# we achieve O(N+M) instead of O(N*M)
fast_check: set[ProperType] = set()
for item in _flattened(self.right.relevant_items()):
p_item = get_proper_type(item)
if isinstance(p_item, LiteralType):
fast_check.add(p_item)
elif isinstance(p_item, Instance):
if p_item.last_known_value is None:
fast_check.add(p_item)
else:
fast_check.add(p_item.last_known_value)
for item in left.relevant_items():
p_item = get_proper_type(item)
if p_item in fast_check:
continue
lit_type = mypy.typeops.simple_literal_type(p_item)
if lit_type in fast_check:
continue
if not self._is_subtype(item, self.orig_right):
return False
return True
return all(self._is_subtype(item, self.orig_right) for item in left.items)
def visit_partial_type(self, left: PartialType) -> bool:
# This is indeterminate as we don't really know the complete type yet.
if self.proper_subtype:
# TODO: What's the right thing to do here?
return False
if left.type is None:
# Special case, partial `None`. This might happen when defining
# class-level attributes with explicit `None`.
# We can still recover from this.
# https://github.com/python/mypy/issues/11105
return self.visit_none_type(NoneType())
raise RuntimeError(f'Partial type "{left}" cannot be checked with "issubtype()"')
def visit_type_type(self, left: TypeType) -> bool:
right = self.right
if isinstance(right, TypeType):
return self._is_subtype(left.item, right.item)
if isinstance(right, CallableType):
if self.proper_subtype and not right.is_type_obj():
# We can't accept `Type[X]` as a *proper* subtype of Callable[P, X]
# since this will break transitivity of subtyping.
return False
# This is unsound, we don't check the __init__ signature.
return self._is_subtype(left.item, right.ret_type)
if isinstance(right, Instance):
if right.type.fullname in ["builtins.object", "builtins.type"]:
# TODO: Strictly speaking, the type builtins.type is considered equivalent to
# Type[Any]. However, this would break the is_proper_subtype check in
# conditional_types for cases like isinstance(x, type) when the type
# of x is Type[int]. It's unclear what's the right way to address this.
return True
item = left.item
if isinstance(item, TypeVarType):
item = get_proper_type(item.upper_bound)
if isinstance(item, Instance):
if right.type.is_protocol and is_protocol_implementation(
item, right, proper_subtype=self.proper_subtype, class_obj=True
):
return True
metaclass = item.type.metaclass_type
return metaclass is not None and self._is_subtype(metaclass, right)
return False
def visit_type_alias_type(self, left: TypeAliasType) -> bool:
assert False, f"This should be never called, got {left}"
T = TypeVar("T", bound=Type)
@contextmanager
def pop_on_exit(stack: list[tuple[T, T]], left: T, right: T) -> Iterator[None]:
stack.append((left, right))
yield
stack.pop()
def is_protocol_implementation(
left: Instance,
right: Instance,
proper_subtype: bool = False,
class_obj: bool = False,
skip: list[str] | None = None,
) -> bool:
"""Check whether 'left' implements the protocol 'right'.
If 'proper_subtype' is True, then check for a proper subtype.
Treat recursive protocols by using the 'assuming' structural subtype matrix
(in sparse representation, i.e. as a list of pairs (subtype, supertype)),
see also comment in nodes.TypeInfo. When we enter a check for classes
(A, P), defined as following::
class P(Protocol):
def f(self) -> P: ...
class A:
def f(self) -> A: ...