diff --git a/js/js.tests/test/org/jetbrains/kotlin/js/test/ir/semantics/IrBoxJsTestGenerated.java b/js/js.tests/test/org/jetbrains/kotlin/js/test/ir/semantics/IrBoxJsTestGenerated.java
index 81608f6ec9f..e38a6cec649 100644
--- a/js/js.tests/test/org/jetbrains/kotlin/js/test/ir/semantics/IrBoxJsTestGenerated.java
+++ b/js/js.tests/test/org/jetbrains/kotlin/js/test/ir/semantics/IrBoxJsTestGenerated.java
@@ -1370,6 +1370,94 @@ public class IrBoxJsTestGenerated extends AbstractIrBoxJsTest {
         }
     }
 
+    @TestMetadata("js/js.translator/testData/box/es6classes")
+    @TestDataPath("$PROJECT_ROOT")
+    @RunWith(JUnit3RunnerWithInners.class)
+    public static class Es6classes extends AbstractIrBoxJsTest {
+        private void runTest(String testDataFilePath) throws Exception {
+            KotlinTestUtils.runTest0(this::doTest, TargetBackend.JS_IR, testDataFilePath);
+        }
+
+        public void testAllFilesPresentInEs6classes() throws Exception {
+            KotlinTestUtils.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("js/js.translator/testData/box/es6classes"), Pattern.compile("^([^_](.+))\\.kt$"), null, TargetBackend.JS_IR, true);
+        }
+
+        @TestMetadata("builtItTypes.kt")
+        public void testBuiltItTypes() throws Exception {
+            runTest("js/js.translator/testData/box/es6classes/builtItTypes.kt");
+        }
+
+        @TestMetadata("defaultPrimary.kt")
+        public void testDefaultPrimary() throws Exception {
+            runTest("js/js.translator/testData/box/es6classes/defaultPrimary.kt");
+        }
+
+        @TestMetadata("defaultPrimaryExtendsAny.kt")
+        public void testDefaultPrimaryExtendsAny() throws Exception {
+            runTest("js/js.translator/testData/box/es6classes/defaultPrimaryExtendsAny.kt");
+        }
+
+        @TestMetadata("defaultPrimaryExtendsExternal.kt")
+        public void testDefaultPrimaryExtendsExternal() throws Exception {
+            runTest("js/js.translator/testData/box/es6classes/defaultPrimaryExtendsExternal.kt");
+        }
+
+        @TestMetadata("defaultPrimaryWithSuper.kt")
+        public void testDefaultPrimaryWithSuper() throws Exception {
+            runTest("js/js.translator/testData/box/es6classes/defaultPrimaryWithSuper.kt");
+        }
+
+        @TestMetadata("delegation.kt")
+        public void testDelegation() throws Exception {
+            runTest("js/js.translator/testData/box/es6classes/delegation.kt");
+        }
+
+        @TestMetadata("fieldAccess.kt")
+        public void testFieldAccess() throws Exception {
+            runTest("js/js.translator/testData/box/es6classes/fieldAccess.kt");
+        }
+
+        @TestMetadata("inheritedFromExternalBySecondaryCtor.kt")
+        public void testInheritedFromExternalBySecondaryCtor() throws Exception {
+            runTest("js/js.translator/testData/box/es6classes/inheritedFromExternalBySecondaryCtor.kt");
+        }
+
+        @TestMetadata("inheritedFromExternalClass.kt")
+        public void testInheritedFromExternalClass() throws Exception {
+            runTest("js/js.translator/testData/box/es6classes/inheritedFromExternalClass.kt");
+        }
+
+        @TestMetadata("initBlocks.kt")
+        public void testInitBlocks() throws Exception {
+            runTest("js/js.translator/testData/box/es6classes/initBlocks.kt");
+        }
+
+        @TestMetadata("innerClasses.kt")
+        public void testInnerClasses() throws Exception {
+            runTest("js/js.translator/testData/box/es6classes/innerClasses.kt");
+        }
+
+        @TestMetadata("isInitializedFieldBeforeObjectCreation.kt")
