From f97484365c60bc0effbe0597784a1e9707c5ffeb Mon Sep 17 00:00:00 2001
From: JohannesS <JohannesS@lucanet.com>
Date: Fri, 12 Mar 2021 15:36:35 +0100
Subject: [PATCH] JS: fix overrides with default methods

---
 .../javascript/rendering/Renderer.java        | 46 +++++++++++--------
 tests/src/test/java/org/teavm/vm/VMTest.java  | 23 +++++++++-
 2 files changed, 47 insertions(+), 22 deletions(-)

diff --git a/core/src/main/java/org/teavm/backend/javascript/rendering/Renderer.java b/core/src/main/java/org/teavm/backend/javascript/rendering/Renderer.java
index df81bd32c..f2cc4e754 100644
--- a/core/src/main/java/org/teavm/backend/javascript/rendering/Renderer.java
+++ b/core/src/main/java/org/teavm/backend/javascript/rendering/Renderer.java
@@ -22,6 +22,7 @@ import java.util.ArrayList;
 import java.util.Collection;
 import java.util.HashMap;
 import java.util.HashSet;
+import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Properties;
@@ -621,16 +622,16 @@ public class Renderer implements RenderingManager {
             }
             writer.append(',').ws();
 
-            List<MethodReference> virtualMethods = new ArrayList<>();
+            Map<MethodDescriptor, MethodReference> virtualMethods = new LinkedHashMap<>();
+            collectMethodsToCopyFromInterfaces(classSource.get(cls.getName()), virtualMethods);
             for (PreparedMethod method : cls.getMethods()) {
                 if (!method.methodHolder.getModifiers().contains(ElementModifier.STATIC)
                         && method.methodHolder.getLevel() != AccessLevel.PRIVATE) {
-                    virtualMethods.add(method.reference);
+                    virtualMethods.put(method.reference.getDescriptor(), method.reference);
                 }
             }
-            collectMethodsToCopyFromInterfaces(classSource.get(cls.getName()), virtualMethods);
 
-            renderVirtualDeclarations(virtualMethods);
+            renderVirtualDeclarations(virtualMethods.values());
             debugEmitter.emitClass(null);
         }
         writer.append("]);").newLine();
@@ -702,7 +703,7 @@ public class Renderer implements RenderingManager {
         }
     }
 
-    private void collectMethodsToCopyFromInterfaces(ClassReader cls, List<MethodReference> targetList) {
+    private void collectMethodsToCopyFromInterfaces(ClassReader cls, Map<MethodDescriptor, MethodReference> target) {
         Set<MethodDescriptor> implementedMethods = new HashSet<>();
         ClassReader superclass = cls;
         while (superclass != null) {
@@ -717,35 +718,40 @@ public class Renderer implements RenderingManager {
         }
 
         Set<String> visitedClasses = new HashSet<>();
-        for (String ifaceName : cls.getInterfaces()) {
-            ClassReader iface = classSource.get(ifaceName);
-            if (iface != null) {
-                collectMethodsToCopyFromInterfacesImpl(iface, targetList, implementedMethods, visitedClasses);
+        superclass = cls;
+        while (superclass != null) {
+            for (String ifaceName : superclass.getInterfaces()) {
+                ClassReader iface = classSource.get(ifaceName);
+                if (iface != null) {
+                    collectMethodsToCopyFromInterfacesImpl(iface, target, implementedMethods, visitedClasses);
+                }
             }
+            superclass = superclass.getParent() != null ? classSource.get(superclass.getParent()) : null;
         }
     }
 
-    private void collectMethodsToCopyFromInterfacesImpl(ClassReader cls, List<MethodReference> targetList,
-            Set<MethodDescriptor> visited, Set<String> visitedClasses) {
+    private void collectMethodsToCopyFromInterfacesImpl(ClassReader cls, Map<MethodDescriptor, MethodReference> target,
+            Set<MethodDescriptor> implementedMethods, Set<String> visitedClasses) {
         if (!visitedClasses.add(cls.getName())) {
             return;
         }
 
+        for (String ifaceName : cls.getInterfaces()) {
+            ClassReader iface = classSource.get(ifaceName);
+            if (iface != null) {
+                collectMethodsToCopyFromInterfacesImpl(iface, target, implementedMethods, visitedClasses);
+            }
+        }
+
         for (MethodReader method : cls.getMethods()) {
             if (!method.hasModifier(ElementModifier.STATIC)
                     && !method.hasModifier(ElementModifier.ABSTRACT)) {
-                if (visited.add(method.getDescriptor())) {
-                    targetList.add(method.getReference());
+                MethodDescriptor descriptor = method.getDescriptor();
+                if (!implementedMethods.contains(descriptor)) {
+                    target.put(descriptor, method.getReference());
                 }
             }
         }
-
-        for (String ifaceName : cls.getInterfaces()) {
-            ClassReader iface = classSource.get(ifaceName);
-            if (iface != null) {
-                collectMethodsToCopyFromInterfacesImpl(iface, targetList, visited, visitedClasses);
-            }
-        }
     }
 
     private static Object getDefaultValue(ValueType type) {
diff --git a/tests/src/test/java/org/teavm/vm/VMTest.java b/tests/src/test/java/org/teavm/vm/VMTest.java
index b55f287e3..b70475803 100644
--- a/tests/src/test/java/org/teavm/vm/VMTest.java
+++ b/tests/src/test/java/org/teavm/vm/VMTest.java
@@ -491,8 +491,20 @@ public class VMTest {
 
     @Test
     public void indirectDefaultMethod() {
-        PathJoint o = new PathJoint();
-        assertEquals("SecondPath.foo", o.foo());
+        StringBuilder sb = new StringBuilder();
+        for (FirstPath o : new FirstPath[] { new PathJoint(), new FirstPathOptimizationPrevention() }) {
+            sb.append(o.foo()).append(";");
+        }
+        assertEquals("SecondPath.foo;FirstPath.foo;", sb.toString());
+    }
+
+    @Test
+    public void indirectDefaultMethodSubclass() {
+        StringBuilder sb = new StringBuilder();
+        for (FirstPath o : new FirstPath[] { new PathJointSubclass(), new FirstPathOptimizationPrevention() }) {
+            sb.append(o.foo()).append(";");
+        }
+        assertEquals("SecondPath.foo;FirstPath.foo;", sb.toString());
     }
 
     interface FirstPath {
@@ -511,6 +523,13 @@ public class VMTest {
     class PathJoint implements FirstPath, SecondPath {
     }
 
+    class PathJointSubclass extends PathJoint implements FirstPath {
+    }
+
+    class FirstPathOptimizationPrevention implements FirstPath {
+        // Used to ensure that the implementation of FirstPath.foo() is not optimized away by TeaVM.
+    }
+
     @Test
     public void cloneArray() {
         String[] a = new String[] { "foo" };