Fix "not initialized" on lateinit property (KT-9369)

compiler/frontend/src/org/jetbrains/kotlin/cfg/JetFlowInformationProvider.java

@@ -376,7 +376,8 @@ public class JetFlowInformationProvider {
         boolean isDefinitelyInitialized = ctxt.exitInitState.definitelyInitialized();
         VariableDescriptor variableDescriptor = ctxt.variableDescriptor;
         if (variableDescriptor instanceof PropertyDescriptor) {
-            if (!trace.get(BindingContext.BACKING_FIELD_REQUIRED, (PropertyDescriptor) variableDescriptor)) {
+            PropertyDescriptor propertyDescriptor = (PropertyDescriptor) variableDescriptor;
+            if (propertyDescriptor.isLateInit() || !trace.get(BindingContext.BACKING_FIELD_REQUIRED, propertyDescriptor)) {
                 isDefinitelyInitialized = true;
             }
         }

compiler/testData/diagnostics/tests/LateInit.kt

@@ -54,4 +54,12 @@ public abstract class AbstractClass {
 
 public class AbstractClassImpl : AbstractClass() {
     override lateinit var str: String
+}
+
+public class B {
+    lateinit var a: String
+
+    init {
+        a.length()
+    }
 }

compiler/testData/diagnostics/tests/LateInit.txt

@@ -45,6 +45,14 @@ public final class AbstractClassImpl : AbstractClass {
     public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
 }
 
+public final class B {
+    public constructor B()
+    public final lateinit var a: kotlin.String
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
 public final class CustomDelegate {
     public constructor CustomDelegate()
     public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean