Multiplatform Project: Fix impl-by-header search and vice versa

idea/src/org/jetbrains/kotlin/idea/highlighter/markers/DeclaredHeaderMarker.kt

@@ -50,14 +50,7 @@ fun ModuleDescriptor.hasDeclarationOf(descriptor: MemberDescriptor) = declaratio
 
 private fun ModuleDescriptor.declarationOf(descriptor: MemberDescriptor): DeclarationDescriptor? =
         with (HeaderImplDeclarationChecker(this)) {
-            when (descriptor) {
-                is CallableMemberDescriptor ->
-                    descriptor.findNamesakesFromTheSameModule().filter { it.isHeader }.firstOrNull()
-                is ClassifierDescriptorWithTypeParameters ->
-                    descriptor.findClassifiersFromTheSameModule().filter { it is ClassDescriptor && it.isHeader }.firstOrNull()
-                else ->
-                    null
-            }
+            descriptor.findCompatibleDescriptors().firstOrNull { it.isHeader }
         }
 
 fun getHeaderDeclarationTooltip(declaration: KtDeclaration): String? {
@@ -87,4 +80,4 @@ internal fun KtDeclaration.liftToHeader(): KtDeclaration? {
         hasModifier(KtTokens.IMPL_KEYWORD) -> headerDeclarationIfAny()
         else -> null
     }
-}
+}

idea/src/org/jetbrains/kotlin/idea/highlighter/markers/ImplementedHeaderMarker.kt

@@ -33,11 +33,7 @@ fun ModuleDescriptor.hasImplementationsOf(descriptor: MemberDescriptor) =
 
 private fun ModuleDescriptor.implementationsOf(descriptor: MemberDescriptor): List<DeclarationDescriptor> =
         with (HeaderImplDeclarationChecker(this)) {
-            when (descriptor) {
-                is CallableMemberDescriptor -> descriptor.findNamesakesFromTheSameModule().filter { it.isImpl }
-                is ClassDescriptor -> descriptor.findClassifiersFromTheSameModule().filter { it.isImpl }
-                else -> emptyList()
-            }
+            descriptor.findCompatibleDescriptors().filter { it.isImpl }
         }
 
 fun getPlatformImplementationTooltip(declaration: KtDeclaration): String? {