False positive: unreachable
Open
Nobody has claimed this yet.
bug
false-positive
topic-reachability
- Dominant language
- Python
- Stars
- 20.6k
- Forks
- 3.3k
- PR merge metrics
- PR metrics pending
Description
Bug Report
false positive unreachable
To Reproduce
a: object = None
def foo() -> None:
global a
a = None
bar()
if a:
print("hi")
def bar() -> None:
global a
a = 1
Expected Behavior
no error
Actual Behavior
main.py:8: error: Statement is unreachable
Found 1 error in 1 file (checked 1 source file)
(Write what happened.)
Your Environment
https://mypy-play.net/?mypy=latest&python=3.10&flags=warn-unreachable&gist=c41cd432e95c591743aa1369f36823d1
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 reproducer in the issue and run it in mypy-play with warn-unreachable enabled. Trace why the assignment performed by bar() is not considered before the if a check. Done means mypy no longer reports the demonstrated statement as unreachable while preserving the existing unreachable warning 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