PyCQA / PyCQA/pycodestyle

Spurious E231 for nested format substitutions

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Python
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Description

For

x = 1
digits = 1
print(f"{x:0.{digits:d}f}")  # admittedly the :d is not needed in this minimal repro, but still valid.

pycodestyle 2.11.1 spuriously complains about a missing whitespace after the second colon in the f-string:

test.py:3:21: E231 missing whitespace after ':'

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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

Start by running pycodestyle 2.11.1 on the Python snippet in the issue and trace the E231 path that handles colons in f-string substitutions. Done means this valid nested format expression no longer reports E231, with a regression check covering the example.

Written by the indexing model from the issue text.

Assessment

Tech stack
python
Domain
tooling
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Active
Clarity
Mostly clear
Newbie friendliness
68/100

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