"""Miscellaneous type operations and helpers for use during type checking. NOTE: These must not be accessed from mypy.nodes or mypy.types to avoid import cycles. These must not be called from the semantic analysis main pass since these may assume that MROs are ready. """ from __future__ import annotations import itertools from collections.abc import Iterable, Sequence from typing import Any, Callable, TypeVar, cast from mypy.copytype import copy_type from mypy.expandtype import expand_type, expand_type_by_instance from mypy.maptype import map_instance_to_supertype from mypy.nodes import ( ARG_OPT, ARG_POS, ARG_STAR, ARG_STAR2, SYMBOL_FUNCBASE_TYPES, Decorator, Expression, FuncBase, FuncDef, FuncItem, OverloadedFuncDef, StrExpr, SymbolNode, TypeInfo, Var, ) from mypy.state import state from mypy.types import ( AnyType, CallableType, ExtraAttrs, FormalArgument, FunctionLike, Instance, LiteralType, NoneType, NormalizedCallableType, Overloaded, Parameters, ParamSpecType, PartialType, ProperType, TupleType, Type, TypeAliasType, TypedDictType, TypeOfAny, TypeQuery, TypeType, TypeVarLikeType, TypeVarTupleType, TypeVarType, UninhabitedType, UnionType, UnpackType, flatten_nested_unions, get_proper_type, get_proper_types, ) from mypy.typetraverser import TypeTraverserVisitor from mypy.typevars import fill_typevars def is_recursive_pair(s: Type, t: Type) -> bool: """Is this a pair of recursive types? There may be more cases, and we may be forced to use e.g. has_recursive_types() here, but this function is called in very hot code, so we try to keep it simple and return True only in cases we know may have problems. """ if isinstance(s, TypeAliasType) and s.is_recursive: return ( isinstance(get_proper_type(t), (Instance, UnionType)) or isinstance(t, TypeAliasType) and t.is_recursive # Tuple types are special, they can cause an infinite recursion even if # the other type is not recursive, because of the tuple fallback that is # calculated "on the fly". or isinstance(get_proper_type(s), TupleType) ) if isinstance(t, TypeAliasType) and t.is_recursive: return ( isinstance(get_proper_type(s), (Instance, UnionType)) or isinstance(s, TypeAliasType) and s.is_recursive # Same as above. or isinstance(get_proper_type(t), TupleType) ) return False def tuple_fallback(typ: TupleType) -> Instance: """Return fallback type for a tuple.""" info = typ.partial_fallback.type if info.fullname != "builtins.tuple": return typ.partial_fallback items = [] for item in typ.items: if isinstance(item, UnpackType): unpacked_type = get_proper_type(item.type) if isinstance(unpacked_type, TypeVarTupleType): unpacked_type = get_proper_type(unpacked_type.upper_bound) if ( isinstance(unpacked_type, Instance) and unpacked_type.type.fullname == "builtins.tuple" ): items.append(unpacked_type.args[0]) else: raise NotImplementedError else: items.append(item) return Instance( info, # Note: flattening recursive unions is dangerous, since it can fool recursive # types optimization in subtypes.py and go into infinite recursion. [make_simplified_union(items, handle_recursive=False)], extra_attrs=typ.partial_fallback.extra_attrs, ) def get_self_type(func: CallableType, default_self: Instance | TupleType) -> Type | None: if isinstance(get_proper_type(func.ret_type), UninhabitedType): return func.ret_type elif func.arg_types and func.arg_types[0] != default_self and func.arg_kinds[0] == ARG_POS: return func.arg_types[0] else: return None def type_object_type(info: TypeInfo, named_type: Callable[[str], Instance]) -> ProperType: """Return the type of a type object. For a generic type G with type variables T and S the type is generally of form Callable[..., G[T, S]] where ... are argument types for the __init__/__new__ method (without the self argument). Also, the fallback type will be 'type' instead of 'function'. """ # We take the type from whichever of __init__ and __new__ is first # in the MRO, preferring __init__ if there is a tie. init_method = info.get("__init__") new_method = info.get("__new__") if not init_method or not is_valid_constructor(init_method.node): # Must be an invalid class definition. return AnyType(TypeOfAny.from_error) # There *should* always be a __new__ method except the test stubs # lack it, so just copy init_method in that situation new_method = new_method or init_method if not is_valid_constructor(new_method.node): # Must be an invalid class definition. return AnyType(TypeOfAny.from_error) # The two is_valid_constructor() checks ensure this. assert isinstance(new_method.node, (SYMBOL_FUNCBASE_TYPES, Decorator)) assert isinstance(init_method.node, (SYMBOL_FUNCBASE_TYPES, Decorator)) init_index = info.mro.index(init_method.node.info) new_index = info.mro.index(new_method.node.info) fallback = info.metaclass_type or named_type("builtins.type") if init_index < new_index: method: FuncBase | Decorator = init_method.node is_new = False elif init_index > new_index: method = new_method.node is_new = True else: if init_method.node.info.fullname == "builtins.object": # Both are defined by object. But if we've got a bogus # base class, we can't know for sure, so check for that. if info.fallback_to_any: # Construct a universal callable as the prototype. any_type = AnyType(TypeOfAny.special_form) sig = CallableType( arg_types=[any_type, any_type], arg_kinds=[ARG_STAR, ARG_STAR2], arg_names=["_args", "_kwds"], ret_type=any_type, fallback=named_type("builtins.function"), ) return class_callable(sig, info, fallback, None, is_new=False) # Otherwise prefer __init__ in a tie. It isn't clear that this # is the right thing, but __new__ caused problems with # typeshed (#5647). method = init_method.node is_new = False # Construct callable type based on signature of __init__. Adjust # return type and insert type arguments. if isinstance(method, FuncBase): t = function_type(method, fallback) else: assert isinstance(method.type, ProperType) assert isinstance(method.type, FunctionLike) # is_valid_constructor() ensures this t = method.type return type_object_type_from_function(t, info, method.info, fallback, is_new) def is_valid_constructor(n: SymbolNode | None) -> bool: """Does this node represents a valid constructor method? This includes normal functions, overloaded functions, and decorators that return a callable type. """ if isinstance(n, SYMBOL_FUNCBASE_TYPES): return True if isinstance(n, Decorator): return isinstance(get_proper_type(n.type), FunctionLike) return False def type_object_type_from_function( signature: FunctionLike, info: TypeInfo, def_info: TypeInfo, fallback: Instance, is_new: bool ) -> FunctionLike: # We first need to record all non-trivial (explicit) self types in __init__, # since they will not be available after we bind them. Note, we use explicit # self-types only in the defining class, similar to __new__ (but not exactly the same, # see comment in class_callable below). This is mostly useful for annotating library # classes such as subprocess.Popen. default_self = fill_typevars(info) if not is_new and not info.is_newtype: orig_self_types = [get_self_type(it, default_self) for it in signature.items] else: orig_self_types = [None] * len(signature.items) # The __init__ method might come from a generic superclass 'def_info' # with type variables that do not map identically to the type variables of # the class 'info' being constructed. For example: # # class A(Generic[T]): # def __init__(self, x: T) -> None: ... # class B(A[List[T]]): # ... # # We need to map B's __init__ to the type (List[T]) -> None. signature = bind_self( signature, original_type=default_self, is_classmethod=is_new, # Explicit instance self annotations have special handling in class_callable(), # we don't need to bind any type variables in them if they are generic. ignore_instances=True, ) signature = cast(FunctionLike, map_type_from_supertype(signature, info, def_info)) special_sig: str | None = None if def_info.fullname == "builtins.dict": # Special signature! special_sig = "dict" if isinstance(signature, CallableType): return class_callable(signature, info, fallback, special_sig, is_new, orig_self_types[0]) else: # Overloaded __init__/__new__. assert isinstance(signature, Overloaded) items: list[CallableType] = [] for item, orig_self in zip(signature.items, orig_self_types): items.append(class_callable(item, info, fallback, special_sig, is_new, orig_self)) return Overloaded(items) def class_callable( init_type: CallableType, info: TypeInfo, type_type: Instance, special_sig: str | None, is_new: bool, orig_self_type: Type | None = None, ) -> CallableType: """Create a type object type based on the signature of __init__.""" variables: list[TypeVarLikeType] = [] variables.extend(info.defn.type_vars) variables.extend(init_type.variables) from mypy.subtypes import is_subtype init_ret_type = get_proper_type(init_type.ret_type) orig_self_type = get_proper_type(orig_self_type) default_ret_type = fill_typevars(info) explicit_type = init_ret_type if is_new else orig_self_type if ( isinstance(explicit_type, (Instance, TupleType, UninhabitedType)) # We have to skip protocols, because it can be a subtype of a return type # by accident. Like `Hashable` is a subtype of `object`. See #11799 and isinstance(default_ret_type, Instance) and not default_ret_type.type.is_protocol # Only use the declared return type from __new__ or declared self in __init__ # if it is actually returning a subtype of what we would return otherwise. and is_subtype(explicit_type, default_ret_type, ignore_type_params=True) ): ret_type: Type = explicit_type else: ret_type = default_ret_type callable_type = init_type.copy_modified( ret_type=ret_type, fallback=type_type, name=None, variables=variables, special_sig=special_sig, ) c = callable_type.with_name(info.name) return c 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 = fill_typevars(sub_info) if isinstance(inst_type, TupleType): inst_type = tuple_fallback(inst_type) # 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 