RustPython / RustPython/Parser

Incorrect f-string parsing

Open
#88 1 comment 4 reactions 0 assignees View on GitHub

Nobody has claimed this yet.

bug
Dominant language
Rust
Stars
117
Forks
38
Avg merge
4d 7h
Merged PRs (30d)
1

Description

Originally reported as https://github.com/astral-sh/ruff/issues/5044:

Not the best string ever, but ruff doesn't handle it like Python

λ cat test.py
print(f"$N_{{img}}\in\{{0,1,2\}}$")
λ python test.py
$N_{img}\in\{0,1,2\}$
λ ruff check test.py --select F401
error: Failed to parse test.py:1:25: f-string: unterminated string

Contributor guide

No contributing guide indexed for this repository

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Reproduce the report with the provided test.py contents and compare Python's output with ruff check test.py --select F401. Trace how this f-string is parsed and ensure the parser accepts the escaped braces and backslashes instead of reporting an unterminated string. Done means the example parses without the reported error and matches Python's behavior.

Written by the indexing model from the issue text.

Assessment

Tech stack
python, rust
Domain
compilers
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

Get new issues in your inbox

A short digest of beginner-friendly GitHub issues.