From 8c131f47907180f7ed55a4cd71d173e2bc044177 Mon Sep 17 00:00:00 2001
From: Mikhail Glukhikh <Mikhail.Glukhikh@jetbrains.com>
Date: Wed, 30 Mar 2016 14:29:47 +0300
Subject: [PATCH] KT-11666: Implicit nothing is allowed for overridden function
 / properties

---
 .../kotlin/resolve/DeclarationsChecker.kt       |  2 +-
 .../diagnostics/tests/implicitNothing.kt        | 14 ++++++++++++++
 .../diagnostics/tests/implicitNothing.txt       | 17 +++++++++++++++++
 3 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/compiler/frontend/src/org/jetbrains/kotlin/resolve/DeclarationsChecker.kt b/compiler/frontend/src/org/jetbrains/kotlin/resolve/DeclarationsChecker.kt
index 569bfbe7eb4..d9d8aed04f5 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/resolve/DeclarationsChecker.kt
+++ b/compiler/frontend/src/org/jetbrains/kotlin/resolve/DeclarationsChecker.kt
@@ -705,7 +705,7 @@ class DeclarationsChecker(
         descriptor.returnType?.let {
             if (declaration.typeReference == null) {
                 val target = declaration.nameIdentifier ?: declaration
-                if (it.isNothing()) {
+                if (it.isNothing() && !declaration.hasModifier(KtTokens.OVERRIDE_KEYWORD)) {
                     trace.report(
                             (if (declaration is KtProperty) IMPLICIT_NOTHING_PROPERTY_TYPE else IMPLICIT_NOTHING_RETURN_TYPE).on(target)
                     )
diff --git a/compiler/testData/diagnostics/tests/implicitNothing.kt b/compiler/testData/diagnostics/tests/implicitNothing.kt
index ef43da2e8ea..84235471582 100644
--- a/compiler/testData/diagnostics/tests/implicitNothing.kt
+++ b/compiler/testData/diagnostics/tests/implicitNothing.kt
@@ -34,3 +34,17 @@ class Klass {
         <!UNREACHABLE_CODE!>val <!UNUSED_VARIABLE!>x<!> =<!> y
     }
 }
+
+interface Base {
+    val x: Int
+
+    fun foo(): String
+}
+
+class Derived : Base {
+    // Ok for override
+    
+    override val x = null!!
+
+    override fun foo() = null!!
+}
diff --git a/compiler/testData/diagnostics/tests/implicitNothing.txt b/compiler/testData/diagnostics/tests/implicitNothing.txt
index 3a4daf0cdbd..6d79c4fdc15 100644
--- a/compiler/testData/diagnostics/tests/implicitNothing.txt
+++ b/compiler/testData/diagnostics/tests/implicitNothing.txt
@@ -8,6 +8,23 @@ public fun check(): kotlin.Unit
 public fun foo(): kotlin.Nothing
 public fun gav(): kotlin.Any
 
+public interface Base {
+    public abstract val x: kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public abstract fun foo(): kotlin.String
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class Derived : Base {
+    public constructor Derived()
+    public open override /*1*/ val x: kotlin.Nothing
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ fun foo(): kotlin.Nothing
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
 public final class Klass {
     public constructor Klass()
     public final val y: kotlin.Nothing