+        public void testIsInitializedFieldBeforeObjectCreation() throws Exception {
+            runTest("js/js.translator/testData/box/es6classes/isInitializedFieldBeforeObjectCreation.kt");
+        }
+
+        @TestMetadata("primaryToSecondary.kt")
+        public void testPrimaryToSecondary() throws Exception {
+            runTest("js/js.translator/testData/box/es6classes/primaryToSecondary.kt");
+        }
+
+        @TestMetadata("typeCorrectness.kt")
+        public void testTypeCorrectness() throws Exception {
+            runTest("js/js.translator/testData/box/es6classes/typeCorrectness.kt");
+        }
+
+        @TestMetadata("unboxChain.kt")
+        public void testUnboxChain() throws Exception {
+            runTest("js/js.translator/testData/box/es6classes/unboxChain.kt");
+        }
+    }
+
     @TestMetadata("js/js.translator/testData/box/examples")
     @TestDataPath("$PROJECT_ROOT")
     @RunWith(JUnit3RunnerWithInners.class)
diff --git a/js/js.tests/test/org/jetbrains/kotlin/js/test/semantics/BoxJsTestGenerated.java b/js/js.tests/test/org/jetbrains/kotlin/js/test/semantics/BoxJsTestGenerated.java
index d838c628b77..e56c443975c 100644
--- a/js/js.tests/test/org/jetbrains/kotlin/js/test/semantics/BoxJsTestGenerated.java
+++ b/js/js.tests/test/org/jetbrains/kotlin/js/test/semantics/BoxJsTestGenerated.java
@@ -1375,6 +1375,94 @@ public class BoxJsTestGenerated extends AbstractBoxJsTest {
         }
     }
 
+    @TestMetadata("js/js.translator/testData/box/es6classes")
+    @TestDataPath("$PROJECT_ROOT")
+    @RunWith(JUnit3RunnerWithInners.class)
+    public static class Es6classes extends AbstractBoxJsTest {
+        private void runTest(String testDataFilePath) throws Exception {
+            KotlinTestUtils.runTest0(this::doTest, TargetBackend.JS, testDataFilePath);
+        }
+
+        public void testAllFilesPresentInEs6classes() throws Exception {
+            KotlinTestUtils.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("js/js.translator/testData/box/es6classes"), Pattern.compile("^([^_](.+))\\.kt$"), null, TargetBackend.JS, true);
+        }
+
+        @TestMetadata("builtItTypes.kt")
+        public void testBuiltItTypes() throws Exception {
+            runTest("js/js.translator/testData/box/es6classes/builtItTypes.kt");
+        }
+
+        @TestMetadata("defaultPrimary.kt")
+        public void testDefaultPrimary() throws Exception {
+            runTest("js/js.translator/testData/box/es6classes/defaultPrimary.kt");
+        }
+
+        @TestMetadata("defaultPrimaryExtendsAny.kt")
+        public void testDefaultPrimaryExtendsAny() throws Exception {
+            runTest("js/js.translator/testData/box/es6classes/defaultPrimaryExtendsAny.kt");
+        }
+
+        @TestMetadata("defaultPrimaryExtendsExternal.kt")
+        public void testDefaultPrimaryExtendsExternal() throws Exception {
+            runTest("js/js.translator/testData/box/es6classes/defaultPrimaryExtendsExternal.kt");
+        }
+
+        @TestMetadata("defaultPrimaryWithSuper.kt")
+        public void testDefaultPrimaryWithSuper() throws Exception {
+            runTest("js/js.translator/testData/box/es6classes/defaultPrimaryWithSuper.kt");
+        }
+
+        @TestMetadata("delegation.kt")
+        public void testDelegation() throws Exception {
+            runTest("js/js.translator/testData/box/es6classes/delegation.kt");
+        }
+
+        @TestMetadata("fieldAccess.kt")
+        public void testFieldAccess() throws Exception {
+            runTest("js/js.translator/testData/box/es6classes/fieldAccess.kt");
+        }
+
+        @TestMetadata("inheritedFromExternalBySecondaryCtor.kt")
+        public void testInheritedFromExternalBySecondaryCtor() throws Exception {
+            runTest("js/js.translator/testData/box/es6classes/inheritedFromExternalBySecondaryCtor.kt");
+        }
+
+        @TestMetadata("inheritedFromExternalClass.kt")
+        public void testInheritedFromExternalClass() throws Exception {
+            runTest("js/js.translator/testData/box/es6classes/inheritedFromExternalClass.kt");
+        }
+
+        @TestMetadata("initBlocks.kt")
+        public void testInitBlocks() throws Exception {
+            runTest("js/js.translator/testData/box/es6classes/initBlocks.kt");
+        }
+
+        @TestMetadata("innerClasses.kt")
+        public void testInnerClasses() throws Exception {
+            runTest("js/js.translator/testData/box/es6classes/innerClasses.kt");
+        }
+
+        @TestMetadata("isInitializedFieldBeforeObjectCreation.kt")
+        public void testIsInitializedFieldBeforeObjectCreation() throws Exception {
+            runTest("js/js.translator/testData/box/es6classes/isInitializedFieldBeforeObjectCreation.kt");
+        }
+
+        @TestMetadata("primaryToSecondary.kt")
+        public void testPrimaryToSecondary() throws Exception {
+            runTest("js/js.translator/testData/box/es6classes/primaryToSecondary.kt");
+        }
+
+        @TestMetadata("typeCorrectness.kt")
+        public void testTypeCorrectness() throws Exception {
+            runTest("js/js.translator/testData/box/es6classes/typeCorrectness.kt");
+        }
+
+        @TestMetadata("unboxChain.kt")
+        public void testUnboxChain() throws Exception {
+            runTest("js/js.translator/testData/box/es6classes/unboxChain.kt");
+        }
+    }
+
     @TestMetadata("js/js.translator/testData/box/examples")
     @TestDataPath("$PROJECT_ROOT")
     @RunWith(JUnit3RunnerWithInners.class)
diff --git a/js/js.translator/testData/box/es6classes/builtItTypes.kt b/js/js.translator/testData/box/es6classes/builtItTypes.kt
new file mode 100644
index 00000000000..16014901e26
--- /dev/null
+++ b/js/js.translator/testData/box/es6classes/builtItTypes.kt
@@ -0,0 +1,10 @@
+// EXPECTED_REACHABLE_NODES: 1331
+fun box(): String {
+    val s = String()
+    val ints = Array<Int>(2) { i -> (i + 2) * 2 }
+
+    assertEquals(4, ints[0])
+    assertEquals(6, ints[1])
+
+    return "OK" + s
+}
diff --git a/js/js.translator/testData/box/es6classes/defaultPrimary.kt b/js/js.translator/testData/box/es6classes/defaultPrimary.kt
new file mode 100644
index 00000000000..5fa9dd8533e
--- /dev/null
+++ b/js/js.translator/testData/box/es6classes/defaultPrimary.kt
@@ -0,0 +1,30 @@
+// EXPECTED_REACHABLE_NODES: 1344
+open class A(var value: Int) {
+    init {
+        value *= 2
+    }
+}
+
+class B : A {
+    init {
+        value /= 6
+    }
+
+    constructor(x: Int) : super(x) {
+        value *= 18
+    }
+
+    constructor() : this(18) {
+        value *= 12
+    }
+}
+
+fun box(): String {
+    val bs1 = B(15)
+    assertEquals(90, bs1.value)
+
+    val bs2 = B()
+    assertEquals(72 * 18, bs2.value)
+
+    return "OK"
+}
diff --git a/js/js.translator/testData/box/es6classes/defaultPrimaryExtendsAny.kt b/js/js.translator/testData/box/es6classes/defaultPrimaryExtendsAny.kt
new file mode 100644
index 00000000000..a55d451d58d
--- /dev/null
+++ b/js/js.translator/testData/box/es6classes/defaultPrimaryExtendsAny.kt
@@ -0,0 +1,32 @@
+// EXPECTED_REACHABLE_NODES: 1347
+var sideEffect = ""
+
+abstract class A {
+    fun print(a: Any) { sideEffect += "#$a" }
+
+    constructor(x: Int, y: Int) {
+        print(x + y)
