Alex Waygood af886b06c9 [ty] Allow if type(x) is Y narrowing for types other than class-literal types (#22729) ...

## Summary

Fixes https://github.com/astral-sh/ty/issues/2565.

This PR adds support for `if type(x) is Y` narrowing where `Y` is a
subclass-of type, type-alias type, or typevar type.

## Test Plan

mdtests

2026-01-20 08:23:00 +00:00

..

annotations

[ty] Ban NewTypes with generic bases (#22653)

2026-01-17 15:23:53 +00:00

assignment

[ty] Subtyping for bidirectional inference (#21930)

2025-12-30 17:03:20 -05:00

binary

[ty] highlight special type syntax in hovers as xml (#22005)

2025-12-16 14:20:35 +00:00

boolean

Revert "[ty] Better control flow for boolean expressions that are inside if (#18010)" (#18150)

2025-05-17 08:27:32 -04:00

boundness_declaredness

[ty] Reformulation of public symbol inference test suite (#20667)

2025-10-01 14:26:17 +02:00

call

[ty] Infer implicit type of cls in __new__ methods (#22584)

2026-01-15 15:42:16 -05:00

class

[ty] Fix super() with TypeVar-annotated self and cls parameter (#22208)

2026-01-07 19:56:09 -05:00

comparison

[ty] Support comparisons between variable-length tuples (#21824)

2026-01-06 12:09:40 -05:00

comprehensions

[ty] fix global symbol lookup from eager scopes (#21317)

2025-11-12 10:15:51 -08:00

conditional

[ty] Fix match exhaustiveness for enum | None unions (#22290)

2025-12-29 22:19:28 -05:00

dataclasses

[ty] Avoid overload errors when detecting dataclass-on-tuple (#22687)

2026-01-19 13:55:11 +00:00

declaration

[ty] Format conflicting types as an enumeration (#18956)

2025-06-26 14:29:33 +02:00

decorators

[ty] Support own instance members for type(...) classes (#22480)

2026-01-13 09:36:03 -05:00

diagnostics

[ty] Avoid reporting overload errors for successful union variants (#22688)

2026-01-19 08:40:31 -05:00

directives

[ty] Minor improvements to assert_type diagnostics (#21811)

2025-12-05 12:33:30 +00:00

doc

ty_python_semantic: add union type context to function call type errors

2025-05-09 13:40:51 -04:00

exception

Update pre-commit dependencies (#22281)

2025-12-29 17:11:28 +00:00

expression

[ty] Fix @Todo type for starred expressions (#22503)

2026-01-13 21:09:29 +00:00

external

[ty] Lockfiles for mdtests with external dependencies (#22077)

2025-12-19 14:29:52 +01:00

function

[ty] Allow ... as a default value for any parameter if the function is in an if TYPE_CHECKING block (#22624)

2026-01-16 16:32:38 +00:00

generics

[ty] Add basic support for overloads in ParamSpec (#21946)

2026-01-20 04:14:05 +00:00

ide_support

[ty] Make ModuleType and object attributes available on namespace packages (#22606)

2026-01-16 08:42:58 +00:00

import

[ty] Make ModuleType and object attributes available on namespace packages (#22606)

2026-01-16 08:42:58 +00:00

libraries

[ty] Generic types aliases (implicit and PEP 613) (#21553)

2025-11-28 20:38:24 +01:00

literal

[ty] Respect debug text interpolation in f-strings (#22151)

2025-12-22 20:21:28 -05:00

loops

[ty] Respect intersections in iterations (#21965)

2025-12-19 12:36:37 -05:00

narrow

[ty] Allow if type(x) is Y narrowing for types other than class-literal types (#22729)

2026-01-20 08:23:00 +00:00

regression

[ty] Fix an mdtest title (#22439)

2026-01-07 16:34:56 +00:00

scopes

[ty] Make ModuleType and object attributes available on namespace packages (#22606)

2026-01-16 08:42:58 +00:00

shadowing

[ty] Make the implicit shadowing message on invalid assignment diagnostic info (#22219)

2025-12-29 10:30:48 +01:00

snapshots

[ty] Avoid reporting overload errors for successful union variants (#22688)

2026-01-19 08:40:31 -05:00

stubs

[ty] Better invalid-assignment diagnostics (#21476)

2025-11-18 14:31:04 +01:00

subscript

[ty] Make special cases for subscript inference exhaustive (#22035)

2026-01-15 00:18:54 +00:00

suppressions

[ty] Add respect-type-ignore-comments configuration option (#22137)

2025-12-23 08:36:51 +01:00

type_compendium

[ty] Fix @Todo type for starred expressions (#22503)

2026-01-13 21:09:29 +00:00

type_display

[ty] don't expand type aliases via type mappings unless necessary (#22241)

2025-12-29 19:02:56 -08:00

type_of

[ty]: consolidate type[] types in a union when displaying them in diagnostics (#22592)

2026-01-15 15:20:58 +00:00

type_properties

[ty] Recognize string-literal types as subtypes of Sequence[Literal[chars]] (#22415)

2026-01-18 17:43:44 +00:00

type_qualifiers

[ty] Improve rendering of default values for function args (#22010)

2025-12-16 13:39:19 -05:00

unary

[ty] Improve diagnostics for unsupported binary operations and unsupported augmented assignments (#21947)

2025-12-12 21:53:29 +00:00

with

[ty] Type inference for @asynccontextmanager (#21876)

