gpui(linux): Fix RefCell borrow panic when callbacks register new callbacks#49533
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ConradIrwin merged 2 commits intozed-industries:mainfrom Feb 25, 2026
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mikayla-maki
approved these changes
Feb 18, 2026
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while I think this is a correct change, there’s a deeper problem here that every workspace is rebinding a window-level event. This should be hoisted up to the multiworkspace. |
…lbacks
On Linux (Wayland and X11), callbacks were invoked while the Callbacks
RefCell was still borrowed. If a callback tried to register a new
callback (e.g., on_window_should_close during workspace creation), it
would panic with "already borrowed".
The bug pattern was:
```rust
if let Some(ref mut fun) = self.callbacks.borrow_mut().input {
fun(input); // Panics if fun() tries to borrow_mut() callbacks
}
```
Fix by using take-call-restore pattern (matching macOS implementation):
```rust
let callback = self.callbacks.borrow_mut().input.take();
if let Some(mut fun) = callback {
let result = fun(input);
self.callbacks.borrow_mut().input = Some(fun);
}
```
Fixed locations:
- Wayland: handle_toplevel_decoration_event (2x), set_size_and_scale,
handle_input, set_focused, set_hovered, set_appearance
- X11: refresh, handle_input, set_active, set_hovered, set_appearance
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
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…lbacks (zed-industries#49533) ## Summary Fixes RefCell borrow panic on Linux (Wayland and X11) when callbacks try to register new callbacks. **Root cause:** Linux GPUI backends invoked callbacks while still holding a `RefCell` borrow on the `Callbacks` struct. If a callback tried to register a new callback (e.g., `on_window_should_close`), it would panic with "already borrowed: BorrowMutError". **Bug pattern:** ```rust // Callback runs while borrow is held - panics if callback borrows callbacks if let Some(ref mut fun) = self.callbacks.borrow_mut().input { fun(input); } Fix: Apply the take-call-restore pattern (already used in macOS backend): // Take callback out, release borrow, call, restore let callback = self.callbacks.borrow_mut().input.take(); if let Some(mut fun) = callback { let result = fun(input); self.callbacks.borrow_mut().input = Some(fun); } Changes - Wayland (window.rs): Fixed 6 callback invocations - X11 (window.rs): Fixed 4 callback invocations Test plan - cargo check -p gpui compiles successfully - Tested on Linux (Wayland) - no more RefCell panic Release Notes: - Fixed a crash on Linux when window callbacks attempted to register new callbacks Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>
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Summary
Fixes RefCell borrow panic on Linux (Wayland and X11) when callbacks try to register new callbacks.
Root cause: Linux GPUI backends invoked callbacks while still holding a
RefCellborrow on theCallbacksstruct. If a callback tried to register a newcallback (e.g.,
on_window_should_close), it would panic with "already borrowed: BorrowMutError".Bug pattern: