Support platform/impl modifiers for classes

Do not report "unused parameter" for parameters of platform declarations. Do
not allow platform class constructors to have val/var parameters or have an
explicit delegation call to another constructor. Do not allow platform classes
to have 'init' blocks.

Also suppress the "supertype not initialized" error for platform classes: the
supertype should be initialized in the impl class

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

@@ -636,9 +636,8 @@ class ControlFlowInformationProvider private constructor(
         when (owner) {
             is KtPrimaryConstructor -> if (!element.hasValOrVar()) {
                 val containingClass = owner.getContainingClassOrObject()
-                val containingClassDescriptor = trace.get(
-                        DECLARATION_TO_DESCRIPTOR, containingClass)
-                if (!DescriptorUtils.isAnnotationClass(containingClassDescriptor)) {
+                val containingClassDescriptor = trace.get(DECLARATION_TO_DESCRIPTOR, containingClass) as? ClassDescriptor
+                if (!DescriptorUtils.isAnnotationClass(containingClassDescriptor) && containingClassDescriptor?.isPlatform == false) {
                     report(UNUSED_PARAMETER.on(element, variableDescriptor), ctxt)
                 }
             }
@@ -652,6 +651,7 @@ class ControlFlowInformationProvider private constructor(
                 if (isMain
                     || functionDescriptor.isOverridableOrOverrides
                     || owner.hasModifier(KtTokens.OVERRIDE_KEYWORD)
+                    || functionDescriptor.isPlatform || functionDescriptor.isImpl
                     || OperatorNameConventions.GET_VALUE == functionName
                     || OperatorNameConventions.SET_VALUE == functionName
                     || OperatorNameConventions.PROPERTY_DELEGATED == functionName) {

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

@@ -493,7 +493,8 @@ public interface Errors {
 
     DiagnosticFactory0<KtDeclaration> PLATFORM_DECLARATION_WITH_BODY = DiagnosticFactory0.create(ERROR, DECLARATION_SIGNATURE);
     DiagnosticFactory0<KtParameter> PLATFORM_DECLARATION_WITH_DEFAULT_PARAMETER = DiagnosticFactory0.create(ERROR);
-
+    DiagnosticFactory0<KtConstructorDelegationCall> PLATFORM_CLASS_CONSTRUCTOR_DELEGATION_CALL = DiagnosticFactory0.create(ERROR);
+    DiagnosticFactory0<KtParameter> PLATFORM_CLASS_CONSTRUCTOR_PROPERTY_PARAMETER = DiagnosticFactory0.create(ERROR);
     DiagnosticFactory0<KtExpression> PLATFORM_PROPERTY_INITIALIZER = DiagnosticFactory0.create(ERROR);
 
     ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

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

@@ -259,7 +259,8 @@ public class DefaultErrorMessages {
 
         MAP.put(PLATFORM_DECLARATION_WITH_BODY, "Platform declaration must not have a body");
         MAP.put(PLATFORM_DECLARATION_WITH_DEFAULT_PARAMETER, "Platform declaration cannot have parameters with default values");
-
+        MAP.put(PLATFORM_CLASS_CONSTRUCTOR_DELEGATION_CALL, "Explicit delegation call for constructor of a platform class is not allowed");
+        MAP.put(PLATFORM_CLASS_CONSTRUCTOR_PROPERTY_PARAMETER, "Platform class constructor cannot have a property parameter");
         MAP.put(PLATFORM_PROPERTY_INITIALIZER, "Platform property cannot have an initializer");
 
         MAP.put(PROJECTION_ON_NON_CLASS_TYPE_ARGUMENT, "Projections are not allowed on type arguments of functions and properties");

compiler/frontend/src/org/jetbrains/kotlin/psi/KtConstructorDelegationCall.java

@@ -20,6 +20,7 @@ import com.intellij.lang.ASTNode;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.jetbrains.kotlin.KtNodeTypes;
+import org.jetbrains.kotlin.parsing.KotlinParsing;
 
 import java.util.Collections;
 import java.util.List;
@@ -65,6 +66,14 @@ public class KtConstructorDelegationCall extends KtElementImpl implements KtCall
         return findChildByClass(KtConstructorDelegationReferenceExpression.class);
     }
 
+    /**
+     * @return true if this delegation call is not present in the source code. Note that we always parse delegation calls
+     * for secondary constructors, even if there's no explicit call in the source (see {@link KotlinParsing#parseSecondaryConstructor}).
+     *
+     *     class Foo {
+     *         constructor(name: String)   // <--- implicit constructor delegation call (empty element after RPAR)
+     *     }
+     */
     public boolean isImplicit() {
         KtConstructorDelegationReferenceExpression callee = getCalleeExpression();
         return callee != null && callee.getFirstChild() == null;

