Unified obtaining psi element for descriptor. Now code for finding effective descriptors of fake override and finding source element for original declarations are separated. Old method DescriptorToSourceUtils.descriptorToDeclaration is still there, because it has ~90 usages.

idea/idea-analysis/src/org/jetbrains/kotlin/idea/codeInsight/DescriptorToDeclarationUtil.kt

@@ -18,38 +18,38 @@ package org.jetbrains.kotlin.idea.codeInsight
 
 import com.intellij.openapi.project.Project
 import com.intellij.psi.PsiElement
-import org.jetbrains.kotlin.descriptors.DeclarationDescriptor
 import org.jetbrains.kotlin.psi.JetFile
 import org.jetbrains.kotlin.resolve.DescriptorToSourceUtils
 import org.jetbrains.kotlin.idea.decompiler.navigation.DecompiledNavigationUtils
 import org.jetbrains.kotlin.idea.references.BuiltInsReferenceResolver
-import java.util.HashSet
-import org.jetbrains.kotlin.descriptors.PackageViewDescriptor
 import com.intellij.psi.JavaPsiFacade
 import org.jetbrains.kotlin.idea.search.allScope
 import org.jetbrains.kotlin.utils.addIfNotNull
+import org.jetbrains.kotlin.descriptors.CallableMemberDescriptor.Kind.*
+import java.util.*
+import org.jetbrains.kotlin.descriptors.*
 
+// TODO rename it it DescriptorToSourceIde
 public object DescriptorToDeclarationUtil {
     public fun getDeclaration(project: Project, descriptor: DeclarationDescriptor): PsiElement? {
-        var elements: Collection<PsiElement> = DescriptorToSourceUtils.descriptorToDeclarations(descriptor)
-        if (elements.isEmpty()) {
-            elements = findDecompiledAndBuiltInDeclarations(project, descriptor)
-        }
-
-        return elements.firstOrNull()
+        // TODO optimize it!
+        return resolveToPsiElements(project, descriptor).firstOrNull()
     }
 
     public fun resolveToPsiElements(project: Project, targetDescriptor: DeclarationDescriptor): Collection<PsiElement> {
         val result = HashSet<PsiElement>()
 
-        // todo: remove getOriginal()
-        val originalDescriptor = targetDescriptor.getOriginal()
-        result.addAll(DescriptorToSourceUtils.descriptorToDeclarations(originalDescriptor))
-        result.addAll(DescriptorToDeclarationUtil.findDecompiledAndBuiltInDeclarations(project, originalDescriptor))
+        val effectiveReferencedDescriptors: Collection<DeclarationDescriptor> = DescriptorToSourceUtils.getEffectiveReferencedDescriptors(targetDescriptor)
 
-        if (originalDescriptor is PackageViewDescriptor) {
+        for (descriptor in effectiveReferencedDescriptors) {
+            result.addIfNotNull(DescriptorToSourceUtils.getSourceFromDescriptor(descriptor))
+            result.addIfNotNull(findBuiltinDeclaration(project, descriptor))
+            result.addIfNotNull(DecompiledNavigationUtils.getDeclarationFromDecompiledClassFile(project, descriptor))
+        }
+
+        if (targetDescriptor is PackageViewDescriptor) {
             val psiFacade = JavaPsiFacade.getInstance(project)
-            val fqName = originalDescriptor.getFqName().asString()
+            val fqName = targetDescriptor.getFqName().asString()
             result.addIfNotNull(psiFacade.findPackage(fqName))
             result.addIfNotNull(psiFacade.findClass(fqName, project.allScope()))
         }
@@ -58,17 +58,8 @@ public object DescriptorToDeclarationUtil {
         return result.filter { element -> result.none { element != it && it.getNavigationElement() == element } }
     }
 
-    private fun findDecompiledAndBuiltInDeclarations(project: Project, descriptor: DeclarationDescriptor): Collection<PsiElement> {
+    private fun findBuiltinDeclaration(project: Project, descriptor: DeclarationDescriptor): PsiElement? {
         val libraryReferenceResolver = project.getComponent(javaClass<BuiltInsReferenceResolver>())
-        val elements = libraryReferenceResolver!!.resolveBuiltInSymbol(descriptor)
-        if (elements.isNotEmpty()) {
-            return elements
-        }
-
-        val decompiledDeclaration = DecompiledNavigationUtils.getDeclarationFromDecompiledClassFile(project, descriptor)
-        if (decompiledDeclaration != null) {
-            return setOf(decompiledDeclaration)
-        }
-        return setOf()
+        return libraryReferenceResolver!!.resolveBuiltInSymbol(descriptor)
     }
 }

idea/idea-analysis/src/org/jetbrains/kotlin/idea/decompiler/navigation/DecompiledNavigationUtils.java

