fix(async): potential UB in the scheduler implementation #177
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The way we accessed UnsafeCell in the posted event handler was oddly similar to the bad example in the reference[1]. It's not an exact match since we don't have a _shared_ reference to the cell, but I'd still prefer to use the documented way to access the underlying data. [1]: https://doc.rust-lang.org/stable/std/cell/struct.UnsafeCell.html#memory-layout
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Pull Request Overview
This PR fixes a potential undefined behavior (UB) issue in the async scheduler implementation by correcting how UnsafeCell is accessed. The change ensures compliance with Rust's documented safe patterns for UnsafeCell usage, moving away from a pattern that resembled problematic examples in the official documentation.
- Updates the
Schedulerstruct to wrapSchedulerInnerinUnsafeCellat construction time - Modifies the event handler to use the documented
UnsafeCell::raw_get()method for safe access - Improves safety documentation with clearer explanation and reference to official guidelines
ensh63
approved these changes
Jul 21, 2025
xeioex
approved these changes
Jul 22, 2025
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The way we accessed UnsafeCell in the posted event handler was oddly similar to the bad example in the reference1.
It's not an exact match since we don't have a shared reference to the cell, but I'd still prefer to use the documented way to access the underlying data.