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 map_type_from_supertype(typ, sub_info, super_info):
"""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<S> ...
class C<T> is D<E<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)
# 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 interpreterd 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 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 instance_alias_type(alias: TypeAlias,
builtin_type: Callable[[str], Instance]) -> Type:
"""Type of a type alias node targeting an instance, when appears in runtime context.
As usual, we first erase any unbound type variables to Any.
"""
assert isinstance(alias.target, Instance), "Must be called only with aliases to classes"
target = set_any_tvars(alias.target, alias.alias_tvars, alias.line, alias.column)
assert isinstance(target, Instance)
tp = type_object_type(target.type, builtin_type)
return expand_type_by_instance(tp, target)
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 instance_alias_type(alias: TypeAlias,
builtin_type: Callable[[str], Instance]) -> Type:
"""Type of a type alias node targeting an instance, when appears in runtime context.
As usual, we first erase any unbound type variables to Any.
"""
target: Type = get_proper_type(alias.target)
assert isinstance(get_proper_type(target),
Instance), "Must be called only with aliases to classes"
target = get_proper_type(set_any_tvars(alias, alias.line, alias.column))
assert isinstance(target, Instance)
tp = type_object_type(target.type, builtin_type)
return expand_type_by_instance(tp, target)
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 add_class_tvars(t: Type, itype: Instance, isuper: Optional[Instance], is_classmethod: bool,
builtin_type: Callable[[str], Instance],
original_type: Type) -> Type:
"""Instantiate type variables during analyze_class_attribute_access,
e.g T and Q in the following:
class A(Generic[T]):
@classmethod
def foo(cls: Type[Q]) -> Tuple[T, Q]: ...
class B(A[str]): pass
B.foo()
original_type is the value of the type B in the expression B.foo()
"""
# TODO: verify consistency between Q and T
info = itype.type # type: TypeInfo
if is_classmethod:
assert isuper is not None
t = expand_type_by_instance(t, isuper)
# We add class type variables if the class method is accessed on class object
# without applied type arguments, this matches the behavior of __init__().
# For example (continuing the example in docstring):
# A # The type of callable is def [T] () -> A[T], _not_ def () -> A[Any]
# A[int] # The type of callable is def () -> A[int]
# and
# A.foo # The type is generic def [T] () -> Tuple[T, A[T]]
# A[int].foo # The type is non-generic def () -> Tuple[int, A[int]]
#
# This behaviour is useful for defining alternative constructors for generic classes.
# To achieve such behaviour, we add the class type variables that are still free
# (i.e. appear in the return type of the class object on which the method was accessed).
free_ids = {t.id for t in itype.args if isinstance(t, TypeVarType)}
if isinstance(t, CallableType):
# NOTE: in practice either all or none of the variables are free, since
# visit_type_application() will detect any type argument count mismatch and apply
# a correct number of Anys.
tvars = [TypeVarDef(n, n, i + 1, [], builtin_type('builtins.object'), tv.variance)
for (i, n), tv in zip(enumerate(info.type_vars), info.defn.type_vars)
# use 'is' to avoid id clashes with unrelated variables
if any(tv.id is id for id in free_ids)]
if is_classmethod:
t = bind_self(t, original_type, is_classmethod=True)
return t.copy_modified(variables=tvars + t.variables)
elif isinstance(t, Overloaded):
return Overloaded([cast(CallableType, add_class_tvars(item, itype, isuper, is_classmethod,
builtin_type, original_type))
for item in t.items()])
return t
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:
if isinstance(signature, FunctionLike) and name != '__call__':
# TODO: use proper treatment of special methods on unions instead
# of this hack here and below (i.e. mx.self_type).
dispatched_type = meet.meet_types(mx.original_type, typ)
signature = check_self_arg(signature, dispatched_type, method.is_class,
mx.context, name, mx.msg)
signature = bind_self(signature, mx.self_type, is_classmethod=method.is_class)
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 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_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,
original_type: Type,
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.
original_type is the type of E in the expression E.var
"""
# 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) and not t.is_type_obj():
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 = bind_self(functype, original_type)
if var.is_property:
# A property cannot have an overloaded type => the cast
# is fine.
assert isinstance(signature, CallableType)
return 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 analyse_member_access(name, typ, node, is_lvalue, is_super, tuple_type, msg, override_info=None):
"""Analyse member 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)
"""
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 Any()
# The base object has an instance type.
itype = typ
info = itype.type
if override_info:
info = override_info
# Look up the member. First look up the method dictionary.
method = None
if not is_lvalue:
method = info.get_method(name)
if method:
# Found a method. The call below has a unique result for all valid
# programs.
itype = map_instance_to_supertype(itype, method.info)
return expand_type_by_instance(method_type(method), itype)
else:
# Not a method.
return analyse_member_var_access(name, itype, info, node, is_lvalue, is_super, msg)
elif isinstance(typ, Any):
# The base object has dynamic type.
return Any()
elif isinstance(typ, TupleType):
# Actually look up from the tuple type.
return analyse_member_access(name, tuple_type, node, is_lvalue, is_super, tuple_type, msg)
elif isinstance(typ, Callable) and (typ).is_type_obj():
# Class attribute access.
return msg.not_implemented("class attributes", node)
else:
# The base object has an unsupported type.
return msg.has_no_member(typ, name, node)
def add_class_tvars(t: ProperType, itype: Instance, isuper: Optional[Instance],
is_classmethod: bool,
builtin_type: Callable[[str], Instance],
original_type: Type,
original_vars: Optional[List[TypeVarDef]] = None) -> Type:
"""Instantiate type variables during analyze_class_attribute_access,
e.g T and Q in the following:
class A(Generic[T]):
@classmethod
def foo(cls: Type[Q]) -> Tuple[T, Q]: ...
class B(A[str]): pass
B.foo()
original_type is the value of the type B in the expression B.foo() or the corresponding
component in case if a union (this is used to bind the self-types); original_vars are type
variables of the class callable on which the method was accessed.
"""
# TODO: verify consistency between Q and T
if is_classmethod:
assert isuper is not None
t = get_proper_type(expand_type_by_instance(t, isuper))
# We add class type variables if the class method is accessed on class object
# without applied type arguments, this matches the behavior of __init__().
# For example (continuing the example in docstring):
# A # The type of callable is def [T] () -> A[T], _not_ def () -> A[Any]
# A[int] # The type of callable is def () -> A[int]
# and
# A.foo # The type is generic def [T] () -> Tuple[T, A[T]]
# A[int].foo # The type is non-generic def () -> Tuple[int, A[int]]
#
# This behaviour is useful for defining alternative constructors for generic classes.
# To achieve such behaviour, we add the class type variables that are still free
# (i.e. appear in the return type of the class object on which the method was accessed).
if isinstance(t, CallableType):
tvars = original_vars if original_vars is not None else []
if is_classmethod:
t = bind_self(t, original_type, is_classmethod=True)
return t.copy_modified(variables=tvars + t.variables)
elif isinstance(t, Overloaded):
return Overloaded([cast(CallableType, add_class_tvars(item, itype, isuper, is_classmethod,
builtin_type, original_type,
original_vars=original_vars))
for item in t.items()])
return t
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 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 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 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 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 analyse_member_var_access(name, itype, info, node, is_lvalue, is_super, msg):
"""Analyse member 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)
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):
# Class-level function object becomes a bound method.
functype = t
check_method_type(functype, itype, node, msg)
return method_type(functype)
return t
else:
if not var.is_ready:
msg.cannot_determine_type(var.name(), node)
# Implicit 'any' type.
return Any()
elif isinstance(v, FuncDef):
# Found a getter or a setter.
raise NotImplementedError()
# Could not find the member.
if is_super:
msg.undefined_in_superclass(name, node)
return Any()
else:
return msg.has_no_member(itype, name, node)
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 analyze_descriptor_access(descriptor_type: Type,
mx: MemberContext) -> Type:
"""Type check descriptor access.
Arguments:
descriptor_type: The type of the descriptor attribute being accessed
(the type of ``f`` in ``a.f`` when ``f`` is a descriptor).
mx: The current member access context.
Return:
The return type of the appropriate ``__get__`` overload for the descriptor.
"""
instance_type = get_proper_type(mx.original_type)
descriptor_type = get_proper_type(descriptor_type)
if isinstance(descriptor_type, UnionType):
# Map the access over union types
return make_simplified_union([
analyze_descriptor_access(typ, mx) 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:
mx.msg.fail(
message_registry.DESCRIPTOR_GET_NOT_CALLABLE.format(
descriptor_type), mx.context)
return AnyType(TypeOfAny.from_error)
bound_method = analyze_decorator_or_funcbase_access(
defn=dunder_get,
itype=descriptor_type,
info=descriptor_type.type,
self_type=descriptor_type,
name='__set__',
mx=mx)
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 = NoneType()
elif isinstance(instance_type, TypeType):
owner_type = instance_type.item
instance_type = NoneType()
else:
owner_type = instance_type
callable_name = mx.chk.expr_checker.method_fullname(
descriptor_type, "__get__")
dunder_get_type = mx.chk.expr_checker.transform_callee_type(
callable_name,
dunder_get_type,
[
TempNode(instance_type, context=mx.context),
TempNode(TypeType.make_normalized(owner_type), context=mx.context)
],
[ARG_POS, ARG_POS],
mx.context,
object_type=descriptor_type,
)
_, inferred_dunder_get_type = mx.chk.expr_checker.check_call(
dunder_get_type, [
TempNode(instance_type, context=mx.context),
TempNode(TypeType.make_normalized(owner_type), context=mx.context)
], [ARG_POS, ARG_POS],
mx.context,
object_type=descriptor_type,
callable_name=callable_name)
inferred_dunder_get_type = get_proper_type(inferred_dunder_get_type)
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):
mx.msg.fail(
message_registry.DESCRIPTOR_GET_NOT_CALLABLE.format(
descriptor_type), mx.context)
return AnyType(TypeOfAny.from_error)
return inferred_dunder_get_type.ret_type
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 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 _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 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 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 add_class_tvars(
t: ProperType,
isuper: Optional[Instance],
is_classmethod: bool,
original_type: Type,
original_vars: Optional[Sequence[TypeVarLikeType]] = None) -> Type:
"""Instantiate type variables during analyze_class_attribute_access,
e.g T and Q in the following:
class A(Generic[T]):
@classmethod
def foo(cls: Type[Q]) -> Tuple[T, Q]: ...
