JS: when translating nested classes of local classes, capture closure variables via outermost local class. See KT-12566

compiler/testData/codegen/box/localClasses/ownClosureOfInnerLocalClass.kt

@@ -1,6 +1,3 @@
-// IGNORE_BACKEND: JS
-// Enable when KT-12566 gets fixed
-
 fun box(): String {
     var log = ""
 

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

@@ -11100,13 +11100,7 @@ public class JsCodegenBoxTestGenerated extends AbstractJsCodegenBoxTest {
         @TestMetadata("ownClosureOfInnerLocalClass.kt")
         public void testOwnClosureOfInnerLocalClass() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/localClasses/ownClosureOfInnerLocalClass.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("withclosure.kt")

js/js.translator/src/org/jetbrains/kotlin/js/translate/context/TranslationContext.java

@@ -166,6 +166,11 @@ public class TranslationContext {
         return new TranslationContext(this, staticContext, dynamicContext, aliasingContext.inner(), usageTracker, descriptor);
     }
 
+    @NotNull
+    public TranslationContext inner(@NotNull MemberDescriptor descriptor) {
+        return new TranslationContext(this, staticContext, dynamicContext, aliasingContext.inner(), usageTracker, descriptor);
+    }
+
     @NotNull
     public TranslationContext innerBlock(@NotNull JsBlock block) {
         return new TranslationContext(this, staticContext, dynamicContext.innerBlock(block), aliasingContext, usageTracker,
@@ -379,7 +384,7 @@ public class TranslationContext {
 
     @Nullable
     public JsExpression getAliasForDescriptor(@NotNull DeclarationDescriptor descriptor) {
-        JsNameRef nameRef = captureIfNeedAndGetCapturedName(descriptor);
+        JsExpression nameRef = captureIfNeedAndGetCapturedName(descriptor);
         if (nameRef != null) {
             return nameRef;
         }
@@ -459,15 +464,23 @@ public class TranslationContext {
     }
 
     @Nullable
-    private JsNameRef captureIfNeedAndGetCapturedName(DeclarationDescriptor descriptor) {
+    private JsExpression captureIfNeedAndGetCapturedName(DeclarationDescriptor descriptor) {
         if (usageTracker != null) {
             usageTracker.used(descriptor);
 
             JsName name = getNameForCapturedDescriptor(usageTracker, descriptor);
             if (name != null) {
-                JsNameRef result = name.makeRef();
+                JsExpression result;
                 if (shouldCaptureViaThis()) {
-                    result.setQualifier(JsLiteral.THIS);
+                    result = JsLiteral.THIS;
+                    int depth = getOuterLocalClassDepth();
+                    for (int i = 0; i < depth; ++i) {
+                        result = new JsNameRef(Namer.OUTER_FIELD_NAME, result);
+                    }
+                    result = new JsNameRef(name, result);
+                }
+                else {
+                    result = name.makeRef();
                 }
                 return result;
             }
@@ -476,6 +489,25 @@ public class TranslationContext {
         return null;
     }
 
+    private int getOuterLocalClassDepth() {
+        if (usageTracker == null) return 0;
+        MemberDescriptor capturingDescriptor = usageTracker.getContainingDescriptor();
+        if (!(capturingDescriptor instanceof ClassDescriptor)) return 0;
+
+        ClassDescriptor capturingClassDescriptor = (ClassDescriptor) capturingDescriptor;
+        ClassDescriptor currentDescriptor = classDescriptor;
+        if (currentDescriptor == null) return 0;
+
+        int depth = 0;
+        while (currentDescriptor != capturingClassDescriptor) {
+            DeclarationDescriptor container = currentDescriptor.getContainingDeclaration();
+            if (!(container instanceof ClassDescriptor)) return 0;
+            currentDescriptor = (ClassDescriptor) container;
+            depth++;
+        }
+        return depth;
+    }
+
     private boolean shouldCaptureViaThis() {
         if (declarationDescriptor == null) return false;
 

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

@@ -79,7 +79,7 @@ class ClassTranslator private constructor(
         context.addDeclarationStatement(constructorFunction.makeStmt())
         val enumInitFunction = if (descriptor.kind == ClassKind.ENUM_CLASS) createEnumInitFunction() else null
 
-        val nonConstructorContext = context.innerWithUsageTracker(scope, descriptor)
+        val nonConstructorContext = context.withUsageTrackerIfNecessary(scope, descriptor)
         nonConstructorContext.startDeclaration()
         val delegationTranslator = DelegationTranslator(classDeclaration, nonConstructorContext)
         translatePropertiesAsConstructorParameters(nonConstructorContext)
@@ -93,7 +93,7 @@ class ClassTranslator private constructor(
         addMetadataType()
         context.addClass(descriptor)
         addSuperclassReferences()
-        classDeclaration.getSecondaryConstructors().forEach { generateSecondaryConstructor(context, it) }
+        classDeclaration.secondaryConstructors.forEach { generateSecondaryConstructor(context, it) }
 
         generatedBridgeMethods()
 
