Define applicability for platform/impl modifiers

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

@@ -90,8 +90,8 @@ object ModifierCheckerCore {
             CONST_KEYWORD     to EnumSet.of(MEMBER_PROPERTY, TOP_LEVEL_PROPERTY),
             OPERATOR_KEYWORD  to EnumSet.of(FUNCTION),
             INFIX_KEYWORD     to EnumSet.of(FUNCTION),
-            PLATFORM_KEYWORD  to EnumSet.of(FUNCTION, TOP_LEVEL_PROPERTY_WITHOUT_FIELD_OR_DELEGATE, CLASS_ONLY, OBJECT, INTERFACE, INNER_CLASS, ENUM_CLASS, ANNOTATION_CLASS), // TODO
-            IMPL_KEYWORD      to EnumSet.of(FUNCTION, TOP_LEVEL_PROPERTY_WITHOUT_FIELD_OR_DELEGATE, CLASS_ONLY, OBJECT, INTERFACE, INNER_CLASS, ENUM_CLASS, ANNOTATION_CLASS) // TODO
+            PLATFORM_KEYWORD  to EnumSet.of(TOP_LEVEL_FUNCTION, TOP_LEVEL_PROPERTY_WITHOUT_FIELD_OR_DELEGATE, CLASS_ONLY, OBJECT, INTERFACE, INNER_CLASS, ENUM_CLASS, ANNOTATION_CLASS),
+            IMPL_KEYWORD      to EnumSet.of(TOP_LEVEL_FUNCTION, MEMBER_FUNCTION, TOP_LEVEL_PROPERTY, MEMBER_PROPERTY, CONSTRUCTOR, CLASS_ONLY, OBJECT, INTERFACE, INNER_CLASS, ENUM_CLASS, ANNOTATION_CLASS, TYPEALIAS)
     )
 
     val featureDependencies = mapOf(

compiler/testData/diagnostics/tests/multiplatform/modifierApplicability.kt

@@ -0,0 +1,35 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+<!WRONG_MODIFIER_TARGET!>platform<!> typealias Foo = String
+
+class Outer <!WRONG_MODIFIER_TARGET!>platform<!> constructor() {
+    platform class Nested
+
+    <!WRONG_MODIFIER_TARGET!>platform<!> init {}
+
+    <!NON_ABSTRACT_FUNCTION_WITH_NO_BODY!><!WRONG_MODIFIER_TARGET!>platform<!> fun foo()<!>
+    <!WRONG_MODIFIER_TARGET!>platform<!> val bar: Int
+}
+
+fun foo() {
+    <!WRONG_MODIFIER_TARGET!>platform<!> fun localFun()
+    <!WRONG_MODIFIER_TARGET!>platform<!> var <!UNUSED_VARIABLE!>x<!> = 42
+    <!WRONG_MODIFIER_TARGET!>platform<!> class Bar
+}
+
+// MODULE: m2-jvm
+// FILE: jvm.kt
+
+class Outer impl constructor() {
+    <!PLATFORM_DEFINITION_WITHOUT_DECLARATION!>impl<!> class Nested
+
+    <!WRONG_MODIFIER_TARGET!>impl<!> init {}
+}
+
+fun foo() {
+    <!WRONG_MODIFIER_TARGET!>impl<!> fun localFun() {}
+    <!WRONG_MODIFIER_TARGET!>impl<!> var <!UNUSED_VARIABLE!>x<!> = 42
+    <!PLATFORM_DEFINITION_WITHOUT_DECLARATION, WRONG_MODIFIER_TARGET!>impl<!> class Bar
+}

compiler/testData/diagnostics/tests/multiplatform/modifierApplicability.txt

@@ -0,0 +1,41 @@
+// -- Module: <m1-common> --
+package
+
+public fun foo(): kotlin.Unit
+
+public final class Outer {
+    public constructor Outer()
+    public final val bar: kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public final platform fun foo(): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+
+    public final platform class Nested {
+        public constructor Nested()
+        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 typealias Foo = kotlin.String
+
+
+// -- Module: <m2-jvm> --
+package
+
+public fun foo(): kotlin.Unit
+
+public final class Outer {
+    public constructor Outer()
+    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 Nested {
+        public constructor Nested()
+        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 +12556,12 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                 KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/diagnostics/tests/multiplatform"), Pattern.compile("^(.+)\\.kt$"), TargetBackend.ANY, true);
             }
 
+            @TestMetadata("modifierApplicability.kt")
+            public void testModifierApplicability() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/multiplatform/modifierApplicability.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("compiler/testData/diagnostics/tests/multiplatform/platformClass")
             @TestDataPath("$PROJECT_ROOT")
             @RunWith(JUnit3RunnerWithInners.class)