def map_type_from_supertype(typ: Type, sub_info: TypeInfo, super_info: TypeInfo) -> Type:
"""Map type variables in a type defined in a supertype context to be valid
in the subtype context. Assume that the result is unique; if more than
one type is possible, return one of the alternatives.
For example, assume
. class D(Generic[S]) ...
. class C(D[E[T]], Generic[T]) ...
Now S in the context of D would be mapped to E[T] in the context of C.
"""
# Create the type of self in subtype, of form t[a1, ...].
inst_type = self_type(sub_info)
if isinstance(inst_type, TupleType):
inst_type = inst_type.fallback
# Map the type of self to supertype. This gets us a description of the
# supertype type variables in terms of subtype variables, i.e. t[t1, ...]
# so that any type variables in tN are to be interpreted in subtype
# context.
inst_type = map_instance_to_supertype(inst_type, super_info)
# Finally expand the type variables in type with those in the previously
# constructed type. Note that both type and inst_type may have type
# variables, but in type they are interpreted in supertype context while
# in inst_type they are interpreted in subtype context. This works even if
# the names of type variables in supertype and subtype overlap.
return expand_type_by_instance(typ, inst_type)
def is_proper_subtype(t: Type, s: Type) -> bool:
"""Check if t is a proper subtype of s?
For proper subtypes, there's no need to rely on compatibility due to
Any types. Any instance type t is also a proper subtype of t.
"""
# FIX tuple types
if isinstance(t, Instance):
if isinstance(s, Instance):
if not t.type.has_base(s.type.fullname()):
return False
def check_argument(left: Type, right: Type, variance: int) -> bool:
if variance == COVARIANT:
return is_proper_subtype(left, right)
elif variance == CONTRAVARIANT:
return is_proper_subtype(right, left)
else:
return sametypes.is_same_type(left, right)
# Map left type to corresponding right instances.
t = map_instance_to_supertype(t, s.type)
return all(check_argument(ta, ra, tvar.variance) for ta, ra, tvar in
zip(t.args, s.args, s.type.defn.type_vars))
return False
else:
return sametypes.is_same_type(t, s)
def visit_instance(self, left: Instance) -> bool:
if left.type.fallback_to_any:
return True
right = self.right
if isinstance(right, TupleType) and right.fallback.type.is_enum:
return is_subtype(left, right.fallback)
if isinstance(right, Instance):
if right.type.is_cached_subtype_check(left, right):
return True
# NOTE: left.type.mro may be None in quick mode if there
# was an error somewhere.
if left.type.mro is not None:
for base in left.type.mro:
# TODO: Also pass recursively ignore_declared_variance
if base._promote and is_subtype(
base._promote, self.right, self.check_type_parameter,
ignore_pos_arg_names=self.ignore_pos_arg_names):
right.type.record_subtype_cache_entry(left, right)
return True
rname = right.type.fullname()
# Always try a nominal check if possible,
# there might be errors that a user wants to silence *once*.
if ((left.type.has_base(rname) or rname == 'builtins.object') and
not self.ignore_declared_variance):
# Map left type to corresponding right instances.
t = map_instance_to_supertype(left, right.type)
nominal = all(self.check_type_parameter(lefta, righta, tvar.variance)
for lefta, righta, tvar in
zip(t.args, right.args, right.type.defn.type_vars))
if nominal:
right.type.record_subtype_cache_entry(left, right)
return nominal
if right.type.is_protocol and is_protocol_implementation(left, right):
return True
return False
if isinstance(right, TypeType):
item = right.item
if isinstance(item, TupleType):
item = item.fallback
if is_named_instance(left, 'builtins.type'):
return is_subtype(TypeType(AnyType(TypeOfAny.special_form)), right)
if left.type.is_metaclass():
if isinstance(item, AnyType):
return True
if isinstance(item, Instance):
# Special-case enum since we don't have better way of expressing it
if (is_named_instance(left, 'enum.EnumMeta')
and is_named_instance(item, 'enum.Enum')):
return True
return is_named_instance(item, 'builtins.object')
if isinstance(right, CallableType):
# Special case: Instance can be a subtype of Callable.
call = find_member('__call__', left, left)
if call:
return is_subtype(call, right)
return False
else:
return False
def analyse_member_var_access(name: str, itype: Instance, info: TypeInfo,
node: Context, is_lvalue: bool, is_super: bool,
msg: MessageBuilder,
report_type: Type = None) -> Type:
"""Analyse attribute access that does not target a method.
This is logically part of analyse_member_access and the arguments are
similar.
"""
# It was not a method. Try looking up a variable.
v = lookup_member_var_or_accessor(info, name, is_lvalue)
vv = v
if isinstance(vv, Decorator):
# The associated Var node of a decorator contains the type.
v = vv.var
if isinstance(v, Var):
# Found a member variable.
var = v
itype = map_instance_to_supertype(itype, var.info)
if var.type:
t = expand_type_by_instance(var.type, itype)
if var.is_initialized_in_class and isinstance(t, FunctionLike):
if is_lvalue:
if var.is_property:
msg.read_only_property(name, info, node)
else:
msg.cant_assign_to_method(node)
if not var.is_staticmethod:
# Class-level function objects and classmethods become bound
# methods: the former to the instance, the latter to the
# class.
functype = cast(FunctionLike, t)
check_method_type(functype, itype, node, msg)
signature = method_type(functype)
if var.is_property:
# A property cannot have an overloaded type => the cast
# is fine.
return cast(Callable, signature).ret_type
else:
return signature
return t
else:
if not var.is_ready:
msg.cannot_determine_type(var.name(), node)
# Implicit 'Any' type.
return AnyType()
elif isinstance(v, FuncDef):
assert False, "Did not expect a function"
# Could not find the member.
if is_super:
msg.undefined_in_superclass(name, node)
return AnyType()
else:
return msg.has_no_attr(report_type or itype, name, node)
def visit_instance(self, template: Instance) -> List[Constraint]:
actual = self.actual
res = [] # type: List[Constraint]
if isinstance(actual, Instance):
instance = actual
if (self.direction == SUBTYPE_OF and
template.type.has_base(instance.type.fullname())):
mapped = map_instance_to_supertype(template, instance.type)
for i in range(len(instance.args)):
# The constraints for generic type parameters are
# invariant. Include constraints from both directions
# to achieve the effect.
res.extend(infer_constraints(
mapped.args[i], instance.args[i], self.direction))
res.extend(infer_constraints(
mapped.args[i], instance.args[i], neg_op(self.direction)))
return res
elif (self.direction == SUPERTYPE_OF and
instance.type.has_base(template.type.fullname())):
mapped = map_instance_to_supertype(instance, template.type)
for j in range(len(template.args)):
# The constraints for generic type parameters are
# invariant.
res.extend(infer_constraints(
template.args[j], mapped.args[j], self.direction))
res.extend(infer_constraints(
template.args[j], mapped.args[j], neg_op(self.direction)))
return res
if isinstance(actual, AnyType):
# IDEA: Include both ways, i.e. add negation as well?
return self.infer_against_any(template.args)
if (isinstance(actual, TupleType) and
(is_named_instance(template, 'typing.Iterable') or
is_named_instance(template, 'typing.Container') or
is_named_instance(template, 'typing.Sequence') or
is_named_instance(template, 'typing.Reversible'))
and self.direction == SUPERTYPE_OF):
for item in actual.items:
cb = infer_constraints(template.args[0], item, SUPERTYPE_OF)
res.extend(cb)
return res
else:
return []
def _find_simplecdata_base_arg(tp: Instance, api: 'mypy.plugin.CheckerPluginInterface'
) -> Optional[Type]:
"""Try to find a parametrized _SimpleCData in tp's bases and return its single type argument.
None is returned if _SimpleCData appears nowhere in tp's (direct or indirect) bases.
"""
if tp.type.has_base('ctypes._SimpleCData'):
simplecdata_base = map_instance_to_supertype(tp,
api.named_generic_type('ctypes._SimpleCData', [AnyType(TypeOfAny.special_form)]).type)
assert len(simplecdata_base.args) == 1, '_SimpleCData takes exactly one type argument'
return simplecdata_base.args[0]
return None
def analyze_member_var_access(name: str, itype: Instance, info: TypeInfo,
node: Context, is_lvalue: bool, is_super: bool,
builtin_type: Callable[[str], Instance],
not_ready_callback: Callable[[str, Context], None],
msg: MessageBuilder,
original_type: Type,
chk: 'mypy.checker.TypeChecker' = None) -> Type:
"""Analyse attribute access that does not target a method.
This is logically part of analyze_member_access and the arguments are similar.
original_type is the type of E in the expression E.var
"""
# It was not a method. Try looking up a variable.
v = lookup_member_var_or_accessor(info, name, is_lvalue)
vv = v
if isinstance(vv, Decorator):
# The associated Var node of a decorator contains the type.
v = vv.var
if isinstance(v, Var):
return analyze_var(name, v, itype, info, node, is_lvalue, msg,
original_type, not_ready_callback)
elif isinstance(v, FuncDef):
assert False, "Did not expect a function"
elif not v and name not in ['__getattr__', '__setattr__', '__getattribute__']:
if not is_lvalue:
for method_name in ('__getattribute__', '__getattr__'):
method = info.get_method(method_name)
# __getattribute__ is defined on builtins.object and returns Any, so without
# the guard this search will always find object.__getattribute__ and conclude
# that the attribute exists
if method and method.info.fullname() != 'builtins.object':
function = function_type(method, builtin_type('builtins.function'))
bound_method = bind_self(function, original_type)
typ = map_instance_to_supertype(itype, method.info)
getattr_type = expand_type_by_instance(bound_method, typ)
if isinstance(getattr_type, CallableType):
return getattr_type.ret_type
if itype.type.fallback_to_any:
return AnyType()
# Could not find the member.
if is_super:
msg.undefined_in_superclass(name, node)
return AnyType()
else:
if chk and chk.should_suppress_optional_error([itype]):
return AnyType()
return msg.has_no_attr(original_type, name, node)
def analyze_member_var_access(
name: str,
itype: Instance,
info: TypeInfo,
node: Context,
is_lvalue: bool,
is_super: bool,
builtin_type: Callable[[str], Instance],
not_ready_callback: Callable[[str, Context], None],
msg: MessageBuilder,
report_type: Type = None,
chk: "mypy.checker.TypeChecker" = None,
) -> Type:
"""Analyse attribute access that does not target a method.
This is logically part of analyze_member_access and the arguments are
similar.
"""
# It was not a method. Try looking up a variable.
v = lookup_member_var_or_accessor(info, name, is_lvalue)
vv = v
if isinstance(vv, Decorator):
# The associated Var node of a decorator contains the type.
v = vv.var
if isinstance(v, Var):
return analyze_var(name, v, itype, info, node, is_lvalue, msg, not_ready_callback)
elif isinstance(v, FuncDef):
assert False, "Did not expect a function"
elif not v and name not in ["__getattr__", "__setattr__"]:
if not is_lvalue:
method = info.get_method("__getattr__")
if method:
typ = map_instance_to_supertype(itype, method.info)
getattr_type = expand_type_by_instance(
method_type_with_fallback(method, builtin_type("builtins.function")), typ
)
if isinstance(getattr_type, CallableType):
return getattr_type.ret_type
if itype.type.fallback_to_any:
return AnyType()
# Could not find the member.
if is_super:
msg.undefined_in_superclass(name, node)
return AnyType()
else:
if chk and chk.should_suppress_optional_error([itype]):
return AnyType()
return msg.has_no_attr(report_type or itype, name, node)
def analyze_var(
name: str,
var: Var,
itype: Instance,
info: TypeInfo,
node: Context,
is_lvalue: bool,
msg: MessageBuilder,
not_ready_callback: Callable[[str, Context], None],
) -> Type:
"""Analyze access to an attribute via a Var node.
This is conceptually part of analyze_member_access and the arguments are similar.
"""
# Found a member variable.
itype = map_instance_to_supertype(itype, var.info)
typ = var.type
if typ:
if isinstance(typ, PartialType):
return handle_partial_attribute_type(typ, is_lvalue, msg, var)
t = expand_type_by_instance(typ, itype)
if is_lvalue and var.is_property and not var.is_settable_property:
# TODO allow setting attributes in subclass (although it is probably an error)
msg.read_only_property(name, info, node)
if var.is_initialized_in_class and isinstance(t, FunctionLike):
if is_lvalue:
if var.is_property:
if not var.is_settable_property:
msg.read_only_property(name, info, node)
else:
msg.cant_assign_to_method(node)
if not var.is_staticmethod:
# Class-level function objects and classmethods become bound
# methods: the former to the instance, the latter to the
# class.
functype = t
check_method_type(functype, itype, var.is_classmethod, node, msg)
signature = method_type(functype)
if var.is_property:
# A property cannot have an overloaded type => the cast
# is fine.
return cast(CallableType, signature).ret_type
else:
return signature
return t
else:
if not var.is_ready:
not_ready_callback(var.name(), node)
# Implicit 'Any' type.
return AnyType()
def join_instances_via_supertype(t: Instance, s: Instance) -> Type:
# Give preference to joins via duck typing relationship, so that
# join(int, float) == float, for example.
if t.type._promote and is_subtype(t.type._promote, s):
return join_types(t.type._promote, s)
elif s.type._promote and is_subtype(s.type._promote, t):
return join_types(t, s.type._promote)
res = s
mapped = map_instance_to_supertype(t, t.type.bases[0].type)
join = join_instances(mapped, res)
# If the join failed, fail. This is a defensive measure (this might
# never happen).
if isinstance(join, ErrorType):
return join
# Now the result must be an Instance, so the cast below cannot fail.
res = cast(Instance, join)
return res
def analyze_instance_member_access(name: str,
typ: Instance,
mx: MemberContext,
override_info: Optional[TypeInfo]) -> Type:
if name == '__init__' and not mx.is_super:
# Accessing __init__ in statically typed code would compromise
# type safety unless used via super().
mx.msg.fail(message_registry.CANNOT_ACCESS_INIT, mx.context)
return AnyType(TypeOfAny.from_error)
# The base object has an instance type.
info = typ.type
if override_info:
info = override_info
if (state.find_occurrences and
info.name() == state.find_occurrences[0] and
name == state.find_occurrences[1]):
mx.msg.note("Occurrence of '{}.{}'".format(*state.find_occurrences), mx.context)
# Look up the member. First look up the method dictionary.
method = info.get_method(name)
if method:
if method.is_property:
assert isinstance(method, OverloadedFuncDef)
first_item = cast(Decorator, method.items[0])
return analyze_var(name, first_item.var, typ, info, mx)
if mx.is_lvalue:
mx.msg.cant_assign_to_method(mx.context)
signature = function_type(method, mx.builtin_type('builtins.function'))
signature = freshen_function_type_vars(signature)
if name == '__new__':
# __new__ is special and behaves like a static method -- don't strip
# the first argument.
pass
else:
signature = bind_self(signature, mx.original_type)
typ = map_instance_to_supertype(typ, method.info)
member_type = expand_type_by_instance(signature, typ)
freeze_type_vars(member_type)
return member_type
else:
# Not a method.
return analyze_member_var_access(name, typ, info, mx)
def join_instances_via_supertype(t: Instance, s: Instance) -> Type:
# Give preference to joins via duck typing relationship, so that
# join(int, float) == float, for example.
if t.type._promote and is_subtype(t.type._promote, s):
return join_types(t.type._promote, s)
elif s.type._promote and is_subtype(s.type._promote, t):
return join_types(t, s.type._promote)
# Compute the "best" supertype of t when joined with s.
# The definition of "best" may evolve; for now it is the one with
# the longest MRO. Ties are broken by using the earlier base.
best = None # type: Type
for base in t.type.bases:
mapped = map_instance_to_supertype(t, base.type)
res = join_instances(mapped, s)
if best is None or is_better(res, best):
best = res
assert best is not None
return best
def join_instances_via_supertype(t: Instance, s: Instance) -> Type:
# Give preference to joins via duck typing relationship, so that
# join(int, float) == float, for example.
if t.type._promote and is_subtype(t.type._promote, s):
return join_types(t.type._promote, s)
elif s.type._promote and is_subtype(s.type._promote, t):
return join_types(t, s.type._promote)
# Compute the "best" supertype of t when joined with s.
# The definition of "best" may evolve; for now it is the one with
# the longest MRO. Ties are broken by using the earlier base.
best = None # type: Type
for base in t.type.bases:
mapped = map_instance_to_supertype(t, base.type)
res = join_instances(mapped, s)
if best is None or is_better(res, best):
best = res
assert best is not None
return best
def visit_instance(self, left: Instance) -> bool:
right = self.right
if isinstance(right, Instance):
if left.type._promote and is_subtype(left.type._promote, self.right, self.check_type_parameter):
return True
rname = right.type.fullname()
if not left.type.has_base(rname) and rname != "builtins.object":
return False
# Map left type to corresponding right instances.
t = map_instance_to_supertype(left, right.type)
return all(
self.check_type_parameter(lefta, righta, tvar.variance)
for lefta, righta, tvar in zip(t.args, right.args, right.type.defn.type_vars)
)
else:
return False
def visit_instance(self, left: Instance) -> bool:
if left.type.fallback_to_any:
return True
right = self.right
if isinstance(right, TupleType) and right.fallback.type.is_enum:
return is_subtype(left, right.fallback)
if isinstance(right, Instance):
# NOTO: left.type.mro may be None in quick mode if there
# was an error somewhere.
if left.type.mro is not None:
for base in left.type.mro:
if base._promote and is_subtype(
base._promote,
self.right,
self.check_type_parameter,
ignore_pos_arg_names=self.ignore_pos_arg_names):
return True
rname = right.type.fullname()
if not left.type.has_base(rname) and rname != 'builtins.object':
return False
# Map left type to corresponding right instances.
t = map_instance_to_supertype(left, right.type)
return all(
self.check_type_parameter(lefta, righta, tvar.variance)
for lefta, righta, tvar in zip(t.args, right.args,
right.type.defn.type_vars))
if isinstance(right, TypeType):
item = right.item
if isinstance(item, TupleType):
item = item.fallback
if is_named_instance(left, 'builtins.type'):
return is_subtype(TypeType(AnyType()), right)
if left.type.is_metaclass():
if isinstance(item, AnyType):
return True
if isinstance(item, Instance):
# Special-case enum since we don't have better way of expressing it
if (is_named_instance(left, 'enum.EnumMeta')
and is_named_instance(item, 'enum.Enum')):
return True
return is_named_instance(item, 'builtins.object')
return False
def analyze_member_var_access(name: str,
itype: Instance,
info: TypeInfo,
node: Context,
is_lvalue: bool,
is_super: bool,
builtin_type: Callable[[str], Instance],
msg: MessageBuilder,
report_type: Type = None) -> Type:
"""Analyse attribute access that does not target a method.
