Fix isInitialized for companion lateinit properties

Instead of trying to access a missing field `Foo.foo`, call the
synthetic accessor `Foo.access$getFoo$cp` which, as per previous commit,
no longer contains the lateinit assertion

 #KT-21862 Fixed

compiler/backend/src/org/jetbrains/kotlin/codegen/ExpressionCodegen.java

@@ -2084,10 +2084,19 @@ public class ExpressionCodegen extends KtVisitor<StackValue, StackValue> impleme
                 couldUseDirectAccessToProperty(propertyDescriptor, false, isDelegatedProperty, context, state.getShouldInlineConstVals());
 
         if (fieldAccessorKind == AccessorKind.LATEINIT_INTRINSIC) {
-            skipPropertyAccessors = !isPrivateProperty || context.getClassOrPackageParentContext() == backingFieldContext;
+            skipPropertyAccessors =
+                    (!isPrivateProperty || context.getClassOrPackageParentContext() == backingFieldContext) &&
+                    !isBackingFieldMovedFromCompanion;
 
             if (!skipPropertyAccessors) {
-                propertyDescriptor = backingFieldContext.getAccessor(propertyDescriptor, fieldAccessorKind, delegateType, superCallTarget);
+                if (isBackingFieldMovedFromCompanion && context.getContextDescriptor() instanceof AccessorForPropertyBackingField) {
+                    propertyDescriptor = (PropertyDescriptor) backingFieldContext.getParentContext()
+                            .getAccessor(propertyDescriptor, AccessorKind.IN_CLASS_COMPANION, delegateType, superCallTarget);
+                }
+                else {
+                    propertyDescriptor =
+                            backingFieldContext.getAccessor(propertyDescriptor, fieldAccessorKind, delegateType, superCallTarget);
+                }
             }
             ownerDescriptor = propertyDescriptor;
         }

compiler/testData/codegen/box/properties/lateinit/isInitializedAndDeinitialize/companionObjectField.kt

@@ -0,0 +1,41 @@
+// WITH_RUNTIME
+
+class Class {
+    companion object {
+        lateinit var public: String
+        private lateinit var private: String
+
+        fun test() {
+            if (::public.isInitialized) throw AssertionError("Fail 1")
+            public = "OK"
+            if (public != "OK") throw AssertionError("Fail 2")
+
+            if (::private.isInitialized) throw AssertionError("Fail 3")
+            private = "OK"
+            if (private != "OK") throw AssertionError("Fail 4")
+        }
+    }
+}
+
+class Interface {
+    companion object {
+        lateinit var public: String
+        private lateinit var private: String
+
+        fun test() {
+            if (::public.isInitialized) throw AssertionError("Fail 5")
+            public = "OK"
+            if (public != "OK") throw AssertionError("Fail 6")
+
+            if (::private.isInitialized) throw AssertionError("Fail 7")
+            private = "OK"
+            if (private != "OK") throw AssertionError("Fail 8")
+        }
+    }
+}
+
+fun box(): String {
+    Class.test()
+    Interface.test()
+    return "OK"
+}

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

@@ -17860,6 +17860,11 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
                     KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/codegen/box/properties/lateinit/isInitializedAndDeinitialize"), Pattern.compile("^(.+)\\.kt$"), TargetBackend.JVM, true);
                 }
 
+                @TestMetadata("companionObjectField.kt")
+                public void testCompanionObjectField() throws Exception {
+                    runTest("compiler/testData/codegen/box/properties/lateinit/isInitializedAndDeinitialize/companionObjectField.kt");
+                }
+
                 @TestMetadata("emptyLhs.kt")
                 public void testEmptyLhs() throws Exception {
                     runTest("compiler/testData/codegen/box/properties/lateinit/isInitializedAndDeinitialize/emptyLhs.kt");

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

@@ -17860,6 +17860,11 @@ public class LightAnalysisModeTestGenerated extends AbstractLightAnalysisModeTes
                     KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/codegen/box/properties/lateinit/isInitializedAndDeinitialize"), Pattern.compile("^(.+)\\.kt$"), TargetBackend.JVM, true);
                 }
 
+                @TestMetadata("companionObjectField.kt")
+                public void testCompanionObjectField() throws Exception {
+                    runTest("compiler/testData/codegen/box/properties/lateinit/isInitializedAndDeinitialize/companionObjectField.kt");
+                }
+
                 @TestMetadata("emptyLhs.kt")
                 public void testEmptyLhs() throws Exception {
                     runTest("compiler/testData/codegen/box/properties/lateinit/isInitializedAndDeinitialize/emptyLhs.kt");

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

@@ -17865,6 +17865,11 @@ public class IrBlackBoxCodegenTestGenerated extends AbstractIrBlackBoxCodegenTes
                     KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/codegen/box/properties/lateinit/isInitializedAndDeinitialize"), Pattern.compile("^(.+)\\.kt$"), TargetBackend.JVM_IR, true);
                 }
 
+                @TestMetadata("companionObjectField.kt")
+                public void testCompanionObjectField() throws Exception {
+                    runTest("compiler/testData/codegen/box/properties/lateinit/isInitializedAndDeinitialize/companionObjectField.kt");
+                }
+
                 @TestMetadata("emptyLhs.kt")
                 public void testEmptyLhs() throws Exception {
                     runTest("compiler/testData/codegen/box/properties/lateinit/isInitializedAndDeinitialize/emptyLhs.kt");

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

@@ -15350,6 +15350,11 @@ public class IrJsCodegenBoxTestGenerated extends AbstractIrJsCodegenBoxTest {
                     KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/codegen/box/properties/lateinit/isInitializedAndDeinitialize"), Pattern.compile("^(.+)\\.kt$"), TargetBackend.JS_IR, true);
                 }
 
+                @TestMetadata("companionObjectField.kt")
+                public void testCompanionObjectField() throws Exception {
+                    runTest("compiler/testData/codegen/box/properties/lateinit/isInitializedAndDeinitialize/companionObjectField.kt");
+                }
+
                 @TestMetadata("emptyLhs.kt")
                 public void testEmptyLhs() throws Exception {
                     runTest("compiler/testData/codegen/box/properties/lateinit/isInitializedAndDeinitialize/emptyLhs.kt");

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

@@ -16410,6 +16410,11 @@ public class JsCodegenBoxTestGenerated extends AbstractJsCodegenBoxTest {
                     KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/codegen/box/properties/lateinit/isInitializedAndDeinitialize"), Pattern.compile("^(.+)\\.kt$"), TargetBackend.JS, true);
                 }
 
+                @TestMetadata("companionObjectField.kt")
+                public void testCompanionObjectField() throws Exception {
+                    runTest("compiler/testData/codegen/box/properties/lateinit/isInitializedAndDeinitialize/companionObjectField.kt");
+                }
+
                 @TestMetadata("emptyLhs.kt")
                 public void testEmptyLhs() throws Exception {
                     runTest("compiler/testData/codegen/box/properties/lateinit/isInitializedAndDeinitialize/emptyLhs.kt");