+        print(foo())
+    }
+
+    abstract fun foo(): String
+
+    init {
+        print("init: " + foo())
+    }
+}
+
+class O(val x: String) {
+    inner class I() : A(13, 37) {
+        override fun foo() = x
+    }
+}
+
+fun box(): String {
+    val o = O("OK")
+    val i = o.I()
+
+    assertEquals("#init: OK#50#OK", sideEffect)
+
+    return i.foo()
+}
diff --git a/js/js.translator/testData/box/es6classes/defaultPrimaryExtendsExternal.js b/js/js.translator/testData/box/es6classes/defaultPrimaryExtendsExternal.js
new file mode 100644
index 00000000000..b031ccfb7e1
--- /dev/null
+++ b/js/js.translator/testData/box/es6classes/defaultPrimaryExtendsExternal.js
@@ -0,0 +1,3 @@
+class E {
+    constructor() { }
+}
diff --git a/js/js.translator/testData/box/es6classes/defaultPrimaryExtendsExternal.kt b/js/js.translator/testData/box/es6classes/defaultPrimaryExtendsExternal.kt
new file mode 100644
index 00000000000..4f1995e1378
--- /dev/null
+++ b/js/js.translator/testData/box/es6classes/defaultPrimaryExtendsExternal.kt
@@ -0,0 +1,39 @@
+//IGNORE_BACKEND: JS, JS_IR
+
+var sideEffect = ""
+
+open external class E()
+abstract class A : E {
+    fun print(a: Any) { sideEffect += "#$a" }
+
+    constructor(x: Int, y: Int) : super() {
+        print(x + y)
+        print(foo())
+    }
+
+    constructor(x: Int) : super() {
+        print(x)
+        print(foo())
+    }
+
+    abstract fun foo(): String
+
+    init {
+        print("init: " + foo())
+    }
+}
+
+class O(val x: String) {
+    inner class I() : A(1337) {
+        override fun foo() = x
+    }
+}
+
+fun box(): String {
+    val o = O("OK")
+    val i = o.I()
+
+    assertEquals("#init: OK#1337#OK", sideEffect)
+
+    return i.foo()
+}
diff --git a/js/js.translator/testData/box/es6classes/defaultPrimaryWithSuper.kt b/js/js.translator/testData/box/es6classes/defaultPrimaryWithSuper.kt
new file mode 100644
index 00000000000..1bf26b1c766
--- /dev/null
+++ b/js/js.translator/testData/box/es6classes/defaultPrimaryWithSuper.kt
@@ -0,0 +1,36 @@
+// EXPECTED_REACHABLE_NODES: 1355
+var sideEffect = ""
+
+open class Summator(x: Int, y: Int) {
+    val sum = x + y
+}
+
+abstract class A : Summator {
+    fun print(a: Any) { sideEffect += "#$a" }
+
+    constructor(x: Int, y: Int) : super(x, y) { //try pass `foo()`
+        print(sum)
+        print(foo())
+    }
+
+    abstract fun foo(): String
+
+    init {
+        print("init: " + foo())
+    }
+}
+
+class O(val x: String) {
+    inner class I() : A(13, 37) {
+        override fun foo() = x
+    }
+}
+
+fun box(): String {
+    val o = O("OK")
+    val i = o.I()
+
+    assertEquals("#init: OK#50#OK", sideEffect)
+
+    return i.foo()
+}
diff --git a/js/js.translator/testData/box/es6classes/delegation.kt b/js/js.translator/testData/box/es6classes/delegation.kt
new file mode 100644
index 00000000000..91a14e2c1ae
--- /dev/null
+++ b/js/js.translator/testData/box/es6classes/delegation.kt
@@ -0,0 +1,32 @@
+// EXPECTED_REACHABLE_NODES: 1359
+open class A(val x: Int) {
+    constructor(): this(100)
+}
+
+class PrimaryToPrimary(val p: Int): A(p * p)
+class PrimaryToSecondary(val p: Int): A()
+
+class SecondaryToPrimary : A {
+    constructor() : super(8)
+}
+class SecondaryToSecondary: A {
+    constructor() : super()
+}
+
+fun box(): String {
+    val ptp = PrimaryToPrimary(5)
+    assertEquals(ptp.p, 5)
+    assertEquals(ptp.x, 25)
+
+    val pts = PrimaryToSecondary(9)
+    assertEquals(pts.p, 9)
+    assertEquals(pts.x, 100)
+
+    val stp = SecondaryToPrimary()
+    assertEquals(stp.x, 8)
+
+    val sts = SecondaryToSecondary()
+    assertEquals(sts.x, 100)
+
+    return "OK"
