facebook / facebook/pyrefly

show warning when function returning `Not[Never]` contains a `Never` loop

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#1,132 0 comments 0 reactions 1 assignee Claimed by @asukaminato0721 View on GitHub
scoping-control-flow typechecking
Dominant language
Rust
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Description

### Describe the Bug

```py
def f() -> int:
while True:
pass
```

while being valid within the type system, this code is clearly a mistake, i would expect a warning to be displayed

### Sandbox Link

_No response_

### (Only applicable for extension issues) IDE Information

_No response_

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