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

@@ -169,6 +169,11 @@ public class BodyResolver {
             @NotNull KtSecondaryConstructor constructor,
             @NotNull ClassConstructorDescriptor descriptor
     ) {
+        if (descriptor.isPlatform()) {
+            // For platform classes, we do not resolve constructor delegation calls because they are prohibited
+            return DataFlowInfo.Companion.getEMPTY();
+        }
+
         OverloadResolutionResults<?> results = callResolver.resolveConstructorDelegationCall(
                 trace, scope, outerDataFlowInfo,
                 descriptor, constructor.getDelegationCall());
@@ -362,6 +367,7 @@ public class BodyResolver {
                     descriptor.getUnsubstitutedPrimaryConstructor() != null &&
                     superClass.getKind() != ClassKind.INTERFACE &&
                     !superClass.getConstructors().isEmpty() &&
+                    !descriptor.isPlatform() &&
                     !ErrorUtils.isError(superClass)
                 ) {
                     trace.report(SUPERTYPE_NOT_INITIALIZED.on(specifier));
@@ -556,6 +562,9 @@ public class BodyResolver {
         if (classDescriptor.getConstructors().isEmpty()) {
             trace.report(ANONYMOUS_INITIALIZER_IN_INTERFACE.on(anonymousInitializer));
         }
+        if (classDescriptor.isPlatform()) {
+            trace.report(PLATFORM_DECLARATION_WITH_BODY.on(anonymousInitializer));
+        }
     }
 
     private void processModifiersOnInitializer(@NotNull KtModifierListOwner owner, @NotNull LexicalScope scope) {

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

@@ -228,12 +228,36 @@ class DeclarationsChecker(
         TypeAliasExpander(reportStrategy).expandWithoutAbbreviation(typeAliasExpansion, Annotations.EMPTY)
     }
 
-    private fun checkConstructorDeclaration(constructorDescriptor: ClassConstructorDescriptor, declaration: KtDeclaration) {
+    private fun checkConstructorDeclaration(constructorDescriptor: ClassConstructorDescriptor, declaration: KtConstructor<*>) {
         declaration.checkTypeReferences()
         modifiersChecker.checkModifiersForDeclaration(declaration, constructorDescriptor)
         identifierChecker.checkDeclaration(declaration, trace)
         checkVarargParameters(trace, constructorDescriptor)
         checkConstructorVisibility(constructorDescriptor, declaration)
+        checkPlatformClassConstructor(constructorDescriptor, declaration)
+    }
+
+    private fun checkPlatformClassConstructor(constructorDescriptor: ClassConstructorDescriptor, declaration: KtConstructor<*>) {
+        if (!constructorDescriptor.isPlatform) return
+
+        if (declaration.hasBody()) {
+            trace.report(PLATFORM_DECLARATION_WITH_BODY.on(declaration))
+        }
+
+        if (declaration is KtPrimaryConstructor && !DescriptorUtils.isAnnotationClass(constructorDescriptor.constructedClass)) {
+            for (parameter in declaration.valueParameters) {
+                if (parameter.hasValOrVar()) {
+                    trace.report(PLATFORM_CLASS_CONSTRUCTOR_PROPERTY_PARAMETER.on(parameter))
+                }
+            }
+        }
+
+        if (declaration is KtSecondaryConstructor) {
+            val delegationCall = declaration.getDelegationCall()
+            if (!delegationCall.isImplicit) {
+                trace.report(PLATFORM_CLASS_CONSTRUCTOR_DELEGATION_CALL.on(delegationCall))
+            }
+        }
     }
 
     private fun checkConstructorVisibility(constructorDescriptor: ClassConstructorDescriptor, declaration: KtDeclaration) {
@@ -711,6 +735,7 @@ class DeclarationsChecker(
 
