Fix OwnedRooted<T>::wasm_ty_store missing i31ref check (#12451)

Author: zzjas

crates/wasmtime/src/runtime/gc/enabled/rooting.rs

@@ -1827,7 +1827,15 @@ where
         val_raw: impl Fn(u32) -> ValRaw,
     ) -> Result<()> {
         let gc_ref = self.try_clone_gc_ref(store)?;
-        let raw = store.require_gc_store_mut()?.expose_gc_ref_to_wasm(gc_ref);
+
+        let raw = match store.optional_gc_store_mut() {
+            Some(s) => s.expose_gc_ref_to_wasm(gc_ref),
+            None => {
+                debug_assert!(gc_ref.is_i31());
+                gc_ref.as_raw_non_zero_u32()
+            }
+        };
+
         ptr.write(val_raw(raw.get()));
         Ok(())
     }

tests/all/i31ref.rs

@@ -40,3 +40,41 @@ fn i31ref_to_raw_round_trip() -> Result<()> {
 
     Ok(())
 }
+
+#[test]
+#[cfg_attr(miri, ignore)]
+fn owned_rooted_i31ref_through_typed_wasm_func() -> Result<()> {
+    // OwnedRooted<AnyRef>::wasm_ty_store should handle i31ref values without
+    // requiring a GC heap to be allocated.
+
+    let mut config = Config::new();
+    config.wasm_function_references(true);
+    config.wasm_gc(true);
+
+    let engine = Engine::new(&config)?;
+    let mut store = Store::new(&engine, ());
+
+    let module = Module::new(
+        &engine,
+        r#"(module (func (export "f") (param (ref null any)) (result (ref null any)) local.get 0))"#,
+    )?;
+    let instance = Instance::new(&mut store, &module, &[])?;
+    let f = instance.get_typed_func::<Option<OwnedRooted<AnyRef>>, Option<OwnedRooted<AnyRef>>>(
+        &mut store, "f",
+    )?;
+
+    // No GC heap objects created; the store has no GcStore allocated yet.
+    let anyref = AnyRef::from_i31(&mut store, I31::wrapping_u32(42));
+    let owned = anyref.to_owned_rooted(&mut store)?;
+    let result = f.call(&mut store, Some(owned))?.unwrap();
+    assert_eq!(
+        result
+            .to_rooted(&mut store)
+            .as_i31(&store)?
+            .unwrap()
+            .get_u32(),
+        42
+    );
+
+    Ok(())
+}