This is logically part of analyze_member_access and the arguments are
similar.
"""
# It was not a method. Try looking up a variable.
v = lookup_member_var_or_accessor(info, name, is_lvalue)
vv = v
if isinstance(vv, Decorator):
# The associated Var node of a decorator contains the type.
v = vv.var
if isinstance(v, Var):
return analyze_var(name, v, itype, info, node, is_lvalue, msg)
elif isinstance(v, FuncDef):
assert False, "Did not expect a function"
elif not v and name not in ['__getattr__', '__setattr__']:
if not is_lvalue:
method = info.get_method('__getattr__')
if method:
typ = map_instance_to_supertype(itype, method.info)
getattr_type = expand_type_by_instance(
method_type_with_fallback(
method, builtin_type('builtins.function')), typ)
if isinstance(getattr_type, CallableType):
return getattr_type.ret_type
# Could not find the member.
if is_super:
msg.undefined_in_superclass(name, node)
return AnyType()
else:
return msg.has_no_attr(report_type or itype, name, node)
def analyze_instance_member_access(name: str, typ: Instance, mx: MemberContext,
override_info: Optional[TypeInfo]) -> Type:
if name == '__init__' and not mx.is_super:
# Accessing __init__ in statically typed code would compromise
# type safety unless used via super().
mx.msg.fail(messages.CANNOT_ACCESS_INIT, mx.context)
return AnyType(TypeOfAny.from_error)
# The base object has an instance type.
info = typ.type
if override_info:
info = override_info
if (state.find_occurrences and info.name() == state.find_occurrences[0]
and name == state.find_occurrences[1]):
mx.msg.note("Occurrence of '{}.{}'".format(*state.find_occurrences),
mx.context)
# Look up the member. First look up the method dictionary.
method = info.get_method(name)
if method:
if method.is_property:
assert isinstance(method, OverloadedFuncDef)
first_item = cast(Decorator, method.items[0])
return analyze_var(name, first_item.var, typ, info, mx)
if mx.is_lvalue:
mx.msg.cant_assign_to_method(mx.context)
signature = function_type(method, mx.builtin_type('builtins.function'))
signature = freshen_function_type_vars(signature)
if name == '__new__':
# __new__ is special and behaves like a static method -- don't strip
# the first argument.
pass
else:
signature = bind_self(signature, mx.original_type)
typ = map_instance_to_supertype(typ, method.info)
member_type = expand_type_by_instance(signature, typ)
freeze_type_vars(member_type)
return member_type
else:
# Not a method.
return analyze_member_var_access(name, typ, info, mx)
def visit_instance(self, left: Instance) -> bool:
right = self.right
if isinstance(right, Instance):
if left.type._promote and is_subtype(
left.type._promote, self.right, self.check_type_parameter):
return True
rname = right.type.fullname()
if not left.type.has_base(rname) and rname != 'builtins.object':
return False
# Map left type to corresponding right instances.
t = map_instance_to_supertype(left, right.type)
return all(
self.check_type_parameter(lefta, righta, tvar.variance)
for lefta, righta, tvar in zip(t.args, right.args,
right.type.defn.type_vars))
else:
return False
def visit_instance(self, left: Instance) -> bool:
if left.type.fallback_to_any:
return True
right = self.right
if isinstance(right, TupleType) and right.fallback.type.is_enum:
return is_subtype(left, right.fallback)
if isinstance(right, Instance):
# NOTO: left.type.mro may be None in quick mode if there
# was an error somewhere.
if left.type.mro is not None:
for base in left.type.mro:
if base._promote and is_subtype(
base._promote,
self.right,
self.check_type_parameter,
ignore_pos_arg_names=self.ignore_pos_arg_names):
return True
rname = right.type.fullname()
if not left.type.has_base(rname) and rname != 'builtins.object':
return False
# Map left type to corresponding right instances.
t = map_instance_to_supertype(left, right.type)
return all(
self.check_type_parameter(lefta, righta, tvar.variance)
for lefta, righta, tvar in zip(t.args, right.args,
right.type.defn.type_vars))
if isinstance(right, TypeType):
item = right.item
if isinstance(item, TupleType):
item = item.fallback
if isinstance(item, Instance):
return is_subtype(left, item.type.metaclass_type)
elif isinstance(item, AnyType):
# Special case: all metaclasses are subtypes of Type[Any]
mro = left.type.mro or []
return any(base.fullname() == 'builtins.type' for base in mro)
else:
return False
else:
return False
def analyze_var(name: str, var: Var, itype: Instance, info: TypeInfo,
node: Context, is_lvalue: bool, msg: MessageBuilder,
not_ready_callback: Callable[[str, Context], None]) -> Type:
"""Analyze access to an attribute via a Var node.
This is conceptually part of analyze_member_access and the arguments are similar.
"""
# Found a member variable.
itype = map_instance_to_supertype(itype, var.info)
typ = var.type
if typ:
if isinstance(typ, PartialType):
return handle_partial_attribute_type(typ, is_lvalue, msg, var)
t = expand_type_by_instance(typ, itype)
if var.is_initialized_in_class and isinstance(t, FunctionLike):
if is_lvalue:
if var.is_property:
if not var.is_settable_property:
msg.read_only_property(name, info, node)
else:
msg.cant_assign_to_method(node)
if not var.is_staticmethod:
# Class-level function objects and classmethods become bound
# methods: the former to the instance, the latter to the
# class.
functype = cast(FunctionLike, t)
check_method_type(functype, itype, var.is_classmethod, node,
msg)
signature = method_type(functype)
if var.is_property:
# A property cannot have an overloaded type => the cast
# is fine.
return cast(CallableType, signature).ret_type
else:
return signature
return t
else:
if not var.is_ready:
not_ready_callback(var.name(), node)
# Implicit 'Any' type.
return AnyType()
def visit_instance(self, left: Instance) -> bool:
right = self.right
if isinstance(right, Instance):
if left.type._promote and is_subtype(left.type._promote,
self.right):
return True
rname = right.type.fullname()
if not left.type.has_base(rname) and rname != 'builtins.object':
return False
# Map left type to corresponding right instances.
t = map_instance_to_supertype(left, right.type)
if not is_immutable(right):
result = all(is_equivalent(ta, ra) for (ta, ra) in
zip(t.args, right.args))
else:
result = all(is_subtype(ta, ra) for (ta, ra) in
zip(t.args, right.args))
return result
else:
return False
def visit_instance(self, left: Instance) -> bool:
right = self.right
if isinstance(right, Instance):
if left.type._promote and is_subtype(left.type._promote,
self.right):
return True
rname = right.type.fullname()
if not left.type.has_base(rname) and rname != 'builtins.object':
return False
# Map left type to corresponding right instances.
t = map_instance_to_supertype(left, right.type)
if not is_immutable(right):
result = all(is_equivalent(ta, ra) for (ta, ra) in
zip(t.args, right.args))
else:
result = all(is_subtype(ta, ra) for (ta, ra) in
zip(t.args, right.args))
return result
else:
return False
def is_proper_subtype(t: Type, s: Type) -> bool:
"""Check if t is a proper subtype of s?
For proper subtypes, there's no need to rely on compatibility due to
Any types. Any instance type t is also a proper subtype of t.
"""
# FIX tuple types
if isinstance(t, Instance):
if isinstance(s, Instance):
if not t.type.has_base(s.type.fullname()):
return False
t = map_instance_to_supertype(t, s.type)
if not is_immutable(s):
return all(sametypes.is_same_type(ta, ra) for (ta, ra) in
zip(t.args, s.args))
else:
return all(is_proper_subtype(ta, ra) for (ta, ra) in
zip(t.args, s.args))
return False
else:
return sametypes.is_same_type(t, s)
def is_proper_subtype(t: Type, s: Type) -> bool:
"""Check if t is a proper subtype of s?
For proper subtypes, there's no need to rely on compatibility due to
Any types. Any instance type t is also a proper subtype of t.
"""
# FIX tuple types
if isinstance(t, Instance):
if isinstance(s, Instance):
if not t.type.has_base(s.type.fullname()):
return False
t = map_instance_to_supertype(t, s.type)
if not is_immutable(s):
return all(sametypes.is_same_type(ta, ra) for (ta, ra) in
zip(t.args, s.args))
else:
return all(is_proper_subtype(ta, ra) for (ta, ra) in
zip(t.args, s.args))
return False
else:
return sametypes.is_same_type(t, s)
def visit_instance(self, left: Instance) -> bool:
right = self.right
if isinstance(right, Instance):
if TypeState.is_cached_proper_subtype_check(left, right):
return True
for base in left.type.mro:
if base._promote and is_proper_subtype(base._promote, right):
TypeState.record_proper_subtype_cache_entry(left, right)
return True
if left.type.has_base(right.type.fullname()):
def check_argument(leftarg: Type, rightarg: Type,
variance: int) -> bool:
if variance == COVARIANT:
return is_proper_subtype(leftarg, rightarg)
elif variance == CONTRAVARIANT:
return is_proper_subtype(rightarg, leftarg)
else:
return sametypes.is_same_type(leftarg, rightarg)
# Map left type to corresponding right instances.
left = map_instance_to_supertype(left, right.type)
nominal = all(
check_argument(ta, ra, tvar.variance) for ta, ra, tvar in
zip(left.args, right.args, right.type.defn.type_vars))
if nominal:
TypeState.record_proper_subtype_cache_entry(left, right)
return nominal
if (right.type.is_protocol and is_protocol_implementation(
left, right, proper_subtype=True)):
return True
return False
if isinstance(right, CallableType):
call = find_member('__call__', left, left)
if call:
return is_proper_subtype(call, right)
return False
return False
def _extract_python_type_from_typeengine(api: SemanticAnalyzerPluginInterface,
node: TypeInfo,
type_args) -> Instance:
if node.fullname == "sqlalchemy.sql.sqltypes.Enum" and type_args:
first_arg = type_args[0]
if isinstance(first_arg, NameExpr) and isinstance(
first_arg.node, TypeInfo):
for base_ in first_arg.node.mro:
if base_.fullname == "enum.Enum":
return Instance(first_arg.node, [])
# TODO: support other pep-435 types here
else:
n = api.lookup_fully_qualified("builtins.str")
return Instance(n.node, [])
assert node.has_base("sqlalchemy.sql.type_api.TypeEngine"), (
"could not extract Python type from node: %s" % node)
type_engine = map_instance_to_supertype(
Instance(node, []),
api.modules["sqlalchemy.sql.type_api"].names["TypeEngine"].node,
)
return type_engine.args[-1]
def analyze_var(
name: str, var: Var, itype: Instance, info: TypeInfo, node: Context, is_lvalue: bool, msg: MessageBuilder
) -> Type:
"""Analyze access to an attribute via a Var node.
This is conceptually part of analyze_member_access and the arguments are similar.
"""
# Found a member variable.
itype = map_instance_to_supertype(itype, var.info)
if var.type:
t = expand_type_by_instance(var.type, itype)
if var.is_initialized_in_class and isinstance(t, FunctionLike):
if is_lvalue:
if var.is_property:
if not var.is_settable_property:
msg.read_only_property(name, info, node)
else:
msg.cant_assign_to_method(node)
if not var.is_staticmethod:
# Class-level function objects and classmethods become bound
# methods: the former to the instance, the latter to the
# class.
functype = cast(FunctionLike, t)
check_method_type(functype, itype, node, msg)
signature = method_type(functype)
if var.is_property:
# A property cannot have an overloaded type => the cast
# is fine.
return cast(CallableType, signature).ret_type
else:
return signature
return t
else:
if not var.is_ready:
msg.cannot_determine_type(var.name(), node)
# Implicit 'Any' type.
return AnyType()
def get_expr_by_position(self, pos: int, call: CallExpr) -> Optional[Expression]:
"""Get positional replacement expression from '{0}, {1}'.format(x, y, ...) call.
If the type is from *args, return TempNode(<item type>). Return None in case of
an error.
"""
pos_args = [arg for arg, kind in zip(call.args, call.arg_kinds) if kind == ARG_POS]
if pos < len(pos_args):
return pos_args[pos]
star_args = [arg for arg, kind in zip(call.args, call.arg_kinds) if kind == ARG_STAR]
if not star_args:
return None
# Fall back to *args when present in call.
star_arg = star_args[0]
varargs_type = get_proper_type(self.chk.type_map[star_arg])
if (not isinstance(varargs_type, Instance) or not
varargs_type.type.has_base('typing.Sequence')):
# Error should be already reported.
return TempNode(AnyType(TypeOfAny.special_form))
iter_info = self.chk.named_generic_type('typing.Sequence',
[AnyType(TypeOfAny.special_form)]).type
return TempNode(map_instance_to_supertype(varargs_type, iter_info).args[0])
def get_expr_by_name(self, key: str, call: CallExpr) -> Optional[Expression]:
"""Get named replacement expression from '{name}'.format(name=...) call.
If the type is from **kwargs, return TempNode(<item type>). Return None in case of
an error.
"""
named_args = [arg for arg, kind, name in zip(call.args, call.arg_kinds, call.arg_names)
if kind == ARG_NAMED and name == key]
if named_args:
return named_args[0]
star_args_2 = [arg for arg, kind in zip(call.args, call.arg_kinds) if kind == ARG_STAR2]
if not star_args_2:
return None
star_arg_2 = star_args_2[0]
kwargs_type = get_proper_type(self.chk.type_map[star_arg_2])
if (not isinstance(kwargs_type, Instance) or not
kwargs_type.type.has_base('typing.Mapping')):
# Error should be already reported.
return TempNode(AnyType(TypeOfAny.special_form))
any_type = AnyType(TypeOfAny.special_form)
mapping_info = self.chk.named_generic_type('typing.Mapping',
[any_type, any_type]).type
return TempNode(map_instance_to_supertype(kwargs_type, mapping_info).args[1])
def visit_instance(self, left: Instance) -> bool:
if left.type.fallback_to_any:
return True
right = self.right
if isinstance(right, TupleType) and right.fallback.type.is_enum:
return is_subtype(left, right.fallback)
if isinstance(right, Instance):
if left.type._promote and is_subtype(
left.type._promote, self.right, self.check_type_parameter,
ignore_pos_arg_names=self.ignore_pos_arg_names):
return True
rname = right.type.fullname()
if not left.type.has_base(rname) and rname != 'builtins.object':
return False
# Map left type to corresponding right instances.
t = map_instance_to_supertype(left, right.type)
return all(self.check_type_parameter(lefta, righta, tvar.variance)
for lefta, righta, tvar in
zip(t.args, right.args, right.type.defn.type_vars))
else:
return False
def visit_mapping_pattern(self, o: MappingPattern) -> PatternType:
current_type = get_proper_type(self.type_context[-1])
can_match = True
captures: Dict[Expression, Type] = {}
for key, value in zip(o.keys, o.values):
inner_type = self.get_mapping_item_type(o, current_type, key)
if inner_type is None:
can_match = False
inner_type = self.chk.named_type("builtins.object")
pattern_type = self.accept(value, inner_type)
if is_uninhabited(pattern_type.type):
can_match = False
else:
self.update_type_map(captures, pattern_type.captures)
if o.rest is not None:
mapping = self.chk.named_type("typing.Mapping")
if is_subtype(current_type, mapping) and isinstance(
current_type, Instance):
mapping_inst = map_instance_to_supertype(
current_type, mapping.type)
dict_typeinfo = self.chk.lookup_typeinfo("builtins.dict")
dict_type = fill_typevars(dict_typeinfo)
rest_type = expand_type_by_instance(dict_type, mapping_inst)
else:
object_type = self.chk.named_type("builtins.object")
rest_type = self.chk.named_generic_type(
"builtins.dict", [object_type, object_type])
captures[o.rest] = rest_type
if can_match:
# We can't narrow the type here, as Mapping key is invariant.
new_type = self.type_context[-1]
else:
new_type = UninhabitedType()
return PatternType(new_type, current_type, captures)
def find_node_type(node: Union[Var, FuncBase], itype: Instance, subtype: Type) -> Type:
"""Find type of a variable or method 'node' (maybe also a decorated method).
Apply type arguments from 'itype', and bind 'self' to 'subtype'.
"""
from mypy.checkmember import bind_self
if isinstance(node, FuncBase):
typ = function_type(node,
fallback=Instance(itype.type.mro[-1], [])) # type: Optional[Type]
else:
typ = node.type
if typ is None:
return AnyType(TypeOfAny.from_error)
# We don't need to bind 'self' for static methods, since there is no 'self'.
if isinstance(node, FuncBase) or isinstance(typ, FunctionLike) and not node.is_staticmethod:
assert isinstance(typ, FunctionLike)
signature = bind_self(typ, subtype)
if node.is_property:
assert isinstance(signature, CallableType)
typ = signature.ret_type
else:
typ = signature
itype = map_instance_to_supertype(itype, node.info)
typ = expand_type_by_instance(typ, itype)
return typ
def find_node_type(node: Union[Var, FuncBase], itype: Instance, subtype: Type) -> Type:
"""Find type of a variable or method 'node' (maybe also a decorated method).
Apply type arguments from 'itype', and bind 'self' to 'subtype'.
