KT-18538 Unwrap fake override in ShortenReferences

- Fake override prevents reference shortener from shortening of static
methods declared in the class bases when they are located not in
direct parent of the class (for example, in grand-
or grand-grand-parent)
- The completion uses descriptor with unwrapped fake override when it
performs the insertion. It leads to inserting the name of the base which
actually contains the static method instead of the direct parent class.
Now, when reference shortener compares unwrapped descriptors, this
problem should be fixed during insertion handling

idea/idea-completion/src/org/jetbrains/kotlin/idea/completion/BasicLookupElementFactory.kt

@@ -19,6 +19,7 @@ import org.jetbrains.kotlin.idea.completion.handlers.KotlinClassifierInsertHandl
 import org.jetbrains.kotlin.idea.completion.handlers.KotlinFunctionInsertHandler
 import org.jetbrains.kotlin.idea.core.completion.DeclarationLookupObject
 import org.jetbrains.kotlin.idea.core.completion.PackageLookupObject
+import org.jetbrains.kotlin.idea.core.unwrapIfFakeOverride
 import org.jetbrains.kotlin.idea.highlighter.dsl.DslHighlighterExtension
 import org.jetbrains.kotlin.load.java.JvmAbi
 import org.jetbrains.kotlin.load.java.descriptors.JavaClassDescriptor
@@ -51,10 +52,7 @@ class BasicLookupElementFactory(
         includeClassTypeArguments: Boolean = true,
         parametersAndTypeGrayed: Boolean = false
     ): LookupElement {
-        val _descriptor = if (descriptor is CallableMemberDescriptor)
-            DescriptorUtils.unwrapFakeOverride(descriptor)
-        else
-            descriptor
+        val _descriptor = descriptor.unwrapIfFakeOverride()
         return createLookupElementUnwrappedDescriptor(_descriptor, qualifyNestedClasses, includeClassTypeArguments, parametersAndTypeGrayed)
     }
 

idea/idea-completion/testData/handlers/multifile/StaticMethodFromGrandParent-1.java

@@ -0,0 +1,2 @@
+public class Base extends GrandBase {
+}

idea/idea-completion/testData/handlers/multifile/StaticMethodFromGrandParent-1.kt

@@ -0,0 +1,5 @@
+class Inheritor : Base() {
+    init {
+        fooBa<caret>
+    }
+}

idea/idea-completion/testData/handlers/multifile/StaticMethodFromGrandParent-2.java

@@ -0,0 +1,3 @@
+public class GrandBase {
+    public static void fooBar() {}
+}

idea/idea-completion/testData/handlers/multifile/StaticMethodFromGrandParent.kt.after

@@ -0,0 +1,5 @@
+class Inheritor : Base() {
+    init {
+        fooBar()
+    }
+}

idea/idea-completion/tests/org/jetbrains/kotlin/idea/completion/test/handlers/CompletionMultifileHandlerTest.kt

@@ -30,6 +30,10 @@ class CompletionMultiFileHandlerTest : KotlinCompletionTestCase() {
         doTest()
     }
 
+    fun testStaticMethodFromGrandParent() {
+        doTest('\n', "StaticMethodFromGrandParent-1.java", "StaticMethodFromGrandParent-2.java")
+    }
+
     fun testTopLevelFunctionImport() {
         doTest()
     }
@@ -113,8 +117,13 @@ class CompletionMultiFileHandlerTest : KotlinCompletionTestCase() {
     fun doTest(completionChar: Char = '\n', vararg extraFileNames: String, tailText: String? = null) {
         val fileName = getTestName(false)
 
+        val defaultFiles = listOf("$fileName-1.kt", "$fileName-2.kt")
+        val filteredFiles = defaultFiles.filter { File(testDataPath, it).exists() }
+
+        require(filteredFiles.isNotEmpty()) { "At least one of $defaultFiles should exist!" }
+
         configureByFiles(null, *extraFileNames)
-        configureByFiles(null, "$fileName-1.kt", "$fileName-2.kt")
+        configureByFiles(null, *filteredFiles.toTypedArray())
         complete(2)
         if (myItems != null) {
             val item = if (tailText == null)