[ty] Report redefined legacy TypeVars#25854
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Typing conformance resultsNo changes detected ✅Current numbersThe percentage of diagnostics emitted that were expected errors held steady at 94.36%. The percentage of expected errors that received a diagnostic held steady at 88.82%. The number of fully passing files held steady at 93/134. |
Memory usage reportMemory usage unchanged ✅ |
|
| Lint rule | Added | Removed | Changed |
|---|---|---|---|
invalid-legacy-type-variable |
1 | 0 | 0 |
| Total | 1 | 0 | 0 |
Raw diff:
setuptools (https://github.com/pypa/setuptools)
+ setuptools/_vendor/jaraco/functools/__init__.py:677:1 error[invalid-legacy-type-variable] Cannot redefine `_T` as a type variable65778d4 to
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charliermarsh
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## Summary
An mdtest section is evaluated as a single Python module, even when its
examples are split across multiple fenced code blocks. Some existing
sections therefore define the same legacy `TypeVar` name more than once:
```python
T = TypeVar("T")
# ...
T = TypeVar("T")
```
#25854 will correctly diagnose the second definition, but these
duplicates are incidental to the tests. This separates self-contained
examples into distinct mdtest sections and gives the remaining type
variables distinct names where the examples depend on shared setup. The
expected types and diagnostics are unchanged.
This is the preparatory base for #25854 and doesn't change behavior.
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charlie/avoid-typevar-redefinitions-in-mdtests
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Summary
The
invalid-legacy-type-variablerule already validates the assignment shape and declared name, but it did not report when a name had already been defined in the same scope:The diagnostic points back to the preceding definition and considers earlier bindings and declarations that are reachable from the beginning of the owning scope.
The implementation reuses the existing per-place use-def snapshot and reachability predicates, so it only inspects definitions of the target name rather than scanning every definition in the scope.
Closes astral-sh/ty#3732.