supported_self_type( typ: ProperType, allow_callable: bool = True, allow_instances: bool = True ) -> bool: """Is this a supported kind of explicit self-types? Currently, this means an X or Type[X], where X is an instance or a type variable with an instance upper bound. """ if isinstance(typ, TypeType): return supported_self_type(typ.item) if allow_callable and isinstance(typ, CallableType): # Special case: allow class callable instead of Type[...] as cls annotation, # as well as callable self for callback protocols. return True return isinstance(typ, TypeVarType) or ( allow_instances and isinstance(typ, Instance) and typ != fill_typevars(typ.type) ) F = TypeVar("F", bound=FunctionLike) def bind_self( method: F, original_type: Type | None = None, is_classmethod: bool = False, ignore_instances: bool = False, ) -> F: """Return a copy of `method`, with the type of its first parameter (usually self or cls) bound to original_type. If the type of `self` is a generic type (T, or Type[T] for classmethods), instantiate every occurrence of type with original_type in the rest of the signature and in the return type. original_type is the type of E in the expression E.copy(). It is None in compatibility checks. In this case we treat it as the erasure of the declared type of self. This way we can express "the type of self". For example: T = TypeVar('T', bound='A') class A: def copy(self: T) -> T: ... class B(A): pass b = B().copy() # type: B """ if isinstance(method, Overloaded): items = [] original_type = get_proper_type(original_type) for c in method.items: if isinstance(original_type, Instance): # Filter based on whether declared self type can match actual object type. # For example, if self has type C[int] and method is accessed on a C[str] value, # omit this item. This is best effort since bind_self can be called in many # contexts, and doing complete validation might trigger infinite recursion. # # Note that overload item filtering normally happens elsewhere. This is needed # at least during constraint inference. keep = is_valid_self_type_best_effort(c, original_type) else: keep = True if keep: items.append(bind_self(c, original_type, is_classmethod, ignore_instances)) if len(items) == 0: # If no item matches, returning all items helps avoid some spurious errors items = [ bind_self(c, original_type, is_classmethod, ignore_instances) for c in method.items ] return cast(F, Overloaded(items)) assert isinstance(method, CallableType) func = method if not func.arg_types: # Invalid method, return something. return cast(F, func) if func.arg_kinds[0] in (ARG_STAR, ARG_STAR2): # The signature is of the form 'def foo(*args, ...)'. # In this case we shouldn't drop the first arg, # since func will be absorbed by the *args. # TODO: infer bounds on the type of *args? # In the case of **kwargs we should probably emit an error, but # for now we simply skip it, to avoid crashes down the line. return cast(F, func) self_param_type = get_proper_type(func.arg_types[0]) variables: Sequence[TypeVarLikeType] # Having a def __call__(self: Callable[...], ...) can cause infinite recursion. Although # this special-casing looks not very principled, there is nothing meaningful we can infer # from such definition, since it is inherently indefinitely recursive. allow_callable = func.name is None or not func.name.startswith("__call__ of") if func.variables and supported_self_type( self_param_type, allow_callable=allow_callable, allow_instances=not ignore_instances ): from mypy.infer import infer_type_arguments if original_type is None: # TODO: type check method override (see #7861). original_type = erase_to_bound(self_param_type) original_type = get_proper_type(original_type) # Find which of method type variables appear in the type of "self". self_ids = {tv.id for tv in get_all_type_vars(self_param_type)} self_vars = [tv for tv in func.variables if tv.id in self_ids] # Solve for these type arguments using the actual class or instance type. typeargs = infer_type_arguments( self_vars, self_param_type, original_type, is_supertype=True ) if ( is_classmethod and any(isinstance(get_proper_type(t), UninhabitedType) for t in typeargs) and isinstance(original_type, (Instance, TypeVarType, TupleType)) ): # In case we call a classmethod through an instance x, fallback to type(x). typeargs = infer_type_arguments( self_vars, self_param_type, TypeType(original_type), is_supertype=True ) # Update the method signature with the solutions found. # Technically, some constraints might be unsolvable, make them Never. to_apply = [t if t is not None else UninhabitedType() for t in typeargs] func = expand_type(func, {tv.id: arg for tv, arg in zip(self_vars, to_apply)}) variables = [v for v in func.variables if v not in self_vars] else: variables = func.variables original_type = get_proper_type(original_type) if isinstance(original_type, CallableType) and original_type.is_type_obj(): original_type = TypeType.make_normalized(original_type.ret_type) res = func.copy_modified( arg_types=func.arg_types[1:], arg_kinds=func.arg_kinds[1:], arg_names=func.arg_names[1:], variables=variables, bound_args=[original_type], ) return cast(F, res) def is_valid_self_type_best_effort(c: CallableType, self_type: Instance) -> bool: """Quickly check if self_type might match the self in a callable. Avoid performing any complex type operations. This is performance-critical. Default to returning True if we don't know (or it would be too expensive). """ if ( self_type.args and c.arg_types and isinstance((arg_type := get_proper_type(c.arg_types[0])), Instance) and c.arg_kinds[0] in (ARG_POS, ARG_OPT) and arg_type.args and self_type.type.fullname != "functools._SingleDispatchCallable" ): if self_type.type is not arg_type.type: # We can't map to supertype, since it could trigger expensive checks for # protocol types, so we consevatively assume this is fine. return True # Fast path: no explicit annotation on self if all( ( type(arg) is TypeVarType and type(arg.upper_bound) is Instance and arg.upper_bound.type.fullname == "builtins.object" ) for arg in arg_type.args ): return True from mypy.meet import is_overlapping_types return is_overlapping_types(self_type, c.arg_types[0]) return True def erase_to_bound(t: Type) -> Type: # TODO: use value restrictions to produce a union? t = get_proper_type(t) if isinstance(t, TypeVarType): return t.upper_bound if isinstance(t, TypeType): if isinstance(t.item, TypeVarType): return TypeType.make_normalized(t.item.upper_bound) return t def callable_corresponding_argument( typ: NormalizedCallableType | Parameters, model: FormalArgument ) -> FormalArgument | None: """Return the argument a function that corresponds to `model`""" by_name = typ.argument_by_name(model.name) by_pos = typ.argument_by_position(model.pos) if by_name is None and by_pos is None: return None if by_name is not None and by_pos is not None: if by_name == by_pos: return by_name # If we're dealing with an optional pos-only and an optional # name-only arg, merge them. This is the case for all functions # taking both *args and **args, or a pair of functions like so: # def right(a: int = ...) -> None: ... # def left(__a: int = ..., *, a: int = ...) -> None: ... from mypy.subtypes import is_equivalent if ( not (by_name.required or by_pos.required) and by_pos.name is None and by_name.pos is None and is_equivalent(by_name.typ, by_pos.typ) ): return FormalArgument(by_name.name, by_pos.pos, by_name.typ, False) return by_name if by_name is not None else by_pos def simple_literal_type(t: ProperType | None) -> Instance | None: """Extract the underlying fallback Instance type for a simple Literal""" if isinstance(t, Instance) and t.last_known_value is not None: t = t.last_known_value if isinstance(t, LiteralType): return t.fallback return None def is_simple_literal(t: ProperType) -> bool: if isinstance(t, LiteralType): return t.fallback.type.is_enum or t.fallback.type.fullname == "builtins.str" if isinstance(t, Instance): return t.last_known_value is not None and isinstance(t.last_known_value.value, str) return False def make_simplified_union( items: Sequence[Type], line: int = -1, column: int = -1, *, keep_erased: bool = False, contract_literals: bool = True, handle_recursive: bool = True, ) -> ProperType: """Build union type with redundant union items removed. If only a single item remains, this may return a non-union type. Examples: * [int, str] -> Union[int, str] * [int, object] -> object * [int, int] -> int * [int, Any] -> Union[int, Any] (Any types are not simplified away!) * [Any, Any] -> Any * [int, Union[bytes, str]] -> Union[int, bytes, str] Note: This must NOT be used during semantic analysis, since TypeInfos may not be fully initialized. The keep_erased flag is used for type inference against union types containing type variables. If set to True, keep all ErasedType items. The contract_literals flag indicates whether we need to contract literal types back into a sum type. Set it to False when called by try_expanding_sum_type_ to_union(). """ # Step 1: expand all nested unions items = flatten_nested_unions(items, handle_recursive=handle_recursive) # Step 2: fast path for single item if len(items) == 1: return get_proper_type(items[0]) # Step 3: remove redundant unions simplified_set: Sequence[Type] = _remove_redundant_union_items(items, keep_erased) # Step 4: If more than one literal exists in the union, try to simplify if ( contract_literals and sum(isinstance(get_proper_type(item), LiteralType) for item in simplified_set) > 1 ): simplified_set = try_contracting_literals_in_union(simplified_set) result = get_proper_type(UnionType.make_union(simplified_set, line, column)) nitems = len(items) if nitems > 1 and ( nitems > 2 or not (type(items[0]) is NoneType or type(items[1]) is NoneType) ): # Step 5: At last, we erase any (inconsistent) extra attributes on instances. # Initialize with None instead of an empty set as a micro-optimization. The set # is needed