v0.0.30

Released on 2026-04-13.

As of v0.0.30, ty no longer unions Unknown into most inferred types of unannotated attributes. For example:

class Foo:
    def __init__(self) -> None:
        self.value = 1

reveal_type(Foo().value)  # revealed: int
Foo().value = "x"  # error: [invalid-assignment]

In previous versions, reveal_type(Foo().value) would have included Unknown, so the assignment to "x" would not have been flagged. Since this can affect inferred attribute types throughout a codebase, upgrading may lead to both new and resolved diagnostics. Initializers of None and other non-literal singleton types remain exceptions. See #​24531 for details.

Bug fixes

• Disallow bare ParamSpec in Concatenate prefixes (#​24474)
• Ensure '/' parameter appears before '*' when rendering Callable types (#​24497)
• Ensure nested conditional blocks inherit TYPE_CHECKING state from outer blocks (#​24470)
• Fix bad diagnostic range for incorrect implicit __init_subclass__ calls (#​24541)
• Fix incorrect assignability of type[T] to a metaclass (#​24515)
• Fix stack overflows from recursive types (#​24413)
• Server: fix signature help for ParamSpec-specialized class calls (#​24399)
• Use TypedDict field types as type context to inform the inference of arguments passed to TypedDict constructors (#​24422)

LSP server

• Adjust semantic tokens implementation to ensure that type alias values have "type form" syntax highlighting in IDEs (#​24478)
• Completions: rank symbols from typing and collections higher than third party re-exports (#​23643)
• Ignore unsupported editor-selected Python versions (#​24498)
• Improve TypedDict constructor support in the LSP by synthesizing __init__ (#​24476, #​24522, #​24535)
• Return all attribute definitions for goto definition, rather than just the last definition in the given scope (#​24332)
• Show info subdiagnostics in LSP diagnostic messages (#​24328)
• Use the context of the kind of object a parameter is expected to receive to inform syntax highlighting of arguments passed to call expressions (#​23949)

Diagnostics

• Hide "Rule xyz is enabled"-style hints unless verbose mode was specified (#​24469)
• Improve consistency of pedantic lints complaining about badly named types (#​24575)
• Point to the first reachable declaration, rather than the first declaration, in declaration-based diagnostics (#​24564)

Core type checking

• Add support for functional Enum(...) syntax (#​23602, #​24570, #​24571)
• Allow Final variable assignments in __post_init__ (#​24529)
• Allow partially stringified type[...] annotations, e.g. type["MyClass"] (#​24518)
• Emit a diagnostic when attempting to inherit from a class with __init_subclass__ = None (#​24543)
• Fix TypeGuard and TypeIs narrowing for unbound method calls (#​24612)
• Fix assignability of intersections with bounded TypeVars (#​24502)
• Fix excess subscript argument inference for non-generic types so that list[int][0] leads to 1 diagnostic, rather than 2 (#​24354)
• Inherit dataclass_transform metadata from metaclass bases (#​24615)
• Lazily evaluate declaration reachability in field and enum filters (#​24451)
• Normalize explicit None accessors in manual property construction (#​24492)
• Reject deleting Final attributes (#​24508)
• Respect non-required keys in TypedDict unpacking (#​24446)
• Respect property deleters in attribute deletion checks (#​24500)
• Stop special-casing str constructor (#​24514)
• Stop unioning Unknown into types of un-annotated attributes (#​24531)
• Support super() in metaclass methods (#​24483)
• Tighten up a few edge cases in Concatenate type-expression parsing (#​24172)
• Use basic blocks for determining if a node is in an if TYPE_CHECKING block (#​24394)

Contributors

• @​charliermarsh
• @​Glyphack
• @​MichaReiser
• @​sharkdp
• @​carljm
• @​YilunAllenChen
• @​zanieb
• @​AlexWaygood
• @​thejchap