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

compiler/frontend/src/org/jetbrains/kotlin/resolve/checkers/HeaderImplDeclarationChecker.kt

@@ -71,7 +71,19 @@ class HeaderImplDeclarationChecker(val moduleToCheck: ModuleDescriptor? = null)
     fun checkHeaderDeclarationHasImplementation(
             reportOn: KtDeclaration, descriptor: MemberDescriptor, diagnosticHolder: DiagnosticSink, checkImpl: Boolean
     ) {
-        val compatibility = when (descriptor) {
+        val compatibility = buildCompatibilityMap(descriptor, checkImpl)
+
+        if (compatibility != null && !compatibility.containsKey(Compatible)) {
+            assert(compatibility.keys.all { it is Incompatible })
+            @Suppress("UNCHECKED_CAST")
+            val incompatibility = compatibility as Map<Incompatible, Collection<MemberDescriptor>>
+            diagnosticHolder.report(Errors.HEADER_WITHOUT_IMPLEMENTATION.on(
+                    reportOn, descriptor, moduleToCheck ?: descriptor.module, incompatibility))
+        }
+    }
+
+    private fun buildCompatibilityMap(descriptor: MemberDescriptor, checkImpl: Boolean): Map<Compatibility, List<MemberDescriptor>>? {
+        return when (descriptor) {
             is CallableMemberDescriptor -> {
                 descriptor.findNamesakesFromTheSameModule().filter { impl ->
                     descriptor != impl &&
@@ -91,14 +103,6 @@ class HeaderImplDeclarationChecker(val moduleToCheck: ModuleDescriptor? = null)
             }
             else -> null
         }
-
-        if (compatibility != null && !compatibility.containsKey(Compatible)) {
-            assert(compatibility.keys.all { it is Incompatible })
-            @Suppress("UNCHECKED_CAST")
-            val incompatibility = compatibility as Map<Incompatible, Collection<MemberDescriptor>>
-            diagnosticHolder.report(Errors.HEADER_WITHOUT_IMPLEMENTATION.on(
-                    reportOn, descriptor, moduleToCheck ?: descriptor.module, incompatibility))
-        }
     }
 
     private fun checkImplementationHasHeaderDeclaration(
@@ -144,7 +148,9 @@ class HeaderImplDeclarationChecker(val moduleToCheck: ModuleDescriptor? = null)
         }
     }
 
-    fun CallableMemberDescriptor.findNamesakesFromTheSameModule(): Collection<CallableMemberDescriptor> {
+    fun MemberDescriptor.findCompatibleDescriptors() = buildCompatibilityMap(this, false)?.get(Compatible) ?: emptyList()
+
+    private fun CallableMemberDescriptor.findNamesakesFromTheSameModule(): Collection<CallableMemberDescriptor> {
         val packageFqName = (containingDeclaration as? PackageFragmentDescriptor)?.fqName ?: return emptyList()
         val myModule = moduleToCheck ?: module
         val scope = myModule.getPackage(packageFqName).memberScope
@@ -156,7 +162,7 @@ class HeaderImplDeclarationChecker(val moduleToCheck: ModuleDescriptor? = null)
         } // TODO: only obtain descriptors from our module to start with
     }
 
-    fun ClassifierDescriptorWithTypeParameters.findClassifiersFromTheSameModule(): Collection<ClassifierDescriptorWithTypeParameters> {
+    private fun ClassifierDescriptorWithTypeParameters.findClassifiersFromTheSameModule(): Collection<ClassifierDescriptorWithTypeParameters> {
         val myModule = moduleToCheck ?: module
         val classId = classId ?: return emptyList()
 

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) {
+            descriptor.findCompatibleDescriptors().firstOrNull { it.isHeader }
-                is CallableMemberDescriptor ->
-                    descriptor.findNamesakesFromTheSameModule().filter { it.isHeader }.firstOrNull()
-                is ClassifierDescriptorWithTypeParameters ->
-                    descriptor.findClassifiersFromTheSameModule().filter { it is ClassDescriptor && it.isHeader }.firstOrNull()
-                else ->
-                    null
-            }
         }
 
 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) {
+            descriptor.findCompatibleDescriptors().filter { it.isImpl }
-                is CallableMemberDescriptor -> descriptor.findNamesakesFromTheSameModule().filter { it.isImpl }
-                is ClassDescriptor -> descriptor.findClassifiersFromTheSameModule().filter { it.isImpl }
-                else -> emptyList()
-            }
         }
 
 fun getPlatformImplementationTooltip(declaration: KtDeclaration): String? {