Fix diagnostic for uninitialized extension property without accessors

#KT-8612 Fixed

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/Errors.java

@@ -462,6 +462,8 @@ public interface Errors {
 
     DiagnosticFactory0<KtProperty> MUST_BE_INITIALIZED = DiagnosticFactory0.create(ERROR, DECLARATION_SIGNATURE);
     DiagnosticFactory0<KtProperty> MUST_BE_INITIALIZED_OR_BE_ABSTRACT = DiagnosticFactory0.create(ERROR, DECLARATION_SIGNATURE);
+    DiagnosticFactory0<KtProperty> EXTENSION_PROPERTY_MUST_HAVE_ACCESSORS_OR_BE_ABSTRACT =
+            DiagnosticFactory0.create(ERROR, DECLARATION_SIGNATURE);
     DiagnosticFactory0<KtProperty> UNNECESSARY_LATEINIT = DiagnosticFactory0.create(WARNING, LATEINIT_MODIFIER);
 
     DiagnosticFactory0<KtExpression> EXTENSION_PROPERTY_WITH_BACKING_FIELD = DiagnosticFactory0.create(ERROR);

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/DefaultErrorMessages.java

@@ -231,6 +231,7 @@ public class DefaultErrorMessages {
         MAP.put(BACKING_FIELD_IN_INTERFACE, "Property in an interface cannot have a backing field");
         MAP.put(MUST_BE_INITIALIZED, "Property must be initialized");
         MAP.put(MUST_BE_INITIALIZED_OR_BE_ABSTRACT, "Property must be initialized or be abstract");
+        MAP.put(EXTENSION_PROPERTY_MUST_HAVE_ACCESSORS_OR_BE_ABSTRACT, "Extension property must have accessors or be abstract");
         MAP.put(UNNECESSARY_LATEINIT, "Lateinit is unnecessary: definitely initialized in constructors");
         MAP.put(PROPERTY_INITIALIZER_IN_INTERFACE, "Property initializers are not allowed in interfaces");
         MAP.put(PRIVATE_PROPERTY_IN_INTERFACE, "Abstract property in an interface cannot be private");

compiler/frontend/src/org/jetbrains/kotlin/resolve/DeclarationsChecker.kt

@@ -668,19 +668,19 @@ class DeclarationsChecker(
         val hasAccessorImplementation = propertyDescriptor.hasAccessorImplementation()
 
         val containingDeclaration = propertyDescriptor.containingDeclaration
-        val inTrait = containingDeclaration is ClassDescriptor && containingDeclaration.kind == ClassKind.INTERFACE
+        val inInterface = DescriptorUtils.isInterface(containingDeclaration)
         if (propertyDescriptor.modality == Modality.ABSTRACT) {
             if (!property.hasDelegateExpressionOrInitializer() && property.typeReference == null) {
                 trace.report(PROPERTY_WITH_NO_TYPE_NO_INITIALIZER.on(property))
             }
-            if (inTrait && property.hasModifier(KtTokens.PRIVATE_KEYWORD) && !property.hasModifier(KtTokens.ABSTRACT_KEYWORD)) {
+            if (inInterface && property.hasModifier(KtTokens.PRIVATE_KEYWORD) && !property.hasModifier(KtTokens.ABSTRACT_KEYWORD)) {
                 trace.report(PRIVATE_PROPERTY_IN_INTERFACE.on(property))
             }
             return
         }
 
         val backingFieldRequired = trace.bindingContext.get(BindingContext.BACKING_FIELD_REQUIRED, propertyDescriptor) ?: false
-        if (inTrait && backingFieldRequired && hasAccessorImplementation) {
+        if (inInterface && backingFieldRequired && hasAccessorImplementation) {
             trace.report(BACKING_FIELD_IN_INTERFACE.on(property))
         }
 
@@ -688,7 +688,7 @@ class DeclarationsChecker(
         val delegate = property.delegate
         val isHeader = propertyDescriptor.isHeader
         if (initializer != null) {
-            if (inTrait) {
+            if (inInterface) {
                 trace.report(PROPERTY_INITIALIZER_IN_INTERFACE.on(initializer))
             }
             else if (isHeader) {
@@ -702,15 +702,18 @@ class DeclarationsChecker(
             }
         }
         else if (delegate != null) {
-            if (inTrait) {
+            if (inInterface) {
                 trace.report(DELEGATED_PROPERTY_IN_INTERFACE.on(delegate))
             }
         }
         else {
             val isUninitialized = trace.bindingContext.get(BindingContext.IS_UNINITIALIZED, propertyDescriptor) ?: false
             val isExternal = propertyDescriptor.isEffectivelyExternal()
-            if (backingFieldRequired && !inTrait && !propertyDescriptor.isLateInit && !isHeader && isUninitialized && !isExternal) {
-                if (containingDeclaration !is ClassDescriptor || hasAccessorImplementation) {
+            if (backingFieldRequired && !inInterface && !propertyDescriptor.isLateInit && !isHeader && isUninitialized && !isExternal) {
+                if (propertyDescriptor.extensionReceiverParameter != null && !hasAccessorImplementation) {
+                    trace.report(EXTENSION_PROPERTY_MUST_HAVE_ACCESSORS_OR_BE_ABSTRACT.on(property))
+                }
+                else if (containingDeclaration !is ClassDescriptor || hasAccessorImplementation) {
                     trace.report(MUST_BE_INITIALIZED.on(property))
                 }
                 else {
@@ -723,7 +726,7 @@ class DeclarationsChecker(
             else if (noExplicitTypeOrGetterType(property)) {
                 trace.report(PROPERTY_WITH_NO_TYPE_NO_INITIALIZER.on(property))
             }
-            if (backingFieldRequired && !inTrait && propertyDescriptor.isLateInit && !isUninitialized &&
+            if (backingFieldRequired && !inInterface && propertyDescriptor.isLateInit && !isUninitialized &&
                 trace[MUST_BE_LATEINIT, propertyDescriptor] != true) {
                 trace.report(UNNECESSARY_LATEINIT.on(property))
             }

compiler/testData/diagnostics/tests/extensions/ExtensionFunctions.kt

@@ -36,7 +36,7 @@ fun test() {
 val Int.abs : Int
   get() = if (this > 0) this else -this;
 
