Stream: git-wasmtime

Topic: wasmtime / issue #13308 Runtime abort when debug handler ...

Wasmtime GitHub notifications bot (May 06 2026 at 21:27):

alexcrichton opened issue #13308:

This test:

#[tokio::test]
async fn take_exception_in_debug_handler() -> wasmtime::Result<()> {
    let mut config = Config::new();
    config.wasm_exceptions(true);
    config.guest_debug(true);
    let engine = Engine::new(&config)?;
    let mut store = Store::new(&engine, ());
    store.set_debug_handler(TakeExceptionHandler);

    let module = Module::new(
        &engine,
        r#"
            (module
              (tag $t)
              (func (export "run")
                (block $h (try_table (catch_all $h) (throw $t)))
              )
            )
        "#,
    )?;
    let instance = Instance::new_async(&mut store, &module, &[]).await?;
    let run = instance.get_typed_func::<(), ()>(&mut store, "run")?;
    let err = run.call_async(&mut store, ()).await.unwrap_err();
    assert!(err.is::<wasmtime::ThrownException>());
    return Ok(());

    #[derive(Clone)]
    struct TakeExceptionHandler;

    impl DebugHandler for TakeExceptionHandler {
        type Data = ();

        fn handle(
            &self,
            mut store: StoreContextMut<'_, ()>,
            event: DebugEvent<'_>,
        ) -> impl Future<Output = ()> + Send {
            let did_take = matches!(event, DebugEvent::CaughtExceptionThrown(_));
            // Eat the pending exception that compute_handler put back.
            if did_take {
                let _ = store.take_pending_exception();
            }
            async move {}
        }
    }
}

fails with:

$ cargo test --test all take_exception_in_debug
    Finished `test` profile [unoptimized + debuginfo] target(s) in 0.12s
     Running tests/all/main.rs (target/debug/deps/all-559dd3ff47d782d6)

running 1 test

thread 'debug::take_exception_in_debug_handler' (2522963) panicked at crates/wasmtime/src/runtime/vm/traphandlers.rs:931:26:
called `Option::unwrap()` on a `None` value
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

thread 'debug::take_exception_in_debug_handler' (2522963) panicked at /rustc/59807616e1fa2540724bfbac14d7976d7e4a3860/library/core/src/panicking.rs:225:5:
panic in a function that cannot unwind
stack backtrace:
   ... (big stack trace) ...
error: test failed, to rerun pass `--test all`

Caused by:
  process didn't exit successfully: `/home/alex/code/wasmtime/target/debug/deps/all-559dd3ff47d782d6 take_exception_in_debug` (signal: 6, SIGABRT: process abort signal)

Wasmtime GitHub notifications bot (May 06 2026 at 21:27):

alexcrichton added the wasm-proposal:exceptions label to Issue #13308.

Wasmtime GitHub notifications bot (May 06 2026 at 21:27):

alexcrichton assigned alexcrichton to issue #13308.

Wasmtime GitHub notifications bot (May 07 2026 at 05:14):

alexcrichton added the wasm-proposal:gc label to Issue #13308.

Wasmtime GitHub notifications bot (May 07 2026 at 05:14):

alexcrichton removed the wasm-proposal:gc label from Issue #13308.

Wasmtime GitHub notifications bot (May 07 2026 at 22:44):

alexcrichton closed issue #13308:

This test:

#[tokio::test]
async fn take_exception_in_debug_handler() -> wasmtime::Result<()> {
    let mut config = Config::new();
    config.wasm_exceptions(true);
    config.guest_debug(true);
    let engine = Engine::new(&config)?;
    let mut store = Store::new(&engine, ());
    store.set_debug_handler(TakeExceptionHandler);

    let module = Module::new(
        &engine,
        r#"
            (module
              (tag $t)
              (func (export "run")
                (block $h (try_table (catch_all $h) (throw $t)))
              )
            )
        "#,
    )?;
    let instance = Instance::new_async(&mut store, &module, &[]).await?;
    let run = instance.get_typed_func::<(), ()>(&mut store, "run")?;
    let err = run.call_async(&mut store, ()).await.unwrap_err();
    assert!(err.is::<wasmtime::ThrownException>());
    return Ok(());

    #[derive(Clone)]
    struct TakeExceptionHandler;

    impl DebugHandler for TakeExceptionHandler {
        type Data = ();

        fn handle(
            &self,
            mut store: StoreContextMut<'_, ()>,
            event: DebugEvent<'_>,
        ) -> impl Future<Output = ()> + Send {
            let did_take = matches!(event, DebugEvent::CaughtExceptionThrown(_));
            // Eat the pending exception that compute_handler put back.
            if did_take {
                let _ = store.take_pending_exception();
            }
            async move {}
        }
    }
}

fails with:

$ cargo test --test all take_exception_in_debug
    Finished `test` profile [unoptimized + debuginfo] target(s) in 0.12s
     Running tests/all/main.rs (target/debug/deps/all-559dd3ff47d782d6)

running 1 test

thread 'debug::take_exception_in_debug_handler' (2522963) panicked at crates/wasmtime/src/runtime/vm/traphandlers.rs:931:26:
called `Option::unwrap()` on a `None` value
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

thread 'debug::take_exception_in_debug_handler' (2522963) panicked at /rustc/59807616e1fa2540724bfbac14d7976d7e4a3860/library/core/src/panicking.rs:225:5:
panic in a function that cannot unwind
stack backtrace:
   ... (big stack trace) ...
error: test failed, to rerun pass `--test all`

Caused by:
  process didn't exit successfully: `/home/alex/code/wasmtime/target/debug/deps/all-559dd3ff47d782d6 take_exception_in_debug` (signal: 6, SIGABRT: process abort signal)

Last updated: Jun 01 2026 at 09:49 UTC