Get rid of make_simplified_union() except in error messages
Nobody has claimed this yet.
- Dominant language
- Python
- Stars
- 20.6k
- Forks
- 3.3k
- PR merge metrics
- PR metrics pending
Description
It used to cause various issues and is still causing known bugs (like false negatives in per-file strict optional when map_instance_to_supertype() is involved). Ideally we should replace all calls to it (except in error message formatting code) with UnionType.make_union(). Union constructor already flattens nested unions, we can also make it remove exact duplicates minimize perf impact.
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 searching the mypy repository for calls to make_simplified_union() and separate error-message formatting from type construction. Read UnionType.make_union() and the existing Union constructor behavior, then verify that non-formatting calls use the replacement and run the relevant test suite.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- python
- Domain
- compilers
- Issue type
- Refactor
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100