Improved traps

# Conflicts:
#	lib/js-api/tests/instance.rs

lib/js-api/src/trap.rs

@@ -10,10 +10,16 @@ use wasm_bindgen::JsValue;
 /// indicating the cause.
 #[wasm_bindgen]
 #[derive(Clone)]
-pub struct RuntimeError {
+pub struct WasmerRuntimeError {
     inner: Arc<RuntimeErrorSource>,
 }
 
+/// This type is the same as `WasmerRuntimeError`.
+///
+/// We use the `WasmerRuntimeError` name to not collide with the
+/// `RuntimeError` in JS.
+pub type RuntimeError = WasmerRuntimeError;
+
 impl PartialEq for RuntimeError {
     fn eq(&self, other: &Self) -> bool {
         Arc::ptr_eq(&self.inner, &other.inner)
@@ -56,6 +62,13 @@ impl RuntimeError {
         }
     }
 
+    /// Creates a new user `RuntimeError` with the given `error`.
+    pub fn user(error: impl Error + 'static) -> Self {
+        RuntimeError {
+            inner: Arc::new(RuntimeErrorSource::User(Box::new(error))),
+        }
+    }
+
     /// Raises a custom user Error
     pub fn raise(error: Box<dyn Error + Send + Sync>) -> ! {
         let error = if error.is::<RuntimeError>() {
@@ -127,9 +140,16 @@ pub fn generic_of_jsval<T: FromWasmAbi<Abi = u32>>(
     let ctor_name = Object::get_prototype_of(&js).constructor().name();
     if ctor_name == classname {
         let ptr = Reflect::get(&js, &JsValue::from_str("ptr"))?;
-        let ptr_u32: u32 = ptr.as_f64().ok_or(JsValue::NULL)? as u32;
-        let foo = unsafe { T::from_abi(ptr_u32) };
+        match ptr.as_f64() {
+            Some(ptr_f64) => {
+                let foo = unsafe { T::from_abi(ptr_f64 as u32) };
                 Ok(foo)
+            }
+            None => {
+                // We simply relay the js value
+                Err(js)
+            }
+        }
     } else {
         Err(js)
     }

lib/js-api/tests/instance.rs

@@ -586,6 +586,49 @@ fn test_native_function() {
     assert_eq!(add_one.call(1), Ok(2));
 }
 
+#[wasm_bindgen_test]
+fn test_panic() {
+    let store = Store::default();
+    let module = Module::new(
+        &store,
+        br#"
+(module
+  (type $run_t (func (param i32 i32) (result i32)))
+  (type $early_exit_t (func (param) (result)))
+  (import "env" "early_exit" (func $early_exit (type $early_exit_t)))
+  (func $run (type $run_t) (param $x i32) (param $y i32) (result i32)
+    (call $early_exit)
+    (i32.add
+        local.get $x
+        local.get $y))
+  (export "run" (func $run)))
+"#,
+    )
+    .unwrap();
+
+    fn early_exit() {
+        panic!("Do panic")
+    }
+
+    let import_object = imports! {
+        "env" => {
+            "early_exit" => Function::new_native(&store, early_exit),
+        }
+    };
+    let instance = Instance::new(&module, &import_object).unwrap();
+
+    let run_func: NativeFunc<(i32, i32), i32> =
+        instance.exports.get_native_function("run").unwrap();
+
+    assert!(run_func.call(1, 7).is_err(), "Expected early termination",);
+    let run_func = instance.exports.get_function("run").unwrap();
+
+    assert!(
+        run_func.call(&[Val::I32(1), Val::I32(7)]).is_err(),
+        "Expected early termination",
+    );
+}
+
 #[wasm_bindgen_test]
 fn test_custom_error() {
     let store = Store::default();
@@ -630,14 +673,12 @@ fn test_custom_error() {
     };
     let instance = Instance::new(&module, &import_object).unwrap();
 
-    let run_func: NativeFunc<(i32, i32), i32> =
-        instance.exports.get_native_function("run").unwrap();
-
-    match run_func.call(1, 7) {
+    fn test_result<T: core::fmt::Debug>(result: Result<T, RuntimeError>) {
+        match result {
             Ok(result) => {
                 assert!(
                     false,
-                "Expected early termination with `ExitCode`, found: {}",
+                    "Expected early termination with `ExitCode`, found: {:?}",
                     result
                 );
             }
@@ -653,4 +694,12 @@ fn test_custom_error() {
                 }
             }
         }
+    }
+
+    let run_func: NativeFunc<(i32, i32), i32> =
+        instance.exports.get_native_function("run").unwrap();
+    test_result(run_func.call(1, 7));
+
+    let run_func = instance.exports.get_function("run").unwrap();
+    test_result(run_func.call(&[Val::I32(1), Val::I32(7)]));
 }