python / python/mypy

`isinstance(x, CallableType) and x.is_type_object()` is a code smell

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bug refactoring topic-developer
Dominant language
Python
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Description

While fixing https://github.com/python/mypy/pull/12319 I noticed that if you grep for is_type_object, there are several instances where only CallableTypes are handled. Presumably, these all do the wrong thing for types with overloaded __new__.

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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 searching the mypy codebase for every use of is_type_object and inspect the cases that only handle CallableType. Compare those paths with types having overloaded __new__; the work is complete when the affected cases are identified and their behavior is covered by appropriate tests.

Written by the indexing model from the issue text.

Assessment

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

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