+}
diff --git a/js/js.translator/testData/box/es6classes/fieldAccess.kt b/js/js.translator/testData/box/es6classes/fieldAccess.kt
new file mode 100644
index 00000000000..eb3c6b826c7
--- /dev/null
+++ b/js/js.translator/testData/box/es6classes/fieldAccess.kt
@@ -0,0 +1,13 @@
+// EXPECTED_REACHABLE_NODES: 1340
+open class A(val x: Int)
+
+class B(val p: Int, val q: Int): A(p + q)
+
+fun box(): String {
+    val b = B(2, 3)
+    assertEquals(b.p, 2)
+    assertEquals(b.q, 3)
+    assertEquals(b.x, 5)
+
+    return "OK"
+}
diff --git a/js/js.translator/testData/box/es6classes/inheritedFromExternalBySecondaryCtor.js b/js/js.translator/testData/box/es6classes/inheritedFromExternalBySecondaryCtor.js
new file mode 100644
index 00000000000..18591e90f4f
--- /dev/null
+++ b/js/js.translator/testData/box/es6classes/inheritedFromExternalBySecondaryCtor.js
@@ -0,0 +1,5 @@
+class E {
+    constructor(x, y) {
+        this.t = x + y;
+    }
+}
diff --git a/js/js.translator/testData/box/es6classes/inheritedFromExternalBySecondaryCtor.kt b/js/js.translator/testData/box/es6classes/inheritedFromExternalBySecondaryCtor.kt
new file mode 100644
index 00000000000..90763faf17c
--- /dev/null
+++ b/js/js.translator/testData/box/es6classes/inheritedFromExternalBySecondaryCtor.kt
@@ -0,0 +1,19 @@
+//IGNORE_BACKEND: JS, JS_IR
+
+open external class E(x: Int, y: Int) {
+    val t: Int = definedExternally
+}
+
+open class A(i: Int, j: Int) : E(i, j)
+
+class B : A {
+    constructor() : super(3, 4)
+}
+
+fun box(): String {
+    val b = B()
+
+    assertEquals(7, b.t)
+
+    return "OK"
+}
diff --git a/js/js.translator/testData/box/es6classes/inheritedFromExternalClass.js b/js/js.translator/testData/box/es6classes/inheritedFromExternalClass.js
new file mode 100644
index 00000000000..18591e90f4f
--- /dev/null
+++ b/js/js.translator/testData/box/es6classes/inheritedFromExternalClass.js
@@ -0,0 +1,5 @@
+class E {
+    constructor(x, y) {
+        this.t = x + y;
+    }
+}
diff --git a/js/js.translator/testData/box/es6classes/inheritedFromExternalClass.kt b/js/js.translator/testData/box/es6classes/inheritedFromExternalClass.kt
new file mode 100644
index 00000000000..6c8fd07bd9e
--- /dev/null
+++ b/js/js.translator/testData/box/es6classes/inheritedFromExternalClass.kt
@@ -0,0 +1,17 @@
+//IGNORE_BACKEND: JS, JS_IR
+
+open external class E(x: Int, y: Int) {
+    val t: Int = definedExternally
+}
+
+open class A(i: Int, j: Int) : E(i, j)
+
+class B(val ok: String) : A(2, 3)
+
+fun box(): String {
+    val b = B("OK")
+
+    assertEquals(5, b.t)
+
+    return b.ok
+}
diff --git a/js/js.translator/testData/box/es6classes/initBlocks.kt b/js/js.translator/testData/box/es6classes/initBlocks.kt
new file mode 100644
index 00000000000..eabb95ce703
--- /dev/null
+++ b/js/js.translator/testData/box/es6classes/initBlocks.kt
@@ -0,0 +1,42 @@
+// EXPECTED_REACHABLE_NODES: 1345
+var sideEffect = ""
+
+open class A(var value: Int) {
+    init {
+        sideEffect += "init A###"
+    }
+}
+
+class B : A {
+    init {
+        sideEffect += "init "
+    }
+
+    constructor(x: Int) : super(x) {
+        sideEffect += "ctor to A###"
+    }
+
+    init {
+        sideEffect += "class "
+    }
+
+    constructor() : this(180) {
+        sideEffect += "ctor to B###"
+    }
+
+    init {
+        sideEffect += "B###"
+    }
+}
+
+fun box(): String {
+    val bs1 = B(14)
+    assertEquals("init A###init class B###ctor to A###", sideEffect)
+
+    sideEffect = ""
+
+    val bs2 = B()
+    assertEquals("init A###init class B###ctor to A###ctor to B###", sideEffect)
+
+    return "OK"
+}
