Delegated properties now cannot be used before initialization #KT-10869 Fixed

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

@@ -360,6 +360,14 @@ public class ControlFlowInformationProvider {
         }
     }
 
+    private boolean isDefinitelyInitialized(@NotNull PropertyDescriptor propertyDescriptor) {
+        if (propertyDescriptor.isLateInit()) return true;
+        if (trace.get(BACKING_FIELD_REQUIRED, propertyDescriptor) == Boolean.TRUE) return false;
+        PsiElement property = DescriptorToSourceUtils.descriptorToDeclaration(propertyDescriptor);
+        if (property instanceof KtProperty && ((KtProperty) property).hasDelegate()) return false;
+        return true;
+    }
+
     private void checkIsInitialized(
             @NotNull VariableInitContext ctxt,
             @NotNull KtElement element,
@@ -370,11 +378,8 @@ public class ControlFlowInformationProvider {
 
         boolean isDefinitelyInitialized = ctxt.exitInitState.definitelyInitialized();
         VariableDescriptor variableDescriptor = ctxt.variableDescriptor;
-        if (variableDescriptor instanceof PropertyDescriptor) {
-            PropertyDescriptor propertyDescriptor = (PropertyDescriptor) variableDescriptor;
-            if (propertyDescriptor.isLateInit() || !trace.get(BindingContext.BACKING_FIELD_REQUIRED, propertyDescriptor)) {
-                isDefinitelyInitialized = true;
-            }
+        if (!isDefinitelyInitialized && variableDescriptor instanceof PropertyDescriptor) {
+            isDefinitelyInitialized = isDefinitelyInitialized((PropertyDescriptor) variableDescriptor);
         }
         if (!isDefinitelyInitialized && !varWithUninitializedErrorGenerated.contains(variableDescriptor)) {
             if (!(variableDescriptor instanceof PropertyDescriptor)) {

compiler/frontend/src/org/jetbrains/kotlin/cfg/ControlFlowProcessor.kt

@@ -1001,6 +1001,8 @@ class ControlFlowProcessor(private val trace: BindingTrace) {
             }
             val delegate = property.delegateExpression
             if (delegate != null) {
+                // We do not want to have getDeferredValue(delegate) here, because delegate value will be read anyway later
+                visitAssignment(property, getDeferredValue(null), property)
                 generateInstructions(delegate)
                 if (builder.getBoundValue(delegate) != null) {
                     createSyntheticValue(property, MagicKind.VALUE_CONSUMER, delegate)