backend/tests: Add blackbox tests from Kotlin JVM

Added tests from testData/codegen/box directory. There are blackbox tests
in other directories and they are to be added.

backend.native/tests/external/codegen/blackbox/smartCasts/falseSmartCast.kt

@@ -0,0 +1,17 @@
+open class SuperFoo {
+    public fun bar(): String {
+        if (this is Foo) {
+            superFoo() // Smart cast
+            return baz() // Cannot be cast
+        }
+        return baz()
+    }
+
+    public fun baz() = "OK"
+}
+
+class Foo : SuperFoo() {
+    public fun superFoo() {}
+}
+
+fun box(): String = Foo().bar()

backend.native/tests/external/codegen/blackbox/smartCasts/genericIntersection.kt

@@ -0,0 +1,9 @@
+// See also KT-7801
+class A
+
+fun <T> test(v: T): T {
+    val a: T = if (v !is A) v else v
+    return a
+}
+
+fun box() = test("OK")

backend.native/tests/external/codegen/blackbox/smartCasts/genericSet.kt

@@ -0,0 +1,13 @@
+class Wrapper<T>(var x: T)
+
+inline fun <reified T> change(w: Wrapper<T>, x: Any?) {
+    if (x is T) {
+        w.x = x
+    }
+}
+
+fun box(): String {
+    val w = Wrapper<String>("FAIL")
+    change(w, "OK")
+    return w.x
+}

backend.native/tests/external/codegen/blackbox/smartCasts/implicitExtensionReceiver.kt

@@ -0,0 +1,7 @@
+class A {
+    fun foo() = "OK"
+}
+
+fun A?.bar() = if (this != null) foo() else "FAIL"
+
+fun box() = A().bar()

backend.native/tests/external/codegen/blackbox/smartCasts/implicitMemberReceiver.kt

@@ -0,0 +1,20 @@
+open class A {
+    open val a = "OK"
+}
+
+class B : A() {
+    override val a = "FAIL"
+    fun foo() = "CRUSH"
+}
+
+class C {
+    fun A?.complex(): String {
+        if (this is B) return foo()
+        else if (this != null) return a
+        else return "???"
+    }
+
+    fun bar() = A().complex()
+}
+
+fun box() = C().bar()

backend.native/tests/external/codegen/blackbox/smartCasts/implicitReceiver.kt

@@ -0,0 +1,13 @@
+open class A {
+    class B : A() {
+        val a = "FAIL"
+    }
+
+    fun foo(): String {
+        if (this is B) return a
+        return "OK"
+    }
+}
+
+
+fun box(): String = A().foo()

backend.native/tests/external/codegen/blackbox/smartCasts/implicitReceiverInWhen.kt

@@ -0,0 +1,11 @@
+open class A {
+    fun f(): String =
+            when (this) {
+                is B -> x
+                else -> "FAIL"
+            }
+}
+
+class B(val x: String) : A()
+
+fun box() = B("OK").f()

backend.native/tests/external/codegen/blackbox/smartCasts/implicitToGrandSon.kt

@@ -0,0 +1,13 @@
+open class A {
+    open fun foo() = "FAIL"
+
+    fun bar() = if (this is C) foo() else foo()
+}
+
+open class B : A()
+
+open class C : B() {
+    override fun foo() = "OK"
+}
+
+fun box() = C().bar()

backend.native/tests/external/codegen/blackbox/smartCasts/lambdaArgumentWithoutType.kt

@@ -0,0 +1,15 @@
+// TODO: muted automatically, investigate should it be ran for JS or not
+// IGNORE_BACKEND: JS
+
+class Foo(val s: String)
+fun foo(): Foo? = Foo("OK")
+
+fun <T> run(f: () -> T): T = f()
+
+val foo: Foo = run {
+    val x = foo()
+    if (x == null) throw Exception()
+    x
+}
+
+fun box() = foo.s

backend.native/tests/external/codegen/blackbox/smartCasts/nullSmartCast.kt

@@ -0,0 +1,8 @@
+fun String?.foo() = this ?: "OK"
+
+fun foo(i: Int?): String {
+    if (i == null) return i.foo()
+    return "$i"
+}
+
+fun box() = foo(null)

backend.native/tests/external/codegen/blackbox/smartCasts/smartCastInsideIf.kt

@@ -0,0 +1,15 @@
+class A(val s: String = "FAIL")
+
+private fun foo(a: A?, aOther: A?): A {
+    return if (a == null) {
+        A()
+    }
+    else {
+        if (aOther == null) {
+            return A()
+        }
+        aOther
+    }
+}
+
+fun box() = foo(A("???"), A("OK")).s

backend.native/tests/external/codegen/blackbox/smartCasts/whenSmartCast.kt

@@ -0,0 +1,9 @@
+fun baz(s: String?): Int {
+    if (s == null) return 0
+    return when(s) {
+        "abc" -> s
+        else -> "xyz"
+    }.length
+}
+
+fun box() = if (baz("abc") == 3 && baz("") == 3 && baz(null) == 0) "OK" else "FAIL"