Fix class field gc

Author: dlunch

jvm/src/garbage_collector.rs

@@ -18,7 +18,11 @@ pub fn determine_garbage(
     all_class_instances: &HashSet<Box<dyn ClassInstance>>,
     classes: Vec<Box<dyn ClassInstance>>,
 ) -> Vec<Box<dyn ClassInstance>> {
-    let mut reachable_objects = classes.into_iter().collect::<HashSet<_>>();
+    let mut reachable_objects = HashSet::new();
+
+    classes.into_iter().for_each(|x| {
+        find_reachable_objects(jvm, &x, &mut reachable_objects);
+    });
 
     threads
         .iter()

jvm/tests/test_garbage_collection.rs

@@ -26,8 +26,7 @@ async fn test_garbage_collection() -> JvmResult<()> {
     let _ = jvm.resolve_class("java/util/Random").await?;
     let garbage_count = jvm.collect_garbage()?;
 
-    // temporaries used in class loading should be garbage collected
-    assert_eq!(garbage_count, 1);
+    assert_eq!(garbage_count, 0);
 
     // use loaded class
     jvm.push_native_frame();
@@ -42,7 +41,7 @@ async fn test_garbage_collection() -> JvmResult<()> {
     let garbage_count = jvm.collect_garbage()?;
 
     // temporaries used in class loading should be garbage collected
-    assert_eq!(garbage_count, 9);
+    assert_eq!(garbage_count, 6);
 
     // use loaded class
     jvm.push_native_frame();