class B(A[str]): pass
B.foo()
Args:
t: Declared type of the method (or property)
isuper: Current instance mapped to the superclass where method was defined, this
is usually done by map_instance_to_supertype()
is_classmethod: True if this method is decorated with @classmethod
original_type: The value of the type B in the expression B.foo() or the corresponding
component in case of a union (this is used to bind the self-types)
original_vars: Type variables of the class callable on which the method was accessed
Returns:
Expanded method type with added type variables (when needed).
"""
# TODO: verify consistency between Q and T
# We add class type variables if the class method is accessed on class object
# without applied type arguments, this matches the behavior of __init__().
# For example (continuing the example in docstring):
# A # The type of callable is def [T] () -> A[T], _not_ def () -> A[Any]
# A[int] # The type of callable is def () -> A[int]
# and
# A.foo # The type is generic def [T] () -> Tuple[T, A[T]]
# A[int].foo # The type is non-generic def () -> Tuple[int, A[int]]
#
# This behaviour is useful for defining alternative constructors for generic classes.
# To achieve such behaviour, we add the class type variables that are still free
# (i.e. appear in the return type of the class object on which the method was accessed).
if isinstance(t, CallableType):
tvars = original_vars if original_vars is not None else []
if is_classmethod:
t = freshen_function_type_vars(t)
t = bind_self(t, original_type, is_classmethod=True)
assert isuper is not None
t = cast(CallableType, expand_type_by_instance(t, isuper))
freeze_type_vars(t)
return t.copy_modified(variables=list(tvars) + list(t.variables))
elif isinstance(t, Overloaded):
return Overloaded([
cast(
CallableType,
add_class_tvars(item,
isuper,
is_classmethod,
original_type,
original_vars=original_vars))
for item in t.items
])
if isuper is not None:
t = cast(ProperType, expand_type_by_instance(t, isuper))
return t
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 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_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_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 analyse_member_access(name: str,
typ: Type,
node: Context,
is_lvalue: bool,
is_super: bool,
basic_types: BasicTypes,
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.fail(messages.CANNOT_ASSIGN_TO_METHOD, node)
typ = map_instance_to_supertype(typ, method.info)
return expand_type_by_instance(method_type(method), 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, TupleType):
# Actually look up from the 'tuple' type.
return analyse_member_access(name, basic_types.tuple, node, is_lvalue,
is_super, basic_types, 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,
msg)
if result:
return result
# Look up from the 'type' type.
return analyse_member_access(name,
basic_types.type_type,
node,
is_lvalue,
is_super,
basic_types,
msg,
report_type=report_type)
elif isinstance(typ, FunctionLike):
# Look up from the 'function' type.
return analyse_member_access(name,
basic_types.function,
node,
is_lvalue,
is_super,
basic_types,
msg,
report_type=report_type)
return msg.has_no_attr(report_type, name, node)
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_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_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_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_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)
itype = (Instance)typ
info = itype.type
if override_info:
info = override_info
# Look up the member. First look up the method dictionary.
FuncBase method = None
if not is_lvalue:
method = info.get_method(name)
if method:
# Found a method. The call below has a unique result for all valid
# programs.
itype = map_instance_to_supertype(itype, method.info)
return expand_type_by_instance(method_type(method), itype)
else:
# Not a method.
return analyse_member_var_access(name, itype, info, node,
is_lvalue, is_super, msg)
elif isinstance(typ, Any):
# The base object has dynamic type.
return Any()
elif isinstance(typ, TupleType):
# Actually look up from the tuple type.
return analyse_member_access(name, tuple_type, node, is_lvalue,
is_super, tuple_type, msg)
elif isinstance(typ, Callable) and ((Callable)typ).is_type_obj():
# Class attribute access.
return msg.not_implemented('class attributes', node)
else:
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_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_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