@@ -45,8 +45,7 @@ public final class DecompiledNavigationUtils {
             @NotNull Project project,
             @NotNull DeclarationDescriptor referencedDescriptor
     ) {
-        DeclarationDescriptor effectiveReferencedDescriptor = getEffectiveReferencedDescriptor(referencedDescriptor);
-        VirtualFile virtualFile = findVirtualFileContainingDescriptor(project, effectiveReferencedDescriptor);
+        VirtualFile virtualFile = findVirtualFileContainingDescriptor(project, referencedDescriptor);
 
         if (virtualFile == null || !DecompilerPackage.isKotlinCompiledFile(virtualFile)) return null;
 
@@ -55,19 +54,9 @@ public final class DecompiledNavigationUtils {
             return null;
         }
 
-        return ((JetClsFile) psiFile).getDeclarationForDescriptor(effectiveReferencedDescriptor);
+        return ((JetClsFile) psiFile).getDeclarationForDescriptor(referencedDescriptor);
     }
 
-    //TODO: should be done via some generic mechanism
-    @NotNull
-    private static DeclarationDescriptor getEffectiveReferencedDescriptor(@NotNull DeclarationDescriptor descriptor) {
-        if (descriptor instanceof CallableMemberDescriptor) {
-            return DescriptorUtils.unwrapFakeOverride((CallableMemberDescriptor) descriptor);
-        }
-        return descriptor;
-    }
-
-
     /*
         Find virtual file which contains the declaration of descriptor we're navigating to.
      */

idea/idea-analysis/src/org/jetbrains/kotlin/idea/references/BuiltInsReferenceResolver.java

@@ -57,7 +57,6 @@ import java.net.MalformedURLException;
 import java.net.URL;
 import java.util.*;
 
-import static org.jetbrains.kotlin.resolve.DescriptorUtils.unwrapFakeOverride;
 import static org.jetbrains.kotlin.resolve.descriptorUtil.DescriptorUtilPackage.getClassId;
 import static org.jetbrains.kotlin.serialization.deserialization.DeserializationPackage.findClassAcrossModuleDependencies;
 
@@ -186,11 +185,6 @@ public class BuiltInsReferenceResolver extends AbstractProjectComponent {
 
     @Nullable
     private DeclarationDescriptor findCurrentDescriptorForMember(@NotNull MemberDescriptor originalDescriptor) {
-        if (originalDescriptor instanceof CallableMemberDescriptor &&
-            ((CallableMemberDescriptor) originalDescriptor).getKind() == CallableMemberDescriptor.Kind.FAKE_OVERRIDE) {
-            return findCurrentDescriptorForMember(unwrapFakeOverride((CallableMemberDescriptor) originalDescriptor).getOriginal());
-        }
-
         if (!isFromBuiltinModule(originalDescriptor)) return null;
 
         DeclarationDescriptor containingDeclaration = findCurrentDescriptor(originalDescriptor.getContainingDeclaration());
@@ -240,17 +234,17 @@ public class BuiltInsReferenceResolver extends AbstractProjectComponent {
         return KotlinBuiltIns.getInstance().getBuiltInsModule() == DescriptorUtils.getContainingModule(originalDescriptor);
     }
 
-    @NotNull
-    public Collection<PsiElement> resolveBuiltInSymbol(@NotNull DeclarationDescriptor declarationDescriptor) {
+    @Nullable
+    public PsiElement resolveBuiltInSymbol(@NotNull DeclarationDescriptor declarationDescriptor) {
         if (moduleDescriptor == null) {
-            return Collections.emptyList();
+            return null;
         }
 
-        DeclarationDescriptor descriptor = findCurrentDescriptor(declarationDescriptor.getOriginal());
+        DeclarationDescriptor descriptor = findCurrentDescriptor(declarationDescriptor);
         if (descriptor != null) {
-            return DescriptorToSourceUtils.descriptorToDeclarations(descriptor);
+            return DescriptorToSourceUtils.getSourceFromDescriptor(descriptor);
         }
-        return Collections.emptyList();
+        return null;
     }
 
     public static boolean isFromBuiltIns(@NotNull PsiElement element) {