"""
from mypy.checkmember import bind_self
if isinstance(node, FuncBase):
typ = function_type(node,
fallback=Instance(itype.type.mro[-1], [])) # type: Optional[Type]
else:
typ = node.type
if typ is None:
return AnyType(TypeOfAny.from_error)
# We don't need to bind 'self' for static methods, since there is no 'self'.
if isinstance(node, FuncBase) or isinstance(typ, FunctionLike) and not node.is_staticmethod:
assert isinstance(typ, FunctionLike)
signature = bind_self(typ, subtype)
if node.is_property:
assert isinstance(signature, CallableType)
typ = signature.ret_type
else:
typ = signature
itype = map_instance_to_supertype(itype, node.info)
typ = expand_type_by_instance(typ, itype)
return typ
def visit_instance(self, left: Instance) -> bool:
right = self.right
if isinstance(right, Instance):
if right.type.is_cached_subtype_check(left, right, proper_subtype=True):
return True
for base in left.type.mro:
if base._promote and is_proper_subtype(base._promote, right):
right.type.record_subtype_cache_entry(left, right, proper_subtype=True)
return True
if left.type.has_base(right.type.fullname()):
def check_argument(leftarg: Type, rightarg: Type, variance: int) -> bool:
if variance == COVARIANT:
return is_proper_subtype(leftarg, rightarg)
elif variance == CONTRAVARIANT:
return is_proper_subtype(rightarg, leftarg)
else:
return sametypes.is_same_type(leftarg, rightarg)
# Map left type to corresponding right instances.
left = map_instance_to_supertype(left, right.type)
nominal = all(check_argument(ta, ra, tvar.variance) for ta, ra, tvar in
zip(left.args, right.args, right.type.defn.type_vars))
if nominal:
right.type.record_subtype_cache_entry(left, right, proper_subtype=True)
return nominal
if (right.type.is_protocol and
is_protocol_implementation(left, right, proper_subtype=True)):
return True
return False
if isinstance(right, CallableType):
call = find_member('__call__', left, left)
if call:
return is_proper_subtype(call, right)
return False
return False
def visit_instance(self, left: Instance) -> bool:
right = self.right
if isinstance(right, Instance):
for base in left.type.mro:
if base._promote and is_proper_subtype(base._promote, right):
return True
if not left.type.has_base(right.type.fullname()):
return False
def check_argument(leftarg: Type, rightarg: Type, variance: int) -> bool:
if variance == COVARIANT:
return is_proper_subtype(leftarg, rightarg)
elif variance == CONTRAVARIANT:
return is_proper_subtype(rightarg, leftarg)
else:
return sametypes.is_same_type(leftarg, rightarg)
# Map left type to corresponding right instances.
left = map_instance_to_supertype(left, right.type)
return all(check_argument(ta, ra, tvar.variance) for ta, ra, tvar in
zip(left.args, right.args, right.type.defn.type_vars))
return False
def analyze_member_var_access(name: str, itype: Instance, info: TypeInfo,
node: Context, is_lvalue: bool, is_super: bool,
builtin_type: Callable[[str], Instance],
not_ready_callback: Callable[[str, Context],
None],
msg: MessageBuilder, original_type: Type,
chk: 'mypy.checker.TypeChecker') -> Type:
"""Analyse attribute access that does not target a method.
This is logically part of analyze_member_access and the arguments are similar.
original_type is the type of E in the expression E.var
"""
# It was not a method. Try looking up a variable.
v = lookup_member_var_or_accessor(info, name, is_lvalue)
vv = v
if isinstance(vv, Decorator):
# The associated Var node of a decorator contains the type.
v = vv.var
if isinstance(vv, TypeInfo):
# If the associated variable is a TypeInfo synthesize a Var node for
# the purposes of type checking. This enables us to type check things
# like accessing class attributes on an inner class.
v = Var(name, type=type_object_type(vv, builtin_type))
v.info = info
if isinstance(v, Var):
return analyze_var(name,
v,
itype,
info,
node,
is_lvalue,
msg,
original_type,
not_ready_callback,
chk=chk)
elif isinstance(v, FuncDef):
assert False, "Did not expect a function"
elif not v and name not in [
'__getattr__', '__setattr__', '__getattribute__'
]:
if not is_lvalue:
for method_name in ('__getattribute__', '__getattr__'):
method = info.get_method(method_name)
# __getattribute__ is defined on builtins.object and returns Any, so without
# the guard this search will always find object.__getattribute__ and conclude
# that the attribute exists
if method and method.info.fullname() != 'builtins.object':
function = function_type(method,
builtin_type('builtins.function'))
bound_method = bind_self(function, original_type)
typ = map_instance_to_supertype(itype, method.info)
getattr_type = expand_type_by_instance(bound_method, typ)
if isinstance(getattr_type, CallableType):
return getattr_type.ret_type
else:
setattr_meth = info.get_method('__setattr__')
if setattr_meth and setattr_meth.info.fullname(
) != 'builtins.object':
setattr_func = function_type(setattr_meth,
builtin_type('builtins.function'))
bound_type = bind_self(setattr_func, original_type)
typ = map_instance_to_supertype(itype, setattr_meth.info)
setattr_type = expand_type_by_instance(bound_type, typ)
if isinstance(
setattr_type,
CallableType) and len(setattr_type.arg_types) > 0:
return setattr_type.arg_types[-1]
if itype.type.fallback_to_any:
return AnyType(TypeOfAny.special_form)
# Could not find the member.
if is_super:
msg.undefined_in_superclass(name, node)
return AnyType(TypeOfAny.from_error)
else:
if chk and chk.should_suppress_optional_error([itype]):
return AnyType(TypeOfAny.from_error)
return msg.has_no_attr(original_type, itype, name, node)
def typed_dict_mapping_overlap(
left: ProperType, right: ProperType,
overlapping: Callable[[Type, Type], bool]) -> bool:
"""Check if a TypedDict type is overlapping with a Mapping.
The basic logic here consists of two rules:
* A TypedDict with some required keys is overlapping with Mapping[str, <some type>]
if and only if every key type is overlapping with <some type>. For example:
- TypedDict(x=int, y=str) overlaps with Dict[str, Union[str, int]]
- TypedDict(x=int, y=str) doesn't overlap with Dict[str, int]
Note that any additional non-required keys can't change the above result.
* A TypedDict with no required keys overlaps with Mapping[str, <some type>] if and
only if at least one of key types overlaps with <some type>. For example:
- TypedDict(x=str, y=str, total=False) overlaps with Dict[str, str]
- TypedDict(x=str, y=str, total=False) doesn't overlap with Dict[str, int]
- TypedDict(x=int, y=str, total=False) overlaps with Dict[str, str]
As usual empty, dictionaries lie in a gray area. In general, List[str] and List[str]
are considered non-overlapping despite empty list belongs to both. However, List[int]
and List[<nothing>] are considered overlapping.
So here we follow the same logic: a TypedDict with no required keys is considered
non-overlapping with Mapping[str, <some type>], but is considered overlapping with
Mapping[<nothing>, <nothing>]. This way we avoid false positives for overloads, and also
avoid false positives for comparisons like SomeTypedDict == {} under --strict-equality.
"""
assert not isinstance(left, TypedDictType) or not isinstance(
right, TypedDictType)
if isinstance(left, TypedDictType):
assert isinstance(right, Instance)
typed, other = left, right
else:
assert isinstance(left, Instance)
assert isinstance(right, TypedDictType)
typed, other = right, left
mapping = next(base for base in other.type.mro
if base.fullname() == 'typing.Mapping')
other = map_instance_to_supertype(other, mapping)
key_type, value_type = get_proper_types(other.args)
# TODO: is there a cleaner way to get str_type here?
fallback = typed.as_anonymous().fallback
str_type = fallback.type.bases[0].args[
0] # typing._TypedDict inherits Mapping[str, object]
# Special case: a TypedDict with no required keys overlaps with an empty dict.
if isinstance(key_type, UninhabitedType) and isinstance(
value_type, UninhabitedType):
return not typed.required_keys
if typed.required_keys:
if not overlapping(key_type, str_type):
return False
return all(
overlapping(typed.items[k], value_type)
for k in typed.required_keys)
else:
if not overlapping(key_type, str_type):
return False
non_required = set(typed.items.keys()) - typed.required_keys
return any(
overlapping(typed.items[k], value_type) for k in non_required)
def is_overlapping_types(left: Type,
right: Type,
ignore_promotions: bool = False,
prohibit_none_typevar_overlap: bool = False) -> bool:
"""Can a value of type 'left' also be of type 'right' or vice-versa?
If 'ignore_promotions' is True, we ignore promotions while checking for overlaps.
If 'prohibit_none_typevar_overlap' is True, we disallow None from overlapping with
TypeVars (in both strict-optional and non-strict-optional mode).
"""
left = get_proper_type(left)
right = get_proper_type(right)
def _is_overlapping_types(left: Type, right: Type) -> bool:
'''Encode the kind of overlapping check to perform.
This function mostly exists so we don't have to repeat keyword arguments everywhere.'''
return is_overlapping_types(
left,
right,
ignore_promotions=ignore_promotions,
prohibit_none_typevar_overlap=prohibit_none_typevar_overlap)
# We should never encounter this type.
if isinstance(left, PartialType) or isinstance(right, PartialType):
assert False, "Unexpectedly encountered partial type"
# We should also never encounter these types, but it's possible a few
# have snuck through due to unrelated bugs. For now, we handle these
# in the same way we handle 'Any'.
#
# TODO: Replace these with an 'assert False' once we are more confident.
illegal_types = (UnboundType, ErasedType, DeletedType)
if isinstance(left, illegal_types) or isinstance(right, illegal_types):
return True
# 'Any' may or may not be overlapping with the other type
if isinstance(left, AnyType) or isinstance(right, AnyType):
return True
# When running under non-strict optional mode, simplify away types of
# the form 'Union[A, B, C, None]' into just 'Union[A, B, C]'.
if not state.strict_optional:
if isinstance(left, UnionType):
left = UnionType.make_union(left.relevant_items())
if isinstance(right, UnionType):
right = UnionType.make_union(right.relevant_items())
# We check for complete overlaps next as a general-purpose failsafe.
# If this check fails, we start checking to see if there exists a
# *partial* overlap between types.
#
# These checks will also handle the NoneType and UninhabitedType cases for us.
if (is_proper_subtype(left, right, ignore_promotions=ignore_promotions)
or is_proper_subtype(
right, left, ignore_promotions=ignore_promotions)):
return True
# See the docstring for 'get_possible_variants' for more info on what the
# following lines are doing.
left_possible = get_possible_variants(left)
right_possible = get_possible_variants(right)
# We start by checking multi-variant types like Unions first. We also perform
# the same logic if either type happens to be a TypeVar.
#
# Handling the TypeVars now lets us simulate having them bind to the corresponding
# type -- if we deferred these checks, the "return-early" logic of the other
# checks will prevent us from detecting certain overlaps.
#
# If both types are singleton variants (and are not TypeVars), we've hit the base case:
# we skip these checks to avoid infinitely recursing.
def is_none_typevar_overlap(t1: ProperType, t2: ProperType) -> bool:
return isinstance(t1, NoneType) and isinstance(t2, TypeVarType)
if prohibit_none_typevar_overlap:
if is_none_typevar_overlap(left, right) or is_none_typevar_overlap(
right, left):
return False
if (len(left_possible) > 1 or len(right_possible) > 1
or isinstance(left, TypeVarType)
or isinstance(right, TypeVarType)):
for l in left_possible:
for r in right_possible:
if _is_overlapping_types(l, r):
return True
return False
# Now that we've finished handling TypeVars, we're free to end early
# if one one of the types is None and we're running in strict-optional mode.
# (None only overlaps with None in strict-optional mode).
#
# We must perform this check after the TypeVar checks because
# a TypeVar could be bound to None, for example.
if state.strict_optional and isinstance(left, NoneType) != isinstance(
right, NoneType):
return False
# Next, we handle single-variant types that may be inherently partially overlapping:
#
# - TypedDicts
# - Tuples
#
# If we cannot identify a partial overlap and end early, we degrade these two types
# into their 'Instance' fallbacks.
if isinstance(left, TypedDictType) and isinstance(right, TypedDictType):
return are_typed_dicts_overlapping(left,
right,
ignore_promotions=ignore_promotions)
elif typed_dict_mapping_pair(left, right):
# Overlaps between TypedDicts and Mappings require dedicated logic.
return typed_dict_mapping_overlap(left,
right,
overlapping=_is_overlapping_types)
elif isinstance(left, TypedDictType):
left = left.fallback
elif isinstance(right, TypedDictType):
right = right.fallback
if is_tuple(left) and is_tuple(right):
return are_tuples_overlapping(left,
right,
ignore_promotions=ignore_promotions)
elif isinstance(left, TupleType):
left = tuple_fallback(left)
elif isinstance(right, TupleType):
right = tuple_fallback(right)
# Next, we handle single-variant types that cannot be inherently partially overlapping,
# but do require custom logic to inspect.
#
# As before, we degrade into 'Instance' whenever possible.
if isinstance(left, TypeType) and isinstance(right, TypeType):
return _is_overlapping_types(left.item, right.item)
def _type_object_overlap(left: ProperType, right: ProperType) -> bool:
"""Special cases for type object types overlaps."""
# TODO: these checks are a bit in gray area, adjust if they cause problems.
# 1. Type[C] vs Callable[..., C], where the latter is class object.
if isinstance(left, TypeType) and isinstance(
right, CallableType) and right.is_type_obj():
return _is_overlapping_types(left.item, right.ret_type)
# 2. Type[C] vs Meta, where Meta is a metaclass for C.
if isinstance(left, TypeType) and isinstance(right, Instance):
if isinstance(left.item, Instance):
left_meta = left.item.type.metaclass_type
if left_meta is not None:
return _is_overlapping_types(left_meta, right)
# builtins.type (default metaclass) overlaps with all metaclasses
return right.type.has_base('builtins.type')
elif isinstance(left.item, AnyType):
return right.type.has_base('builtins.type')
# 3. Callable[..., C] vs Meta is considered below, when we switch to fallbacks.
return False
if isinstance(left, TypeType) or isinstance(right, TypeType):
return _type_object_overlap(left, right) or _type_object_overlap(
right, left)
if isinstance(left, CallableType) and isinstance(right, CallableType):
return is_callable_compatible(left,
right,
is_compat=_is_overlapping_types,
ignore_pos_arg_names=True,
allow_partial_overlap=True)
elif isinstance(left, CallableType):
left = left.fallback
elif isinstance(right, CallableType):
right = right.fallback
if isinstance(left, LiteralType) and isinstance(right, LiteralType):
if left.value == right.value:
# If values are the same, we still need to check if fallbacks are overlapping,
# this is done below.
left = left.fallback
right = right.fallback
else:
return False
elif isinstance(left, LiteralType):
left = left.fallback
elif isinstance(right, LiteralType):
right = right.fallback
# Finally, we handle the case where left and right are instances.
if isinstance(left, Instance) and isinstance(right, Instance):
# First we need to handle promotions and structural compatibility for instances
# that came as fallbacks, so simply call is_subtype() to avoid code duplication.
if (is_subtype(left, right, ignore_promotions=ignore_promotions) or
is_subtype(right, left, ignore_promotions=ignore_promotions)):
return True
# Two unrelated types cannot be partially overlapping: they're disjoint.
if left.type.has_base(right.type.fullname()):
left = map_instance_to_supertype(left, right.type)
elif right.type.has_base(left.type.fullname()):
right = map_instance_to_supertype(right, left.type)
else:
return False
if len(left.args) == len(right.args):
# Note: we don't really care about variance here, since the overlapping check
# is symmetric and since we want to return 'True' even for partial overlaps.
#
# For example, suppose we have two types Wrapper[Parent] and Wrapper[Child].
# It doesn't matter whether Wrapper is covariant or contravariant since
# either way, one of the two types will overlap with the other.
#
# Similarly, if Wrapper was invariant, the two types could still be partially
# overlapping -- what if Wrapper[Parent] happened to contain only instances of
# specifically Child?
#
# Or, to use a more concrete example, List[Union[A, B]] and List[Union[B, C]]
# would be considered partially overlapping since it's possible for both lists
# to contain only instances of B at runtime.
for left_arg, right_arg in zip(left.args, right.args):
if _is_overlapping_types(left_arg, right_arg):
return True
return False
# We ought to have handled every case by now: we conclude the
# two types are not overlapping, either completely or partially.
#
# Note: it's unclear however, whether returning False is the right thing
# to do when inferring reachability -- see https://github.com/python/mypy/issues/5529
assert type(left) != type(right)
return False
def analyze_class_attribute_access(itype: Instance,
name: str,
mx: MemberContext) -> Optional[Type]:
"""original_type is the type of E in the expression E.var"""
node = itype.type.get(name)
if not node:
if itype.type.fallback_to_any:
return AnyType(TypeOfAny.special_form)
return None
is_decorated = isinstance(node.node, Decorator)
is_method = is_decorated or isinstance(node.node, FuncBase)
if mx.is_lvalue:
if is_method:
mx.msg.cant_assign_to_method(mx.context)
if isinstance(node.node, TypeInfo):
mx.msg.fail(message_registry.CANNOT_ASSIGN_TO_TYPE, mx.context)
# If a final attribute was declared on `self` in `__init__`, then it
# can't be accessed on the class object.
if node.implicit and isinstance(node.node, Var) and node.node.is_final:
mx.msg.fail(message_registry.CANNOT_ACCESS_FINAL_INSTANCE_ATTR
.format(node.node.name()), mx.context)
# An assignment to final attribute on class object is also always an error,
# independently of types.
if mx.is_lvalue and not mx.chk.get_final_context():
check_final_member(name, itype.type, mx.msg, mx.context)
if itype.type.is_enum and not (mx.is_lvalue or is_decorated or is_method):
return itype
t = node.type
if t:
if isinstance(t, PartialType):
symnode = node.node
assert isinstance(symnode, Var)
return mx.chk.handle_partial_var_type(t, mx.is_lvalue, symnode, mx.context)
# Find the class where method/variable was defined.
if isinstance(node.node, Decorator):
super_info = node.node.var.info # type: Optional[TypeInfo]
elif isinstance(node.node, (Var, SYMBOL_FUNCBASE_TYPES)):
super_info = node.node.info
else:
