Add regression tests for obsolete issues

#KT-2592 Obsolete
 #KT-2768 Obsolete

compiler/testData/diagnostics/tests/regressions/kt2768.kt

@@ -0,0 +1,20 @@
+fun assertEquals<T>(a: T, b: T) {
+    if (a != b) throw AssertionError("$a != $b")
+}
+
+fun main(args: Array<String>) {
+    val bytePos = 128.toByte() // Byte.MAX_VALUE + 1
+    assertEquals(-128, bytePos.toInt()) // correct, wrapped to Byte.MIN_VALUE
+
+    val byteNeg: Byte = <!TYPE_MISMATCH!>-bytePos<!> // should not compile, byteNeg should be Int
+    assertEquals(128, byteNeg.toInt()) // passes, should not be possible
+
+    val shortPos = 32768.toShort() // Short.MAX_VALUE + 1
+    assertEquals(-32768, shortPos.toInt()) // correct, wrapped to Short.MIN_VALUE
+
+    val shortNeg: Short = <!TYPE_MISMATCH!>-shortPos<!> // should not compile, shortNeg should be Int
+    assertEquals(32768, shortNeg.toInt()) // passes, should not be possible
+
+    (-128).toByte()
+    -128.toByte()
+}