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## Summary
And more custom logic around comments in bodies... uff.
Let's say we have the following code
```python
if x == y:
pass # trailing comment of pass
else: # trailing comment of `else`
print("I have no comments")
```
Right now, the formatter attaches the `# trailing comment of `else` as a trailing comment of `pass` because it doesn't "see" that there's an `else` keyword in between (because the else body is just a Vec and not a node).
This PR adds custom logic that attaches the trailing comments after the `else` as dangling comments to the `if` statement. The if statement must then split the dangling comments by `comments.text_position()`:
* All comments up to the first end-of-line comment are leading comments of the `else` keyword.
* All end-of-line comments coming after are `trailing` comments for the `else` keyword.
## Test Plan
I added new unit tests.
### Summary
This PR adds custom logic to handle end-of-line comments of the last statement in a body.
For example:
```python
while True:
if something.changed:
do.stuff() # trailing comment
b
```
The `# trailing comment` is a trailing comment of the `do.stuff()` expression statement. We incorrectly attached the comment as a trailing comment of the enclosing `while` statement because the comment is between the end of the while statement (the `while` statement ends right after `do.stuff()`) and before the `b` statement.
This PR fixes the placement to correctly attach these comments to the last statement in a body (recursively).
## Test Plan
I reviewed the snapshots and they now look correct. This may appear odd because a lot comments have now disappeared. This is the expected result because we use `verbatim` formatting for the block statements (like `while`) and that means that it only formats the inner content of the block, but not any trailing comments. The comments were visible before, because they were associated with the block statement (e.g. `while`).
* Add Format for Stmt
* Implement basic module formatting
This implements formatting each statement in a module with a hard line break in between, so that we can start formatting statements.
Basic testing is done by the snapshots
* Use dummy verbatim formatter for all nodes
* Use new formatter infrastructure in CLI and test
* Expose the new formatter in the CLI
* Merge import blocks
# Summary
We need to support CR line endings (as opposed to LF and CRLF line endings, which are already supported). They're rare, but they do appear in Python code, and we tend to panic on any file that uses them.
Our `Locator` abstraction now supports CR line endings. However, Rust's `str#lines` implementation does _not_.
This PR adds a `UniversalNewlineIterator` implementation that respects all of CR, LF, and CRLF line endings, and plugs it into most of the `.lines()` call sites.
As an alternative design, it could be nice if we could leverage `Locator` for this. We've already computed all of the line endings, so we could probably iterate much more efficiently?
# Test Plan
Largely relying on automated testing, however, also ran over some known failure cases, like #3404.
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.