super_info = None
# Map the type to how it would look as a defining class. For example:
# class C(Generic[T]): ...
# class D(C[Tuple[T, S]]): ...
# D[int, str].method()
# Here itype is D[int, str], isuper is C[Tuple[int, str]].
if not super_info:
isuper = None
else:
isuper = map_instance_to_supertype(itype, super_info)
if isinstance(node.node, Var):
assert isuper is not None
# Check if original variable type has type variables. For example:
# class C(Generic[T]):
# x: T
# C.x # Error, ambiguous access
# C[int].x # Also an error, since C[int] is same as C at runtime
if isinstance(t, TypeVarType) or get_type_vars(t):
# Exception: access on Type[...], including first argument of class methods is OK.
if not isinstance(mx.original_type, TypeType):
mx.msg.fail(message_registry.GENERIC_INSTANCE_VAR_CLASS_ACCESS, mx.context)
# Erase non-mapped variables, but keep mapped ones, even if there is an error.
# In the above example this means that we infer following types:
# C.x -> Any
# C[int].x -> int
t = erase_typevars(expand_type_by_instance(t, isuper))
is_classmethod = ((is_decorated and cast(Decorator, node.node).func.is_class)
or (isinstance(node.node, FuncBase) and node.node.is_class))
result = add_class_tvars(t, itype, isuper, is_classmethod, mx.builtin_type,
mx.original_type)
if not mx.is_lvalue:
result = analyze_descriptor_access(mx.original_type, result, mx.builtin_type,
mx.msg, mx.context, chk=mx.chk)
return result
elif isinstance(node.node, Var):
mx.not_ready_callback(name, mx.context)
return AnyType(TypeOfAny.special_form)
if isinstance(node.node, TypeVarExpr):
mx.msg.fail(message_registry.CANNOT_USE_TYPEVAR_AS_EXPRESSION.format(
itype.type.name(), name), mx.context)
return AnyType(TypeOfAny.from_error)
if isinstance(node.node, TypeInfo):
return type_object_type(node.node, mx.builtin_type)
if isinstance(node.node, MypyFile):
# Reference to a module object.
return mx.builtin_type('types.ModuleType')
if isinstance(node.node, TypeAlias) and isinstance(node.node.target, Instance):
return instance_alias_type(node.node, mx.builtin_type)
if is_decorated:
assert isinstance(node.node, Decorator)
if node.node.type:
return node.node.type
else:
mx.not_ready_callback(name, mx.context)
return AnyType(TypeOfAny.from_error)
else:
return function_type(cast(FuncBase, node.node), mx.builtin_type('builtins.function'))
def analyze_var(name: str,
var: Var,
itype: Instance,
info: TypeInfo,
mx: MemberContext,
*,
implicit: bool = False) -> Type:
"""Analyze access to an attribute via a Var node.
This is conceptually part of analyze_member_access and the arguments are similar.
itype is the class object in which var is defined
original_type is the type of E in the expression E.var
if implicit is True, the original Var was created as an assignment to self
"""
# Found a member variable.
itype = map_instance_to_supertype(itype, var.info)
typ = var.type
if typ:
if isinstance(typ, PartialType):
return mx.chk.handle_partial_var_type(typ, mx.is_lvalue, var,
mx.context)
t = expand_type_by_instance(typ, itype)
if mx.is_lvalue and var.is_property and not var.is_settable_property:
# TODO allow setting attributes in subclass (although it is probably an error)
mx.msg.read_only_property(name, itype.type, mx.context)
if mx.is_lvalue and var.is_classvar:
mx.msg.cant_assign_to_classvar(name, mx.context)
result = t
if var.is_initialized_in_class and isinstance(
t, FunctionLike) and not t.is_type_obj():
if mx.is_lvalue:
if var.is_property:
if not var.is_settable_property:
mx.msg.read_only_property(name, itype.type, mx.context)
else:
mx.msg.cant_assign_to_method(mx.context)
if not var.is_staticmethod:
# Class-level function objects and classmethods become bound methods:
# the former to the instance, the latter to the class.
functype = t
# Use meet to narrow original_type to the dispatched type.
# For example, assume
# * A.f: Callable[[A1], None] where A1 <: A (maybe A1 == A)
# * B.f: Callable[[B1], None] where B1 <: B (maybe B1 == B)
# * x: Union[A1, B1]
# In `x.f`, when checking `x` against A1 we assume x is compatible with A
# and similarly for B1 when checking agains B
dispatched_type = meet.meet_types(mx.original_type, itype)
check_self_arg(functype, dispatched_type, var.is_classmethod,
mx.context, name, mx.msg)
signature = bind_self(functype, mx.original_type,
var.is_classmethod)
if var.is_property:
# A property cannot have an overloaded type => the cast is fine.
assert isinstance(signature, CallableType)
result = signature.ret_type
else:
result = signature
else:
if not var.is_ready:
mx.not_ready_callback(var.name(), mx.context)
# Implicit 'Any' type.
result = AnyType(TypeOfAny.special_form)
fullname = '{}.{}'.format(var.info.fullname(), name)
hook = mx.chk.plugin.get_attribute_hook(fullname)
if result and not mx.is_lvalue and not implicit:
result = analyze_descriptor_access(mx.original_type,
result,
mx.builtin_type,
mx.msg,
mx.context,
chk=mx.chk)
if hook:
result = hook(
AttributeContext(mx.original_type, result, mx.context, mx.chk))
return result
def analyze_member_var_access(name: str, itype: Instance, info: TypeInfo,
mx: MemberContext) -> Type:
"""Analyse attribute access that does not target a method.
This is logically part of analyze_member_access and the arguments are similar.
original_type is the type of E in the expression E.var
"""
# It was not a method. Try looking up a variable.
v = lookup_member_var_or_accessor(info, name, mx.is_lvalue)
vv = v
if isinstance(vv, Decorator):
# The associated Var node of a decorator contains the type.
v = vv.var
if isinstance(vv, TypeInfo):
# If the associated variable is a TypeInfo synthesize a Var node for
# the purposes of type checking. This enables us to type check things
# like accessing class attributes on an inner class.
v = Var(name, type=type_object_type(vv, mx.builtin_type))
v.info = info
if isinstance(vv, TypeAlias) and isinstance(vv.target, Instance):
# Similar to the above TypeInfo case, we allow using
# qualified type aliases in runtime context if it refers to an
# instance type. For example:
# class C:
# A = List[int]
# x = C.A() <- this is OK
typ = instance_alias_type(vv, mx.builtin_type)
v = Var(name, type=typ)
v.info = info
if isinstance(v, Var):
implicit = info[name].implicit
# An assignment to final attribute is always an error,
# independently of types.
if mx.is_lvalue and not mx.chk.get_final_context():
check_final_member(name, info, mx.msg, mx.context)
return analyze_var(name, v, itype, info, mx, implicit=implicit)
elif isinstance(v, FuncDef):
assert False, "Did not expect a function"
elif not v and name not in [
'__getattr__', '__setattr__', '__getattribute__'
]:
if not mx.is_lvalue:
for method_name in ('__getattribute__', '__getattr__'):
method = info.get_method(method_name)
# __getattribute__ is defined on builtins.object and returns Any, so without
# the guard this search will always find object.__getattribute__ and conclude
# that the attribute exists
if method and method.info.fullname() != 'builtins.object':
function = function_type(
method, mx.builtin_type('builtins.function'))
bound_method = bind_self(function, mx.original_type)
typ = map_instance_to_supertype(itype, method.info)
getattr_type = expand_type_by_instance(bound_method, typ)
if isinstance(getattr_type, CallableType):
result = getattr_type.ret_type
# Call the attribute hook before returning.
fullname = '{}.{}'.format(method.info.fullname(), name)
hook = mx.chk.plugin.get_attribute_hook(fullname)
if hook:
result = hook(
AttributeContext(mx.original_type, result,
mx.context, mx.chk))
return result
else:
setattr_meth = info.get_method('__setattr__')
if setattr_meth and setattr_meth.info.fullname(
) != 'builtins.object':
setattr_func = function_type(
setattr_meth, mx.builtin_type('builtins.function'))
bound_type = bind_self(setattr_func, mx.original_type)
typ = map_instance_to_supertype(itype, setattr_meth.info)
setattr_type = expand_type_by_instance(bound_type, typ)
if isinstance(
setattr_type,
CallableType) and len(setattr_type.arg_types) > 0:
return setattr_type.arg_types[-1]
if itype.type.fallback_to_any:
return AnyType(TypeOfAny.special_form)
# Could not find the member.
if mx.is_super:
mx.msg.undefined_in_superclass(name, mx.context)
return AnyType(TypeOfAny.from_error)
else:
if mx.chk and mx.chk.should_suppress_optional_error([itype]):
return AnyType(TypeOfAny.from_error)
return mx.msg.has_no_attr(mx.original_type, itype, name, mx.context)
def analyze_class_attribute_access(
itype: Instance,
name: str,
mx: MemberContext,
override_info: Optional[TypeInfo] = None,
original_vars: Optional[List[TypeVarDef]] = None) -> Optional[Type]:
"""Analyze access to an attribute on a class object.
itype is the return type of the class object callable, original_type is the type
of E in the expression E.var, original_vars are type variables of the class callable
(for generic classes).
"""
info = itype.type
if override_info:
info = override_info
node = info.get(name)
if not node:
if info.fallback_to_any:
return AnyType(TypeOfAny.special_form)
return None
is_decorated = isinstance(node.node, Decorator)
is_method = is_decorated or isinstance(node.node, FuncBase)
if mx.is_lvalue:
if is_method:
mx.msg.cant_assign_to_method(mx.context)
if isinstance(node.node, TypeInfo):
mx.msg.fail(message_registry.CANNOT_ASSIGN_TO_TYPE, mx.context)
# If a final attribute was declared on `self` in `__init__`, then it
# can't be accessed on the class object.
if node.implicit and isinstance(node.node, Var) and node.node.is_final:
mx.msg.fail(
message_registry.CANNOT_ACCESS_FINAL_INSTANCE_ATTR.format(
node.node.name), mx.context)
# An assignment to final attribute on class object is also always an error,
# independently of types.
if mx.is_lvalue and not mx.chk.get_final_context():
check_final_member(name, info, mx.msg, mx.context)
if info.is_enum and not (mx.is_lvalue or is_decorated or is_method):
enum_literal = LiteralType(name, fallback=itype)
# When we analyze enums, the corresponding Instance is always considered to be erased
# due to how the signature of Enum.__new__ is `(cls: Type[_T], value: object) -> _T`
# in typeshed. However, this is really more of an implementation detail of how Enums
# are typed, and we really don't want to treat every single Enum value as if it were
# from type variable substitution. So we reset the 'erased' field here.
return itype.copy_modified(erased=False, last_known_value=enum_literal)
t = node.type
if t:
if isinstance(t, PartialType):
symnode = node.node
assert isinstance(symnode, Var)
return mx.chk.handle_partial_var_type(t, mx.is_lvalue, symnode,
mx.context)
# Find the class where method/variable was defined.
if isinstance(node.node, Decorator):
super_info = node.node.var.info # type: Optional[TypeInfo]
elif isinstance(node.node, (Var, SYMBOL_FUNCBASE_TYPES)):
super_info = node.node.info
else:
super_info = None
# Map the type to how it would look as a defining class. For example:
# class C(Generic[T]): ...
# class D(C[Tuple[T, S]]): ...
# D[int, str].method()
# Here itype is D[int, str], isuper is C[Tuple[int, str]].
if not super_info:
isuper = None
else:
isuper = map_instance_to_supertype(itype, super_info)
if isinstance(node.node, Var):
assert isuper is not None
# Check if original variable type has type variables. For example:
# class C(Generic[T]):
# x: T
# C.x # Error, ambiguous access
# C[int].x # Also an error, since C[int] is same as C at runtime
if isinstance(t, TypeVarType) or has_type_vars(t):
# Exception: access on Type[...], including first argument of class methods is OK.
if not isinstance(get_proper_type(mx.original_type),
TypeType) or node.implicit:
if node.node.is_classvar:
message = message_registry.GENERIC_CLASS_VAR_ACCESS
else:
message = message_registry.GENERIC_INSTANCE_VAR_CLASS_ACCESS
mx.msg.fail(message, mx.context)
# Erase non-mapped variables, but keep mapped ones, even if there is an error.
# In the above example this means that we infer following types:
# C.x -> Any
# C[int].x -> int
t = erase_typevars(expand_type_by_instance(t, isuper))
is_classmethod = (
(is_decorated and cast(Decorator, node.node).func.is_class)
or (isinstance(node.node, FuncBase) and node.node.is_class))
t = get_proper_type(t)
if isinstance(t, FunctionLike) and is_classmethod:
t = check_self_arg(t, mx.self_type, False, mx.context, name,
mx.msg)
result = add_class_tvars(t,
isuper,
is_classmethod,
mx.self_type,
original_vars=original_vars)
if not mx.is_lvalue:
result = analyze_descriptor_access(mx.original_type,
result,
mx.builtin_type,
mx.msg,
mx.context,
chk=mx.chk)
return result
elif isinstance(node.node, Var):
mx.not_ready_callback(name, mx.context)
return AnyType(TypeOfAny.special_form)
if isinstance(node.node, TypeVarExpr):
mx.msg.fail(
message_registry.CANNOT_USE_TYPEVAR_AS_EXPRESSION.format(
info.name, name), mx.context)
return AnyType(TypeOfAny.from_error)
if isinstance(node.node, TypeInfo):
return type_object_type(node.node, mx.builtin_type)
if isinstance(node.node, MypyFile):
# Reference to a module object.
return mx.builtin_type('types.ModuleType')
if (isinstance(node.node, TypeAlias)
and isinstance(get_proper_type(node.node.target), Instance)):
return instance_alias_type(node.node, mx.builtin_type)
if is_decorated:
assert isinstance(node.node, Decorator)
if node.node.type:
return node.node.type
else:
mx.not_ready_callback(name, mx.context)
return AnyType(TypeOfAny.from_error)
else:
assert isinstance(node.node, FuncBase)
typ = function_type(node.node, mx.builtin_type('builtins.function'))
# Note: if we are accessing class method on class object, the cls argument is bound.
# Annotated and/or explicit class methods go through other code paths above, for
# unannotated implicit class methods we do this here.
if node.node.is_class:
typ = bind_self(typ, is_classmethod=True)
return typ
def analyze_member_access(name: str,
typ: Type,
node: Context,
is_lvalue: bool,
is_super: bool,
is_operator: bool,
builtin_type: Callable[[str], Instance],
not_ready_callback: Callable[[str, Context], None],
msg: MessageBuilder, *,
original_type: Type,
chk: 'mypy.checker.TypeChecker',
override_info: Optional[TypeInfo] = None) -> Type:
"""Return the type of attribute `name` of typ.
This is a general operation that supports various different variations:
1. lvalue or non-lvalue access (i.e. setter or getter access)
2. supertype access (when using super(); is_super == True and
override_info should refer to the supertype)
original_type is the most precise inferred or declared type of the base object
that we have available. typ is generally a supertype of original_type.
When looking for an attribute of typ, we may perform recursive calls targeting
the fallback type, for example.
original_type is always the type used in the initial call.
"""
# TODO: this and following functions share some logic with subtypes.find_member,
# consider refactoring.
if isinstance(typ, Instance):
if name == '__init__' and not is_super:
# Accessing __init__ in statically typed code would compromise
# type safety unless used via super().
msg.fail(messages.CANNOT_ACCESS_INIT, node)
return AnyType(TypeOfAny.from_error)
# The base object has an instance type.
info = typ.type
if override_info:
info = override_info
if (experiments.find_occurrences and
info.name() == experiments.find_occurrences[0] and
name == experiments.find_occurrences[1]):
msg.note("Occurrence of '{}.{}'".format(*experiments.find_occurrences), node)
# Look up the member. First look up the method dictionary.
method = info.get_method(name)
if method:
if method.is_property:
assert isinstance(method, OverloadedFuncDef)
first_item = cast(Decorator, method.items[0])
return analyze_var(name, first_item.var, typ, info, node, is_lvalue, msg,
original_type, not_ready_callback, chk=chk)
if is_lvalue:
msg.cant_assign_to_method(node)
signature = function_type(method, builtin_type('builtins.function'))
signature = freshen_function_type_vars(signature)
if name == '__new__':
# __new__ is special and behaves like a static method -- don't strip
# the first argument.
pass
else:
signature = bind_self(signature, original_type)
typ = map_instance_to_supertype(typ, method.info)
member_type = expand_type_by_instance(signature, typ)
freeze_type_vars(member_type)
return member_type
else:
# Not a method.
return analyze_member_var_access(name, typ, info, node,
is_lvalue, is_super, builtin_type,
not_ready_callback, msg,
original_type=original_type, chk=chk)
elif isinstance(typ, AnyType):
# The base object has dynamic type.
return AnyType(TypeOfAny.from_another_any, source_any=typ)
elif isinstance(typ, NoneTyp):
if chk.should_suppress_optional_error([typ]):
return AnyType(TypeOfAny.from_error)
# The only attribute NoneType has are those it inherits from object
return analyze_member_access(name, builtin_type('builtins.object'), node, is_lvalue,
is_super, is_operator, builtin_type, not_ready_callback, msg,
original_type=original_type, chk=chk)
elif isinstance(typ, UnionType):
# The base object has dynamic type.
msg.disable_type_names += 1
results = [analyze_member_access(name, subtype, node, is_lvalue, is_super,
is_operator, builtin_type, not_ready_callback, msg,
original_type=original_type, chk=chk)
for subtype in typ.relevant_items()]
msg.disable_type_names -= 1
return UnionType.make_simplified_union(results)
elif isinstance(typ, TupleType):
# Actually look up from the fallback instance type.
return analyze_member_access(name, typ.fallback, node, is_lvalue, is_super,
is_operator, builtin_type, not_ready_callback, msg,
original_type=original_type, chk=chk)
elif isinstance(typ, TypedDictType):
# Actually look up from the fallback instance type.
return analyze_member_access(name, typ.fallback, node, is_lvalue, is_super,
is_operator, builtin_type, not_ready_callback, msg,
original_type=original_type, chk=chk)
elif isinstance(typ, FunctionLike) and typ.is_type_obj():