         if (containingDescriptor is ClassDescriptor) {
             val inInterface = containingDescriptor.kind == ClassKind.INTERFACE
+            val isPlatformClass = containingDescriptor.isPlatform
             if (hasAbstractModifier && !classCanHaveAbstractMembers(containingDescriptor)) {
                 trace.report(ABSTRACT_FUNCTION_IN_NON_ABSTRACT_CLASS.on(function, functionDescriptor.name.asString(), containingDescriptor))
             }
@@ -726,7 +751,7 @@ class DeclarationsChecker(
                     trace.report(REDUNDANT_OPEN_IN_INTERFACE.on(function))
                 }
             }
-            if (!hasBody && !hasAbstractModifier && !hasExternalModifier && !inInterface) {
+            if (!hasBody && !hasAbstractModifier && !hasExternalModifier && !inInterface && !isPlatformClass) {
                 trace.report(NON_ABSTRACT_FUNCTION_WITH_NO_BODY.on(function, functionDescriptor))
             }
         }

compiler/testData/diagnostics/tests/multiplatform/platformClass/classKinds.kt

@@ -0,0 +1,26 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+platform interface Interface
+
+platform annotation class Anno(val prop: String)
+
+platform object Object
+
+platform class Class
+
+platform enum class En { ENTRY }
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+
+impl interface Interface
+
+impl annotation class Anno(val prop: String)
+
+impl object Object
+
+impl class Class
+
+impl enum class En { ENTRY }

compiler/testData/diagnostics/tests/multiplatform/platformClass/classKinds.txt

@@ -0,0 +1,98 @@
+// -- Module: <m1-common> --
+package
+
+public final platform annotation class Anno : kotlin.Annotation {
+    public constructor Anno(/*0*/ prop: kotlin.String)
+    public final val prop: 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 platform class Class {
+    public constructor Class()
+    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 platform enum class En : kotlin.Enum<En> {
+    enum entry ENTRY
+
+    private constructor En()
+    public final override /*1*/ /*fake_override*/ val name: kotlin.String
+    public final override /*1*/ /*fake_override*/ val ordinal: kotlin.Int
+    protected final override /*1*/ /*fake_override*/ fun clone(): kotlin.Any
+    public final override /*1*/ /*fake_override*/ fun compareTo(/*0*/ other: En): kotlin.Int
+    public final override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public final override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+
+    // Static members
+    public final /*synthesized*/ fun valueOf(/*0*/ value: kotlin.String): En
+    public final /*synthesized*/ fun values(): kotlin.Array<En>
+}
+
+public platform interface Interface {
+    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 platform object Object {
+    private constructor Object()
+    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
+}
+
+
+// -- Module: <m2-jvm> --
+package
+
+public final impl annotation class Anno : kotlin.Annotation {
+    public constructor Anno(/*0*/ prop: kotlin.String)
+    public final val prop: 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 impl class Class {
+    public constructor Class()
+    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 impl enum class En : kotlin.Enum<En> {
+    enum entry ENTRY
+
+    private constructor En()
+    public final override /*1*/ /*fake_override*/ val name: kotlin.String
+    public final override /*1*/ /*fake_override*/ val ordinal: kotlin.Int
+    protected final override /*1*/ /*fake_override*/ fun clone(): kotlin.Any
+    public final override /*1*/ /*fake_override*/ fun compareTo(/*0*/ other: En): kotlin.Int
+    public final override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    protected/*protected and package*/ final override /*1*/ /*fake_override*/ /*isHiddenForResolutionEverywhereBesideSupercalls*/ fun finalize(): kotlin.Unit
+    public final override /*1*/ /*fake_override*/ /*isHiddenForResolutionEverywhereBesideSupercalls*/ fun getDeclaringClass(): java.lang.Class<En!>!
+    public final override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+
+    // Static members
+    public final /*synthesized*/ fun valueOf(/*0*/ value: kotlin.String): En
+    public final /*synthesized*/ fun values(): kotlin.Array<En>
+}
+
+public impl interface Interface {
+    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 impl object Object {
+    private constructor Object()
+    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/multiplatform/platformClass/explicitConstructorDelegation.kt

@@ -0,0 +1,14 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+platform open class A {
+    constructor(s: String)
+
+    constructor(n: Number) : <!PLATFORM_CLASS_CONSTRUCTOR_DELEGATION_CALL!>this<!>("A")
+}
+
+platform class B : A {
+    constructor(i: Int)
+
+    constructor() : <!PLATFORM_CLASS_CONSTRUCTOR_DELEGATION_CALL!>super<!>("B")
+}

compiler/testData/diagnostics/tests/multiplatform/platformClass/explicitConstructorDelegation.txt

@@ -0,0 +1,17 @@
+package
+
+public open platform class A {
+    public constructor A(/*0*/ n: kotlin.Number)
+    public constructor A(/*0*/ s: 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 platform class B : A {
+    public constructor B()
+    public constructor B(/*0*/ i: 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/multiplatform/platformClass/platformClassMember.kt

