core: fix generic types for local variables

jadx-core/src/main/java/jadx/core/dex/visitors/typeresolver/finish/PostTypeResolver.java

@@ -7,6 +7,7 @@ import jadx.core.dex.instructions.args.ArgType;
 import jadx.core.dex.instructions.args.InsnArg;
 import jadx.core.dex.instructions.args.LiteralArg;
 import jadx.core.dex.instructions.args.RegisterArg;
+import jadx.core.dex.instructions.args.TypedVar;
 import jadx.core.dex.nodes.InsnNode;
 import jadx.core.dex.nodes.MethodNode;
 
@@ -88,8 +89,13 @@ public class PostTypeResolver {
 
 			case CHECK_CAST: {
 				ArgType castType = (ArgType) ((IndexInsnNode) insn).getIndex();
-				// workaround for compiler bug (see TestDuplicateCast)
-				insn.getResult().getTypedVar().forceSetType(castType);
+				TypedVar typedVar = insn.getResult().getTypedVar();
+				// don't override generic types of same base class
+				boolean skip = castType.isObject() && castType.getObject().equals(typedVar.getType().getObject());
+				if (!skip) {
+					// workaround for compiler bug (see TestDuplicateCast)
+					typedVar.forceSetType(castType);
+				}
 				return true;
 			}
 

jadx-core/src/test/java/jadx/tests/internal/generics/TestGenerics2.java

+package jadx.tests.internal.generics;
+
+import jadx.api.InternalJadxTest;
+import jadx.core.dex.nodes.ClassNode;
+
+import java.lang.ref.ReferenceQueue;
+import java.lang.ref.WeakReference;
+import java.util.Map;
+
+import org.junit.Test;
+
+import static org.hamcrest.CoreMatchers.containsString;
+import static org.junit.Assert.assertThat;
+
+public class TestGenerics2 extends InternalJadxTest {
+
+	public static class TestCls {
+		private static class ItemReference<V> extends WeakReference<V> {
+			private Object id;
+
+			public ItemReference(V item, Object id, ReferenceQueue<? super V> queue) {
+				super(item, queue);
+				this.id = id;
+			}
+		}
+
+		public static class ItemReferences<V> {
+			private Map<Object, ItemReference<V>> items;
+
+			public V get(Object id) {
+				WeakReference<V> ref = this.items.get(id);
+				return (ref != null) ? ref.get() : null;
+			}
+		}
+	}
+
+	@Test
+	public void test() {
+		ClassNode cls = getClassNode(TestCls.class);
+		String code = cls.getCode().toString();
+		System.out.println(code);
+
+		assertThat(code, containsString("public ItemReference(V item, Object id, ReferenceQueue<? super V> queue) {"));
+		assertThat(code, containsString("public V get(Object id) {"));
+		assertThat(code, containsString("WeakReference<V> ref = "));
+		assertThat(code, containsString("return (ref != null) ? ref.get() : null;"));
+	}
+}