ruff/crates/ty_python_semantic/resources
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
..
corpus Move corpus tests to ty_python_semantic (#18609) 2025-06-11 08:55:30 +02:00
mdtest [ty] Generate the top and bottom materialization of a type (#18594) 2025-06-12 12:06:16 +05:30
primer [ty] Promote projects to good that now no longer hang (#18370) 2025-06-01 17:25:46 +02:00
README.md Rename Red Knot (#17820) 2025-05-03 19:49:15 +02:00

Markdown files within the mdtest/ subdirectory are tests of type inference and type checking; executed by the tests/mdtest.rs integration test.

See crates/ty_test/README.md for documentation of this test format.