@@ -0,0 +1,24 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+platform class Foo {
+    val foo: String
+
+    fun bar(x: Int): Int
+}
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+class Foo {
+    val foo: String = "JVM"
+
+    fun bar(x: Int): Int = x + 1
+}
+
+// MODULE: m3-js(m1-common)
+// FILE: js.kt
+class Foo {
+    val foo: String = "JS"
+
+    fun bar(x: Int): Int = x - 1
+}

compiler/testData/diagnostics/tests/multiplatform/platformClass/platformClassMember.txt

@@ -0,0 +1,37 @@
+// -- Module: <m1-common> --
+package
+
+public final platform class Foo {
+    public constructor Foo()
+    public final val foo: kotlin.String
+    public final platform fun bar(/*0*/ x: kotlin.Int): 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
+}
+
+
+// -- Module: <m2-jvm> --
+package
+
+public final class Foo {
+    public constructor Foo()
+    public final val foo: kotlin.String = "JVM"
+    public final fun bar(/*0*/ x: kotlin.Int): 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
+}
+
+
+// -- Module: <m3-js> --
+package
+
+public final class Foo {
+    public constructor Foo()
+    public final val foo: kotlin.String = "JS"
+    public final fun bar(/*0*/ x: kotlin.Int): 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/multiplatform/platformClass/platformClassWithFunctionBody.kt

@@ -0,0 +1,29 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+platform class Foo(
+        <!PLATFORM_CLASS_CONSTRUCTOR_PROPERTY_PARAMETER!>val constructorProperty: String<!>,
+        constructorParameter: String
+) {
+    <!PLATFORM_DECLARATION_WITH_BODY!>init<!> {
+        <!UNUSED_EXPRESSION, UNUSED_EXPRESSION!>"no"<!>
+    }
+
+    <!PLATFORM_DECLARATION_WITH_BODY!>constructor(s: String)<!> {
+        <!UNUSED_EXPRESSION!>"no"<!>
+    }
+
+    constructor() : <!PLATFORM_CLASS_CONSTRUCTOR_DELEGATION_CALL!>this<!>("no")
+
+    val prop: String = <!PLATFORM_PROPERTY_INITIALIZER!>"no"<!>
+
+    var getSet: String
+        <!PLATFORM_DECLARATION_WITH_BODY!>get()<!> = "no"
+        <!PLATFORM_DECLARATION_WITH_BODY!>set(value)<!> {}
+
+    fun defaultArg(<!PLATFORM_DECLARATION_WITH_DEFAULT_PARAMETER!>value: String = "no"<!>)
+
+    <!PLATFORM_DECLARATION_WITH_BODY!>fun functionWithBody(x: Int): Int<!> {
+        return x + 1
+    }
+}

compiler/testData/diagnostics/tests/multiplatform/platformClass/platformClassWithFunctionBody.txt

@@ -0,0 +1,15 @@
+package
+
+public final platform class Foo {
+    public constructor Foo()
+    public constructor Foo(/*0*/ s: kotlin.String)
+    public constructor Foo(/*0*/ constructorProperty: kotlin.String, /*1*/ constructorParameter: kotlin.String)
+    public final val constructorProperty: kotlin.String
+    public final var getSet: kotlin.String
+    public final val prop: kotlin.String = "no"
+    public final platform fun defaultArg(/*0*/ value: kotlin.String = ...): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public final platform fun functionWithBody(/*0*/ x: kotlin.Int): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

compiler/testData/diagnostics/tests/multiplatform/platformClass/simplePlatformClass.kt

@@ -0,0 +1,12 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+platform class Foo
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+class Foo
+
+// MODULE: m3-js(m1-common)
+// FILE: js.kt
+class Foo

compiler/testData/diagnostics/tests/multiplatform/platformClass/simplePlatformClass.txt

@@ -0,0 +1,31 @@
+// -- Module: <m1-common> --
+package
+
+public final platform class Foo {
+    public constructor Foo()
+    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
+}
+
+
+// -- Module: <m2-jvm> --
+package
+
+public final class Foo {
+    public constructor Foo()
+    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
+}
+
+
+// -- Module: <m3-js> --
+package
+
+public final class Foo {
+    public constructor Foo()
+    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/multiplatform/platformClass/superClass.kt

