[pull] main from wasm-bindgen:main#286
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…5128) * Enforce unwind safety on #[wasm_bindgen] exports under panic=unwind Previously the macro wrapped every exported sync function body in `maybe_catch_unwind(|| { ... })`, but emitted all argument and receiver `from_abi` conversions *inside* that closure. The closure therefore only captured the raw ABI integer parameters (which are trivially UnwindSafe), so the closure-level UnwindSafe bound on `maybe_catch_unwind` was a no-op for the user's actual types — `&self` / `&mut self` methods on structs containing `Cell`, `RefCell`, `Mutex`, etc. compiled cleanly, even though a mid-method panic could leave those types in a torn state observable on the next call. Add explicit type-level assertions in the export codegen: * `&self` / `&mut self` -> `Self: RefUnwindSafe` * `&T` / `&mut T` args -> `T: RefUnwindSafe` * owned arg / `self` -> `T: UnwindSafe` These map to two no-op helpers `__rt::assert_ref_unwind_safe` / `__rt::assert_unwind_safe` which only carry the trait bound under `cfg(panic = "unwind")`. Stdlib's blanket `&mut T: !UnwindSafe` would otherwise reject every `&mut self` method unconditionally, so the asserted property is the *logical* unwind-safety (`RefUnwindSafe` on the underlying type), separate from the closure's own `UnwindSafe` bound. Users whose type is genuinely safe to observe after a caught panic can opt in with `impl RefUnwindSafe for MyType {}` or by wrapping interior- mutable fields in `std::panic::AssertUnwindSafe`. The in-tree examples that needed updating: * `SetterCompute(Rc<Cell<u32>>)` -> field wrapped in `AssertUnwindSafe` * `WasmBindgenTestContext` -> manual `impl RefUnwindSafe` (the test harness intentionally drives state through interior mutability while orchestrating panicking test execution) Includes a positive runtime test in `tests/wasm/unwind.rs` covering an exported `&mut self` method that panics mid-mutation on a `RefUnwindSafe` struct, verifying both that the panic is caught and that pre-panic mutations remain observable on subsequent calls. The negative cases are documented inline; they fail at compile time when uncommented under `panic = "unwind"`. The check is a complete no-op outside `panic = "unwind"` builds. The helpers are compile-time bounds, not runtime assertions, and 'assert' overlaps with std's catch_unwind family of *_assert_unwind_safe wrappers (which mean 'AssertUnwindSafe', i.e. the opposite). 'ensure' reads as a compile-time requirement without that ambiguity.
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