Fix copying of non-abstract functions of interfaces in JS BE

Fix copying of non-abstract functions of interfaces to implementing
classes when implementing class inherits interface via 2+ paths.

See KT-18187

compiler/testData/codegen/box/traits/interfaceWithNonAbstractFunIndirect.kt

@@ -0,0 +1,29 @@
+interface I {
+    fun foo(): String = "foo"
+
+    fun bar(x: String = "default") = "bar:$x"
+}
+
+interface J : I
+
+interface K : J
+
+class A : I, J
+
+class B : K, I
+
+fun box(): String {
+    val foo = A().foo()
+    if (foo != "foo") return "fail1: $foo"
+
+    val bar1 = A().bar()
+    if (bar1 != "bar:default") return "fail2: $bar1"
+
+    val bar2 = A().bar("q")
+    if (bar2 != "bar:q") return "fail3: $bar1"
+
+    val foo2 = B().foo()
+    if (foo2 != "foo") return "fail4: $foo2"
+
+    return "OK"
+}

compiler/testData/codegen/box/traits/kt3500.kt

@@ -1,6 +1,3 @@
-// TODO: muted automatically, investigate should it be ran for JS or not
-// IGNORE_BACKEND: JS
-
 interface BK {
     fun foo(): String = 10.toString()
 }

compiler/tests-ir-jvm/tests/org/jetbrains/kotlin/codegen/ir/IrBlackBoxCodegenTestGenerated.java

@@ -18044,6 +18044,12 @@ public class IrBlackBoxCodegenTestGenerated extends AbstractIrBlackBoxCodegenTes
             doTest(fileName);
         }
 
+        @TestMetadata("interfaceWithNonAbstractFunIndirect.kt")
+        public void testInterfaceWithNonAbstractFunIndirect() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/traits/interfaceWithNonAbstractFunIndirect.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("kt1936.kt")
         public void testKt1936() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/traits/kt1936.kt");

compiler/tests/org/jetbrains/kotlin/codegen/BlackBoxCodegenTestGenerated.java

@@ -18044,6 +18044,12 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
             doTest(fileName);
         }
 
+        @TestMetadata("interfaceWithNonAbstractFunIndirect.kt")
+        public void testInterfaceWithNonAbstractFunIndirect() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/traits/interfaceWithNonAbstractFunIndirect.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("kt1936.kt")
         public void testKt1936() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/traits/kt1936.kt");

compiler/tests/org/jetbrains/kotlin/codegen/LightAnalysisModeTestGenerated.java

@@ -18044,6 +18044,12 @@ public class LightAnalysisModeTestGenerated extends AbstractLightAnalysisModeTes
             doTest(fileName);
         }
 
+        @TestMetadata("interfaceWithNonAbstractFunIndirect.kt")
+        public void testInterfaceWithNonAbstractFunIndirect() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/traits/interfaceWithNonAbstractFunIndirect.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("kt1936.kt")
         public void testKt1936() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/traits/kt1936.kt");

js/js.tests/test/org/jetbrains/kotlin/js/test/semantics/JsCodegenBoxTestGenerated.java

@@ -22148,6 +22148,12 @@ public class JsCodegenBoxTestGenerated extends AbstractJsCodegenBoxTest {
             throw new AssertionError("Looks like this test can be unmuted. Remove IGNORE_BACKEND directive for that.");
         }
 
+        @TestMetadata("interfaceWithNonAbstractFunIndirect.kt")
+        public void testInterfaceWithNonAbstractFunIndirect() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/traits/interfaceWithNonAbstractFunIndirect.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("kt1936.kt")
         public void testKt1936() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/traits/kt1936.kt");
@@ -22193,13 +22199,7 @@ public class JsCodegenBoxTestGenerated extends AbstractJsCodegenBoxTest {
         @TestMetadata("kt3500.kt")
         public void testKt3500() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/traits/kt3500.kt");
-            try {
-                doTest(fileName);
-            }
-            catch (Throwable ignore) {
-                return;
-            }
-            throw new AssertionError("Looks like this test can be unmuted. Remove IGNORE_BACKEND directive for that.");
+            doTest(fileName);
         }
 
         @TestMetadata("kt3579.kt")

js/js.translator/src/org/jetbrains/kotlin/js/translate/declaration/ClassModelGenerator.kt

@@ -156,7 +156,7 @@ class ClassModelGenerator(val context: StaticContext) {
         // If one of overridden members is non-abstract, copy it.
         // When none found, we have nothing to copy, ignore.
         // When multiple found, our current class should provide implementation, ignore.
-        val memberToCopy = member.overriddenDescriptors
+        val memberToCopy = member.findNonRepeatingOverriddenDescriptors { overriddenDescriptors }
                 .filter { it.modality != Modality.ABSTRACT }
                 .singleOrNull() ?: return null
 
@@ -171,7 +171,7 @@ class ClassModelGenerator(val context: StaticContext) {
         // If one of overridden members has parameters with default value, copy it.
         // When non found, we have nothing to copy, ignore.
         // When multiple found, our current class should provide implementation, ignore.
-        val memberToCopy = member.overriddenDescriptors
+        val memberToCopy = member.findNonRepeatingOverriddenDescriptors { overriddenDescriptors }
                 .filter { it.hasOrInheritsParametersWithDefaultValue() }
                 .singleOrNull() ?: return null
 
@@ -182,6 +182,23 @@ class ClassModelGenerator(val context: StaticContext) {
         return if (!memberToCopy.kind.isReal) findOptionalArgsMemberToCopy(memberToCopy) else memberToCopy
     }
 
+    private fun <T : CallableMemberDescriptor> T.findNonRepeatingOverriddenDescriptors(
+            getTypedOverriddenDescriptors: T.() -> Collection<T>
+    ): List<T> {
+        val allDescriptors = mutableSetOf<T>()
+        val repeatedDescriptors = mutableSetOf<T>()
+        fun walk(descriptor: T) {
+            if (!allDescriptors.add(descriptor)) return
+            val overridden = descriptor.getTypedOverriddenDescriptors()
+            repeatedDescriptors += overridden
+            overridden.forEach { walk(it) }
+        }
+
+        val directOverriddenDescriptors = getTypedOverriddenDescriptors()
+        directOverriddenDescriptors.forEach { walk(it) }
+        return directOverriddenDescriptors.filter { it !in repeatedDescriptors }
+    }
+
     private fun generateBridgeMethods(descriptor: ClassDescriptor, model: JsClassModel) {
         generateBridgesToTraitImpl(descriptor, model)
         generateOtherBridges(descriptor, model)