ruff/crates/ty_python_semantic/resources/mdtest/generics
Shunsuke Shibayama 5e42926eee
[ty] improve bad specialization results & error messages (#21840)
## Summary

This PR includes the following changes:

* When attempting to specialize a non-generic type (or a type that is
already specialized), the result is `Unknown`. Also, the error message
is improved.
* When an implicit type alias is incorrectly specialized, the result is
`Unknown`. Also, the error message is improved.
* When only some of the type alias bounds and constraints are not
satisfied, not all substitutions are `Unknown`.
* Double specialization is prohibited. e.g. `G[int][int]`

Furthermore, after applying this PR, the fuzzing tests for seeds 1052
and 4419, which panic in main, now pass.
This is because the false recursions on type variables have been
removed.

```python
# name_2[0] => Unknown
class name_1[name_2: name_2[0]]:
    def name_4(name_3: name_2, /):
        if name_3:
            pass

#  (name_5 if unique_name_0 else name_1)[0] => Unknown
def name_4[name_5: (name_5 if unique_name_0 else name_1)[0], **name_1](): ...
```

## Test Plan

New corpus test
mdtest files updated
2025-12-11 19:21:34 -08:00
..
legacy [ty] improve bad specialization results & error messages (#21840) 2025-12-11 19:21:34 -08:00
pep695 [ty] improve bad specialization results & error messages (#21840) 2025-12-11 19:21:34 -08:00
builtins.md [ty] Support using legacy typing aliases for generic classes in type annotations (#18404) 2025-06-03 12:09:51 +01:00
scoping.md [ty] Create a specialization from a constraint set (#21414) 2025-11-19 14:20:33 -05:00
specialize_constrained.md [ty] Fix non-determinism in `ConstraintSet.specialize_constrained` (#21744) 2025-12-03 10:19:39 -05:00