"""Verify properties of type arguments, like 'int' in C[int] being valid. This must happen after semantic analysis since there can be placeholder types until the end of semantic analysis, and these break various type operations, including subtype checks. """ from __future__ import annotations from typing import Sequence from mypy import errorcodes as codes, message_registry from mypy.errorcodes import ErrorCode from mypy.errors import Errors from mypy.messages import format_type from mypy.mixedtraverser import MixedTraverserVisitor from mypy.nodes import Block, ClassDef, Context, FakeInfo, FuncItem, MypyFile from mypy.options import Options from mypy.scope import Scope from mypy.subtypes import is_same_type, is_subtype from mypy.typeanal import set_any_tvars from mypy.types import ( AnyType, Instance, Parameters, ParamSpecType, TupleType, Type, TypeAliasType, TypeOfAny, TypeVarLikeType, TypeVarTupleType, TypeVarType, UnboundType, UnpackType, flatten_nested_tuples, get_proper_type, get_proper_types, split_with_prefix_and_suffix, ) class TypeArgumentAnalyzer(MixedTraverserVisitor): def __init__(self, errors: Errors, options: Options, is_typeshed_file: bool) -> None: super().__init__() self.errors = errors self.options = options self.is_typeshed_file = is_typeshed_file self.scope = Scope() # Should we also analyze function definitions, or only module top-levels? self.recurse_into_functions = True # Keep track of the type aliases already visited. This is needed to avoid # infinite recursion on types like A = Union[int, List[A]]. self.seen_aliases: set[TypeAliasType] = set() def visit_mypy_file(self, o: MypyFile) -> None: self.errors.set_file(o.path, o.fullname, scope=self.scope, options=self.options) with self.scope.module_scope(o.fullname): super().visit_mypy_file(o) def visit_func(self, defn: FuncItem) -> None: if not self.recurse_into_functions: return with self.scope.function_scope(defn): super().visit_func(defn) def visit_class_def(self, defn: ClassDef) -> None: with self.scope.class_scope(defn.info): super().visit_class_def(defn) def visit_block(self, o: Block) -> None: if not o.is_unreachable: super().visit_block(o) def visit_type_alias_type(self, t: TypeAliasType) -> None: super().visit_type_alias_type(t) if t in self.seen_aliases: # Avoid infinite recursion on recursive type aliases. # Note: it is fine to skip the aliases we have already seen in non-recursive # types, since errors there have already been reported. return self.seen_aliases.add(t) # Some recursive aliases may produce spurious args. In principle this is not very # important, as we would simply ignore them when expanding, but it is better to keep # correct aliases. Also, variadic aliases are better to check when fully analyzed, # so we do this here. assert t.alias is not None, f"Unfixed type alias {t.type_ref}" args = flatten_nested_tuples(t.args) if t.alias.tvar_tuple_index is not None: correct = len(args) >= len(t.alias.alias_tvars) - 1 if any( isinstance(a, UnpackType) and isinstance(get_proper_type(a.type), Instance) for a in args ): correct = True else: correct = len(args) == len(t.alias.alias_tvars) if not correct: if t.alias.tvar_tuple_index is not None: exp_len = f"at least {len(t.alias.alias_tvars) - 1}" else: exp_len = f"{len(t.alias.alias_tvars)}" self.fail( f"Bad number of arguments for type alias, expected: {exp_len}, given: {len(args)}", t, code=codes.TYPE_ARG, ) t.args = set_any_tvars( t.alias, t.line, t.column, self.options, from_error=True, fail=self.fail ).args else: t.args = args is_error = self.validate_args(t.alias.name, t.args, t.alias.alias_tvars, t) if not is_error: # If there was already an error for the alias itself, there is no point in checking # the expansion, most likely it will result in the same kind of error. get_proper_type(t).accept(self) def visit_instance(self, t: Instance) -> None: # Type argument counts were checked in the main semantic analyzer pass. We assume # that the counts are correct here. info = t.type if isinstance(info, FakeInfo): return # https://github.com/python/mypy/issues/11079 