ty 0.0.30

on Python PyPI

Release Notes

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

Install ty 0.0.30

Install prebuilt binaries via shell script

curl --proto '=https' --tlsv1.2 -LsSf https://releases.astral.sh/github/ty/releases/download/0.0.30/ty-installer.sh | sh

Install prebuilt binaries via powershell script

powershell -ExecutionPolicy Bypass -c "irm https://releases.astral.sh/github/ty/releases/download/0.0.30/ty-installer.ps1 | iex"

Download ty 0.0.30

Verifying GitHub Artifact Attestations

The artifacts in this release have attestations generated with GitHub Artifact Attestations. These can be verified by using the GitHub CLI:

gh attestation verify <file-path of downloaded artifact> --repo astral-sh/ty

You can also download the attestation from GitHub and verify against that directly:

gh attestation verify <file-path of downloaded artifact> --bundle <file-path of downloaded attestation>