KT-8716 Exception on attempt to implement function

#KT-8716 Fixed

idea/idea-core/src/org/jetbrains/kotlin/idea/core/overrideImplement/ImplementMethodsHandler.kt

@@ -27,7 +27,7 @@ import org.jetbrains.kotlin.resolve.OverrideResolver
 public class ImplementMethodsHandler : OverrideImplementMethodsHandler(), IntentionAction {
     override fun collectMethodsToGenerate(descriptor: ClassDescriptor, project: Project): Collection<OverrideMemberChooserObject> {
         return OverrideResolver.getMissingImplementations(descriptor)
-                .map { OverrideMemberChooserObject(project, it, it) }
+                .map { OverrideMemberChooserObject.create(project, it, it) }
     }
 
     override fun getChooserTitle() = "Implement Members"

idea/idea-core/src/org/jetbrains/kotlin/idea/core/overrideImplement/OverrideMemberChooserObject.kt

@@ -16,13 +16,50 @@
 
 package org.jetbrains.kotlin.idea.core.overrideImplement
 
+import com.intellij.codeInsight.generation.ClassMember
+import com.intellij.codeInsight.generation.MemberChooserObject
+import com.intellij.codeInsight.generation.MemberChooserObjectBase
 import com.intellij.openapi.project.Project
+import com.intellij.psi.PsiElement
 import org.jetbrains.kotlin.descriptors.CallableMemberDescriptor
+import org.jetbrains.kotlin.descriptors.ClassifierDescriptor
 import org.jetbrains.kotlin.idea.codeInsight.DescriptorToSourceUtilsIde
 import org.jetbrains.kotlin.idea.core.util.DescriptorMemberChooserObject
 
-class OverrideMemberChooserObject(
+interface OverrideMemberChooserObject : ClassMember {
-        project: Project,
+    val descriptor: CallableMemberDescriptor
-        val member: CallableMemberDescriptor,
+    val immediateSuper: CallableMemberDescriptor
-        val immediateSuper: CallableMemberDescriptor
+
-) : DescriptorMemberChooserObject(DescriptorToSourceUtilsIde.getAnyDeclaration(project, member)!!, member)
+    companion object {
+        fun create(project: Project, descriptor: CallableMemberDescriptor, immediateSuper: CallableMemberDescriptor): OverrideMemberChooserObject {
+            val declaration = DescriptorToSourceUtilsIde.getAnyDeclaration(project, descriptor)
+            if (declaration != null) {
+                return WithDeclaration(descriptor, declaration, immediateSuper)
+            }
+            else {
+                return WithoutDeclaration(descriptor, immediateSuper)
+            }
+        }
+
+        private class WithDeclaration(
+                descriptor: CallableMemberDescriptor,
+                declaration: PsiElement,
+                override val immediateSuper: CallableMemberDescriptor
+        ) : DescriptorMemberChooserObject(declaration, descriptor), OverrideMemberChooserObject {
+
+            override val descriptor: CallableMemberDescriptor
+                get() = super<DescriptorMemberChooserObject>.descriptor as CallableMemberDescriptor
+        }
+
+        private class WithoutDeclaration(
+                override val descriptor: CallableMemberDescriptor,
+                override val immediateSuper: CallableMemberDescriptor
+        ) : MemberChooserObjectBase(DescriptorMemberChooserObject.getText(descriptor), DescriptorMemberChooserObject.getIcon(null, descriptor)), OverrideMemberChooserObject {
+
+            override fun getParentNodeDelegate(): MemberChooserObject? {
+                val parentClassifier = descriptor.containingDeclaration as? ClassifierDescriptor ?: return null
+                return MemberChooserObjectBase(DescriptorMemberChooserObject.getText(parentClassifier), DescriptorMemberChooserObject.getIcon(null, parentClassifier))
+            }
+        }
+    }
+}

idea/idea-core/src/org/jetbrains/kotlin/idea/core/overrideImplement/OverrideMethodsHandler.kt