# Class attribute.
# TODO super?
ret_type = typ.items()[0].ret_type
if isinstance(ret_type, TupleType):
ret_type = ret_type.fallback
if isinstance(ret_type, Instance):
if not is_operator:
# When Python sees an operator (eg `3 == 4`), it automatically translates that
# into something like `int.__eq__(3, 4)` instead of `(3).__eq__(4)` as an
# optimization.
#
# While it normally it doesn't matter which of the two versions are used, it
# does cause inconsistencies when working with classes. For example, translating
# `int == int` to `int.__eq__(int)` would not work since `int.__eq__` is meant to
# compare two int _instances_. What we really want is `type(int).__eq__`, which
# is meant to compare two types or classes.
#
# This check makes sure that when we encounter an operator, we skip looking up
# the corresponding method in the current instance to avoid this edge case.
# See https://github.com/python/mypy/pull/1787 for more info.
result = analyze_class_attribute_access(ret_type, name, node, is_lvalue,
builtin_type, not_ready_callback, msg,
original_type=original_type)
if result:
return result
# Look up from the 'type' type.
return analyze_member_access(name, typ.fallback, node, is_lvalue, is_super,
is_operator, builtin_type, not_ready_callback, msg,
original_type=original_type, chk=chk)
else:
assert False, 'Unexpected type {}'.format(repr(ret_type))
elif isinstance(typ, FunctionLike):
# Look up from the 'function' type.
return analyze_member_access(name, typ.fallback, node, is_lvalue, is_super,
is_operator, builtin_type, not_ready_callback, msg,
original_type=original_type, chk=chk)
elif isinstance(typ, TypeVarType):
return analyze_member_access(name, typ.upper_bound, node, is_lvalue, is_super,
is_operator, builtin_type, not_ready_callback, msg,
original_type=original_type, chk=chk)
elif isinstance(typ, DeletedType):
msg.deleted_as_rvalue(typ, node)
return AnyType(TypeOfAny.from_error)
elif isinstance(typ, TypeType):
# Similar to FunctionLike + is_type_obj() above.
item = None
fallback = builtin_type('builtins.type')
ignore_messages = msg.copy()
ignore_messages.disable_errors()
if isinstance(typ.item, Instance):
item = typ.item
elif isinstance(typ.item, AnyType):
return analyze_member_access(name, fallback, node, is_lvalue, is_super,
is_operator, builtin_type, not_ready_callback,
ignore_messages, original_type=original_type, chk=chk)
elif isinstance(typ.item, TypeVarType):
if isinstance(typ.item.upper_bound, Instance):
item = typ.item.upper_bound
elif isinstance(typ.item, TupleType):
item = typ.item.fallback
elif isinstance(typ.item, FunctionLike) and typ.item.is_type_obj():
item = typ.item.fallback
elif isinstance(typ.item, TypeType):
# Access member on metaclass object via Type[Type[C]]
if isinstance(typ.item.item, Instance):
item = typ.item.item.type.metaclass_type
if item and not is_operator:
# See comment above for why operators are skipped
result = analyze_class_attribute_access(item, name, node, is_lvalue,
builtin_type, not_ready_callback, msg,
original_type=original_type)
if result:
if not (isinstance(result, AnyType) and item.type.fallback_to_any):
return result
else:
# We don't want errors on metaclass lookup for classes with Any fallback
msg = ignore_messages
if item is not None:
fallback = item.type.metaclass_type or fallback
return analyze_member_access(name, fallback, node, is_lvalue, is_super,
is_operator, builtin_type, not_ready_callback, msg,
original_type=original_type, chk=chk)
if chk.should_suppress_optional_error([typ]):
return AnyType(TypeOfAny.from_error)
return msg.has_no_attr(original_type, typ, name, node)
def expand_actual_type(self,
actual_type: Type,
actual_kind: nodes.ArgKind,
formal_name: Optional[str],
formal_kind: nodes.ArgKind) -> Type:
"""Return the actual (caller) type(s) of a formal argument with the given kinds.
If the actual argument is a tuple *args, return the next individual tuple item that
maps to the formal arg.
If the actual argument is a TypedDict **kwargs, return the next matching typed dict
value type based on formal argument name and kind.
This is supposed to be called for each formal, in order. Call multiple times per
formal if multiple actuals map to a formal.
"""
actual_type = get_proper_type(actual_type)
if actual_kind == nodes.ARG_STAR:
if isinstance(actual_type, Instance) and actual_type.args:
from mypy.subtypes import is_subtype
if is_subtype(actual_type, self.context.iterable_type):
return map_instance_to_supertype(
actual_type,
self.context.iterable_type.type,
).args[0]
else:
# We cannot properly unpack anything other
# than `Iterable` type with `*`.
# Just return `Any`, other parts of code would raise
# a different error for improper use.
return AnyType(TypeOfAny.from_error)
elif isinstance(actual_type, TupleType):
# Get the next tuple item of a tuple *arg.
if self.tuple_index >= len(actual_type.items):
# Exhausted a tuple -- continue to the next *args.
self.tuple_index = 1
else:
self.tuple_index += 1
return actual_type.items[self.tuple_index - 1]
elif isinstance(actual_type, ParamSpecType):
# ParamSpec is valid in *args but it can't be unpacked.
return actual_type
else:
return AnyType(TypeOfAny.from_error)
elif actual_kind == nodes.ARG_STAR2:
from mypy.subtypes import is_subtype
if isinstance(actual_type, TypedDictType):
if formal_kind != nodes.ARG_STAR2 and formal_name in actual_type.items:
# Lookup type based on keyword argument name.
assert formal_name is not None
else:
# Pick an arbitrary item if no specified keyword is expected.
formal_name = (set(actual_type.items.keys()) - self.kwargs_used).pop()
self.kwargs_used.add(formal_name)
return actual_type.items[formal_name]
elif (
isinstance(actual_type, Instance) and
len(actual_type.args) > 1 and
is_subtype(actual_type, self.context.mapping_type)
):
# Only `Mapping` type can be unpacked with `**`.
# Other types will produce an error somewhere else.
return map_instance_to_supertype(
actual_type,
self.context.mapping_type.type,
).args[1]
elif isinstance(actual_type, ParamSpecType):
# ParamSpec is valid in **kwargs but it can't be unpacked.
return actual_type
else:
return AnyType(TypeOfAny.from_error)
else:
# No translation for other kinds -- 1:1 mapping.
return actual_type
def analyze_member_access(name: str, typ: Type, node: Context, is_lvalue: bool,
is_super: bool,
builtin_type: Callable[[str], Instance],
not_ready_callback: Callable[[str, Context], None],
msg: MessageBuilder, override_info: TypeInfo = None,
report_type: Type = None) -> Type:
"""Analyse attribute access.
This is a general operation that supports various different variations:
1. lvalue or non-lvalue access (i.e. setter or getter access)
2. supertype access (when using super(); is_super == True and
override_info should refer to the supertype)
"""
report_type = report_type or typ
if isinstance(typ, Instance):
if name == '__init__' and not is_super:
# Accessing __init__ in statically typed code would compromise
# type safety unless used via super().
msg.fail(messages.CANNOT_ACCESS_INIT, node)
return AnyType()
# The base object has an instance type.
info = typ.type
if override_info:
info = override_info
# Look up the member. First look up the method dictionary.
method = info.get_method(name)
if method:
if method.is_property:
assert isinstance(method, OverloadedFuncDef)
method = cast(OverloadedFuncDef, method)
return analyze_var(name, method.items[0].var, typ, info, node, is_lvalue, msg,
not_ready_callback)
if is_lvalue:
msg.cant_assign_to_method(node)
typ = map_instance_to_supertype(typ, method.info)
if name == '__new__':
# __new__ is special and behaves like a static method -- don't strip
# the first argument.
signature = function_type(method, builtin_type('builtins.function'))
else:
signature = method_type_with_fallback(method, builtin_type('builtins.function'))
return expand_type_by_instance(signature, typ)
else:
# Not a method.
return analyze_member_var_access(name, typ, info, node,
is_lvalue, is_super, builtin_type,
not_ready_callback, msg,
report_type=report_type)
elif isinstance(typ, AnyType):
# The base object has dynamic type.
return AnyType()
elif isinstance(typ, UnionType):
# The base object has dynamic type.
msg.disable_type_names += 1
results = [analyze_member_access(name, subtype, node, is_lvalue,
is_super, builtin_type, not_ready_callback, msg)
for subtype in typ.items]
msg.disable_type_names -= 1
return UnionType.make_simplified_union(results)
elif isinstance(typ, TupleType):
# Actually look up from the fallback instance type.
return analyze_member_access(name, typ.fallback, node, is_lvalue,
is_super, builtin_type, not_ready_callback, msg)
elif isinstance(typ, FunctionLike) and typ.is_type_obj():
# Class attribute.
# TODO super?
ret_type = typ.items()[0].ret_type
if isinstance(ret_type, TupleType):
ret_type = ret_type.fallback
if isinstance(ret_type, Instance):
result = analyze_class_attribute_access(ret_type, name, node, is_lvalue,
builtin_type, not_ready_callback, msg)
if result:
return result
# Look up from the 'type' type.
return analyze_member_access(name, typ.fallback, node, is_lvalue, is_super,
builtin_type, not_ready_callback, msg,
report_type=report_type)
else:
assert False, 'Unexpected type {}'.format(repr(ret_type))
elif isinstance(typ, FunctionLike):
# Look up from the 'function' type.
return analyze_member_access(name, typ.fallback, node, is_lvalue, is_super,
builtin_type, not_ready_callback, msg,
report_type=report_type)
elif isinstance(typ, TypeVarType):
return analyze_member_access(name, typ.upper_bound, node, is_lvalue, is_super,
builtin_type, not_ready_callback, msg,
report_type=report_type)
elif isinstance(typ, DeletedType):
msg.deleted_as_rvalue(typ, node)
return AnyType()
return msg.has_no_attr(report_type, name, node)
def analyze_descriptor_access(instance_type: Type,
descriptor_type: Type,
builtin_type: Callable[[str], Instance],
msg: MessageBuilder,
context: Context, *,
chk: 'mypy.checker.TypeChecker') -> Type:
"""Type check descriptor access.
Arguments:
instance_type: The type of the instance on which the descriptor
attribute is being accessed (the type of ``a`` in ``a.f`` when
``f`` is a descriptor).
descriptor_type: The type of the descriptor attribute being accessed
(the type of ``f`` in ``a.f`` when ``f`` is a descriptor).
context: The node defining the context of this inference.
Return:
The return type of the appropriate ``__get__`` overload for the descriptor.
"""
if isinstance(descriptor_type, UnionType):
# Map the access over union types
return UnionType.make_simplified_union([
analyze_descriptor_access(instance_type, typ, builtin_type,
msg, context, chk=chk)
for typ in descriptor_type.items
])
elif not isinstance(descriptor_type, Instance):
return descriptor_type
if not descriptor_type.type.has_readable_member('__get__'):
return descriptor_type
dunder_get = descriptor_type.type.get_method('__get__')
if dunder_get is None:
msg.fail(message_registry.DESCRIPTOR_GET_NOT_CALLABLE.format(descriptor_type), context)
return AnyType(TypeOfAny.from_error)
function = function_type(dunder_get, builtin_type('builtins.function'))
bound_method = bind_self(function, descriptor_type)
typ = map_instance_to_supertype(descriptor_type, dunder_get.info)
dunder_get_type = expand_type_by_instance(bound_method, typ)
if isinstance(instance_type, FunctionLike) and instance_type.is_type_obj():
owner_type = instance_type.items()[0].ret_type
instance_type = NoneTyp()
elif isinstance(instance_type, TypeType):
owner_type = instance_type.item
instance_type = NoneTyp()
else:
owner_type = instance_type
_, inferred_dunder_get_type = chk.expr_checker.check_call(
dunder_get_type,
[TempNode(instance_type), TempNode(TypeType.make_normalized(owner_type))],
[ARG_POS, ARG_POS], context)
if isinstance(inferred_dunder_get_type, AnyType):
# check_call failed, and will have reported an error
return inferred_dunder_get_type
if not isinstance(inferred_dunder_get_type, CallableType):
msg.fail(message_registry.DESCRIPTOR_GET_NOT_CALLABLE.format(descriptor_type), context)
return AnyType(TypeOfAny.from_error)
return inferred_dunder_get_type.ret_type
def _analyze_member_access(name: str,
typ: Type,
mx: MemberContext,
override_info: Optional[TypeInfo] = None) -> Type:
# TODO: this and following functions share some logic with subtypes.find_member,
# consider refactoring.
if isinstance(typ, Instance):
if name == '__init__' and not mx.is_super:
# Accessing __init__ in statically typed code would compromise
# type safety unless used via super().
mx.msg.fail(messages.CANNOT_ACCESS_INIT, mx.context)
return AnyType(TypeOfAny.from_error)
# The base object has an instance type.
info = typ.type
if override_info:
info = override_info
if (experiments.find_occurrences and
info.name() == experiments.find_occurrences[0] and
name == experiments.find_occurrences[1]):
mx.msg.note("Occurrence of '{}.{}'".format(*experiments.find_occurrences), mx.context)
# Look up the member. First look up the method dictionary.
method = info.get_method(name)
if method:
if method.is_property:
assert isinstance(method, OverloadedFuncDef)
first_item = cast(Decorator, method.items[0])
return analyze_var(name, first_item.var, typ, info, mx)
if mx.is_lvalue:
mx.msg.cant_assign_to_method(mx.context)
signature = function_type(method, mx.builtin_type('builtins.function'))
signature = freshen_function_type_vars(signature)
if name == '__new__':
# __new__ is special and behaves like a static method -- don't strip
# the first argument.
pass
else:
signature = bind_self(signature, mx.original_type)
typ = map_instance_to_supertype(typ, method.info)
member_type = expand_type_by_instance(signature, typ)
freeze_type_vars(member_type)
return member_type
else:
# Not a method.
return analyze_member_var_access(name, typ, info, mx)
elif isinstance(typ, AnyType):
# The base object has dynamic type.
return AnyType(TypeOfAny.from_another_any, source_any=typ)
elif isinstance(typ, NoneTyp):
if mx.chk.should_suppress_optional_error([typ]):
return AnyType(TypeOfAny.from_error)
is_python_3 = mx.chk.options.python_version[0] >= 3
# In Python 2 "None" has exactly the same attributes as "object". Python 3 adds a single
# extra attribute, "__bool__".
if is_python_3 and name == '__bool__':
return CallableType(arg_types=[],
arg_kinds=[],
arg_names=[],
ret_type=mx.builtin_type('builtins.bool'),
fallback=mx.builtin_type('builtins.function'))
else:
return _analyze_member_access(name, mx.builtin_type('builtins.object'), mx)
elif isinstance(typ, UnionType):
# The base object has dynamic type.
mx.msg.disable_type_names += 1
results = [_analyze_member_access(name, subtype, mx)
for subtype in typ.relevant_items()]
mx.msg.disable_type_names -= 1
return UnionType.make_simplified_union(results)
elif isinstance(typ, (TupleType, TypedDictType, LiteralType)):
# Actually look up from the fallback instance type.
return _analyze_member_access(name, typ.fallback, mx)
elif isinstance(typ, FunctionLike) and typ.is_type_obj():
# Class attribute.
# TODO super?
ret_type = typ.items()[0].ret_type
if isinstance(ret_type, TupleType):
ret_type = ret_type.fallback
if isinstance(ret_type, Instance):
if not mx.is_operator:
# When Python sees an operator (eg `3 == 4`), it automatically translates that
# into something like `int.__eq__(3, 4)` instead of `(3).__eq__(4)` as an
# optimization.
#
# While it normally it doesn't matter which of the two versions are used, it
# does cause inconsistencies when working with classes. For example, translating
# `int == int` to `int.__eq__(int)` would not work since `int.__eq__` is meant to
# compare two int _instances_. What we really want is `type(int).__eq__`, which
# is meant to compare two types or classes.
#
# This check makes sure that when we encounter an operator, we skip looking up
# the corresponding method in the current instance to avoid this edge case.
# See https://github.com/python/mypy/pull/1787 for more info.
result = analyze_class_attribute_access(ret_type, name, mx)
if result:
return result
# Look up from the 'type' type.
return _analyze_member_access(name, typ.fallback, mx)
else:
assert False, 'Unexpected type {}'.format(repr(ret_type))
elif isinstance(typ, FunctionLike):
# Look up from the 'function' type.
return _analyze_member_access(name, typ.fallback, mx)
elif isinstance(typ, TypeVarType):
return _analyze_member_access(name, typ.upper_bound, mx)
elif isinstance(typ, DeletedType):
mx.msg.deleted_as_rvalue(typ, mx.context)
return AnyType(TypeOfAny.from_error)
elif isinstance(typ, TypeType):
# Similar to FunctionLike + is_type_obj() above.
item = None
fallback = mx.builtin_type('builtins.type')
ignore_messages = mx.msg.copy()
ignore_messages.disable_errors()
if isinstance(typ.item, Instance):
item = typ.item
elif isinstance(typ.item, AnyType):
mx = mx.copy_modified(messages=ignore_messages)
return _analyze_member_access(name, fallback, mx)
elif isinstance(typ.item, TypeVarType):
if isinstance(typ.item.upper_bound, Instance):
item = typ.item.upper_bound
elif isinstance(typ.item, TupleType):
item = typ.item.fallback
elif isinstance(typ.item, FunctionLike) and typ.item.is_type_obj():
item = typ.item.fallback
elif isinstance(typ.item, TypeType):
# Access member on metaclass object via Type[Type[C]]
if isinstance(typ.item.item, Instance):
item = typ.item.item.type.metaclass_type
if item and not mx.is_operator:
# See comment above for why operators are skipped
result = analyze_class_attribute_access(item, name, mx)
if result:
if not (isinstance(result, AnyType) and item.type.fallback_to_any):
return result
else:
# We don't want errors on metaclass lookup for classes with Any fallback
mx = mx.copy_modified(messages=ignore_messages)
if item is not None:
fallback = item.type.metaclass_type or fallback
return _analyze_member_access(name, fallback, mx)
if mx.chk.should_suppress_optional_error([typ]):
return AnyType(TypeOfAny.from_error)
return mx.msg.has_no_attr(mx.original_type, typ, name, mx.context)
def visit_instance(self, template: Instance) -> List[Constraint]:
original_actual = actual = self.actual
res = [] # type: List[Constraint]
if isinstance(actual, (CallableType, Overloaded)) and template.type.is_protocol:
if template.type.protocol_members == ['__call__']:
# Special case: a generic callback protocol
if not any(is_same_type(template, t) for t in template.type.inferring):
template.type.inferring.append(template)
call = mypy.subtypes.find_member('__call__', template, actual)
assert call is not None
if mypy.subtypes.is_subtype(actual, erase_typevars(call)):
subres = infer_constraints(call, actual, self.direction)
res.extend(subres)
template.type.inferring.pop()
return res
if isinstance(actual, CallableType) and actual.fallback is not None:
actual = actual.fallback
if isinstance(actual, Overloaded) and actual.fallback is not None:
actual = actual.fallback
if isinstance(actual, TypedDictType):
actual = actual.as_anonymous().fallback
if isinstance(actual, Instance):
instance = actual
erased = erase_typevars(template)
assert isinstance(erased, Instance)
# We always try nominal inference if possible,
# it is much faster than the structural one.
if (self.direction == SUBTYPE_OF and
template.type.has_base(instance.type.fullname())):
mapped = map_instance_to_supertype(template, instance.type)
tvars = mapped.type.defn.type_vars
for i in range(len(instance.args)):