very rarely, so we try to avoid constructing it. extra_attrs_set: set[ExtraAttrs] | None = None for item in items: instance = try_getting_instance_fallback(item) if instance and instance.extra_attrs: if extra_attrs_set is None: extra_attrs_set = {instance.extra_attrs} else: extra_attrs_set.add(instance.extra_attrs) if extra_attrs_set is not None and len(extra_attrs_set) > 1: fallback = try_getting_instance_fallback(result) if fallback: fallback.extra_attrs = None return result def _remove_redundant_union_items(items: list[Type], keep_erased: bool) -> list[Type]: from mypy.subtypes import is_proper_subtype # The first pass through this loop, we check if later items are subtypes of earlier items. # The second pass through this loop, we check if earlier items are subtypes of later items # (by reversing the remaining items) for _direction in range(2): new_items: list[Type] = [] # seen is a map from a type to its index in new_items seen: dict[ProperType, int] = {} unduplicated_literal_fallbacks: set[Instance] | None = None for ti in items: proper_ti = get_proper_type(ti) # UninhabitedType is always redundant if isinstance(proper_ti, UninhabitedType): continue duplicate_index = -1 # Quickly check if we've seen this type if proper_ti in seen: duplicate_index = seen[proper_ti] elif ( isinstance(proper_ti, LiteralType) and unduplicated_literal_fallbacks is not None and proper_ti.fallback in unduplicated_literal_fallbacks ): # This is an optimisation for unions with many LiteralType # We've already checked for exact duplicates. This means that any super type of # the LiteralType must be a super type of its fallback. If we've gone through # the expensive loop below and found no super type for a previous LiteralType # with the same fallback, we can skip doing that work again and just add the type # to new_items pass else: # If not, check if we've seen a supertype of this type for j, tj in enumerate(new_items): tj = get_proper_type(tj) # If tj is an Instance with a last_known_value, do not remove proper_ti # (unless it's an instance with the same last_known_value) if ( isinstance(tj, Instance) and tj.last_known_value is not None and not ( isinstance(proper_ti, Instance) and tj.last_known_value == proper_ti.last_known_value ) ): continue if is_proper_subtype( ti, tj, keep_erased_types=keep_erased, ignore_promotions=True ): duplicate_index = j break if duplicate_index != -1: # If deleted subtypes had more general truthiness, use that orig_item = new_items[duplicate_index] if not orig_item.can_be_true and ti.can_be_true: new_items[duplicate_index] = true_or_false(orig_item) elif not orig_item.can_be_false and ti.can_be_false: new_items[duplicate_index] = true_or_false(orig_item) else: # We have a non-duplicate item, add it to new_items seen[proper_ti] = len(new_items) new_items.append(ti) if isinstance(proper_ti, LiteralType): if unduplicated_literal_fallbacks is None: unduplicated_literal_fallbacks = set() unduplicated_literal_fallbacks.add(proper_ti.fallback) items = new_items if len(items) <= 1: break items.reverse() return items def _get_type_method_ret_type(t: ProperType, *, name: str) -> Type | None: # For Enum literals the ret_type can change based on the Enum # we need to check the type of the enum rather than the literal if isinstance(t, LiteralType) and t.is_enum_literal(): t = t.fallback if isinstance(t, Instance): sym = t.type.get(name) if sym: sym_type = get_proper_type(sym.type) if isinstance(sym_type, CallableType): return sym_type.ret_type return None def true_only(t: Type) -> ProperType: """ Restricted version of t with only True-ish values """ t = get_proper_type(t) if not t.can_be_true: # All values of t are False-ish, so there are no true values in it return UninhabitedType(line=t.line, column=t.column) elif not t.can_be_false: # All values of t are already True-ish, so true_only is idempotent in this case return t elif isinstance(t, UnionType): # The true version of a union type is the union of the true versions of its components new_items = [true_only(item) for item in t.items] can_be_true_items = [item for item in new_items if item.can_be_true] return make_simplified_union(can_be_true_items, line=t.line, column=t.column) else: ret_type = _get_type_method_ret_type(t, name="__bool__") or _get_type_method_ret_type( t, name="__len__" ) if ret_type and not ret_type.can_be_true: return UninhabitedType(line=t.line, column=t.column) new_t = copy_type(t) new_t.can_be_false = False return new_t def false_only(t: Type) -> ProperType: """ Restricted version of t with only False-ish values """ t = get_proper_type(t) if not t.can_be_false: if state.strict_optional: # All values of t are True-ish, so there are no false values in it return UninhabitedType(line=t.line) else: # When strict optional checking is disabled, everything can be # False-ish since anything can be None return NoneType(line=t.line) elif not t.can_be_true: # All values of t are already False-ish, so false_only is idempotent