diff --git a/js/js.translator/testData/box/es6classes/innerClasses.kt b/js/js.translator/testData/box/es6classes/innerClasses.kt
new file mode 100644
index 00000000000..68fd8b8ad3c
--- /dev/null
+++ b/js/js.translator/testData/box/es6classes/innerClasses.kt
@@ -0,0 +1,19 @@
+// EXPECTED_REACHABLE_NODES: 1343
+abstract class A {
+    abstract fun foo(): String
+
+    val ss = foo() + "K"
+}
+
+class O(val s: String) {
+    inner class I() : A() {
+        override fun foo() = s
+    }
+
+    fun result() = I().ss
+}
+
+fun box(): String {
+    val o = O("O")
+    return o.result()
+}
diff --git a/js/js.translator/testData/box/es6classes/isInitializedFieldBeforeObjectCreation.kt b/js/js.translator/testData/box/es6classes/isInitializedFieldBeforeObjectCreation.kt
new file mode 100644
index 00000000000..31564c75f5e
--- /dev/null
+++ b/js/js.translator/testData/box/es6classes/isInitializedFieldBeforeObjectCreation.kt
@@ -0,0 +1,19 @@
+// EXPECTED_REACHABLE_NODES: 1342
+//WITH_RUNTIME
+
+package test
+
+import test.A.p
+
+object A {
+    lateinit var p: String
+    var result: String
+
+    init {
+        result = if (::p.isInitialized) "FAIL" else "OK"
+    }
+}
+
+fun box(): String {
+    return A.result
+}
diff --git a/js/js.translator/testData/box/es6classes/primaryToSecondary.kt b/js/js.translator/testData/box/es6classes/primaryToSecondary.kt
new file mode 100644
index 00000000000..50366aa3939
--- /dev/null
+++ b/js/js.translator/testData/box/es6classes/primaryToSecondary.kt
@@ -0,0 +1,15 @@
+// EXPECTED_REACHABLE_NODES: 1341
+open class A(val x: Int, val y: Int) {
+    constructor(x: Int) : this(x, x)
+}
+
+class B(x: Int) : A(x)
+
+fun box(): String {
+    val b = B(45)
+
+    assertEquals(b.x, 45)
+    assertEquals(b.y, 45)
+
+    return "OK"
+}
diff --git a/js/js.translator/testData/box/es6classes/typeCorrectness.kt b/js/js.translator/testData/box/es6classes/typeCorrectness.kt
new file mode 100644
index 00000000000..ad06ca9149c
--- /dev/null
+++ b/js/js.translator/testData/box/es6classes/typeCorrectness.kt
@@ -0,0 +1,45 @@
+// EXPECTED_REACHABLE_NODES: 1358
+open class A(var value: Int)
+
+open class B : A {
+    constructor(x: Int) : super(x)
+
+    constructor() : this(180)
+}
+
+open class C(val q: Int) : B(q * q) {
+    constructor() : this(11)
+}
+
+class D : C {
+    constructor() : super()
+}
+
+class E(e: Int) : C(e)
+
+fun box(): String {
+    val ap = A(0) as A
+
+    val bs1 = B(12) as B
+    bs1 as A
+    val bs2 = B() as B
+    bs2 as A
+
+    val cp = C(14) as C
+    cp as B
+    cp as A
+    val cs = C() as C
+    cs as B
+    cs as A
+
+    val ds = D() as D
+    ds as C
+    ds as B
+    ds as A
+    val ep = E(56)  as E
+    ep as C
+    ep as B
+    ep as A
+
+    return "OK"
+}
diff --git a/js/js.translator/testData/box/es6classes/unboxChain.kt b/js/js.translator/testData/box/es6classes/unboxChain.kt
new file mode 100644
index 00000000000..c2b7fb6b8c3
--- /dev/null
+++ b/js/js.translator/testData/box/es6classes/unboxChain.kt
@@ -0,0 +1,24 @@
+// EXPECTED_REACHABLE_NODES: 1371
+inline class I1(val a: Int)
+inline class I2(val i: I1)
+inline class I3(val i: I2)
+inline class I4(val i: I3)
+inline class I5(val i: I4)
+
+class TestDefault(val def: I5 = I5(I4(I3(I2(I1(999))))))
+
+class TestGen<T>(val gen: T)
+
+fun box(): String {
+    val x = I5(I4(I3(I2(I1(1337)))))
+    assertEquals(1337, x.i.i.i.i.a)
+
+    val testDefault = TestDefault()
+    assertEquals(999, testDefault.def.i.i.i.i.a)
+
+    val testDefaultGen = TestGen(I5(I4(I3(I2(I1(1953))))))
+    assertTrue(testDefault.def.i.i.i.i.a is Int)
+    assertEquals(1953, testDefaultGen.gen.i.i.i.i.a)
+
+    return "OK"
+}