mirrors/ruff
1
0
Fork 0
mirror of https://github.com/astral-sh/ruff.git synced 2025-07-12 15:45:07 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions 3
ruff/crates/ruff_python_formatter
History
Exact
Brent Westbrook dcf31c9348
[syntax-errors] PEP 701 f-strings before Python 3.12 (#16543) 
## Summary

This PR detects the use of PEP 701 f-strings before 3.12. This one
sounded difficult and ended up being pretty easy, so I think there's a
good chance I've over-simplified things. However, from experimenting in
the Python REPL and checking with [pyright], I think this is correct.
pyright actually doesn't even flag the comment case, but Python does.

I also checked pyright's implementation for
[quotes](98dc4469cc/packages/pyright-internal/src/analyzer/checker.ts (L1379-L1398))
and
[escapes](98dc4469cc/packages/pyright-internal/src/analyzer/checker.ts (L1365-L1377))
and think I've approximated how they do it.

Python's error messages also point to the simple approach of these
characters simply not being allowed:

```pycon
Python 3.11.11 (main, Feb 12 2025, 14:51:05) [Clang 19.1.6 ] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> f'''multiline {
... expression # comment
... }'''
  File "<stdin>", line 3
    }'''
        ^
SyntaxError: f-string expression part cannot include '#'
>>> f'''{not a line \
... continuation}'''
  File "<stdin>", line 2
    continuation}'''
                    ^
SyntaxError: f-string expression part cannot include a backslash
>>> f'hello {'world'}'
  File "<stdin>", line 1
    f'hello {'world'}'
              ^^^^^
SyntaxError: f-string: expecting '}'
```

And since escapes aren't allowed, I don't think there are any tricky
cases where nested quotes or comments can sneak in.

It's also slightly annoying that the error is repeated for every nested
quote character, but that also mirrors pyright, although they highlight
the whole nested string, which is a little nicer. However, their check
is in the analysis phase, so I don't think we have such easy access to
the quoted range, at least without adding another mini visitor.

## Test Plan

New inline tests

[pyright]:
https://pyright-play.net/?pythonVersion=3.11&strict=true&code=EYQw5gBAvBAmCWBjALgCgO4gHaygRgEoAoEaCAIgBpyiiBiCLAUwGdknYIBHAVwHt2LIgDMA5AFlwSCJhwAuCAG8IoMAG1Rs2KIC6EAL6iIxosbPmLlq5foRWiEAAcmERAAsQAJxAomnltY2wuSKogA6WKIAdABWfPBYqCAE%2BuSBVqbpWVm2iHwAtvlMWMgB2ekiolUAgq4FjgA2TAAeEMieSADWCsoV5qoaqrrGDJ5MiDz%2B8ABuLqosAIREhlXlaybrmyYMXsDw7V4AnoysyAmQ5SIhwYo3d9cheADUeKlv5O%2BpQA
2025-03-18 11:12:15 -04:00
..
resources/test/fixtures [syntax-errors] PEP 701 f-strings before Python 3.12 (#16543) 2025-03-18 11:12:15 -04:00
src [formatter] Stabilize fix for single-with-item formatting with trailing comment (#16603) 2025-03-13 15:37:37 +01:00
tests [formatter] Stabilize fix for single-with-item formatting with trailing comment (#16603) 2025-03-13 15:37:37 +01:00
Cargo.toml Bump MSRV to Rust 1.80 (#13826) 2024-10-20 10:55:36 +02:00
CONTRIBUTING.md Update pre-commit dependencies (#14719) 2024-12-02 06:02:56 +00:00
generate.py Standardise ruff config (#15558) 2025-01-21 12:09:11 +01:00
orphan_rules_in_the_formatter.svg Generate FormatRule definitions (#4724) 2023-06-01 08:38:53 +02:00
README.md Add f-string formatting to the docs (#15367) 2025-01-09 10:20:06 +01:00

README.md

Ruff Formatter

The Ruff formatter is an extremely fast Python code formatter that ships as part of the ruff CLI.

Goals

The formatter is designed to be a drop-in replacement for Black, but with an excessive focus on performance and direct integration with Ruff.

Specifically, the formatter is intended to emit near-identical output when run over Black-formatted code. When run over extensive Black-formatted projects like Django and Zulip, > 99.9% of lines are formatted identically. When migrating an existing project from Black to Ruff, you should expect to see a few differences on the margins, but the vast majority of your code should be unchanged.

If you identify deviations in your project, spot-check them against the intentional deviations enumerated below, as well as the unintentional deviations filed in the issue tracker. If you've identified a new deviation, please file an issue.

When run over non-Black-formatted code, the formatter makes some different decisions than Black, and so more deviations should be expected, especially around the treatment of end-of-line comments. For details, see Style Guide.

Getting started

Head to The Ruff Formatter for usage instructions and a comparison to Black.