in this case return t elif isinstance(t, UnionType): # The false version of a union type is the union of the false versions of its components new_items = [false_only(item) for item in t.items] can_be_false_items = [item for item in new_items if item.can_be_false] return make_simplified_union(can_be_false_items, line=t.line, column=t.column) elif isinstance(t, Instance) and t.type.fullname in ("builtins.str", "builtins.bytes"): return LiteralType("", fallback=t) elif isinstance(t, Instance) and t.type.fullname == "builtins.int": return LiteralType(0, fallback=t) else: ret_type = _get_type_method_ret_type(t, name="__bool__") or _get_type_method_ret_type( t, name="__len__" ) if ret_type: if not ret_type.can_be_false: return UninhabitedType(line=t.line) elif isinstance(t, Instance): if t.type.is_final or t.type.is_enum: return UninhabitedType(line=t.line) elif isinstance(t, LiteralType) and t.is_enum_literal(): return UninhabitedType(line=t.line) new_t = copy_type(t) new_t.can_be_true = False return new_t def true_or_false(t: Type) -> ProperType: """ Unrestricted version of t with both True-ish and False-ish values """ t = get_proper_type(t) if isinstance(t, UnionType): new_items = [true_or_false(item) for item in t.items] return make_simplified_union(new_items, line=t.line, column=t.column) new_t = copy_type(t) new_t.can_be_true = new_t.can_be_true_default() new_t.can_be_false = new_t.can_be_false_default() return new_t def erase_def_to_union_or_bound(tdef: TypeVarLikeType) -> Type: # TODO(PEP612): fix for ParamSpecType if isinstance(tdef, ParamSpecType): return AnyType(TypeOfAny.from_error) if isinstance(tdef, TypeVarType) and tdef.values: return make_simplified_union(tdef.values) else: return tdef.upper_bound def erase_to_union_or_bound(typ: TypeVarType) -> ProperType: if typ.values: return make_simplified_union(typ.values) else: return get_proper_type(typ.upper_bound) def function_type(func: FuncBase, fallback: Instance) -> FunctionLike: if func.type: assert isinstance(func.type, FunctionLike) return func.type else: # Implicit type signature with dynamic types. if isinstance(func, FuncItem): return callable_type(func, fallback) else: # Broken overloads can have self.type set to None. # TODO: should we instead always set the type in semantic analyzer? assert isinstance(func, OverloadedFuncDef) any_type = AnyType(TypeOfAny.from_error) dummy = CallableType( [any_type, any_type], [ARG_STAR, ARG_STAR2], [None, None], any_type, fallback, line=func.line, is_ellipsis_args=True, ) # Return an Overloaded, because some callers may expect that # an OverloadedFuncDef has an Overloaded type. return Overloaded([dummy]) def callable_type( fdef: FuncItem, fallback: Instance, ret_type: Type | None = None ) -> CallableType: # TODO: somewhat unfortunate duplication with prepare_method_signature in semanal if fdef.info and (not fdef.is_static or fdef.name == "__new__") and fdef.arg_names: self_type: Type = fill_typevars(fdef.info) if fdef.is_class or fdef.name == "__new__": self_type = TypeType.make_normalized(self_type) args = [self_type] + [AnyType(TypeOfAny.unannotated)] * (len(fdef.arg_names) - 1) else: args = [AnyType(TypeOfAny.unannotated)] * len(fdef.arg_names) return CallableType( args, fdef.arg_kinds, fdef.arg_names, ret_type or AnyType(TypeOfAny.unannotated), fallback, name=fdef.name, line=fdef.line, column=fdef.column, implicit=True, # We need this for better error messages, like missing `self` note: definition=fdef if isinstance(fdef, FuncDef) else None, ) def try_getting_str_literals(expr: Expression, typ: Type) -> list[str] | None: """If the given expression or type corresponds to a string literal or a union of string literals, returns a list of the underlying strings. Otherwise, returns None. Specifically, this function is guaranteed to return a list with one or more strings if one of the following is true: 1. 'expr' is a StrExpr 2. 'typ' is a LiteralType containing a string 3. 'typ' is a UnionType containing only LiteralType of strings """ if isinstance(expr, StrExpr): return [expr.value] # TODO: See if we can eliminate this function and call the below one directly return try_getting_str_literals_from_type(typ) def try_getting_str_literals_from_type(typ: Type) -> list[str] | None: """If the given expression or type corresponds to a string Literal or a union of string Literals, returns a list of the underlying strings. Otherwise, returns None. For example, if we had the type 'Literal["foo", "bar"]' as input, this function would return a list of strings ["foo", "bar"]. """ return try_getting_literals_from_type(typ, str, "builtins.str") def try_getting_int_literals_from_type(typ: Type) -> list[int] | None: """If the given expression or type corresponds to an int Literal or a union of int Literals, returns a list of the underlying ints. Otherwise, returns None. For example, if we had the type 'Literal[1, 2, 3]' as input, this function would return a list of ints [1, 2, 3]. """ return try_getting_literals_from_type(typ, int, "builtins.int") T = TypeVar("T") def try_getting_literals_from_type( typ: Type, target_literal_type: type[T], target_fullname: str ) -> list[T] | None: """If the given expression or type corresponds to a Literal or union of Literals where the underlying values correspond to the given target type, returns a list of those underlying values. Otherwise, returns None. """ typ = get_proper_type(typ) if isinstance(typ, Instance) and typ.last_known_value is not None: possible_literals: list[Type] = [typ.last_known_value] elif isinstance(typ, UnionType): possible_literals = list(typ.items) else: possible_literals = [typ] literals: list[T] = [] for lit in get_proper_types(possible_literals): if isinstance(lit, LiteralType) and lit.fallback.type.fullname == target_fullname: val = lit.value if isinstance(val, target_literal_type): literals.append(val) else: return None else: return None return literals def is_literal_type_like(t: Type | None) -> bool: """Returns 'true' if the given type context is potentially either a LiteralType, a Union of LiteralType, or something similar. """ t = get_proper_type(t) if t is None: return False elif isinstance(t, LiteralType): return True elif isinstance(t, UnionType): return any(is_literal_type_like(item) for item in t.items) elif isinstance(t, TypeVarType): return is_literal_type_like(t.upper_bound) or any( is_literal_type_like(item) for item in t.values ) else: return False def is_singleton_type(typ: Type) -> bool: """Returns 'true' if this type is a "singleton type" -- if there exists exactly only one runtime value associated with this type. That is, given two values 'a' and 'b' that have the same type 't', 'is_singleton_type(t)' returns True if and only if the expression 'a is b' is always true. Currently, this returns True when given NoneTypes, enum LiteralTypes, enum types with a single value and ... (Ellipses). Note that other kinds of LiteralTypes cannot count as singleton types. For example, suppose we do 'a = 100000 + 1' and 'b = 100001'. It is not guaranteed that 'a is b' will always be true -- some implementations of Python will end up constructing two distinct instances of 100001. """ typ = get_proper_type(typ) return typ.is_singleton_type() def try_expanding_sum_type_to_union(typ: Type, target_fullname: str) -> ProperType: """Attempts to recursively expand any enum Instances with the given target_fullname into a Union of all of its component LiteralTypes. For example, if we have: class Color(Enum): RED = 1 BLUE = 2 YELLOW = 3 class Status(Enum): SUCCESS = 1 FAILURE = 2 UNKNOWN = 3 ...and if we call `try_expanding_sum_type_to_union(Union[Color, Status], 'module.Color')`, this function will return Literal[Color.RED, Color.BLUE, Color.YELLOW, Status]. """ typ = get_proper_type(typ) if isinstance(typ, UnionType): items = [ try_expanding_sum_type_to_union(item, target_fullname) for item in typ.relevant_items() ] return make_simplified_union(items, contract_literals=False) if isinstance(typ, Instance) and typ.type.fullname == target_fullname: if typ.type.fullname == "builtins.bool": items = [LiteralType(True, typ), LiteralType(False, typ)] return make_simplified_union(items, contract_literals=False) if typ.type.is_enum: items = [LiteralType(name, typ) for name in typ.type.enum_members] if not items: return typ return make_simplified_union(items, contract_literals=False) return typ def try_contracting_literals_in_union(types: Sequence[Type]) -> list[ProperType]: """Contracts any literal types back into a sum type if possible. Requires a flattened union and does not descend into children. Will replace the first instance of the literal with the sum type and remove all others. If we call `try_contracting_union(Literal[Color.RED, Color.BLUE, Color.YELLOW])`, this function will return Color. We also treat `Literal[True, False]` as `bool`. """ proper_types = [get_proper_type(typ) for typ in types] sum_types: dict[str, tuple[set[Any], list[int]]] = {} marked_for_deletion = set() for idx, typ in enumerate(proper_types): if isinstance(typ, LiteralType): fullname = typ.fallback.type.fullname if typ.fallback.type.is_enum or isinstance(typ.value, bool): if fullname not in sum_types: sum_types[fullname] = ( ( set(typ.fallback.type.enum_members) if typ.fallback.type.is_enum else {True, False} ), [], ) literals, indexes = sum_types[fullname] literals.discard(typ.value) indexes.append(idx) if not literals: first, *rest = indexes proper_types[first] = typ.fallback marked_for_deletion |= set(rest) return list( itertools.compress( proper_types, [(i not in marked_for_deletion) for i in range(len(proper_types))] ) ) def coerce_to_literal(typ: Type) -> Type: """Recursively converts any Instances that have a last_known_value or are instances of enum types with a single value into the corresponding LiteralType. """ original_type = typ typ = get_proper_type(typ) if isinstance(typ, UnionType): new_items = [coerce_to_literal(item) for item in typ.items] return UnionType.make_union(new_items) elif isinstance(typ, Instance): if typ.last_known_value: return typ.last_known_value elif typ.type.is_enum: enum_values = typ.type.enum_members if len(enum_values) == 1: return LiteralType(value=enum_values[0], fallback=typ) return original_type def get_type_vars(tp: Type) -> list[TypeVarType]: return cast("list[TypeVarType]", tp.accept(TypeVarExtractor())) def get_all_type_vars(tp: Type) -> list[TypeVarLikeType]: # TODO: should we always use this function instead of get_type_vars() above? return tp.accept(TypeVarExtractor(include_all=True)) class TypeVarExtractor(TypeQuery[list[TypeVarLikeType]]): def __init__(self, include_all: bool = False) -> None: super().