mypy doesn't detect use before declaration when on the same line and there is a function call
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bug
- Dominant language
- Python
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Description
Bug Report
mypy doesn't detect use before declaration when:
- the use is on the same line as the declaration.
- there is a function call around the used-before-declaration variable
To Reproduce
https://mypy-play.net/?mypy=latest&python=3.11&gist=0d661a8817115f77bed9a655fe21fba1
Expected Behavior
A "Name "i" is not defined" error is raised - since the code fails at runtime.
Actual Behavior
No errors reported
Note:
- replacing
int(...)with a different function (e.g., a user-defined one) also produces the bug as long as the argument of the function isint. - Removing the function call (
i: int = i) makes mypy properly produce the error "Name "i" is not defined".
Your Environment
- Mypy version used: 1.4.1
- Mypy command-line flags: none
- Mypy configuration options from
mypy.ini(and other config files): none - Python version used: Python 3.10.6
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 with the linked mypy-play reproduction and compare the same-line annotated assignment with and without the function call. Trace how mypy analyzes the annotation and initializer, then add a regression test covering the reported case and verify that it emits a "Name "i" is not defined" error.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- python
- Domain
- devtools
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100