# The constraints for generic type parameters depend on variance.
# Include constraints from both directions if invariant.
if tvars[i].variance != CONTRAVARIANT:
res.extend(infer_constraints(
mapped.args[i], instance.args[i], self.direction))
if tvars[i].variance != COVARIANT:
res.extend(infer_constraints(
mapped.args[i], instance.args[i], neg_op(self.direction)))
return res
elif (self.direction == SUPERTYPE_OF and
instance.type.has_base(template.type.fullname())):
mapped = map_instance_to_supertype(instance, template.type)
tvars = template.type.defn.type_vars
for j in range(len(template.args)):
# The constraints for generic type parameters depend on variance.
# Include constraints from both directions if invariant.
if tvars[j].variance != CONTRAVARIANT:
res.extend(infer_constraints(
template.args[j], mapped.args[j], self.direction))
if tvars[j].variance != COVARIANT:
res.extend(infer_constraints(
template.args[j], mapped.args[j], neg_op(self.direction)))
return res
if (template.type.is_protocol and self.direction == SUPERTYPE_OF and
# We avoid infinite recursion for structural subtypes by checking
# whether this type already appeared in the inference chain.
# This is a conservative way break the inference cycles.
# It never produces any "false" constraints but gives up soon
# on purely structural inference cycles, see #3829.
# Note that we use is_protocol_implementation instead of is_subtype
# because some type may be considered a subtype of a protocol
# due to _promote, but still not implement the protocol.
not any(is_same_type(template, t) for t in template.type.inferring) and
mypy.subtypes.is_protocol_implementation(instance, erased)):
template.type.inferring.append(template)
self.infer_constraints_from_protocol_members(res, instance, template,
original_actual, template)
template.type.inferring.pop()
return res
elif (instance.type.is_protocol and self.direction == SUBTYPE_OF and
# We avoid infinite recursion for structural subtypes also here.
not any(is_same_type(instance, i) for i in instance.type.inferring) and
mypy.subtypes.is_protocol_implementation(erased, instance)):
instance.type.inferring.append(instance)
self.infer_constraints_from_protocol_members(res, instance, template,
template, instance)
instance.type.inferring.pop()
return res
if isinstance(actual, AnyType):
# IDEA: Include both ways, i.e. add negation as well?
return self.infer_against_any(template.args, actual)
if (isinstance(actual, TupleType) and
(is_named_instance(template, 'typing.Iterable') or
is_named_instance(template, 'typing.Container') or
is_named_instance(template, 'typing.Sequence') or
is_named_instance(template, 'typing.Reversible'))
and self.direction == SUPERTYPE_OF):
for item in actual.items:
cb = infer_constraints(template.args[0], item, SUPERTYPE_OF)
res.extend(cb)
return res
elif isinstance(actual, TupleType) and self.direction == SUPERTYPE_OF:
return infer_constraints(template, actual.fallback, self.direction)
else:
return []
def analyze_member_access(
name: str,
typ: Type,
node: Context,
is_lvalue: bool,
is_super: bool,
is_operator: bool,
builtin_type: Callable[[str], Instance],
not_ready_callback: Callable[[str, Context], None],
msg: MessageBuilder,
override_info: TypeInfo = None,
report_type: Type = None,
chk: "mypy.checker.TypeChecker" = None,
) -> Type:
"""Analyse attribute access.
This is a general operation that supports various different variations:
1. lvalue or non-lvalue access (i.e. setter or getter access)
2. supertype access (when using super(); is_super == True and
override_info should refer to the supertype)
"""
report_type = report_type or typ
if isinstance(typ, Instance):
if name == "__init__" and not is_super:
# Accessing __init__ in statically typed code would compromise
# type safety unless used via super().
msg.fail(messages.CANNOT_ACCESS_INIT, node)
return AnyType()
# The base object has an instance type.
info = typ.type
if override_info:
info = override_info
# Look up the member. First look up the method dictionary.
method = info.get_method(name)
if method:
if method.is_property:
assert isinstance(method, OverloadedFuncDef)
return analyze_var(name, method.items[0].var, typ, info, node, is_lvalue, msg, not_ready_callback)
if is_lvalue:
msg.cant_assign_to_method(node)
typ = map_instance_to_supertype(typ, method.info)
if name == "__new__":
# __new__ is special and behaves like a static method -- don't strip
# the first argument.
signature = function_type(method, builtin_type("builtins.function"))
else:
signature = method_type_with_fallback(method, builtin_type("builtins.function"))
return expand_type_by_instance(signature, typ)
else:
# Not a method.
return analyze_member_var_access(
name,
typ,
info,
node,
is_lvalue,
is_super,
builtin_type,
not_ready_callback,
msg,
report_type=report_type,
chk=chk,
)
elif isinstance(typ, AnyType):
# The base object has dynamic type.
return AnyType()
elif isinstance(typ, NoneTyp):
if chk and chk.should_suppress_optional_error([typ]):
return AnyType()
# The only attribute NoneType has are those it inherits from object
return analyze_member_access(
name,
builtin_type("builtins.object"),
node,
is_lvalue,
is_super,
is_operator,
builtin_type,
not_ready_callback,
msg,
report_type=report_type,
chk=chk,
)
elif isinstance(typ, UnionType):
# The base object has dynamic type.
msg.disable_type_names += 1
results = [
analyze_member_access(
name, subtype, node, is_lvalue, is_super, is_operator, builtin_type, not_ready_callback, msg, chk=chk
)
for subtype in typ.items
]
msg.disable_type_names -= 1
return UnionType.make_simplified_union(results)
elif isinstance(typ, TupleType):
# Actually look up from the fallback instance type.
return analyze_member_access(
name, typ.fallback, node, is_lvalue, is_super, is_operator, builtin_type, not_ready_callback, msg, chk=chk
)
elif isinstance(typ, FunctionLike) and typ.is_type_obj():
# Class attribute.
# TODO super?
ret_type = typ.items()[0].ret_type
if isinstance(ret_type, TupleType):
ret_type = ret_type.fallback
if isinstance(ret_type, Instance):
if not is_operator:
# When Python sees an operator (eg `3 == 4`), it automatically translates that
# into something like `int.__eq__(3, 4)` instead of `(3).__eq__(4)` as an
# optimation.
#
# While it normally it doesn't matter which of the two versions are used, it
# does cause inconsistencies when working with classes. For example, translating
# `int == int` to `int.__eq__(int)` would not work since `int.__eq__` is meant to
# compare two int _instances_. What we really want is `type(int).__eq__`, which
# is meant to compare two types or classes.
#
# This check makes sure that when we encounter an operator, we skip looking up
# the corresponding method in the current instance to avoid this edge case.
# See https://github.com/python/mypy/pull/1787 for more info.
result = analyze_class_attribute_access(
ret_type, name, node, is_lvalue, builtin_type, not_ready_callback, msg
)
if result:
return result
# Look up from the 'type' type.
return analyze_member_access(
name,
typ.fallback,
node,
is_lvalue,
is_super,
is_operator,
builtin_type,
not_ready_callback,
msg,
report_type=report_type,
chk=chk,
)
else:
assert False, "Unexpected type {}".format(repr(ret_type))
elif isinstance(typ, FunctionLike):
# Look up from the 'function' type.
return analyze_member_access(
name,
typ.fallback,
node,
is_lvalue,
is_super,
is_operator,
builtin_type,
not_ready_callback,
msg,
report_type=report_type,
chk=chk,
)
elif isinstance(typ, TypeVarType):
return analyze_member_access(
name,
typ.upper_bound,
node,
is_lvalue,
is_super,
is_operator,
builtin_type,
not_ready_callback,
msg,
report_type=report_type,
chk=chk,
)
elif isinstance(typ, DeletedType):
msg.deleted_as_rvalue(typ, node)
return AnyType()
elif isinstance(typ, TypeType):
# Similar to FunctionLike + is_type_obj() above.
item = None
if isinstance(typ.item, Instance):
item = typ.item
elif isinstance(typ.item, TypeVarType):
if isinstance(typ.item.upper_bound, Instance):
item = typ.item.upper_bound
if item and not is_operator:
# See comment above for why operators are skipped
result = analyze_class_attribute_access(item, name, node, is_lvalue, builtin_type, not_ready_callback, msg)
if result:
return result
fallback = builtin_type("builtins.type")
return analyze_member_access(
name,
fallback,
node,
is_lvalue,
is_super,
is_operator,
builtin_type,
not_ready_callback,
msg,
report_type=report_type,
chk=chk,
)
if chk and chk.should_suppress_optional_error([typ]):
return AnyType()
return msg.has_no_attr(report_type, name, node)
def analyze_member_var_access(name: str,
itype: Instance,
info: TypeInfo,
mx: MemberContext) -> Type:
"""Analyse attribute access that does not target a method.
This is logically part of analyze_member_access and the arguments are similar.
original_type is the type of E in the expression E.var
"""
# It was not a method. Try looking up a variable.
v = lookup_member_var_or_accessor(info, name, mx.is_lvalue)
vv = v
if isinstance(vv, Decorator):
# The associated Var node of a decorator contains the type.
v = vv.var
if isinstance(vv, TypeInfo):
# If the associated variable is a TypeInfo synthesize a Var node for
# the purposes of type checking. This enables us to type check things
# like accessing class attributes on an inner class.
v = Var(name, type=type_object_type(vv, mx.builtin_type))
v.info = info
if isinstance(vv, TypeAlias) and isinstance(vv.target, Instance):
# Similar to the above TypeInfo case, we allow using
# qualified type aliases in runtime context if it refers to an
# instance type. For example:
# class C:
# A = List[int]
# x = C.A() <- this is OK
typ = instance_alias_type(vv, mx.builtin_type)
v = Var(name, type=typ)
v.info = info
if isinstance(v, Var):
implicit = info[name].implicit
# An assignment to final attribute is always an error,
# independently of types.
if mx.is_lvalue and not mx.chk.get_final_context():
check_final_member(name, info, mx.msg, mx.context)
return analyze_var(name, v, itype, info, mx, implicit=implicit)
elif isinstance(v, FuncDef):
assert False, "Did not expect a function"
elif (not v and name not in ['__getattr__', '__setattr__', '__getattribute__'] and
not mx.is_operator):
if not mx.is_lvalue:
for method_name in ('__getattribute__', '__getattr__'):
method = info.get_method(method_name)
# __getattribute__ is defined on builtins.object and returns Any, so without
# the guard this search will always find object.__getattribute__ and conclude
# that the attribute exists
if method and method.info.fullname() != 'builtins.object':
function = function_type(method, mx.builtin_type('builtins.function'))
bound_method = bind_self(function, mx.original_type)
typ = map_instance_to_supertype(itype, method.info)
getattr_type = expand_type_by_instance(bound_method, typ)
if isinstance(getattr_type, CallableType):
result = getattr_type.ret_type
# Call the attribute hook before returning.
fullname = '{}.{}'.format(method.info.fullname(), name)
hook = mx.chk.plugin.get_attribute_hook(fullname)
if hook:
result = hook(AttributeContext(mx.original_type, result,
mx.context, mx.chk))
return result
else:
setattr_meth = info.get_method('__setattr__')
if setattr_meth and setattr_meth.info.fullname() != 'builtins.object':
setattr_func = function_type(setattr_meth, mx.builtin_type('builtins.function'))
bound_type = bind_self(setattr_func, mx.original_type)
typ = map_instance_to_supertype(itype, setattr_meth.info)
setattr_type = expand_type_by_instance(bound_type, typ)
if isinstance(setattr_type, CallableType) and len(setattr_type.arg_types) > 0:
return setattr_type.arg_types[-1]
if itype.type.fallback_to_any:
return AnyType(TypeOfAny.special_form)
# Could not find the member.
if mx.is_super:
mx.msg.undefined_in_superclass(name, mx.context)
return AnyType(TypeOfAny.from_error)
else:
if mx.chk and mx.chk.should_suppress_optional_error([itype]):
return AnyType(TypeOfAny.from_error)
return mx.msg.has_no_attr(mx.original_type, itype, name, mx.context)
def is_overlapping_types(left: Type,
right: Type,
ignore_promotions: bool = False,
prohibit_none_typevar_overlap: bool = False) -> bool:
"""Can a value of type 'left' also be of type 'right' or vice-versa?
If 'ignore_promotions' is True, we ignore promotions while checking for overlaps.
If 'prohibit_none_typevar_overlap' is True, we disallow None from overlapping with
TypeVars (in both strict-optional and non-strict-optional mode).
"""
def _is_overlapping_types(left: Type, right: Type) -> bool:
'''Encode the kind of overlapping check to perform.
This function mostly exists so we don't have to repeat keyword arguments everywhere.'''
return is_overlapping_types(
left, right,
ignore_promotions=ignore_promotions,
prohibit_none_typevar_overlap=prohibit_none_typevar_overlap)
# We should never encounter this type.
if isinstance(left, PartialType) or isinstance(right, PartialType):
assert False, "Unexpectedly encountered partial type"
# We should also never encounter these types, but it's possible a few
# have snuck through due to unrelated bugs. For now, we handle these
# in the same way we handle 'Any'.
#
# TODO: Replace these with an 'assert False' once we are more confident.
illegal_types = (UnboundType, ErasedType, DeletedType)
if isinstance(left, illegal_types) or isinstance(right, illegal_types):
return True
# 'Any' may or may not be overlapping with the other type
if isinstance(left, AnyType) or isinstance(right, AnyType):
return True
# When running under non-strict optional mode, simplify away types of
# the form 'Union[A, B, C, None]' into just 'Union[A, B, C]'.
if not state.strict_optional:
if isinstance(left, UnionType):
left = UnionType.make_union(left.relevant_items())
if isinstance(right, UnionType):
right = UnionType.make_union(right.relevant_items())
# We check for complete overlaps next as a general-purpose failsafe.
# If this check fails, we start checking to see if there exists a
# *partial* overlap between types.
#
# These checks will also handle the NoneTyp and UninhabitedType cases for us.
if (is_proper_subtype(left, right, ignore_promotions=ignore_promotions)
or is_proper_subtype(right, left, ignore_promotions=ignore_promotions)):
return True
# See the docstring for 'get_possible_variants' for more info on what the
# following lines are doing.
left_possible = get_possible_variants(left)
right_possible = get_possible_variants(right)
# We start by checking multi-variant types like Unions first. We also perform
# the same logic if either type happens to be a TypeVar.
#
# Handling the TypeVars now lets us simulate having them bind to the corresponding
# type -- if we deferred these checks, the "return-early" logic of the other
# checks will prevent us from detecting certain overlaps.
#
# If both types are singleton variants (and are not TypeVars), we've hit the base case:
# we skip these checks to avoid infinitely recursing.
def is_none_typevar_overlap(t1: Type, t2: Type) -> bool:
return isinstance(t1, NoneTyp) and isinstance(t2, TypeVarType)
if prohibit_none_typevar_overlap:
if is_none_typevar_overlap(left, right) or is_none_typevar_overlap(right, left):
return False
if (len(left_possible) > 1 or len(right_possible) > 1
or isinstance(left, TypeVarType) or isinstance(right, TypeVarType)):
for l in left_possible:
for r in right_possible:
if _is_overlapping_types(l, r):
return True
return False
# Now that we've finished handling TypeVars, we're free to end early
# if one one of the types is None and we're running in strict-optional mode.
# (None only overlaps with None in strict-optional mode).
#
# We must perform this check after the TypeVar checks because
# a TypeVar could be bound to None, for example.
if state.strict_optional and isinstance(left, NoneTyp) != isinstance(right, NoneTyp):
return False
# Next, we handle single-variant types that may be inherently partially overlapping:
#
# - TypedDicts
# - Tuples
#
# If we cannot identify a partial overlap and end early, we degrade these two types
# into their 'Instance' fallbacks.
if isinstance(left, TypedDictType) and isinstance(right, TypedDictType):
return are_typed_dicts_overlapping(left, right, ignore_promotions=ignore_promotions)
elif isinstance(left, TypedDictType):
left = left.fallback
elif isinstance(right, TypedDictType):
right = right.fallback
if is_tuple(left) and is_tuple(right):
return are_tuples_overlapping(left, right, ignore_promotions=ignore_promotions)
elif isinstance(left, TupleType):
left = left.fallback
elif isinstance(right, TupleType):
