From 67b59fa72fed63590720a0bc7e8f7c594a5ed62a Mon Sep 17 00:00:00 2001
From: Denis Zharkov <denis.zharkov@jetbrains.com>
Date: Fri, 18 Mar 2016 11:16:06 +0300
Subject: [PATCH] Prohibit nested intersection types in return position

 #KT-11490 Fixed
---
 .../kotlin/resolve/DeclarationsChecker.kt     |  3 ++-
 .../tests/implicitNestedIntersection.kt       |  9 +++++++
 .../tests/implicitNestedIntersection.txt      | 24 +++++++++++++++++++
 .../checkers/DiagnosticsTestGenerated.java    |  6 +++++
 4 files changed, 41 insertions(+), 1 deletion(-)
 create mode 100644 compiler/testData/diagnostics/tests/implicitNestedIntersection.kt
 create mode 100644 compiler/testData/diagnostics/tests/implicitNestedIntersection.txt

diff --git a/compiler/frontend/src/org/jetbrains/kotlin/resolve/DeclarationsChecker.kt b/compiler/frontend/src/org/jetbrains/kotlin/resolve/DeclarationsChecker.kt
index 423758ca810..1501bc1130c 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/resolve/DeclarationsChecker.kt
+++ b/compiler/frontend/src/org/jetbrains/kotlin/resolve/DeclarationsChecker.kt
@@ -35,6 +35,7 @@ import org.jetbrains.kotlin.types.KotlinType
 import org.jetbrains.kotlin.types.SubstitutionUtils
 import org.jetbrains.kotlin.types.TypeUtils
 import org.jetbrains.kotlin.types.checker.KotlinTypeChecker
+import org.jetbrains.kotlin.types.typeUtil.contains
 import org.jetbrains.kotlin.types.typeUtil.isNothing
 import java.util.*
 
@@ -707,7 +708,7 @@ class DeclarationsChecker(
                             (if (declaration is KtProperty) IMPLICIT_NOTHING_PROPERTY_TYPE else IMPLICIT_NOTHING_RETURN_TYPE).on(target)
                     )
                 }
-                if (it.constructor is IntersectionTypeConstructor) {
+                if (it.contains { type -> type.constructor is IntersectionTypeConstructor }) {
                     trace.report(IMPLICIT_INTERSECTION_TYPE.on(target, it))
                 }
             }
diff --git a/compiler/testData/diagnostics/tests/implicitNestedIntersection.kt b/compiler/testData/diagnostics/tests/implicitNestedIntersection.kt
new file mode 100644
index 00000000000..f65fbf7af98
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/implicitNestedIntersection.kt
@@ -0,0 +1,9 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+interface In<in E>
+open class A : In<A>
+open class B : In<B>
+
+fun <T> select(x: T, y: T) = x
+
+fun <!IMPLICIT_INTERSECTION_TYPE!>foo2<!>() = select(A(), B()) // Type is In<A & B> is prohibited in return position
diff --git a/compiler/testData/diagnostics/tests/implicitNestedIntersection.txt b/compiler/testData/diagnostics/tests/implicitNestedIntersection.txt
new file mode 100644
index 00000000000..690b5058242
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/implicitNestedIntersection.txt
@@ -0,0 +1,24 @@
+package
+
+public fun foo2(): In<{A & B}>
+public fun </*0*/ T> select(/*0*/ x: T, /*1*/ y: T): T
+
+public open class A : In<A> {
+    public constructor A()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public open class B : In<B> {
+    public constructor B()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public interface In</*0*/ in E> {
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
diff --git a/compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java b/compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java
index 413f225a279..a72407035a0 100644
--- a/compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java
+++ b/compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java
@@ -301,6 +301,12 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
             doTest(fileName);
         }
 
+        @TestMetadata("implicitNestedIntersection.kt")
+        public void testImplicitNestedIntersection() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/implicitNestedIntersection.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("implicitNothing.kt")
         public void testImplicitNothing() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/implicitNothing.kt");