diff --git a/mypy/applytype.py b/mypy/applytype.py index eecd555bf90d..4847570b1712 100644 --- a/mypy/applytype.py +++ b/mypy/applytype.py @@ -1,17 +1,24 @@ from __future__ import annotations -from typing import Callable, Sequence +from typing import Callable, Iterable, Sequence import mypy.subtypes from mypy.erasetype import erase_typevars from mypy.expandtype import expand_type -from mypy.nodes import Context +from mypy.nodes import Context, TypeInfo +from mypy.type_visitor import TypeTranslator +from mypy.typeops import get_all_type_vars from mypy.types import ( AnyType, CallableType, + Instance, + Parameters, + ParamSpecFlavor, ParamSpecType, PartialType, + ProperType, Type, + TypeAliasType, TypeVarId, TypeVarLikeType, TypeVarTupleType, @@ -19,6 +26,7 @@ UninhabitedType, UnpackType, get_proper_type, + remove_dups, ) @@ -170,3 +178,126 @@ def apply_generic_arguments( type_guard=type_guard, type_is=type_is, ) + + +def apply_poly(tp: CallableType, poly_tvars: Sequence[TypeVarLikeType]) -> CallableType | None: + """Make free type variables generic in the type if possible. + + This will translate the type `tp` while trying to create valid bindings for + type variables `poly_tvars` while traversing the type. This follows the same rules + as we do during semantic analysis phase, examples: + * Callable[Callable[[T], T], T] -> def [T] (def (T) -> T) -> T + * Callable[[], Callable[[T], T]] -> def () -> def [T] (T -> T) + * List[T] -> None (not possible) + """ + try: + return tp.copy_modified( + arg_types=[t.accept(PolyTranslator(poly_tvars)) for t in tp.arg_types], + ret_type=tp.ret_type.accept(PolyTranslator(poly_tvars)), + variables=[], + ) + except PolyTranslationError: + return None + + +class PolyTranslationError(Exception): + pass + + +class PolyTranslator(TypeTranslator): + """Make free type variables generic in the type if possible. + + See docstring for apply_poly() for details. + """ + + def __init__( + self, + poly_tvars: Iterable[TypeVarLikeType], + bound_tvars: frozenset[TypeVarLikeType] = frozenset(), + seen_aliases: frozenset[TypeInfo] = frozenset(), + ) -> None: + self.poly_tvars = set(poly_tvars) + # This is a simplified version of TypeVarScope used during semantic analysis. + self.bound_tvars = bound_tvars + self.seen_aliases = seen_aliases + + def collect_vars(self, t: CallableType | Parameters) -> list[TypeVarLikeType]: + found_vars = [] + for arg in t.arg_types: + for tv in get_all_type_vars(arg): + if isinstance(tv, ParamSpecType): + normalized: TypeVarLikeType = tv.copy_modified( + flavor=ParamSpecFlavor.BARE, prefix=Parameters([], [], []) + ) + else: + normalized = tv + if normalized in self.poly_tvars and normalized not in self.bound_tvars: + found_vars.append(normalized) + return remove_dups(found_vars) + + def visit_callable_type(self, t: CallableType) -> Type: + found_vars = self.collect_vars(t) + self.bound_tvars |= set(found_vars) + result = super().visit_callable_type(t) + self.bound_tvars -= set(found_vars) + + assert isinstance(result, ProperType) and isinstance(result, CallableType) + result.variables = list(result.variables) + found_vars + return result + + def visit_type_var(self, t: TypeVarType) -> Type: + if t in self.poly_tvars and t not in self.bound_tvars: + raise PolyTranslationError() + return super().visit_type_var(t) + + def visit_param_spec(self, t: ParamSpecType) -> Type: + if t in self.poly_tvars and t not in self.bound_tvars: + raise PolyTranslationError() + return super().visit_param_spec(t) + + def visit_type_var_tuple(self, t: TypeVarTupleType) -> Type: + if t in self.poly_tvars and t not in self.bound_tvars: + raise PolyTranslationError() + return super().visit_type_var_tuple(t) + + def visit_type_alias_type(self, t: TypeAliasType) -> Type: + if not t.args: + return t.copy_modified() + if