"""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 collections.abc import Callable

from mypy import errorcodes as codes, message_registry

from mypy.errorcodes import ErrorCode

from mypy.errors import Errors

from mypy.message_registry import INVALID_PARAM_SPEC_LOCATION, INVALID_PARAM_SPEC_LOCATION_NOTE

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.types import (

AnyType,

CallableType,

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,

)

from mypy.typevartuples import erased_vars

class TypeArgumentAnalyzer(MixedTraverserVisitor):

def __init__(

self,

errors: Errors,

options: Options,

is_typeshed_file: bool,

named_type: Callable[[str, list[Type]], Instance],

) -> None:

super().__init__()

self.errors = errors

self.options = options

self.is_typeshed_file = is_typeshed_file

self.named_type = named_type

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.is_recursive:

if t in self.seen_aliases:

# Avoid infinite recursion on recursive type aliases.

return

self.seen_aliases.add(t)

assert t.alias is not None, f"Unfixed type alias {t.type_ref}"

is_error, is_invalid = self.validate_args(

t.alias.name, tuple(t.args), t.alias.alias_tvars, t

)

if is_invalid:

# If there is an arity error (e.g. non-Parameters used for ParamSpec etc.),

# then it is safer to erase the arguments completely, to avoid crashes later.

# TODO: can we move this logic to typeanal.py?

t.args = erased_vars(t.alias.alias_tvars, TypeOfAny.from_error)

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.

if t.args:

# Since we always allow unbounded type variables in alias definitions, we need

# to verify the arguments satisfy the upper bounds of the expansion as well.

get_proper_type(t).accept(self)

if t.is_recursive:

self.seen_aliases.discard(t)

def visit_tuple_type(self, t: TupleType) -> None:

t.items = flatten_nested_tuples(t.items)

for i, it in enumerate(t.items):

if self.check_non_paramspec(it, "tuple", t):

t.items[i] = AnyType(TypeOfAny.from_error)

# We could also normalize Tuple[*tuple[X, ...]] -> tuple[X, ...] like in

# expand_type() but we can't do this here since it is not a translator visitor,

# and we need to return an Instance instead of TupleType.

super().visit_tuple_type(t)

def visit_callable_type(self, t: CallableType) -> None:

super().visit_callable_type(t)

t.normalize_trivial_unpack()

def visit_instance(self, t: Instance) -> None:

super().visit_instance(t)

# 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

_, is_invalid = self.validate_args(info.name, t.args, info.defn.type_vars, t)

if is_invalid:

t.args = tuple(erased_vars(info.defn.type_vars, TypeOfAny.from_error))

if t.type.fullname == "builtins.tuple" and len(t.args) == 1:

# Normalize Tuple[*Tuple[X, ...], ...] -> Tuple[X, ...]

arg = t.args[0]

if isinstance(arg, UnpackType):

unpacked = get_proper_type(arg.type)

if isinstance(unpacked, Instance):

assert unpacked.type.fullname == "builtins.tuple"

t.args = unpacked.args

def check_non_paramspec(self, arg: Type, tv_kind: str, context: Context) -> bool:

if isinstance(arg, ParamSpecType):

self.fail(

INVALID_PARAM_SPEC_LOCATION.format(format_type(arg, self.options)),

context,

code=codes.VALID_TYPE,

)

self.note(

INVALID_PARAM_SPEC_LOCATION_NOTE.format(arg.name), context, code=codes.VALID_TYPE

)

return True

if isinstance(arg, Parameters):

self.fail(

f"Cannot use {format_type(arg, self.options)} for {tv_kind},"

" only for ParamSpec",

context,

code=codes.VALID_TYPE,

)

return True

return False

def validate_args(

self, name: str, args: tuple[Type, ...], type_vars: list[TypeVarLikeType], ctx: Context

) -> tuple[bool, bool]:

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 = start + (TupleType(list(middle), tvt.tuple_fallback),) + end

is_error = False

is_invalid = False

for arg, tvar in zip(args, type_vars):

context = ctx if arg.line < 0 else arg

if isinstance(tvar, TypeVarType):

if self.check_non_paramspec(arg, "regular type variable", context):

is_invalid = True

continue

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

if tvar.values:

if isinstance(arg, TypeVarType):

arg_values = arg.values

if not arg_values:

is_error = True

self.fail(

message_registry.INVALID_TYPEVAR_AS_TYPEARG.format(arg.name, name),

context,

code=codes.TYPE_VAR,

)

continue

else:

arg_values = [arg]

if self.check_type_var_values(

name, arg_values, tvar.name, tvar.values, context

):

is_error = True

# Check against upper bound. Since it's object the vast majority of the time,

# add fast path to avoid a potentially slow subtype check.

upper_bound = tvar.upper_bound

object_upper_bound = (

type(upper_bound) is Instance

and upper_bound.type.fullname == "builtins.object"

)

if not object_upper_bound and not is_subtype(arg, upper_bound):

is_error = True

self.fail(

message_registry.INVALID_TYPEVAR_ARG_BOUND.format(

format_type(arg, self.options),

name,

format_type(upper_bound, self.options),

),

context,

code=codes.TYPE_VAR,

)

elif isinstance(tvar, ParamSpecType):

if not isinstance(

get_proper_type(arg), (ParamSpecType, Parameters, AnyType, UnboundType)

):

is_invalid = True

self.fail(

"Can only replace ParamSpec with a parameter types list or"

f" another ParamSpec, got {format_type(arg, self.options)}",

context,

code=codes.VALID_TYPE,

)

elif isinstance(tvar, TypeVarTupleType):

p_arg = get_proper_type(arg)

assert isinstance(p_arg, TupleType)

for it in p_arg.items:

if self.check_non_paramspec(it, "TypeVarTuple", context):

is_invalid = True

if is_invalid:

is_error = True

return is_error, is_invalid

def visit_unpack_type(self, typ: UnpackType) -> None:

super().visit_unpack_type(typ)

proper_type = get_proper_type(typ.type)

if isinstance(proper_type, TupleType):

return

if isinstance(proper_type, TypeVarTupleType):

return

# TODO: this should probably be .has_base("builtins.tuple"), also elsewhere. This is

# tricky however, since this needs map_instance_to_supertype() available in many places.

if isinstance(proper_type, Instance) and proper_type.type.fullname == "builtins.tuple":

return

if not isinstance(proper_type, (UnboundType, AnyType)):

# Avoid extra errors if there were some errors already. Also interpret plain Any

# as tuple[Any, ...] (this is better for the code in type checker).

self.fail(

message_registry.INVALID_UNPACK.format(format_type(proper_type, self.options)),

typ.type,

code=codes.VALID_TYPE,

)

typ.type = self.named_type("builtins.tuple", [AnyType(TypeOfAny.from_error)])

def check_type_var_values(

self, name: str, actuals: list[Type], arg_name: str, valids: list[Type], context: Context

) -> bool:

if self.in_type_alias_expr:

# See testValidTypeAliasValues - we do not enforce typevar compatibility

# at the definition site. We check instantiation validity later.

return False

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)