Confusing error: incompatible type "Type[bytes]"; expected "Type[bytes]"
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- Python
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Description
Bug Report
Error message seems to indicate it requires the type it is getting. I could be reading the error message wrong, but this one confuses me.
To Reproduce
- put the code in a file e.g. scratchpad.py
from typing import Type def f(class_type: Type[object]): if class_type in [bytes, bytearray]: return True - run
mypy scratchpad.py
Expected Behavior
no errors
Actual Behavior
scratchpad.py:4: error: List item 0 has incompatible type "Type[bytes]"; expected "Type[bytes]"
Your Environment
- Mypy version used: 0.790
- Mypy command-line flags: n/a
- Mypy configuration options from
mypy.ini(and other config files): n/a - Python version used: 3.8.3
- Operating system and version: OSX 10.15.7
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 running mypy on the issue's scratchpad.py example and confirm the contradictory Type[bytes] diagnostic. Trace the type-checking path involved in the list membership expression; done means the valid example reports no error, as described under Expected Behavior.
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
- Mostly clear
- Newbie friendliness
- 35/100