Add test

Author: soronpo

tests/pos/singleton-ops-test-issue-8280.scala

@@ -0,0 +1,16 @@
+import scala.compiletime.ops.int._
+import scala.compiletime.S
+
+class Foo[T <: Int] {
+  def incP = new Foo[T + 1]
+  def incS = new Foo[S[T]]
+}
+object Foo {
+  def apply[T <: Int & Singleton](value : T) : Foo[T] = new Foo[T]
+}
+
+val fincS   : Foo[2] = Foo(1).incS
+val fincP1  : Foo[2] = Foo(1).incP
+val fincP2a = Foo(1).incP
+val fincP2b : Foo[2] = fincP2a
+val fincP3  : Foo[2] = (new Foo[1]).incP