ruff/crates/ruff_python_parser
Brent Westbrook 24b1b1d52c
[syntax-errors] Duplicate attributes in match class pattern (#17186)
Summary
--

Detects duplicate attributes in a `match` class pattern:

```python
match x:
    case Class(x=1, x=2): ...
```

which are more analogous to the similar check for mapping patterns than
to the
multiple assignments rule.

I also realized that both this and the mapping check would only work on
top-level patterns, despite the possibility that they can be nested
inside other
patterns:

```python
match x:
    case [{"x": 1, "x": 2}]: ...  # false negative in the old version
```

and moved these checks into the recursive pattern visitor instead.

I also tidied up some of the names like the `multiple_case_assignment`
function
and the `MultipleCaseAssignmentVisitor`, which are now doing more than
checking
for multiple assignments.

Test Plan
--

New inline tests for both classes and mappings.
2025-04-03 17:55:37 -04:00
..
resources [syntax-errors] Duplicate attributes in match class pattern (#17186) 2025-04-03 17:55:37 -04:00
src [syntax-errors] Duplicate attributes in match class pattern (#17186) 2025-04-03 17:55:37 -04:00
tests [syntax-errors] Duplicate attributes in match class pattern (#17186) 2025-04-03 17:55:37 -04:00
Cargo.toml Allow passing ParseOptions to inline tests (#16357) 2025-02-27 10:23:15 -05:00
CONTRIBUTING.md Update pre-commit dependencies (#17073) 2025-03-31 07:42:15 +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.