In hindsight, `ruff_python` is too general. A good giveaway is that it's actually a prefix of some other crates. The intent of this crate is to reimplement pieces of the Python standard library and CPython itself, so `ruff_python_stdlib` feels appropriate.
This PR introduces a new `CacheKey` trait for types that can be used as a cache key.
I'm not entirely sure if this is worth the "overhead", but I was surprised to find `HashableHashSet` and got scared when I looked at the time complexity of the `hash` function. These implementations must be extremely slow in hashed collections.
I then searched for usages and quickly realized that only the cache uses these `Hash` implementations, where performance is less sensitive.
This PR introduces a new `CacheKey` trait to communicate the difference between a hash and computing a key for the cache. The new trait can be implemented for types that don't implement `Hash` for performance reasons, and we can define additional constraints on the implementation: For example, we'll want to enforce portability when we add remote caching support. Using a different trait further allows us not to implement it for types without stable identities (e.g. pointers) or use other implementations than the standard hash function.
Currently the quote style of the first string in a file is used for autodetecting what to use when rewriting code for fixes. This is an okay heuristic, but often the first line in a file is a docstring, rather than a string constant, and it's not uncommon for pre-Black code to have different quoting styles for those.
For example, in the Google style guide:
https://google.github.io/styleguide/pyguide.html
> Be consistent with your choice of string quote character within a file. Pick ' or " and stick with it. ... Docstrings must use """ regardless.
This branch adjusts the logic to instead skip over any `"""` triple doublequote string tokens. The default, if there are no single quoted strings, is still to use double quote as the style.
Implement PYI006 "bad version info comparison"
## What it does
Ensures that you only `<` and `>=` for version info comparisons with
`sys.version_info` in `.pyi` files. All other comparisons such as
`<`, `<=` and `==` are banned.
## Why is this bad?
```python
>>> import sys
>>> print(sys.version_info)
sys.version_info(major=3, minor=8, micro=10, releaselevel='final', serial=0)
>>> print(sys.version_info > (3, 8))
True
>>> print(sys.version_info == (3, 8))
False
>>> print(sys.version_info <= (3, 8))
False
>>> print(sys.version_info in (3, 8))
False
```
Co-authored-by: Charlie Marsh <charlie.r.marsh@gmail.com>
