Summary

Fixes #5003.

Python applies NFKC normalization to identifiers that use unicode characters. That means that F821 should not be emitted if ruff encounters the following snippet (but on main, it is), as from Python's perspective, these are all the same identifier:

𝒞 = 500
print(𝒞)
print(C + 𝒞)  # ruff says `C` isn't defined
print(C / 𝒞)
print(C == 𝑪 == 𝒞 == 𝓒 == 𝕮)  # ruff says `C`, `𝑪`, ... isn't defined

I fixed this false positive by changing the bindings field in ruff_python_semantic/scope.rs so that identifiers are always unicode-normalized according to NFKC before being stored in the hashmap. An alternative approach I played around with was to unicode-normalize identifiers in the AST itself. However, this would have had undesirable consequences: the formatter would have started eagerly normalizing unicode characters in identifiers when it reformatted a Python file.

Test Plan

cargo test