ruff/crates/ty_vendored/ty_extensions
Dhruv Manilawala ef4108af2a
[ty] Generate the top and bottom materialization of a type (#18594)
## Summary

This is to support https://github.com/astral-sh/ruff/pull/18607.

This PR adds support for generating the top materialization (or upper
bound materialization) and the bottom materialization (or lower bound
materialization) of a type. This is the most general and the most
specific form of the type which is fully static, respectively.
    
More concretely, `T'`, the top materialization of `T`, is the type `T`
with all occurrences
of dynamic type (`Any`, `Unknown`, `@Todo`) replaced as follows:

- In covariant position, it's replaced with `object`
- In contravariant position, it's replaced with `Never`
- In invariant position, it's replaced with an unresolved type variable

(For an invariant position, it should actually be replaced with an
existential type, but this is not currently representable in our type
system, so we use an unresolved type variable for now instead.)

The bottom materialization is implemented in the same way, except we
start out in "contravariant" position.

## Test Plan

Add test cases for various types.
2025-06-12 12:06:16 +05:30
..
README.md Rename Red Knot (#17820) 2025-05-03 19:49:15 +02:00
ty_extensions.pyi [ty] Generate the top and bottom materialization of a type (#18594) 2025-06-12 12:06:16 +05:30

README.md

The build.rs copies the ty_extensions.pyi file in this directory into the vendor/typeshed/stdlib directory.