self.validate_args(info.name, t.args, info.defn.type_vars, t) super().visit_instance(t) def validate_args( self, name: str, args: Sequence[Type], type_vars: list[TypeVarLikeType], ctx: Context ) -> bool: # TODO: we need to do flatten_nested_tuples and validate arg count for instances # similar to how do we do this for type aliases above, but this may have perf penalty. if any(isinstance(v, TypeVarTupleType) for v in type_vars): prefix = next(i for (i, v) in enumerate(type_vars) if isinstance(v, TypeVarTupleType)) tvt = type_vars[prefix] assert isinstance(tvt, TypeVarTupleType) start, middle, end = split_with_prefix_and_suffix( tuple(args), prefix, len(type_vars) - prefix - 1 ) args = list(start) + [TupleType(list(middle), tvt.tuple_fallback)] + list(end) is_error = False for (i, arg), tvar in zip(enumerate(args), type_vars): if isinstance(tvar, TypeVarType): if isinstance(arg, ParamSpecType): # TODO: Better message is_error = True self.fail(f'Invalid location for ParamSpec "{arg.name}"', ctx) self.note( "You can use ParamSpec as the first argument to Callable, e.g., " "'Callable[{}, int]'".format(arg.name), ctx, ) continue if tvar.values: if isinstance(arg, TypeVarType): if self.in_type_alias_expr: # Type aliases are allowed to use unconstrained type variables # error will be checked at substitution point. continue arg_values = arg.values if not arg_values: is_error = True self.fail( message_registry.INVALID_TYPEVAR_AS_TYPEARG.format(arg.name, name), ctx, code=codes.TYPE_VAR, ) continue else: arg_values = [arg] if self.check_type_var_values(name, arg_values, tvar.name, tvar.values, ctx): is_error = True if not is_subtype(arg, tvar.upper_bound): if self.in_type_alias_expr and isinstance(arg, TypeVarType): # Type aliases are allowed to use unconstrained type variables # error will be checked at substitution point. continue is_error = True self.fail( message_registry.INVALID_TYPEVAR_ARG_BOUND.format( format_type(arg, self.options), name, format_type(tvar.upper_bound, self.options), ), ctx, code=codes.TYPE_VAR, ) elif isinstance(tvar, ParamSpecType): if not isinstance( get_proper_type(arg), (ParamSpecType, Parameters, AnyType, UnboundType) ): self.fail( "Can only replace ParamSpec with a parameter types list or" f" another ParamSpec, got {format_type(arg, self.options)}", ctx, ) return is_error def visit_unpack_type(self, typ: UnpackType) -> None: proper_type = get_proper_type(typ.type) if isinstance(proper_type, TupleType): return if isinstance(proper_type, TypeVarTupleType): return if isinstance(proper_type, Instance) and proper_type.type.fullname == "builtins.tuple": return if ( isinstance(proper_type, UnboundType) or isinstance(proper_type, AnyType) and proper_type.type_of_any == TypeOfAny.from_error ): return # TODO: Infer something when it can't be unpacked to allow rest of # typechecking to work. self.fail( message_registry.INVALID_UNPACK.format(format_type(proper_type, self.options)), typ ) def check_type_var_values( self, name: str, actuals: list[Type], arg_name: str, valids: list[Type], context: Context ) -> bool: is_error = False for actual in get_proper_types(actuals): # We skip UnboundType here, since they may appear in defn.bases, # the error will be caught when visiting info.bases, that have bound type # variables. if not isinstance(actual, (AnyType, UnboundType)) and not any( is_same_type(actual, value) for value in valids ): is_error = True if len(actuals) > 1 or not isinstance(actual, Instance): self.fail( message_registry.INVALID_TYPEVAR_ARG_VALUE.format(name), context, code=codes.TYPE_VAR, ) else: class_name = f'"{name}"' actual_type_name = f'"{actual.type.name}"' self.fail( message_registry.INCOMPATIBLE_TYPEVAR_VALUE.format( arg_name, class_name, actual_type_name ), context, code=codes.TYPE_VAR, ) return is_error def fail(self, msg: str, context: Context, *, code: ErrorCode | None = None) -> None: self.errors.report(context.line, context.column, msg, code=code) def note(self, msg: str, context: Context, *, code: ErrorCode | None = None) -> None: self.errors.report(context.line, context.column, msg, severity="note", code=code)