right = right.fallback
# Next, we handle single-variant types that cannot be inherently partially overlapping,
# but do require custom logic to inspect.
#
# As before, we degrade into 'Instance' whenever possible.
if isinstance(left, TypeType) and isinstance(right, TypeType):
# TODO: Can Callable[[...], T] and Type[T] be partially overlapping?
return _is_overlapping_types(left.item, right.item)
if isinstance(left, CallableType) and isinstance(right, CallableType):
return is_callable_compatible(left, right,
is_compat=_is_overlapping_types,
ignore_pos_arg_names=True,
allow_partial_overlap=True)
elif isinstance(left, CallableType):
left = left.fallback
elif isinstance(right, CallableType):
right = right.fallback
if isinstance(left, LiteralType) and isinstance(right, LiteralType):
return left == right
elif isinstance(left, LiteralType):
left = left.fallback
elif isinstance(right, LiteralType):
right = right.fallback
# Finally, we handle the case where left and right are instances.
if isinstance(left, Instance) and isinstance(right, Instance):
if left.type.is_protocol and is_protocol_implementation(right, left):
return True
if right.type.is_protocol and is_protocol_implementation(left, right):
return True
# Two unrelated types cannot be partially overlapping: they're disjoint.
# We don't need to handle promotions because they've already been handled
# by the calls to `is_subtype(...)` up above (and promotable types never
# have any generic arguments we need to recurse on).
if left.type.has_base(right.type.fullname()):
left = map_instance_to_supertype(left, right.type)
elif right.type.has_base(left.type.fullname()):
right = map_instance_to_supertype(right, left.type)
else:
return False
if len(left.args) == len(right.args):
# Note: we don't really care about variance here, since the overlapping check
# is symmetric and since we want to return 'True' even for partial overlaps.
#
# For example, suppose we have two types Wrapper[Parent] and Wrapper[Child].
# It doesn't matter whether Wrapper is covariant or contravariant since
# either way, one of the two types will overlap with the other.
#
# Similarly, if Wrapper was invariant, the two types could still be partially
# overlapping -- what if Wrapper[Parent] happened to contain only instances of
# specifically Child?
#
# Or, to use a more concrete example, List[Union[A, B]] and List[Union[B, C]]
# would be considered partially overlapping since it's possible for both lists
# to contain only instances of B at runtime.
for left_arg, right_arg in zip(left.args, right.args):
if _is_overlapping_types(left_arg, right_arg):
return True
return False
# We ought to have handled every case by now: we conclude the
# two types are not overlapping, either completely or partially.
#
# Note: it's unclear however, whether returning False is the right thing
# to do when inferring reachability -- see https://github.com/python/mypy/issues/5529
assert type(left) != type(right)
return False
def analyse_member_access(name: str, typ: Type, node: Context, is_lvalue: bool,
is_super: bool,
builtin_type: Function[[str], Instance],
msg: MessageBuilder, override_info: TypeInfo = None,
report_type: Type = None) -> Type:
"""Analyse attribute access.
This is a general operation that supports various different variations:
1. lvalue or non-lvalue access (i.e. setter or getter access)
2. supertype access (when using super(); is_super == True and
override_info should refer to the supertype)
"""
report_type = report_type or typ
if isinstance(typ, Instance):
if name == '__init__' and not is_super:
# Accessing __init__ in statically typed code would compromise
# type safety unless used via super().
msg.fail(messages.CANNOT_ACCESS_INIT, node)
return AnyType()
# The base object has an instance type.
info = typ.type
if override_info:
info = override_info
# Look up the member. First look up the method dictionary.
method = info.get_method(name)
if method:
if is_lvalue:
msg.cant_assign_to_method(node)
typ = map_instance_to_supertype(typ, method.info)
return expand_type_by_instance(
method_type(method, builtin_type('builtins.function')), typ)
else:
# Not a method.
return analyse_member_var_access(name, typ, info, node,
is_lvalue, is_super, msg,
report_type=report_type)
elif isinstance(typ, AnyType):
# The base object has dynamic type.
return AnyType()
elif isinstance(typ, UnionType):
# The base object has dynamic type.
msg.disable_type_names += 1
results = [analyse_member_access(name, subtype, node, is_lvalue,
is_super, builtin_type, msg)
for subtype in typ.items]
msg.disable_type_names -= 1
return UnionType.make_simplified_union(results)
elif isinstance(typ, TupleType):
# Actually look up from the fallback instance type.
return analyse_member_access(name, typ.fallback, node, is_lvalue,
is_super, builtin_type, msg)
elif (isinstance(typ, FunctionLike) and
cast(FunctionLike, typ).is_type_obj()):
# Class attribute.
# TODO super?
sig = cast(FunctionLike, typ)
itype = cast(Instance, sig.items()[0].ret_type)
result = analyse_class_attribute_access(itype, name, node, is_lvalue, builtin_type, msg)
if result:
return result
# Look up from the 'type' type.
return analyse_member_access(name, sig.fallback, node, is_lvalue, is_super,
builtin_type, msg, report_type=report_type)
elif isinstance(typ, FunctionLike):
# Look up from the 'function' type.
return analyse_member_access(name, typ.fallback, node, is_lvalue, is_super,
builtin_type, msg, report_type=report_type)
return msg.has_no_attr(report_type, name, node)
def visit_instance(self, template: Instance) -> List[Constraint]:
original_actual = actual = self.actual
res = [] # type: List[Constraint]
if isinstance(actual, CallableType) and actual.fallback is not None:
actual = actual.fallback
if isinstance(actual, TypedDictType):
actual = actual.as_anonymous().fallback
if isinstance(actual, Instance):
instance = actual
# We always try nominal inference if possible,
# it is much faster than the structural one.
if (self.direction == SUBTYPE_OF and
template.type.has_base(instance.type.fullname())):
mapped = map_instance_to_supertype(template, instance.type)
for i in range(len(instance.args)):
# The constraints for generic type parameters are
# invariant. Include constraints from both directions
# to achieve the effect.
res.extend(infer_constraints(
mapped.args[i], instance.args[i], self.direction))
res.extend(infer_constraints(
mapped.args[i], instance.args[i], neg_op(self.direction)))
return res
elif (self.direction == SUPERTYPE_OF and
instance.type.has_base(template.type.fullname())):
mapped = map_instance_to_supertype(instance, template.type)
for j in range(len(template.args)):
# The constraints for generic type parameters are
# invariant.
res.extend(infer_constraints(
template.args[j], mapped.args[j], self.direction))
res.extend(infer_constraints(
template.args[j], mapped.args[j], neg_op(self.direction)))
return res
if (template.type.is_protocol and self.direction == SUPERTYPE_OF and
# We avoid infinite recursion for structural subtypes by checking
# whether this type already appeared in the inference chain.
# This is a conservative way break the inference cycles.
# It never produces any "false" constraints but gives up soon
# on purely structural inference cycles, see #3829.
not any(is_same_type(template, t) for t in template.type.inferring) and
mypy.subtypes.is_subtype(instance, erase_typevars(template))):
template.type.inferring.append(template)
self.infer_constraints_from_protocol_members(res, instance, template,
original_actual, template)
template.type.inferring.pop()
return res
elif (instance.type.is_protocol and self.direction == SUBTYPE_OF and
# We avoid infinite recursion for structural subtypes also here.
not any(is_same_type(instance, i) for i in instance.type.inferring) and
mypy.subtypes.is_subtype(erase_typevars(template), instance)):
instance.type.inferring.append(instance)
self.infer_constraints_from_protocol_members(res, instance, template,
template, instance)
instance.type.inferring.pop()
return res
if isinstance(actual, AnyType):
# IDEA: Include both ways, i.e. add negation as well?
return self.infer_against_any(template.args, actual)
if (isinstance(actual, TupleType) and
(is_named_instance(template, 'typing.Iterable') or
is_named_instance(template, 'typing.Container') or
is_named_instance(template, 'typing.Sequence') or
is_named_instance(template, 'typing.Reversible'))
and self.direction == SUPERTYPE_OF):
for item in actual.items:
cb = infer_constraints(template.args[0], item, SUPERTYPE_OF)
res.extend(cb)
return res
elif isinstance(actual, TupleType) and self.direction == SUPERTYPE_OF:
return infer_constraints(template, actual.fallback, self.direction)
else:
return []
def visit_instance(self, template: Instance) -> List[Constraint]:
original_actual = actual = self.actual
res = [] # type: List[Constraint]
if isinstance(
actual,
(CallableType, Overloaded)) and template.type.is_protocol:
if template.type.protocol_members == ['__call__']:
# Special case: a generic callback protocol
if not any(
mypy.sametypes.is_same_type(template, t)
for t in template.type.inferring):
template.type.inferring.append(template)
call = mypy.subtypes.find_member('__call__', template,
actual)
assert call is not None
if mypy.subtypes.is_subtype(actual, erase_typevars(call)):
subres = infer_constraints(call, actual,
self.direction)
res.extend(subres)
template.type.inferring.pop()
return res
if isinstance(actual, CallableType) and actual.fallback is not None:
actual = actual.fallback
if isinstance(actual, Overloaded) and actual.fallback is not None:
actual = actual.fallback
if isinstance(actual, TypedDictType):
actual = actual.as_anonymous().fallback
if isinstance(actual, Instance):
instance = actual
erased = erase_typevars(template)
assert isinstance(erased, Instance)
# We always try nominal inference if possible,
# it is much faster than the structural one.
if (self.direction == SUBTYPE_OF
and template.type.has_base(instance.type.fullname())):
mapped = map_instance_to_supertype(template, instance.type)
tvars = mapped.type.defn.type_vars
for i in range(len(instance.args)):
# The constraints for generic type parameters depend on variance.
# Include constraints from both directions if invariant.
if tvars[i].variance != CONTRAVARIANT:
res.extend(
infer_constraints(mapped.args[i], instance.args[i],
self.direction))
if tvars[i].variance != COVARIANT:
res.extend(
infer_constraints(mapped.args[i], instance.args[i],
neg_op(self.direction)))
return res
elif (self.direction == SUPERTYPE_OF
and instance.type.has_base(template.type.fullname())):
mapped = map_instance_to_supertype(instance, template.type)
tvars = template.type.defn.type_vars
for j in range(len(template.args)):
# The constraints for generic type parameters depend on variance.
# Include constraints from both directions if invariant.
if tvars[j].variance != CONTRAVARIANT:
res.extend(
infer_constraints(template.args[j], mapped.args[j],
self.direction))
if tvars[j].variance != COVARIANT:
res.extend(
infer_constraints(template.args[j], mapped.args[j],
neg_op(self.direction)))
return res
if (template.type.is_protocol and self.direction == SUPERTYPE_OF
and
# We avoid infinite recursion for structural subtypes by checking
# whether this type already appeared in the inference chain.
# This is a conservative way break the inference cycles.
# It never produces any "false" constraints but gives up soon
# on purely structural inference cycles, see #3829.
# Note that we use is_protocol_implementation instead of is_subtype
# because some type may be considered a subtype of a protocol
# due to _promote, but still not implement the protocol.
not any(
mypy.sametypes.is_same_type(template, t)
for t in template.type.inferring)
and mypy.subtypes.is_protocol_implementation(
instance, erased)):
template.type.inferring.append(template)
self.infer_constraints_from_protocol_members(
res, instance, template, original_actual, template)
template.type.inferring.pop()
return res
elif (instance.type.is_protocol and self.direction == SUBTYPE_OF
and
# We avoid infinite recursion for structural subtypes also here.
not any(
mypy.sametypes.is_same_type(instance, i)
for i in instance.type.inferring)
and mypy.subtypes.is_protocol_implementation(
erased, instance)):
instance.type.inferring.append(instance)
self.infer_constraints_from_protocol_members(
res, instance, template, template, instance)
instance.type.inferring.pop()
return res
if isinstance(actual, AnyType):
# IDEA: Include both ways, i.e. add negation as well?
return self.infer_against_any(template.args, actual)
if (isinstance(actual, TupleType)
and (is_named_instance(template, 'typing.Iterable')
or is_named_instance(template, 'typing.Container')
or is_named_instance(template, 'typing.Sequence')
or is_named_instance(template, 'typing.Reversible'))
and self.direction == SUPERTYPE_OF):
for item in actual.items:
cb = infer_constraints(template.args[0], item, SUPERTYPE_OF)
res.extend(cb)
return res
elif isinstance(actual, TupleType) and self.direction == SUPERTYPE_OF:
return infer_constraints(template,
mypy.typeops.tuple_fallback(actual),
self.direction)
else:
return []
def analyze_member_access(name: str,
typ: Type,
node: Context,
is_lvalue: bool,
is_super: bool,
is_operator: bool,
builtin_type: Callable[[str], Instance],
not_ready_callback: Callable[[str, Context], None],
msg: MessageBuilder,
*,
original_type: Type,
override_info: TypeInfo = None,
chk: 'mypy.checker.TypeChecker' = None) -> Type:
"""Return the type of attribute `name` of typ.
This is a general operation that supports various different variations:
1. lvalue or non-lvalue access (i.e. setter or getter access)
2. supertype access (when using super(); is_super == True and
override_info should refer to the supertype)
original_type is the most precise inferred or declared type of the base object
that we have available. typ is generally a supertype of original_type.
When looking for an attribute of typ, we may perform recursive calls targeting
the fallback type, for example.
original_type is always the type used in the initial call.
"""
if isinstance(typ, Instance):
if name == '__init__' and not is_super:
# Accessing __init__ in statically typed code would compromise
# type safety unless used via super().
msg.fail(messages.CANNOT_ACCESS_INIT, node)
return AnyType()
# The base object has an instance type.
info = typ.type
if override_info:
info = override_info
if (experiments.find_occurrences
and info.name() == experiments.find_occurrences[0]
and name == experiments.find_occurrences[1]):
msg.note(
"Occurrence of '{}.{}'".format(*experiments.find_occurrences),
node)
# Look up the member. First look up the method dictionary.
method = info.get_method(name)
if method:
if method.is_property:
assert isinstance(method, OverloadedFuncDef)
return analyze_var(name, method.items[0].var, typ, info, node,
is_lvalue, msg, original_type,
not_ready_callback)
if is_lvalue:
msg.cant_assign_to_method(node)
signature = function_type(method,
builtin_type('builtins.function'))
signature = freshen_function_type_vars(signature)
if name == '__new__':
# __new__ is special and behaves like a static method -- don't strip
# the first argument.
pass
else:
signature = bind_self(signature, original_type)
typ = map_instance_to_supertype(typ, method.info)
member_type = expand_type_by_instance(signature, typ)
freeze_type_vars(member_type)
return member_type
else:
# Not a method.
return analyze_member_var_access(name,
typ,
info,
node,
is_lvalue,
is_super,
builtin_type,
not_ready_callback,
msg,
original_type=original_type,
chk=chk)
elif isinstance(typ, AnyType):
# The base object has dynamic type.
return AnyType()
elif isinstance(typ, NoneTyp):
if chk and chk.should_suppress_optional_error([typ]):
return AnyType()
# The only attribute NoneType has are those it inherits from object
return analyze_member_access(name,
builtin_type('builtins.object'),
node,
is_lvalue,
is_super,
is_operator,
builtin_type,
not_ready_callback,
msg,
original_type=original_type,
chk=chk)
elif isinstance(typ, UnionType):
# The base object has dynamic type.
msg.disable_type_names += 1
results = [
analyze_member_access(name,
subtype,
node,
is_lvalue,
is_super,
is_operator,
builtin_type,
not_ready_callback,
msg,
original_type=original_type,
chk=chk) for subtype in typ.items
]
msg.disable_type_names -= 1
return UnionType.make_simplified_union(results)
elif isinstance(typ, TupleType):
# Actually look up from the fallback instance type.
return analyze_member_access(name,
typ.fallback,
node,
is_lvalue,
is_super,
is_operator,
builtin_type,
not_ready_callback,
msg,
original_type=original_type,
chk=chk)
elif isinstance(typ, TypedDictType):
# Actually look up from the fallback instance type.
return analyze_member_access(name,
typ.fallback,
node,
is_lvalue,
is_super,
is_operator,
builtin_type,
not_ready_callback,
msg,
original_type=original_type,
chk=chk)
elif isinstance(typ, FunctionLike) and typ.is_type_obj():
# Class attribute.
# TODO super?
ret_type = typ.items()[0].ret_type
if isinstance(ret_type, TupleType):
ret_type = ret_type.fallback
if isinstance(ret_type, Instance):
if not is_operator:
# When Python sees an operator (eg `3 == 4`), it automatically translates that
# into something like `int.__eq__(3, 4)` instead of `(3).__eq__(4)` as an
# optimization.
#
# While it normally it doesn't matter which of the two versions are used, it
# does cause inconsistencies when working with classes. For example, translating
# `int == int` to `int.__eq__(int)` would not work since `int.__eq__` is meant to
# compare two int _instances_. What we really want is `type(int).__eq__`, which
# is meant to compare two types or classes.
#
# This check makes sure that when we encounter an operator, we skip looking up
# the corresponding method in the current instance to avoid this edge case.
# See https://github.com/python/mypy/pull/1787 for more info.
result = analyze_class_attribute_access(
ret_type,
name,
node,
is_lvalue,
builtin_type,
not_ready_callback,
msg,
original_type=original_type)
if result:
return result
# Look up from the 'type' type.
return analyze_member_access(name,
typ.fallback,
node,
is_lvalue,
is_super,
is_operator,
builtin_type,
not_ready_callback,
msg,
original_type=original_type,
chk=chk)
else:
assert False, 'Unexpected type {}'.format(repr(ret_type))
elif isinstance(typ, FunctionLike):
# Look up from the 'function' type.
return analyze_member_access(name,
typ.fallback,
node,
is_lvalue,
is_super,
is_operator,
builtin_type,
not_ready_callback,
msg,
original_type=original_type,
chk=chk)
elif isinstance(typ, TypeVarType):
return analyze_member_access(name,
typ.upper_bound,
node,
is_lvalue,
is_super,
is_operator,
builtin_type,
not_ready_callback,
msg,
original_type=original_type,
chk=chk)
elif isinstance(typ, DeletedType):
msg.deleted_as_rvalue(typ, node)
return AnyType()
elif isinstance(typ, TypeType):
# Similar to FunctionLike + is_type_obj() above.
item = None
if isinstance(typ.item, Instance):
item = typ.item
elif isinstance(typ.item, TypeVarType):
if isinstance(typ.item.upper_bound, Instance):
item = typ.item.upper_bound
if item and not is_operator:
# See comment above for why operators are skipped
result = analyze_class_attribute_access(
item,
name,
node,
is_lvalue,
builtin_type,
not_ready_callback,
msg,
original_type=original_type)
if result:
return result
fallback = builtin_type('builtins.type')
if item is not None:
fallback = item.type.metaclass_type or fallback
return analyze_member_access(name,
fallback,
node,
is_lvalue,
is_super,
is_operator,
builtin_type,
not_ready_callback,
msg,
original_type=original_type,
chk=chk)
if chk and chk.should_suppress_optional_error([typ]):
return AnyType()
return msg.has_no_attr(original_type, name, node)
def analyze_member_access(name: str,
typ: Type,
node: Context,
is_lvalue: bool,
is_super: bool,
builtin_type: Callable[[str], Instance],
msg: MessageBuilder,
override_info: TypeInfo = None,
report_type: Type = None) -> Type:
"""Analyse attribute access.