__init__(self._merge) self.include_all = include_all def _merge(self, iter: Iterable[list[TypeVarLikeType]]) -> list[TypeVarLikeType]: out = [] for item in iter: out.extend(item) return out def visit_type_var(self, t: TypeVarType) -> list[TypeVarLikeType]: return [t] def visit_param_spec(self, t: ParamSpecType) -> list[TypeVarLikeType]: return [t] if self.include_all else [] def visit_type_var_tuple(self, t: TypeVarTupleType) -> list[TypeVarLikeType]: return [t] if self.include_all else [] def freeze_all_type_vars(member_type: Type) -> None: member_type.accept(FreezeTypeVarsVisitor()) class FreezeTypeVarsVisitor(TypeTraverserVisitor): def visit_callable_type(self, t: CallableType) -> None: for v in t.variables: v.id.meta_level = 0 super().visit_callable_type(t) def custom_special_method(typ: Type, name: str, check_all: bool = False) -> bool: """Does this type have a custom special method such as __format__() or __eq__()? If check_all is True ensure all items of a union have a custom method, not just some. """ typ = get_proper_type(typ) if isinstance(typ, Instance): method = typ.type.get(name) if method and isinstance(method.node, (SYMBOL_FUNCBASE_TYPES, Decorator, Var)): if method.node.info: return not method.node.info.fullname.startswith(("builtins.", "typing.")) return False if isinstance(typ, UnionType): if check_all: return all(custom_special_method(t, name, check_all) for t in typ.items) return any(custom_special_method(t, name) for t in typ.items) if isinstance(typ, TupleType): return custom_special_method(tuple_fallback(typ), name, check_all) if isinstance(typ, FunctionLike) and typ.is_type_obj(): # Look up __method__ on the metaclass for class objects. return custom_special_method(typ.fallback, name, check_all) if isinstance(typ, AnyType): # Avoid false positives in uncertain cases. return True # TODO: support other types (see ExpressionChecker.has_member())? return False def separate_union_literals(t: UnionType) -> tuple[Sequence[LiteralType], Sequence[Type]]: """Separate literals from other members in a union type.""" literal_items = [] union_items = [] for item in t.items: proper = get_proper_type(item) if isinstance(proper, LiteralType): literal_items.append(proper) else: union_items.append(item) return literal_items, union_items def try_getting_instance_fallback(typ: Type) -> Instance | None: """Returns the Instance fallback for this type if one exists or None.""" typ = get_proper_type(typ) if isinstance(typ, Instance): return typ elif isinstance(typ, LiteralType): return typ.fallback elif isinstance(typ, NoneType): return None # Fast path for None, which is common elif isinstance(typ, FunctionLike): return typ.fallback elif isinstance(typ, TupleType): return typ.partial_fallback elif isinstance(typ, TypedDictType): return typ.fallback elif isinstance(typ, TypeVarType): return try_getting_instance_fallback(typ.upper_bound) return None def fixup_partial_type(typ: Type) -> Type: """Convert a partial type that we couldn't resolve into something concrete. This means, for None we make it Optional[Any], and for anything else we fill in all of the type arguments with Any. """ if not isinstance(typ, PartialType): return typ if typ.type is None: return UnionType.make_union([AnyType(TypeOfAny.unannotated), NoneType()]) else: return Instance(typ.type, [AnyType(TypeOfAny.unannotated)] * len(typ.type.type_vars)) def get_protocol_member( left: Instance, member: str, class_obj: bool, is_lvalue: bool = False ) -> Type | None: if member == "__call__" and class_obj: # Special case: class objects always have __call__ that is just the constructor. def named_type(fullname: str) -> Instance: return Instance(left.type.mro[-1], []) return type_object_type(left.type, named_type) if member == "__call__" and left.type.is_metaclass(): # Special case: we want to avoid falling back to metaclass __call__ # if constructor signature didn't match, this can cause many false negatives. return None from mypy.subtypes import find_member subtype = find_member(member, left, left, class_obj=class_obj, is_lvalue=is_lvalue) if isinstance(subtype, PartialType): subtype = ( NoneType() if subtype.type is None else Instance( subtype.type, [AnyType(TypeOfAny.unannotated)] * len(subtype.type.type_vars) ) ) return subtype