KT-13544: support typealiases in JS backend

compiler/testData/codegen/box/typealias/typeAliasCompanion.kt

@@ -0,0 +1,9 @@
+class A {
+    companion object {
+        val result = "OK"
+    }
+}
+
+typealias Alias = A.Companion
+
+fun box(): String = Alias.result

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

@@ -15550,6 +15550,12 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
             doTest(fileName);
         }
 
+        @TestMetadata("typeAliasCompanion.kt")
+        public void testTypeAliasCompanion() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/typealias/typeAliasCompanion.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("typeAliasConstructor.kt")
         public void testTypeAliasConstructor() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/typealias/typeAliasConstructor.kt");

generators/src/org/jetbrains/kotlin/generators/tests/GenerateTests.kt

@@ -1205,6 +1205,10 @@ fun main(args: Array<String>) {
         testClass<AbstractNonLocalReturnsTest>() {
             model("codegen/boxInline/nonLocalReturns/", targetBackend = TargetBackend.JS)
         }
+
+        testClass<AbstractTypeAliasesTests>() {
+            model("codegen/box/typealias/", targetBackend = TargetBackend.JS)
+        }
     }
 }
 

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

@@ -0,0 +1,67 @@
+/*
+ * Copyright 2010-2016 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.jetbrains.kotlin.js.test.semantics;
+
+import com.intellij.testFramework.TestDataPath;
+import org.jetbrains.kotlin.test.JUnit3RunnerWithInners;
+import org.jetbrains.kotlin.test.KotlinTestUtils;
+import org.jetbrains.kotlin.test.TestMetadata;
+import org.junit.runner.RunWith;
+
+import java.io.File;
+import java.util.regex.Pattern;
+
+/** This class is generated by {@link org.jetbrains.kotlin.generators.tests.TestsPackage}. DO NOT MODIFY MANUALLY */
+@SuppressWarnings("all")
+@TestMetadata("compiler/testData/codegen/box/typealias")
+@TestDataPath("$PROJECT_ROOT")
+@RunWith(JUnit3RunnerWithInners.class)
+public class TypeAliasesTestsGenerated extends AbstractTypeAliasesTests {
+    public void testAllFilesPresentInTypealias() throws Exception {
+        KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/codegen/box/typealias"), Pattern.compile("^(.+)\\.kt$"), true);
+    }
+
+    @TestMetadata("localTypeAlias.kt")
+    public void testLocalTypeAlias() throws Exception {
+        String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/typealias/localTypeAlias.kt");
+        doTest(fileName);
+    }
+
+    @TestMetadata("simple.kt")
+    public void testSimple() throws Exception {
+        String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/typealias/simple.kt");
+        doTest(fileName);
+    }
+
+    @TestMetadata("typeAliasCompanion.kt")
+    public void testTypeAliasCompanion() throws Exception {
+        String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/typealias/typeAliasCompanion.kt");
+        doTest(fileName);
+    }
+
+    @TestMetadata("typeAliasConstructor.kt")
+    public void testTypeAliasConstructor() throws Exception {
+        String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/typealias/typeAliasConstructor.kt");
+        doTest(fileName);
+    }
+
+    @TestMetadata("typeAliasObject.kt")
+    public void testTypeAliasObject() throws Exception {
+        String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/typealias/typeAliasObject.kt");
+        doTest(fileName);
+    }
+}

js/js.tests/test/org/jetbrains/kotlin/js/test/semantics/abstractClassesForGeneratedTests.kt

@@ -68,3 +68,5 @@ abstract class AbstractRttiTest : SingleFileTranslationTest("rtti/")
 abstract class AbstractCastTest : SingleFileTranslationTest("expression/cast/")
 
 abstract class AbstractLightReflectionTest : SingleFileTranslationTest("reflection/light/")
+
+abstract class AbstractTypeAliasesTests : AbstractBlackBoxTest("typealiases/")

js/js.translator/src/org/jetbrains/kotlin/js/translate/declaration/DeclarationBodyVisitor.java

@@ -142,4 +142,10 @@ public class DeclarationBodyVisitor extends TranslatorVisitor<Void> {
         }
         initializerStatements.add(statement);
     }
+
+    @Override
+    public Void visitTypeAlias(@NotNull KtTypeAlias typeAlias, TranslationContext data) {
+        // Resolved by front-end, not used by backend
+        return null;
+    }
 }

js/js.translator/src/org/jetbrains/kotlin/js/translate/expression/ExpressionVisitor.java

@@ -590,6 +590,12 @@ public final class ExpressionVisitor extends TranslatorVisitor<JsNode> {
         return JsEmpty.INSTANCE;
     }
 
+    @Override
+    public JsNode visitTypeAlias(@NotNull KtTypeAlias typeAlias, TranslationContext data) {
+        // Resolved by front-end, not used by backend
+        return JsEmpty.INSTANCE;
+    }
+
     private static ClassTranslator.TranslationResult translateClassOrObject(
             @NotNull KtClassOrObject declaration,
             @NotNull ClassDescriptor descriptor,

js/js.translator/src/org/jetbrains/kotlin/js/translate/utils/BindingUtils.java

@@ -106,7 +106,7 @@ public final class BindingUtils {
     public static DeclarationDescriptor getDescriptorForReferenceExpression(@NotNull BindingContext context,
             @NotNull KtReferenceExpression reference) {
         if (BindingContextUtils.isExpressionWithValidReference(reference, context)) {
-            return BindingContextUtils.getNotNull(context, BindingContext.REFERENCE_TARGET, reference);
+            return resolveObjectViaTypeAlias(BindingContextUtils.getNotNull(context, BindingContext.REFERENCE_TARGET, reference));
         }
         return null;
     }
@@ -114,7 +114,24 @@ public final class BindingUtils {
     @Nullable
     private static DeclarationDescriptor getNullableDescriptorForReferenceExpression(@NotNull BindingContext context,
             @NotNull KtReferenceExpression reference) {
-        return context.get(BindingContext.REFERENCE_TARGET, reference);
+        DeclarationDescriptor descriptor = context.get(BindingContext.REFERENCE_TARGET, reference);
+        return descriptor != null ? resolveObjectViaTypeAlias(descriptor) : null;
+    }
+
+    @NotNull
+    private static DeclarationDescriptor resolveObjectViaTypeAlias(@NotNull DeclarationDescriptor descriptor) {
+        if (descriptor instanceof TypeAliasDescriptor) {
+            ClassDescriptor classDescriptor = ((TypeAliasDescriptor) descriptor).getClassDescriptor();
+            assert classDescriptor != null : "Class descriptor must be non-null in resolved typealias: " + descriptor;
+            if (classDescriptor.getKind() != ClassKind.OBJECT) {
+                classDescriptor = classDescriptor.getCompanionObjectDescriptor();
+                assert classDescriptor != null : "Resolved typealias must have non-null class descriptor: " + descriptor;
+            }
+            return classDescriptor;
+        }
+        else {
+            return descriptor;
+        }
     }
 
     public static boolean isVariableReassignment(@NotNull BindingContext context, @NotNull KtExpression expression) {