Prohibit inheritance by delegation in expect classes

#KT-20431 Fixed

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

@@ -572,6 +572,8 @@ public interface Errors {
     DiagnosticFactory0<PsiElement> EXPECTED_LATEINIT_PROPERTY = DiagnosticFactory0.create(ERROR);
     DiagnosticFactory0<PsiElement> SUPERTYPE_INITIALIZED_IN_EXPECTED_CLASS = DiagnosticFactory0.create(ERROR);
 
+    DiagnosticFactory0<KtDelegatedSuperTypeEntry> IMPLEMENTATION_BY_DELEGATION_IN_EXPECT_CLASS = DiagnosticFactory0.create(ERROR);
+
     DiagnosticFactory0<KtTypeAlias> ACTUAL_TYPE_ALIAS_NOT_TO_CLASS = DiagnosticFactory0.create(ERROR, DECLARATION_SIGNATURE);
     DiagnosticFactory0<KtTypeAlias>
             ACTUAL_TYPE_ALIAS_TO_CLASS_WITH_DECLARATION_SITE_VARIANCE = DiagnosticFactory0.create(ERROR, DECLARATION_SIGNATURE);

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

@@ -274,6 +274,8 @@ public class DefaultErrorMessages {
         MAP.put(EXPECTED_LATEINIT_PROPERTY, "Expected property cannot be lateinit");
         MAP.put(SUPERTYPE_INITIALIZED_IN_EXPECTED_CLASS, "Expected classes cannot initialize supertypes");
 
+        MAP.put(IMPLEMENTATION_BY_DELEGATION_IN_EXPECT_CLASS, "Implementation by delegation in expected classes is prohibited");
+
         MAP.put(ACTUAL_TYPE_ALIAS_NOT_TO_CLASS, "Right-hand side of actual type alias should be a class, not another type alias");
         MAP.put(ACTUAL_TYPE_ALIAS_TO_CLASS_WITH_DECLARATION_SITE_VARIANCE, "Aliased class should not have type parameters with declaration-site variance");
         MAP.put(ACTUAL_TYPE_ALIAS_WITH_USE_SITE_VARIANCE, "Right-hand side of actual type alias cannot contain use-site variance or star projections");

compiler/frontend/src/org/jetbrains/kotlin/resolve/BodyResolver.java

@@ -304,7 +304,11 @@ public class BodyResolver {
                     KotlinType expectedType = supertype != null ? supertype : NO_EXPECTED_TYPE;
                     typeInferrer.getType(scope, delegateExpression, expectedType, outerDataFlowInfo, trace);
                 }
-                if (primaryConstructor == null) {
+
+                if (descriptor.isExpect()) {
+                    trace.report(IMPLEMENTATION_BY_DELEGATION_IN_EXPECT_CLASS.on(specifier));
+                }
+                else if (primaryConstructor == null) {
                     trace.report(UNSUPPORTED.on(specifier, "Delegation without primary constructor is not supported"));
                 }
             }

compiler/testData/diagnostics/tests/multiplatform/headerClass/inheritanceByDelegationInExpectClass.kt

@@ -0,0 +1,10 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+interface A
+
+class B : A
+expect class Foo(b: B) : <!IMPLEMENTATION_BY_DELEGATION_IN_EXPECT_CLASS!>A by b<!>
+
+expect class Bar : <!IMPLEMENTATION_BY_DELEGATION_IN_EXPECT_CLASS!>A by B()<!>

compiler/testData/diagnostics/tests/multiplatform/headerClass/inheritanceByDelegationInExpectClass.txt

@@ -0,0 +1,27 @@
+package
+
+public interface A {
+    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 B : A {
+    public constructor B()
+    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 expect class Bar : A {
+    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 expect class Foo : A {
+    public constructor Foo(/*0*/ b: B)
+    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/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java

@@ -14115,6 +14115,12 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                     doTest(fileName);
                 }
 
+                @TestMetadata("inheritanceByDelegationInExpectClass.kt")
+                public void testInheritanceByDelegationInExpectClass() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/multiplatform/headerClass/inheritanceByDelegationInExpectClass.kt");
+                    doTest(fileName);
+                }
+
                 @TestMetadata("memberPropertyKinds.kt")
                 public void testMemberPropertyKinds() throws Exception {
                     String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/multiplatform/headerClass/memberPropertyKinds.kt");

compiler/tests/org/jetbrains/kotlin/checkers/javac/DiagnosticsUsingJavacTestGenerated.java

@@ -14115,6 +14115,12 @@ public class DiagnosticsUsingJavacTestGenerated extends AbstractDiagnosticsUsing
                     doTest(fileName);
                 }
 
+                @TestMetadata("inheritanceByDelegationInExpectClass.kt")
+                public void testInheritanceByDelegationInExpectClass() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/multiplatform/headerClass/inheritanceByDelegationInExpectClass.kt");
+                    doTest(fileName);
+                }
+
                 @TestMetadata("memberPropertyKinds.kt")
                 public void testMemberPropertyKinds() throws Exception {
                     String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/multiplatform/headerClass/memberPropertyKinds.kt");