ruff/crates/ruff_python_parser
Brent Westbrook b3c884f4f3
[syntax-errors] Parenthesized keyword argument names after Python 3.8 (#16482)
Summary
--

Unlike the other syntax errors detected so far, parenthesized keyword
arguments are only allowed *before* 3.8. It sounds like they were only
accidentally allowed before that [^1].

As an aside, you get a pretty confusing error from Python for this, so
it's nice that we can catch it:

```pycon
>>> def f(**kwargs): ...
... f((a)=1)
...
  File "<python-input-0>", line 2
    f((a)=1)
       ^^^
SyntaxError: expression cannot contain assignment, perhaps you meant "=="?
>>>
```
Test Plan
--
Inline tests.

[^1]: https://github.com/python/cpython/issues/78822
2025-03-06 12:18:13 -05:00
..
resources [syntax-errors] Parenthesized keyword argument names after Python 3.8 (#16482) 2025-03-06 12:18:13 -05:00
src [syntax-errors] Parenthesized keyword argument names after Python 3.8 (#16482) 2025-03-06 12:18:13 -05:00
tests [syntax-errors] Parenthesized keyword argument names after Python 3.8 (#16482) 2025-03-06 12:18:13 -05:00
Cargo.toml Allow passing ParseOptions to inline tests (#16357) 2025-02-27 10:23:15 -05:00
CONTRIBUTING.md py-fuzzer: recommend using uvx rather than uv run to run the fuzzer (#14645) 2024-11-27 22:19:52 +00:00
README.md Add basic docs for the parser crate (#11199) 2024-04-29 17:08:07 +00:00

Ruff Python Parser

Ruff's Python parser is a hand-written recursive descent parser which can parse Python source code into an Abstract Syntax Tree (AST). It also utilizes the Pratt parsing technique to parse expressions with different precedence.

Try out the parser in the playground.

Python version support

The parser supports the latest Python syntax, which is currently Python 3.12. It does not throw syntax errors if it encounters a syntax feature that is not supported by the target-version. This will be fixed in a future release (see https://github.com/astral-sh/ruff/issues/6591).

Contributing

Refer to the contributing guidelines to get started and GitHub issues with the parser label for issues that need help.