fix(moonbit): clean up async metadata and tests

Author: peter-jerry-ye

crates/moonbit/src/async_support.rs

@@ -82,8 +82,12 @@ impl AsyncSupport {
         self.is_async = true;
     }
 
+    pub(crate) fn uses_runtime(&self) -> bool {
+        self.is_async || !self.futures.is_empty()
+    }
+
     pub(crate) fn emit_utils(&self, files: &mut Files) {
-        if !self.is_async && self.futures.is_empty() {
+        if !self.uses_runtime() {
             return;
         }
 

crates/moonbit/src/lib.rs

@@ -155,6 +155,9 @@ impl MoonBit {
     fn write_moon_pkg(&self, moon_pkg: &mut Source, imports: Option<&Imports>, link: bool) {
         // Disable warning for invalid inline wasm
         moon_pkg.push_str("{\n\"warn-list\": \"-44\"");
+        if self.async_support.uses_runtime() {
+            moon_pkg.push_str(",\n\"supported-targets\": \"+wasm\"");
+        }
         // Dependencies
         if let Some(imports) = imports {
             moon_pkg.push_str(",\n\"import\": [\n");