-<!MUST_BE_INITIALIZED!>val <T> T.foo : T<!>
+<!EXTENSION_PROPERTY_MUST_HAVE_ACCESSORS_OR_BE_ABSTRACT!>val <T> T.foo : T<!>
 
 fun Int.foo() = this
 

compiler/testData/diagnostics/tests/properties/extensionPropertyMustHaveAccessorsOrBeAbstract.kt

@@ -0,0 +1,25 @@
+<!EXTENSION_PROPERTY_MUST_HAVE_ACCESSORS_OR_BE_ABSTRACT!>val String.test1: Int<!>
+<!EXTENSION_PROPERTY_MUST_HAVE_ACCESSORS_OR_BE_ABSTRACT!>var String.test2: Int<!>
+
+<!EXTENSION_PROPERTY_MUST_HAVE_ACCESSORS_OR_BE_ABSTRACT!>var String.test3: Int<!>; public set
+
+class C {
+    <!EXTENSION_PROPERTY_MUST_HAVE_ACCESSORS_OR_BE_ABSTRACT!>val String.test1: Int<!>
+    <!EXTENSION_PROPERTY_MUST_HAVE_ACCESSORS_OR_BE_ABSTRACT!>var String.test2: Int<!>
+    <!EXTENSION_PROPERTY_MUST_HAVE_ACCESSORS_OR_BE_ABSTRACT!>var String.test3: Int<!>; public set
+}
+
+interface I {
+    val String.test1: Int
+    var String.test2: Int
+    var String.test3: Int; public set
+}
+
+abstract class A {
+    <!EXTENSION_PROPERTY_MUST_HAVE_ACCESSORS_OR_BE_ABSTRACT!>val String.test1: Int<!>
+    <!EXTENSION_PROPERTY_MUST_HAVE_ACCESSORS_OR_BE_ABSTRACT!>var String.test2: Int<!>
+    <!EXTENSION_PROPERTY_MUST_HAVE_ACCESSORS_OR_BE_ABSTRACT!>var String.test3: Int<!>; public set
+
+    abstract val String.testA1: Int
+    abstract var String.testA2: Int
+}

compiler/testData/diagnostics/tests/properties/extensionPropertyMustHaveAccessorsOrBeAbstract.txt

@@ -0,0 +1,36 @@
+package
+
+public val kotlin.String.test1: kotlin.Int
+public var kotlin.String.test2: kotlin.Int
+public var kotlin.String.test3: kotlin.Int
+
+public abstract class A {
+    public constructor A()
+    public final val kotlin.String.test1: kotlin.Int
+    public final var kotlin.String.test2: kotlin.Int
+    public final var kotlin.String.test3: kotlin.Int
+    public abstract val kotlin.String.testA1: kotlin.Int
+    public abstract var kotlin.String.testA2: kotlin.Int
+    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 C {
+    public constructor C()
+    public final val kotlin.String.test1: kotlin.Int
+    public final var kotlin.String.test2: kotlin.Int
+    public final var kotlin.String.test3: kotlin.Int
+    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 interface I {
+    public abstract val kotlin.String.test1: kotlin.Int
+    public abstract var kotlin.String.test2: kotlin.Int
+    public abstract var kotlin.String.test3: kotlin.Int
+    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
+}

compiler/testData/diagnostics/tests/script/topLevelPropertiesWithGetSet.kts

@@ -34,6 +34,6 @@ set(value) {}
 <!UNRESOLVED_REFERENCE!>get<!>() = 42
 <!UNRESOLVED_REFERENCE!>set<!>(<!UNRESOLVED_REFERENCE!>value<!>) {}
 
-<!MUST_BE_INITIALIZED_OR_BE_ABSTRACT!>var String.testExtVarLineBreakSemi: Int<!>;
+<!EXTENSION_PROPERTY_MUST_HAVE_ACCESSORS_OR_BE_ABSTRACT!>var String.testExtVarLineBreakSemi: Int<!>;
 <!UNRESOLVED_REFERENCE!>get<!>() = 42
 <!UNRESOLVED_REFERENCE!>set<!>(<!UNRESOLVED_REFERENCE!>value<!>) {}

compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java

@@ -15838,6 +15838,12 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                 KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/diagnostics/tests/properties"), Pattern.compile("^(.+)\\.kt$"), TargetBackend.ANY, true);
             }
 
+            @TestMetadata("extensionPropertyMustHaveAccessorsOrBeAbstract.kt")
+            public void testExtensionPropertyMustHaveAccessorsOrBeAbstract() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/properties/extensionPropertyMustHaveAccessorsOrBeAbstract.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("compiler/testData/diagnostics/tests/properties/inferenceFromGetters")
             @TestDataPath("$PROJECT_ROOT")
             @RunWith(JUnit3RunnerWithInners.class)