wip: JSPI awaiting JS bug

Author: vados-cosmonic

crates/js-component-bindgen/src/function_bindgen.rs

@@ -1230,13 +1230,7 @@ impl Bindgen for FunctionBindgen<'_> {
             Instruction::IterBasePointer => results.push("base".to_string()),
 
             Instruction::CallWasm { name, sig } => {
-                let get_or_create_async_state_fn = self.intrinsic(Intrinsic::Component(
-                    ComponentIntrinsic::GetOrCreateAsyncState,
-                ));
-                let current_task_get_fn =
-                    self.intrinsic(Intrinsic::AsyncTask(AsyncTaskIntrinsic::GetCurrentTask));
                 let debug_log_fn = self.intrinsic(Intrinsic::DebugLog);
-
                 uwriteln!(
                     self.src,
                     "{debug_log_fn}('{prefix} [Instruction::CallWasm] enter', {{
@@ -1251,8 +1245,6 @@ impl Bindgen for FunctionBindgen<'_> {
                     has_post_return = self.post_return.is_some(),
                 );
 
-                let component_instance_idx = self.canon_opts.instance.as_u32();
-
                 // Inject machinery for starting a 'current' task
                 self.start_current_task(
                     inst,

crates/js-component-bindgen/src/transpile_bindgen.rs

@@ -3694,8 +3694,13 @@ impl<'a> Instantiator<'a, '_> {
                 uwriteln!(self.src.js, "let {local_name};");
                 self.bindgen
                     .all_core_exported_funcs
-                    // NOTE: we need
-                    .push((core_export_fn.clone(), requires_async_porcelain || is_async));
+                    // NOTE: this breaks because using WebAssembly.promising and trying to
+                    // await JS from the host is a bug ("trying to suspend JS frames")
+                    //
+                    // We trigger this either with --async-imports *OR* by widening the check as below
+                    //
+                    // .push((core_export_fn.clone(), requires_async_porcelain || is_async));
+                    .push((core_export_fn.clone(), requires_async_porcelain));
                 local_name
             }
         };

packages/jco/test/p3/ported/wasmtime/component-async/post-return.js

@@ -87,6 +87,11 @@ suite('post-return async sleep scenario', () => {
                 transpile: {
                     extraArgs: {
                         minify: false,
+                        asyncImports: [
+                            // NOTE: without this async import specified, attempting to
+                            // sleep across JS frames will fail.
+                            'local:local/sleep#sleep-millis',
+                        ],
                     }
                 },
             });