not t.is_recursive: + return get_proper_type(t).accept(self) + # We can't handle polymorphic application for recursive generic aliases + # without risking an infinite recursion, just give up for now. + raise PolyTranslationError() + + def visit_instance(self, t: Instance) -> Type: + if t.type.has_param_spec_type: + # We need this special-casing to preserve the possibility to store a + # generic function in an instance type. Things like + # forall T . Foo[[x: T], T] + # are not really expressible in current type system, but this looks like + # a useful feature, so let's keep it. + param_spec_index = next( + i for (i, tv) in enumerate(t.type.defn.type_vars) if isinstance(tv, ParamSpecType) + ) + p = get_proper_type(t.args[param_spec_index]) + if isinstance(p, Parameters): + found_vars = self.collect_vars(p) + self.bound_tvars |= set(found_vars) + new_args = [a.accept(self) for a in t.args] + self.bound_tvars -= set(found_vars) + + repl = new_args[param_spec_index] + assert isinstance(repl, ProperType) and isinstance(repl, Parameters) + repl.variables = list(repl.variables) + list(found_vars) + return t.copy_modified(args=new_args) + # There is the same problem with callback protocols as with aliases + # (callback protocols are essentially more flexible aliases to callables). + if t.args and t.type.is_protocol and t.type.protocol_members == ["__call__"]: + if t.type in self.seen_aliases: + raise PolyTranslationError() + call = mypy.subtypes.find_member("__call__", t, t, is_operator=True) + assert call is not None + return call.accept( + PolyTranslator(self.poly_tvars, self.bound_tvars, self.seen_aliases | {t.type}) + ) + return super().visit_instance(t) diff --git a/mypy/checkexpr.py b/mypy/checkexpr.py index 8e6af0218c32..779d63c8d385 100644 --- a/mypy/checkexpr.py +++ b/mypy/checkexpr.py @@ -115,7 +115,6 @@ non_method_protocol_members, ) from mypy.traverser import has_await_expression -from mypy.type_visitor import TypeTranslator from mypy.typeanal import ( check_for_explicit_any, fix_instance, @@ -168,7 +167,6 @@ TypeOfAny, TypeType, TypeVarId, - TypeVarLikeType, TypeVarTupleType, TypeVarType, UnboundType, @@ -182,7 +180,6 @@ get_proper_types, has_recursive_types, is_named_instance, - remove_dups, split_with_prefix_and_suffix, ) from mypy.types_utils import ( @@ -2136,7 +2133,7 @@ def infer_function_type_arguments( ) # Try applying inferred polymorphic type if possible, e.g. Callable[[T], T] can # be interpreted as def [T] (T) -> T, but dict[T, T] cannot be expressed. - applied = apply_poly(poly_callee_type, free_vars) + applied = applytype.apply_poly(poly_callee_type, free_vars) if applied is not None and all( a is not None and not isinstance(get_proper_type(a), UninhabitedType) for a in poly_inferred_args @@ -6220,129 +6217,6 @@ def replace_callable_return_type(c: CallableType, new_ret_type: Type) -> Callabl return c.copy_modified(ret_type=new_ret_type) -def apply_poly(tp: CallableType, poly_tvars: Sequence[TypeVarLikeType]) -> CallableType | None: - """Make free type variables generic in the type if possible. - - This will translate the type `tp` while trying to create valid bindings for - type variables `poly_tvars` while traversing the type. This follows the same rules - as we do during semantic analysis phase, examples: - * Callable[Callable[[T], T], T] -> def [T] (def (T) -> T) -> T - * Callable[[], Callable[[T], T]] -> def () -> def [T] (T -> T) - * List[T] -> None (not possible) - """ - try: - return tp.copy_modified( - arg_types=[t.accept(PolyTranslator(poly_tvars)) for t in tp.arg_types], - ret_type=tp.ret_type.accept(PolyTranslator(poly_tvars)), - variables=[], - ) - except PolyTranslationError: - return None - - -class PolyTranslationError(Exception): - pass - - -class PolyTranslator(TypeTranslator): - """Make