JS: insert dummy initializers for property that initialized on init block or in secondary constructors. See KT-8211

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

@@ -3611,6 +3611,12 @@ public class BoxJsTestGenerated extends AbstractBoxJsTest {
             doTest(fileName);
         }
 
+        @TestMetadata("propertyInitializationOrder.kt")
+        public void testPropertyInitializationOrder() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("js/js.translator/testData/box/initialize/propertyInitializationOrder.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("rootPackageValInit.kt")
         public void testRootPackageValInit() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("js/js.translator/testData/box/initialize/rootPackageValInit.kt");

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

@@ -16,16 +16,21 @@
 
 package org.jetbrains.kotlin.js.translate.initializer;
 
-import org.jetbrains.kotlin.js.backend.ast.JsExpression;
-import org.jetbrains.kotlin.js.backend.ast.JsStatement;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.kotlin.builtins.KotlinBuiltIns;
 import org.jetbrains.kotlin.descriptors.PropertyDescriptor;
+import org.jetbrains.kotlin.js.backend.ast.*;
+import org.jetbrains.kotlin.js.translate.context.Namer;
 import org.jetbrains.kotlin.js.translate.context.TranslationContext;
 import org.jetbrains.kotlin.js.translate.declaration.PropertyTranslatorKt;
 import org.jetbrains.kotlin.js.translate.general.TranslatorVisitor;
 import org.jetbrains.kotlin.js.translate.utils.BindingUtils;
 import org.jetbrains.kotlin.js.translate.utils.JsAstUtils;
+import org.jetbrains.kotlin.js.translate.utils.JsDescriptorUtils;
+import org.jetbrains.kotlin.js.translate.utils.TranslationUtils;
 import org.jetbrains.kotlin.psi.*;
+import org.jetbrains.kotlin.resolve.BindingContext;
+import org.jetbrains.kotlin.types.KotlinType;
 
 import static org.jetbrains.kotlin.js.translate.general.Translation.translateAsStatementAndMergeInBlockIfNeeded;
 import static org.jetbrains.kotlin.js.translate.initializer.InitializerUtils.generateInitializerForDelegate;
@@ -49,10 +54,19 @@ public final class InitializerVisitor extends TranslatorVisitor<Void> {
             assert value != null;
             statement = generateInitializerForProperty(context, descriptor, value);
         }
-        if (delegate != null) {
+        else if (delegate != null) {
             assert value != null;
             statement = generateInitializerForDelegate(descriptor, value);
         }
+        else if (Boolean.TRUE.equals(context.bindingContext().get(BindingContext.BACKING_FIELD_REQUIRED, descriptor))) {
+            JsExpression defaultValue = generateDefaultValue(descriptor, context);
+            statement = TranslationUtils.assignmentToBackingField(context, descriptor, defaultValue).makeStmt();
+        }
+        else if (JsDescriptorUtils.isSimpleFinalProperty(descriptor)) {
+            JsExpression defaultValue = generateDefaultValue(descriptor, context);
+            JsName propertyName = context.getNameForDescriptor(descriptor);
+            statement = JsAstUtils.assignment(new JsNameRef(propertyName, JsLiteral.THIS), defaultValue).makeStmt();
+        }
 
         if (statement != null && !JsAstUtils.isEmptyStatement(statement)) {
             context.addStatementsToCurrentBlock(JsAstUtils.flattenStatement(statement));
@@ -61,6 +75,24 @@ public final class InitializerVisitor extends TranslatorVisitor<Void> {
         return null;
     }
 
+    @NotNull
+    private static JsExpression generateDefaultValue(@NotNull PropertyDescriptor property, @NotNull TranslationContext context) {
+        if (property.isLateInit()) return Namer.getUndefinedExpression();
+
+        KotlinType type = property.getType();
+        if (KotlinBuiltIns.isInt(type) || KotlinBuiltIns.isFloat(type) || KotlinBuiltIns.isDouble(type) ||
+            KotlinBuiltIns.isByte(type) || KotlinBuiltIns.isShort(type)
+        ) {
+            return context.program().getNumberLiteral(0);
+        }
+        else if (KotlinBuiltIns.isBoolean(type)) {
+            return JsLiteral.FALSE;
+        }
+        else {
+            return JsLiteral.NULL;
+        }
+    }
+
     @Override
     public Void visitAnonymousInitializer(@NotNull KtAnonymousInitializer initializer, @NotNull TranslationContext context) {
         KtExpression initializerBody = initializer.getBody();

js/js.translator/testData/box/initialize/propertyInitializationOrder.kt

@@ -0,0 +1,66 @@
+open class A {
+    val a: Int
+    open val b: Int
+    val c = 99
+    val d: Int = 555
+        get() = field
+
+    val e: Int
+        get() = field
+
+    @get:JsName("getF")
+    val f: Int
+
+    @get:JsName("getG")
+    val g: Int = 777
+
+    lateinit var h: String
+
+    init {
+        foo()
+        a = 23
+        b = 42
+        e = 987
+        f = 888
+    }
+}
+
+fun foo() {}
+
+fun box(): String {
+    val aBody = js("A").toString()
+    val expectedRegex = build {
+        property("a")
+        field("b")
+        property("c")
+        field("d")
+        field("e")
+        field("f")
+        field("g")
+        property("h")
+    }
+    if (expectedRegex.find(aBody) == null) return "fail"
+
+    return "OK"
+}
+
+fun build(f: RegexBuilder.() -> Unit): Regex {
+    val builder = RegexBuilder()
+    builder.f()
+    return Regex(builder.string + "foo()", RegexOption.MULTILINE)
+}
+
+class RegexBuilder {
+    var string = ""
+
+    fun property(name: String) {
+        string += "this.$name\\s+=$ANY_CHARS"
+    }
+
+    fun field(name: String) {
+        string += "this.$name$FIELD_SUFFIX\\s+=$ANY_CHARS"
+    }
+}
+
+val ANY_CHARS = "(.|\n)+"
+val FIELD_SUFFIX = "_[a-zA-Z0-9\\\$_]+"