Request: opt-in rule preventing duplicate error codes
Open
Nobody has claimed this yet.
feature
priority-2-low
topic-type-ignore
- Dominant language
- Python
- Stars
- 20.6k
- Forks
- 3.3k
- PR merge metrics
- PR metrics pending
Description
Feature
If one specifies an error code twice, mypy allows it:
foo = 1
foo = "hi" # type: ignore[assignment,assignment]
Pitch
Can we add an opt-in rule to have mypy disallow duplicate error codes?
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by tracing how mypy parses type: ignore[assignment,assignment] and how optional diagnostic rules are configured. Define the duplicate-code behavior and its opt-in configuration, then add coverage showing that repeated error codes are rejected only when the rule is enabled.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- python
- Domain
- devtools
- Issue type
- Feature
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100