free type variables generic in the type if possible. - - See docstring for apply_poly() for details. - """ - - def __init__( - self, - poly_tvars: Iterable[TypeVarLikeType], - bound_tvars: frozenset[TypeVarLikeType] = frozenset(), - seen_aliases: frozenset[TypeInfo] = frozenset(), - ) -> None: - self.poly_tvars = set(poly_tvars) - # This is a simplified version of TypeVarScope used during semantic analysis. - self.bound_tvars = bound_tvars - self.seen_aliases = seen_aliases - - def collect_vars(self, t: CallableType | Parameters) -> list[TypeVarLikeType]: - found_vars = [] - for arg in t.arg_types: - for tv in get_all_type_vars(arg): - if isinstance(tv, ParamSpecType): - normalized: TypeVarLikeType = tv.copy_modified( - flavor=ParamSpecFlavor.BARE, prefix=Parameters([], [], []) - ) - else: - normalized = tv - if normalized in self.poly_tvars and normalized not in self.bound_tvars: - found_vars.append(normalized) - return remove_dups(found_vars) - - def visit_callable_type(self, t: CallableType) -> Type: - found_vars = self.collect_vars(t) - self.bound_tvars |= set(found_vars) - result = super().visit_callable_type(t) - self.bound_tvars -= set(found_vars) - - assert isinstance(result, ProperType) and isinstance(result, CallableType) - result.variables = list(result.variables) + found_vars - return result - - def visit_type_var(self, t: TypeVarType) -> Type: - if t in self.poly_tvars and t not in self.bound_tvars: - raise PolyTranslationError() - return super().visit_type_var(t) - - def visit_param_spec(self, t: ParamSpecType) -> Type: - if t in self.poly_tvars and t not in self.bound_tvars: - raise PolyTranslationError() - return super().visit_param_spec(t) - - def visit_type_var_tuple(self, t: TypeVarTupleType) -> Type: - if t in self.poly_tvars and t not in self.bound_tvars: - raise PolyTranslationError() - return super().visit_type_var_tuple(t) - - def visit_type_alias_type(self, t: TypeAliasType) -> Type: - if not t.args: - return t.copy_modified() - if not t.is_recursive: - return get_proper_type(t).accept(self) - # We can't handle polymorphic application for recursive generic aliases - # without risking an infinite recursion, just give up for now. - raise PolyTranslationError() - - def visit_instance(self, t: Instance) -> Type: - if t.type.has_param_spec_type: - # We need this special-casing to preserve the possibility to store a - # generic function in an instance type. Things like - # forall T . Foo[[x: T], T] - # are not really expressible in current type system, but this looks like - # a useful feature, so let's keep it. - param_spec_index = next( - i for (i, tv) in enumerate(t.type.defn.type_vars) if isinstance(tv, ParamSpecType) - ) - p = get_proper_type(t.args[param_spec_index]) - if isinstance(p, Parameters): - found_vars = self.collect_vars(p) - self.bound_tvars |= set(found_vars) - new_args = [a.accept(self) for a in t.args] - self.bound_tvars -= set(found_vars) - - repl = new_args[param_spec_index] - assert isinstance(repl, ProperType) and isinstance(repl, Parameters) - repl.variables = list(repl.variables) + list(found_vars) - return t.copy_modified(args=new_args) - # There is the same problem with callback protocols as with aliases - # (callback protocols are essentially more flexible aliases to callables). - if t.args and t.type.is_protocol and t.type.protocol_members == ["__call__"]: - if t.type in self.seen_aliases: - raise PolyTranslationError() - call = find_member("__call__", t, t, is_operator=True) - assert call is not None - return call.accept( - PolyTranslator(self.poly_tvars, self.bound_tvars, self.seen_aliases | {t.type}) - ) - return super().visit_instance(t) - - class ArgInferSecondPassQuery(types.BoolTypeQuery): """Query whether an argument type should be inferred in the second pass.