[Spec tests] Add spec tests for kotlin.Nothing, kotlin.Unit, reference equality and cast expressions

compiler/tests-spec/testData/codegen/box/linked/expressions/equality-expressions/reference-equality-expressions/p-1/pos/2.1.kt

@@ -0,0 +1,28 @@
+// WITH_RUNTIME
+
+/*
+ * KOTLIN CODEGEN BOX SPEC TEST (POSITIVE)
+ *
+ * SPEC VERSION: 0.1-213
+ * PLACE: expressions, equality-expressions, reference-equality-expressions -> paragraph 1 -> sentence 2
+ * RELEVANT PLACES:  expressions, built-in-types-and-their-semantics, kotlin.unit -> paragraph 1 -> sentence 1
+ * NUMBER: 1
+ * DESCRIPTION: check if two values are equal (===) by reference
+ */
+
+fun box(): String {
+    val u1 = foo1()
+    val u2 = foo2()
+    if (u1 === u2) {
+        return ("OK")
+    }
+    return ("NOK")
+}
+
+fun foo1() {
+    return Unit
+}
+
+fun foo2(): Unit {
+    return Unit
+}

compiler/tests-spec/testData/codegen/box/linked/expressions/equality-expressions/reference-equality-expressions/p-1/pos/2.2.kt

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+// WITH_RUNTIME
+
+/*
+ * KOTLIN CODEGEN BOX SPEC TEST (POSITIVE)
+ *
+ * SPEC VERSION: 0.1-213
+ * PLACE: expressions, equality-expressions, reference-equality-expressions -> paragraph 1 -> sentence 2
+ * RELEVANT PLACES:  expressions, built-in-types-and-their-semantics, kotlin.unit -> paragraph 1 -> sentence 1,
+ * expressions, equality-expressions, reference-equality-expressions -> paragraph 3 -> sentence 3
+ * expressions, equality-expressions, reference-equality-expressions -> paragraph 2 -> sentence 1
+ * NUMBER: 2
+ * DESCRIPTION: check if two values are equal (===) by reference
+ */
+
+fun box(): String {
+    val u1 = "foo"
+    val u2 = "foo"
+    if (u1 === u2) {
+        return ("OK")
+    }
+    return ("NOK")
+}

compiler/tests-spec/testData/codegen/box/linked/expressions/equality-expressions/reference-equality-expressions/p-1/pos/2.3.kt

@@ -0,0 +1,20 @@
+// WITH_RUNTIME
+
+/*
+ * KOTLIN CODEGEN BOX SPEC TEST (POSITIVE)
+ *
+ * SPEC VERSION: 0.1-213
+ * PLACE: expressions, equality-expressions, reference-equality-expressions -> paragraph 1 -> sentence 2
+ * RELEVANT PLACES:  expressions, built-in-types-and-their-semantics, kotlin.unit -> paragraph 1 -> sentence 1
+ * NUMBER: 3
+ * DESCRIPTION: check if two values are non-equal (!==) by reference
+ */
+
+fun box(): String {
+    val u1 = "boo"
+    val u2 = "foo"
+    if (u1 !== u2) {
+        return ("OK")
+    }
+    return ("NOK")
+}

compiler/tests-spec/testData/codegen/box/linked/expressions/equality-expressions/reference-equality-expressions/p-1/pos/2.4.kt

@@ -0,0 +1,24 @@
+// WITH_RUNTIME
+
+/*
+ * KOTLIN CODEGEN BOX SPEC TEST (POSITIVE)
+ *
+ * SPEC VERSION: 0.1-213
+ * PLACE: expressions, equality-expressions, reference-equality-expressions -> paragraph 1 -> sentence 2
+ * RELEVANT PLACES: expressions, built-in-types-and-their-semantics, kotlin.unit -> paragraph 1 -> sentence 1
+ * NUMBER: 4
+ * DESCRIPTION: check if values are non-equal (!==) by reference
+ */
+
+fun box(): String {
+    val u1 = "foo"
+    val byteArray = "foo".toByteArray(Charsets.UTF_8)
+    val u2 = byteArray.toString()
+    val u3 = byteArray.toString()
+    if (u1 !== u2 && u1 !== u3 && u2 !== u3 &&
+        u2 !== u1 && u3 !== u1 && u3 !== u2
+    ) {
+        return ("OK")
+    }
+    return ("NOK")
+}

compiler/tests-spec/testData/codegen/box/linked/expressions/equality-expressions/reference-equality-expressions/p-1/pos/2.5.kt

@@ -0,0 +1,29 @@
+// WITH_RUNTIME
+
+/*
+ * KOTLIN CODEGEN BOX SPEC TEST (POSITIVE)
+ *
+ * SPEC VERSION: 0.1-213
+ * PLACE: expressions, equality-expressions, reference-equality-expressions -> paragraph 1 -> sentence 2
+ * RELEVANT PLACES:  expressions, built-in-types-and-their-semantics, kotlin.unit -> paragraph 1 -> sentence 1
+ * NUMBER: 5
+ * DESCRIPTION: two values are equal (===) or non-equal (!==) by reference
+ */
+
+fun box(): String {
+    val c1 = c
+    val c2 = c
+    val v1 = v
+    val v2 = v
+    if (c2 === c1 && c1 === c2 && c1 === c && c2 === c &&
+        v2 === v1 && v1 === v2 && v1 === v && v2 === v &&
+        v2 === c1 && v1 === c2 && v1 === c && v2 === c &&
+        c2 === v1 && c1 === v2 && c1 === v && c2 === v
+    ) {
+        return ("OK")
+    }
+    return ("NOK")
+}
+
+const val c = 1000
+const val v = 1000

compiler/tests-spec/testData/codegen/box/linked/expressions/equality-expressions/reference-equality-expressions/p-1/pos/3.1.kt

@@ -0,0 +1,24 @@
+// WITH_RUNTIME
+
+/*
+ * KOTLIN CODEGEN BOX SPEC TEST (POSITIVE)
+ *
+ * SPEC VERSION: 0.1-213
+ * PLACE: expressions, equality-expressions, reference-equality-expressions -> paragraph 1 -> sentence 3
+ * RELEVANT PLACES:  expressions, built-in-types-and-their-semantics, kotlin.unit -> paragraph 1 -> sentence 1
+ * NUMBER: 1
+ * DESCRIPTION: check equallity by refference via constructor
+ */
+
+fun box(): String {
+    val u2 = mutableListOf<Int>(1, 2, 3)
+    val u3 = u1
+    if (u1 !== u2 && u1 === u3
+    ) {
+        return ("OK")
+    }
+    return ("NOK")
+}
+
+val u1 = mutableListOf<Int>(1, 2, 3)
+