@@ -115,6 +115,18 @@ class ClassTranslator private constructor(
         }
     }
 
+    private fun TranslationContext.withUsageTrackerIfNecessary(scope: JsScope, innerDescriptor: MemberDescriptor): TranslationContext {
+        return if (isLocalClass) {
+            innerWithUsageTracker(scope, innerDescriptor)
+        }
+        else {
+            inner(innerDescriptor)
+        }
+    }
+
+    private val isLocalClass
+        get() = descriptor.containingDeclaration !is ClassOrPackageFragmentDescriptor
+
     private fun translatePrimaryConstructor(
             constructorFunction: JsFunction,
             classContext: TranslationContext,
@@ -303,10 +315,10 @@ class ClassTranslator private constructor(
         for (constructor in sortedConstructors) {
             constructor.superCallGenerator()
 
-            val nonConstructorUsageTracker = nonConstructorContext.usageTracker()!!
+            val nonConstructorUsageTracker = nonConstructorContext.usageTracker()
             val usageTracker = constructor.context.usageTracker()!!
 
-            val nonConstructorCapturedVars = nonConstructorUsageTracker.capturedDescriptors
+            val nonConstructorCapturedVars = if (isLocalClass) nonConstructorUsageTracker!!.capturedDescriptors else setOf()
             val constructorCapturedVars = usageTracker.capturedDescriptors
 
             val capturedVars = (nonConstructorCapturedVars + constructorCapturedVars).distinct()
@@ -319,9 +331,9 @@ class ClassTranslator private constructor(
 
             for (callSite in constructorCallSites) {
                 val closureQualifier = callSite.context.getArgumentForClosureConstructor(classDescriptor.thisAsReceiverParameter)
-                capturedVars.forEach { nonConstructorUsageTracker.used(it) }
+                capturedVars.forEach { nonConstructorUsageTracker!!.used(it) }
                 val closureArgs = capturedVars.map {
-                    val name = nonConstructorUsageTracker.getNameForCapturedDescriptor(it)!!
+                    val name = nonConstructorUsageTracker!!.getNameForCapturedDescriptor(it)!!
                     JsAstUtils.pureFqn(name, closureQualifier)
                 }
                 callSite.invocationArgs.addAll(0, closureArgs)
@@ -332,12 +344,12 @@ class ClassTranslator private constructor(
     private fun addClosureParameters(constructor: ConstructorInfo, nonConstructorContext: TranslationContext) {
         val usageTracker = constructor.context.usageTracker()!!
         val capturedVars = context().getClassOrConstructorClosure(constructor.descriptor) ?: return
-        val nonConstructorUsageTracker = nonConstructorContext.usageTracker()!!
+        val nonConstructorUsageTracker = nonConstructorContext.usageTracker()
 
         val function = constructor.function
         val additionalStatements = mutableListOf<JsStatement>()
         for ((i, capturedVar) in capturedVars.withIndex()) {
-            val fieldName = nonConstructorUsageTracker.capturedDescriptorToJsName[capturedVar]
+            val fieldName = nonConstructorUsageTracker?.capturedDescriptorToJsName?.get(capturedVar)
             val name = usageTracker.capturedDescriptorToJsName[capturedVar] ?: fieldName!!
 
             function.parameters.add(i, JsParameter(name))

js/js.translator/src/org/jetbrains/kotlin/js/translate/initializer/ClassInitializerTranslator.java

@@ -192,11 +192,11 @@ public final class ClassInitializerTranslator extends AbstractTranslator {
                 List<DeclarationDescriptor> superclassClosure = context.getClassOrConstructorClosure(superDescriptor);
                 if (superclassClosure != null) {
                     UsageTracker tracker = context.usageTracker();
-                    assert tracker != null : "Closure exists, therefore UsageTracker must exist too. Translating constructor of " +
-                                             classDescriptor;
-                    for (DeclarationDescriptor capturedValue : superclassClosure) {
-                        tracker.used(capturedValue);
-                        arguments.add(tracker.getCapturedDescriptorToJsName().get(capturedValue).makeRef());
+                    if (tracker != null) {
+                        for (DeclarationDescriptor capturedValue : superclassClosure) {
+                            tracker.used(capturedValue);
+                            arguments.add(tracker.getCapturedDescriptorToJsName().get(capturedValue).makeRef());
+                        }
                     }
                 }