@@ -0,0 +1,17 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+interface I
+open class C
+interface J
+
+platform class Foo : I, C, J
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+class Foo : I, C(), J
+
+// MODULE: m3-js(m1-common)
+// FILE: js.kt
+class Foo : I, J, C()

compiler/testData/diagnostics/tests/multiplatform/platformClass/superClass.txt

@@ -0,0 +1,88 @@
+// -- Module: <m1-common> --
+package
+
+public open class C {
+    public constructor C()
+    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 platform class Foo : I, C, J {
+    public constructor Foo()
+    public open override /*3*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*3*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*3*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface I {
+    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 J {
+    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
+}
+
+
+// -- Module: <m2-jvm> --
+package
+
+public open class C {
+    public constructor C()
+    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 Foo : I, C, J {
+    public constructor Foo()
+    public open override /*3*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*3*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*3*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface I {
+    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 J {
+    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
+}
+
+
+// -- Module: <m3-js> --
+package
+
+public open class C {
+    public constructor C()
+    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 Foo : I, J, C {
+    public constructor Foo()
+    public open override /*3*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*3*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*3*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface I {
+    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 J {
+    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/sourceCompatibility/noMultiplatformProjects.kt

@@ -0,0 +1,7 @@
+<!UNSUPPORTED_FEATURE!>platform<!> fun foo1()
+<!UNSUPPORTED_FEATURE!>platform<!> val bar1 = <!PLATFORM_PROPERTY_INITIALIZER!>42<!>
+<!UNSUPPORTED_FEATURE!>platform<!> class Baz1
+
+<!UNSUPPORTED_FEATURE!>impl<!> fun foo2() = 42
+<!MUST_BE_INITIALIZED!><!UNSUPPORTED_FEATURE!>impl<!> val bar2: Int<!>
+<!UNSUPPORTED_FEATURE!>impl<!> interface Baz2

compiler/testData/diagnostics/tests/sourceCompatibility/noMultiplatformProjects.txt

@@ -0,0 +1,10 @@
+package
+
+public val bar2: kotlin.Int
+public impl fun foo2(): kotlin.Int
+
+public impl interface Baz2 {
+    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

@@ -12556,6 +12556,51 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                 KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/diagnostics/tests/multiplatform"), Pattern.compile("^(.+)\\.kt$"), TargetBackend.ANY, true);
             }
 
+            @TestMetadata("compiler/testData/diagnostics/tests/multiplatform/platformClass")
+            @TestDataPath("$PROJECT_ROOT")
+            @RunWith(JUnit3RunnerWithInners.class)
+            public static class PlatformClass extends AbstractDiagnosticsTest {
+                public void testAllFilesPresentInPlatformClass() throws Exception {
+                    KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/diagnostics/tests/multiplatform/platformClass"), Pattern.compile("^(.+)\\.kt$"), TargetBackend.ANY, true);
+                }
+
+                @TestMetadata("classKinds.kt")
+                public void testClassKinds() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/multiplatform/platformClass/classKinds.kt");
+                    doTest(fileName);
+                }
+
+                @TestMetadata("explicitConstructorDelegation.kt")
+                public void testExplicitConstructorDelegation() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/multiplatform/platformClass/explicitConstructorDelegation.kt");
+                    doTest(fileName);
+                }
+
+                @TestMetadata("platformClassMember.kt")
+                public void testPlatformClassMember() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/multiplatform/platformClass/platformClassMember.kt");
+                    doTest(fileName);
+                }
+
+                @TestMetadata("platformClassWithFunctionBody.kt")
+                public void testPlatformClassWithFunctionBody() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/multiplatform/platformClass/platformClassWithFunctionBody.kt");
+                    doTest(fileName);
+                }
+
+                @TestMetadata("simplePlatformClass.kt")
+                public void testSimplePlatformClass() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/multiplatform/platformClass/simplePlatformClass.kt");
+                    doTest(fileName);
+                }
+
+                @TestMetadata("superClass.kt")
+                public void testSuperClass() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/multiplatform/platformClass/superClass.kt");
+                    doTest(fileName);
+                }
+            }
+
             @TestMetadata("compiler/testData/diagnostics/tests/multiplatform/topLevelFun")
             @TestDataPath("$PROJECT_ROOT")
             @RunWith(JUnit3RunnerWithInners.class)
@@ -19891,6 +19936,12 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("noMultiplatformProjects.kt")
+            public void testNoMultiplatformProjects() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/sourceCompatibility/noMultiplatformProjects.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("noTopLevelSealedInheritance.kt")
             public void testNoTopLevelSealedInheritance() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/sourceCompatibility/noTopLevelSealedInheritance.kt");