@@ -59,7 +59,7 @@ public class OverrideMethodsHandler : OverrideImplementMethodsHandler() {
                     else {
                         immediateSupers.singleOrNull { (it.containingDeclaration as? ClassDescriptor)?.kind == ClassKind.CLASS } ?: immediateSupers.first()
                     }
-                    result.add(OverrideMemberChooserObject(project, realSuper, immediateSuperToUse))
+                    result.add(OverrideMemberChooserObject.create(project, realSuper, immediateSuperToUse))
                 }
             }
         }

idea/idea-core/src/org/jetbrains/kotlin/idea/core/util/DescriptorMemberChooserObject.kt

@@ -40,7 +40,7 @@ import javax.swing.Icon
 
 public open class DescriptorMemberChooserObject(
         psiElement: PsiElement,
-        public val descriptor: DeclarationDescriptor
+        public open val descriptor: DeclarationDescriptor
 ) : PsiElementMemberChooserObject(psiElement, DescriptorMemberChooserObject.getText(descriptor), DescriptorMemberChooserObject.getIcon(psiElement, descriptor)), ClassMemberWithElement {
 
     override fun getParentNodeDelegate(): MemberChooserObject {
@@ -74,29 +74,29 @@ public open class DescriptorMemberChooserObject(
             nameShortness = NameShortness.SHORT
         }
 
-        private fun getText(descriptor: DeclarationDescriptor): String {
+        public fun getText(descriptor: DeclarationDescriptor): String {
             return if (descriptor is ClassDescriptor)
                 descriptor.fqNameSafe.render()
             else
                 MEMBER_RENDERER.render(descriptor)
         }
 
-        private fun getIcon(element: PsiElement, descriptor: DeclarationDescriptor): Icon {
+        public fun getIcon(declaration: PsiElement?, descriptor: DeclarationDescriptor): Icon {
-            if (element.isValid) {
+            if (declaration != null && declaration.isValid) {
-                val isClass = element is PsiClass || element is JetClass
+                val isClass = declaration is PsiClass || declaration is JetClass
                 val flags = if (isClass) 0 else Iconable.ICON_FLAG_VISIBILITY
-                if (element is JetDeclaration) {
+                if (declaration is JetDeclaration) {
                     // kotlin declaration
                     // visibility and abstraction better detect by a descriptor
-                    return JetDescriptorIconProvider.getIcon(descriptor, element, flags)
+                    return JetDescriptorIconProvider.getIcon(descriptor, declaration, flags)
                 }
                 else {
                     // it is better to show java icons for java code
-                    return element.getIcon(flags)
+                    return declaration.getIcon(flags)
                 }
             }
             else {
-                return JetDescriptorIconProvider.getIcon(descriptor, element, 0)
+                return JetDescriptorIconProvider.getIcon(descriptor, declaration, 0)
             }
         }
     }

idea/testData/codeInsight/overrideImplement/ImplementFunctionType.kt

@@ -0,0 +1,3 @@
+class C : (String) -> Boolean {
+    <caret>
+}

idea/testData/codeInsight/overrideImplement/implementFunctionType.kt.after

@@ -0,0 +1,5 @@
+class C : (String) -> Boolean {
+    override fun invoke(p1: String): Boolean {
+        <selection><caret>throw UnsupportedOperationException()</selection>
+    }
+}

idea/tests/org/jetbrains/kotlin/idea/codeInsight/AbstractOverrideImplementTest.kt

@@ -146,7 +146,7 @@ public abstract class AbstractOverrideImplementTest : JetLightCodeInsightFixture
         val classOrObject = PsiTreeUtil.getParentOfType(elementAtCaret, javaClass<JetClassOrObject>())
                             ?: error("Caret should be inside class or object")
 
-        val chooserObjects = handler.collectMethodsToGenerate(classOrObject).sortBy { it.member.name.asString() + " in " + it.immediateSuper.containingDeclaration.name.asString() }
+        val chooserObjects = handler.collectMethodsToGenerate(classOrObject).sortBy { it.descriptor.name.asString() + " in " + it.immediateSuper.containingDeclaration.name.asString() }
         performGenerateCommand(classOrObject, chooserObjects)
     }
 

idea/tests/org/jetbrains/kotlin/idea/codeInsight/OverrideImplementTest.java

@@ -214,4 +214,8 @@ public final class OverrideImplementTest extends AbstractOverrideImplementTest {
     public void testAmbiguousSuper() {
         doMultiOverrideFileTest();
     }
+
+    public void testImplementFunctionType() {
+        doMultiImplementFileTest();
+    }
 }