2025-12-09 22:49:00 +01:00

.mdformat.toml

Rename Red Knot (#17820)

2025-05-03 19:49:15 +02:00

async.md

[ty] Make signature return and parameter types non-optional (#22425)

2026-01-07 09:18:39 -08:00

attributes.md

[ty]: consolidate type[] types in a union when displaying them in diagnostics (#22592)

2026-01-15 15:20:58 +00:00

bidirectional.md

[ty] Infer implicit type of cls in __new__ methods (#22584)

2026-01-15 15:42:16 -05:00

classes.md

[ty] Support starred unpacking in class bases (#22591)

2026-01-15 10:17:11 -05:00

cycle.md

[ty] Improve rendering of default values for function args (#22010)

2025-12-16 13:39:19 -05:00

decorators.md

[ty] Validate constructor arguments when a class is used as a decorator (#22377)

2026-01-17 10:48:59 -05:00

del.md

[ty] Rename non-subscriptable error code to not-subscriptable (#22193)

2025-12-27 11:44:35 +00:00

deprecated.md

[ty] Infer typevar specializations for Callable types (#21551)

2025-12-16 09:16:49 -08:00

descriptor_protocol.md

[ty] Avoid including property in subclasses properties (#22088)

2025-12-30 03:28:03 +00:00

enums.md

[ty] Add diagnostic to catch generic enums (#22482)

2026-01-13 16:55:46 -05:00

exhaustiveness_checking.md

[ty] Exhaustiveness checking for generic classes (#21726)

2025-12-01 13:52:36 +01:00

final.md

[ty] Fix @staticmethod combined with other decorators incorrectly binding self (#22128)

2025-12-24 03:35:09 +00:00

implicit_type_aliases.md

[ty]: consolidate type[] types in a union when displaying them in diagnostics (#22592)

2026-01-15 15:20:58 +00:00

instance_layout_conflict.md

[ty] initial support for slots=True in dataclasses (#20278)

2025-09-07 18:25:35 +01:00

intersection_types.md

[ty] Use "cannot" consistently over "can not" (#21255)

2025-11-03 10:38:20 -05:00

invalid_syntax.md

[ty] Avoid double-inference on non-tuple argument to Annotated (#21837)

2025-12-08 10:24:05 -05:00

known_constants.md

Rename Red Knot (#17820)

2025-05-03 19:49:15 +02:00

liskov.md

[ty] Avoid emitting Liskov repeated violations from grandparent to child (#22484)

2026-01-09 19:27:57 -05:00

literal_promotion.md

[ty] Subtyping for bidirectional inference (#21930)

2025-12-30 17:03:20 -05:00

mdtest_config.md

Rename Red Knot (#17820)

2025-05-03 19:49:15 +02:00

mdtest_custom_typeshed.md

[ty] Remove Type::Tuple (#19669)

2025-08-11 22:03:32 +01:00

metaclass.md

Update class literal display to use <class 'Foo'> style (#17889)

2025-05-06 20:11:25 -04:00

mro.md

[ty] Improve disambiguation of types (#22547)

2026-01-13 14:56:56 +00:00

named_tuple.md

[ty] Avoid overload errors when detecting dataclass-on-tuple (#22687)

2026-01-19 13:55:11 +00:00

overloads.md

[ty] Include type parameters in generic callable display (#22435)

2026-01-13 17:29:08 +00:00

override.md

[ty] emit diagnostics for method definitions and other invalid statements in TypedDict class bodies (#22351)

2026-01-05 11:28:04 -08:00

pep613_type_aliases.md

[ty] Simple syntactic validation for PEP-613 type aliases (#22652)

2026-01-17 15:43:50 +00:00

pep695_type_aliases.md

[ty] Fix stack overflow with recursive type aliases containing tuple … (#22543)

2026-01-13 11:25:01 -08:00

properties.md

[ty] Enable even more goto-definition on inlay hints (#21950)

2025-12-12 12:57:38 -05:00

protocols.md

Fix stack overflow with recursive generic protocols (depth limit) (#21858)

2025-12-09 09:05:18 -08:00

public_types.md

[ty] Improve disambiguation of types (#22547)

2026-01-13 14:56:56 +00:00

statically_known_branches.md

[ty] Rename "possibly unbound" diagnostics to "possibly missing" (#20492)

2025-09-23 14:26:55 +00:00

sys_platform.md

Rename Red Knot (#17820)

2025-05-03 19:49:15 +02:00

sys_version_info.md

[ty] support PEP 613 type aliases (#21394)

2025-11-20 17:59:35 -08:00

t_strings.md

[ty] Add support for PEP 750 t-strings (#20085)

2025-08-25 18:49:49 +00:00

terminal_statements.md

[ty] improve lazy scope place lookup (#19321)

2025-07-25 07:11:11 +00:00

ty_extensions.md

[ty] Uniformly use "not supported" in diagnostics (#21916)

2025-12-11 15:03:55 +00:00

typed_dict.md

[ty] Emit diagnostic for NamedTuple and TypedDict decorated with dataclass (#22672)

2026-01-18 17:20:09 +00:00

union_types.md

[ty]: consolidate type[] types in a union when displaying them in diagnostics (#22592)

2026-01-15 15:20:58 +00:00

unpacking.md

[ty] Infer more precise types for collection literals (#20360)

2025-09-17 18:51:50 -04:00

unreachable.md

[ty] Add subdiagnostic hint if a variable with type Never is used in a type expression (#21660)

2025-11-27 12:48:18 +00:00