This is a general operation that supports various different variations:
1. lvalue or non-lvalue access (i.e. setter or getter access)
2. supertype access (when using super(); is_super == True and
override_info should refer to the supertype)
"""
report_type = report_type or typ
if isinstance(typ, Instance):
if name == '__init__' and not is_super:
# Accessing __init__ in statically typed code would compromise
# type safety unless used via super().
msg.fail(messages.CANNOT_ACCESS_INIT, node)
return AnyType()
# The base object has an instance type.
info = typ.type
if override_info:
info = override_info
# Look up the member. First look up the method dictionary.
method = info.get_method(name)
if method:
if method.is_property:
assert isinstance(method, OverloadedFuncDef)
method = cast(OverloadedFuncDef, method)
return analyze_var(name, method.items[0].var, typ, info, node,
is_lvalue, msg)
if is_lvalue:
msg.cant_assign_to_method(node)
typ = map_instance_to_supertype(typ, method.info)
return expand_type_by_instance(
method_type_with_fallback(method,
builtin_type('builtins.function')),
typ)
else:
# Not a method.
return analyze_member_var_access(name,
typ,
info,
node,
is_lvalue,
is_super,
builtin_type,
msg,
report_type=report_type)
elif isinstance(typ, AnyType):
# The base object has dynamic type.
return AnyType()
elif isinstance(typ, UnionType):
# The base object has dynamic type.
msg.disable_type_names += 1
results = [
analyze_member_access(name, subtype, node, is_lvalue, is_super,
builtin_type, msg) for subtype in typ.items
]
msg.disable_type_names -= 1
return UnionType.make_simplified_union(results)
elif isinstance(typ, TupleType):
# Actually look up from the fallback instance type.
return analyze_member_access(name, typ.fallback, node, is_lvalue,
is_super, builtin_type, msg)
elif isinstance(typ, FunctionLike) and typ.is_type_obj():
# Class attribute.
# TODO super?
itype = cast(Instance, typ.items()[0].ret_type)
result = analyze_class_attribute_access(itype, name, node, is_lvalue,
builtin_type, msg)
if result:
return result
# Look up from the 'type' type.
return analyze_member_access(name,
typ.fallback,
node,
is_lvalue,
is_super,
builtin_type,
msg,
report_type=report_type)
elif isinstance(typ, FunctionLike):
# Look up from the 'function' type.
return analyze_member_access(name,
typ.fallback,
node,
is_lvalue,
is_super,
builtin_type,
msg,
report_type=report_type)
elif isinstance(typ, TypeVarType):
return analyze_member_access(name,
typ.upper_bound,
node,
is_lvalue,
is_super,
builtin_type,
msg,
report_type=report_type)
return msg.has_no_attr(report_type, name, node)
def analyze_descriptor_access(instance_type: Type, descriptor_type: Type,
builtin_type: Callable[[str], Instance],
msg: MessageBuilder, context: Context, *,
chk: 'mypy.checker.TypeChecker') -> Type:
"""Type check descriptor access.
Arguments:
instance_type: The type of the instance on which the descriptor
attribute is being accessed (the type of ``a`` in ``a.f`` when
``f`` is a descriptor).
descriptor_type: The type of the descriptor attribute being accessed
(the type of ``f`` in ``a.f`` when ``f`` is a descriptor).
context: The node defining the context of this inference.
Return:
The return type of the appropriate ``__get__`` overload for the descriptor.
"""
if isinstance(descriptor_type, UnionType):
# Map the access over union types
return UnionType.make_simplified_union([
analyze_descriptor_access(instance_type,
typ,
builtin_type,
msg,
context,
chk=chk) for typ in descriptor_type.items
])
elif not isinstance(descriptor_type, Instance):
return descriptor_type
if not descriptor_type.type.has_readable_member('__get__'):
return descriptor_type
dunder_get = descriptor_type.type.get_method('__get__')
if dunder_get is None:
msg.fail(
message_registry.DESCRIPTOR_GET_NOT_CALLABLE.format(
descriptor_type), context)
return AnyType(TypeOfAny.from_error)
function = function_type(dunder_get, builtin_type('builtins.function'))
bound_method = bind_self(function, descriptor_type)
typ = map_instance_to_supertype(descriptor_type, dunder_get.info)
dunder_get_type = expand_type_by_instance(bound_method, typ)
if isinstance(instance_type, FunctionLike) and instance_type.is_type_obj():
owner_type = instance_type.items()[0].ret_type
instance_type = NoneTyp()
elif isinstance(instance_type, TypeType):
owner_type = instance_type.item
instance_type = NoneTyp()
else:
owner_type = instance_type
_, inferred_dunder_get_type = chk.expr_checker.check_call(
dunder_get_type, [
TempNode(instance_type),
TempNode(TypeType.make_normalized(owner_type))
], [ARG_POS, ARG_POS], context)
if isinstance(inferred_dunder_get_type, AnyType):
# check_call failed, and will have reported an error
return inferred_dunder_get_type
if not isinstance(inferred_dunder_get_type, CallableType):
msg.fail(
message_registry.DESCRIPTOR_GET_NOT_CALLABLE.format(
descriptor_type), context)
return AnyType(TypeOfAny.from_error)
return inferred_dunder_get_type.ret_type
def visit_instance(self, template: Instance) -> List[Constraint]:
original_actual = actual = self.actual
res: List[Constraint] = []
if isinstance(
actual,
(CallableType, Overloaded)) and template.type.is_protocol:
if template.type.protocol_members == ['__call__']:
# Special case: a generic callback protocol
if not any(
mypy.sametypes.is_same_type(template, t)
for t in template.type.inferring):
template.type.inferring.append(template)
call = mypy.subtypes.find_member('__call__',
template,
actual,
is_operator=True)
assert call is not None
if mypy.subtypes.is_subtype(actual, erase_typevars(call)):
subres = infer_constraints(call, actual,
self.direction)
res.extend(subres)
template.type.inferring.pop()
return res
if isinstance(actual, CallableType) and actual.fallback is not None:
actual = actual.fallback
if isinstance(actual, Overloaded) and actual.fallback is not None:
actual = actual.fallback
if isinstance(actual, TypedDictType):
actual = actual.as_anonymous().fallback
if isinstance(actual, LiteralType):
actual = actual.fallback
if isinstance(actual, Instance):
instance = actual
erased = erase_typevars(template)
assert isinstance(erased, Instance) # type: ignore
# We always try nominal inference if possible,
# it is much faster than the structural one.
if (self.direction == SUBTYPE_OF
and template.type.has_base(instance.type.fullname)):
mapped = map_instance_to_supertype(template, instance.type)
tvars = mapped.type.defn.type_vars
# N.B: We use zip instead of indexing because the lengths might have
# mismatches during daemon reprocessing.
for tvar, mapped_arg, instance_arg in zip(
tvars, mapped.args, instance.args):
# TODO: ParamSpecType
if isinstance(tvar, TypeVarType):
# The constraints for generic type parameters depend on variance.
# Include constraints from both directions if invariant.
if tvar.variance != CONTRAVARIANT:
res.extend(
infer_constraints(mapped_arg, instance_arg,
self.direction))
if tvar.variance != COVARIANT:
res.extend(
infer_constraints(mapped_arg, instance_arg,
neg_op(self.direction)))
return res
elif (self.direction == SUPERTYPE_OF
and instance.type.has_base(template.type.fullname)):
mapped = map_instance_to_supertype(instance, template.type)
tvars = template.type.defn.type_vars
# N.B: We use zip instead of indexing because the lengths might have
# mismatches during daemon reprocessing.
for tvar, mapped_arg, template_arg in zip(
tvars, mapped.args, template.args):
# TODO: ParamSpecType
if isinstance(tvar, TypeVarType):
# The constraints for generic type parameters depend on variance.
# Include constraints from both directions if invariant.
if tvar.variance != CONTRAVARIANT:
res.extend(
infer_constraints(template_arg, mapped_arg,
self.direction))
if tvar.variance != COVARIANT:
res.extend(
infer_constraints(template_arg, mapped_arg,
neg_op(self.direction)))
return res
if (template.type.is_protocol and self.direction == SUPERTYPE_OF
and
# We avoid infinite recursion for structural subtypes by checking
# whether this type already appeared in the inference chain.
# This is a conservative way to break the inference cycles.
# It never produces any "false" constraints but gives up soon
# on purely structural inference cycles, see #3829.
# Note that we use is_protocol_implementation instead of is_subtype
# because some type may be considered a subtype of a protocol
# due to _promote, but still not implement the protocol.
not any(
mypy.sametypes.is_same_type(template, t)
for t in template.type.inferring)
and mypy.subtypes.is_protocol_implementation(
instance, erased)):
template.type.inferring.append(template)
res.extend(
self.infer_constraints_from_protocol_members(
instance, template, original_actual, template))
template.type.inferring.pop()
return res
elif (instance.type.is_protocol and self.direction == SUBTYPE_OF
and
# We avoid infinite recursion for structural subtypes also here.
not any(
mypy.sametypes.is_same_type(instance, i)
for i in instance.type.inferring)
and mypy.subtypes.is_protocol_implementation(
erased, instance)):
instance.type.inferring.append(instance)
res.extend(
self.infer_constraints_from_protocol_members(
instance, template, template, instance))
instance.type.inferring.pop()
return res
if isinstance(actual, AnyType):
return self.infer_against_any(template.args, actual)
if (isinstance(actual, TupleType)
and is_named_instance(template, TUPLE_LIKE_INSTANCE_NAMES)
and self.direction == SUPERTYPE_OF):
for item in actual.items:
cb = infer_constraints(template.args[0], item, SUPERTYPE_OF)
res.extend(cb)
return res
elif isinstance(actual, TupleType) and self.direction == SUPERTYPE_OF:
return infer_constraints(template,
mypy.typeops.tuple_fallback(actual),
self.direction)
elif isinstance(actual, TypeVarType):
if not actual.values:
return infer_constraints(template, actual.upper_bound,
self.direction)
return []
else:
return []
def analyze_class_attribute_access(itype: Instance, name: str,
mx: MemberContext) -> Optional[Type]:
"""original_type is the type of E in the expression E.var"""
node = itype.type.get(name)
if not node:
if itype.type.fallback_to_any:
return AnyType(TypeOfAny.special_form)
return None
is_decorated = isinstance(node.node, Decorator)
is_method = is_decorated or isinstance(node.node, FuncBase)
if mx.is_lvalue:
if is_method:
mx.msg.cant_assign_to_method(mx.context)
if isinstance(node.node, TypeInfo):
mx.msg.fail(message_registry.CANNOT_ASSIGN_TO_TYPE, mx.context)
# If a final attribute was declared on `self` in `__init__`, then it
# can't be accessed on the class object.
if node.implicit and isinstance(node.node, Var) and node.node.is_final:
mx.msg.fail(
message_registry.CANNOT_ACCESS_FINAL_INSTANCE_ATTR.format(
node.node.name()), mx.context)
# An assignment to final attribute on class object is also always an error,
# independently of types.
if mx.is_lvalue and not mx.chk.get_final_context():
check_final_member(name, itype.type, mx.msg, mx.context)
if itype.type.is_enum and not (mx.is_lvalue or is_decorated or is_method):
return itype
t = node.type
if t:
if isinstance(t, PartialType):
symnode = node.node
assert isinstance(symnode, Var)
return mx.chk.handle_partial_var_type(t, mx.is_lvalue, symnode,
mx.context)
# Find the class where method/variable was defined.
if isinstance(node.node, Decorator):
super_info = node.node.var.info # type: Optional[TypeInfo]
elif isinstance(node.node, (Var, SYMBOL_FUNCBASE_TYPES)):
super_info = node.node.info
else:
super_info = None
# Map the type to how it would look as a defining class. For example:
# class C(Generic[T]): ...
# class D(C[Tuple[T, S]]): ...
# D[int, str].method()
# Here itype is D[int, str], isuper is C[Tuple[int, str]].
if not super_info:
isuper = None
else:
isuper = map_instance_to_supertype(itype, super_info)
if isinstance(node.node, Var):
assert isuper is not None
# Check if original variable type has type variables. For example:
# class C(Generic[T]):
# x: T
# C.x # Error, ambiguous access
# C[int].x # Also an error, since C[int] is same as C at runtime
if isinstance(t, TypeVarType) or get_type_vars(t):
# Exception: access on Type[...], including first argument of class methods is OK.
if not isinstance(mx.original_type, TypeType):
mx.msg.fail(
message_registry.GENERIC_INSTANCE_VAR_CLASS_ACCESS,
mx.context)
# Erase non-mapped variables, but keep mapped ones, even if there is an error.
# In the above example this means that we infer following types:
# C.x -> Any
# C[int].x -> int
t = erase_typevars(expand_type_by_instance(t, isuper))
is_classmethod = (
(is_decorated and cast(Decorator, node.node).func.is_class)
or (isinstance(node.node, FuncBase) and node.node.is_class))
result = add_class_tvars(t, itype, isuper, is_classmethod,
mx.builtin_type, mx.original_type)
if not mx.is_lvalue:
result = analyze_descriptor_access(mx.original_type,
result,
mx.builtin_type,
mx.msg,
mx.context,
chk=mx.chk)
return result
elif isinstance(node.node, Var):
mx.not_ready_callback(name, mx.context)
return AnyType(TypeOfAny.special_form)
if isinstance(node.node, TypeVarExpr):
mx.msg.fail(
message_registry.CANNOT_USE_TYPEVAR_AS_EXPRESSION.format(
itype.type.name(), name), mx.context)
return AnyType(TypeOfAny.from_error)
if isinstance(node.node, TypeInfo):
return type_object_type(node.node, mx.builtin_type)
if isinstance(node.node, MypyFile):
# Reference to a module object.
return mx.builtin_type('types.ModuleType')
if isinstance(node.node, TypeAlias) and isinstance(node.node.target,
Instance):
return instance_alias_type(node.node, mx.builtin_type)
if is_decorated:
assert isinstance(node.node, Decorator)
if node.node.type:
return node.node.type
else:
mx.not_ready_callback(name, mx.context)
return AnyType(TypeOfAny.from_error)
else:
return function_type(cast(FuncBase, node.node),
mx.builtin_type('builtins.function'))
def analyze_var(name: str,
var: Var,
itype: Instance,
info: TypeInfo,
mx: MemberContext, *,
implicit: bool = False) -> Type:
"""Analyze access to an attribute via a Var node.
This is conceptually part of analyze_member_access and the arguments are similar.
itype is the class object in which var is defined
original_type is the type of E in the expression E.var
if implicit is True, the original Var was created as an assignment to self
"""
# Found a member variable.
itype = map_instance_to_supertype(itype, var.info)
typ = var.type
if typ:
if isinstance(typ, PartialType):
return mx.chk.handle_partial_var_type(typ, mx.is_lvalue, var, mx.context)
t = expand_type_by_instance(typ, itype)
if mx.is_lvalue and var.is_property and not var.is_settable_property:
# TODO allow setting attributes in subclass (although it is probably an error)
mx.msg.read_only_property(name, itype.type, mx.context)
if mx.is_lvalue and var.is_classvar:
mx.msg.cant_assign_to_classvar(name, mx.context)
result = t
if var.is_initialized_in_class and isinstance(t, FunctionLike) and not t.is_type_obj():
if mx.is_lvalue:
if var.is_property:
if not var.is_settable_property:
mx.msg.read_only_property(name, itype.type, mx.context)
else:
mx.msg.cant_assign_to_method(mx.context)
if not var.is_staticmethod:
# Class-level function objects and classmethods become bound methods:
# the former to the instance, the latter to the class.
functype = t
# Use meet to narrow original_type to the dispatched type.
# For example, assume
# * A.f: Callable[[A1], None] where A1 <: A (maybe A1 == A)
# * B.f: Callable[[B1], None] where B1 <: B (maybe B1 == B)
# * x: Union[A1, B1]
# In `x.f`, when checking `x` against A1 we assume x is compatible with A
# and similarly for B1 when checking agains B
dispatched_type = meet.meet_types(mx.original_type, itype)
check_self_arg(functype, dispatched_type, var.is_classmethod, mx.context, name,
mx.msg)
signature = bind_self(functype, mx.original_type, var.is_classmethod)
if var.is_property:
# A property cannot have an overloaded type => the cast is fine.
assert isinstance(signature, CallableType)
result = signature.ret_type
else:
result = signature
else:
if not var.is_ready:
mx.not_ready_callback(var.name(), mx.context)
# Implicit 'Any' type.
result = AnyType(TypeOfAny.special_form)
fullname = '{}.{}'.format(var.info.fullname(), name)
hook = mx.chk.plugin.get_attribute_hook(fullname)
if result and not mx.is_lvalue and not implicit:
result = analyze_descriptor_access(mx.original_type, result, mx.builtin_type,
mx.msg, mx.context, chk=mx.chk)
if hook:
result = hook(AttributeContext(mx.original_type, result, mx.context, mx.chk))
return result
