Add regression tests

Author: jchyb

tests/pos/i22974a/Maybe_1.scala

@@ -0,0 +1,14 @@
+package pack
+import Maybe._
+opaque type Maybe[+A] >: (Absent | Present[A]) = Absent | Present[A]
+object Maybe:
+  sealed abstract class Absent
+  case object Absent extends Absent
+  object internal:
+    case class PresentAbsent(val depth: Int)
+  opaque type Present[+A] = A | internal.PresentAbsent
+
+  extension [A](self: Maybe[A]) {
+    inline def flatten[B]: Maybe[B] = ???
+    inline def isDefined: Boolean = ???
+  }

tests/pos/i22974a/macro_1.scala

@@ -0,0 +1,6 @@
+import scala.quoted._
+
+inline def passThorugh(inline condition: Boolean): Any =
+  ${ passThorughImpl('{condition}) }
+
+def passThorughImpl(condition: Expr[Boolean])(using Quotes): Expr[Any] = condition

tests/pos/i22974a/main_2.scala

@@ -0,0 +1,6 @@
+object Test {
+  def main(): Unit =
+    import pack.Maybe
+    val res: Maybe[Maybe[Int]] = ???
+    passThorugh(res.flatten.isDefined)
+}

tests/pos/i22974b.scala

@@ -0,0 +1,18 @@
+object outer:
+  opaque type Queue = Queue.Unsafe
+  object Queue:
+    abstract class Unsafe
+    opaque type Unbounded = Queue
+    object Unbounded:
+      inline def initWith()(f: Unbounded => Unit): Unit =
+        f(Unsafe.init())
+
+      opaque type Unsafe <: Queue.Unsafe = Queue
+      object Unsafe:
+        def init[A](): Unsafe = ???
+
+object Resource:
+  def run: Unit =
+    outer.Queue.Unbounded.initWith() { q =>
+      ???
+    }

tests/pos/i22974c.scala

@@ -0,0 +1,18 @@
+object other:
+  sealed abstract class Absent
+  case object Absent extends Absent
+  case class PresentAbsent(val depth: Int)
+  opaque type Present[+A] = A | PresentAbsent
+  opaque type Maybe[+A] >: (Absent | Present[A]) = Absent | Present[A]
+
+  extension [A](self: Maybe[A]) {
+    inline def flatten[B]: Maybe[B] = if self.isEmpty then Absent else ???
+    def isEmpty: Boolean = self.isInstanceOf[Absent]
+  }
+
+class Test {
+  def main(): Unit =
+    import other.Maybe
+    val res: Maybe[Maybe[Int]] = ???
+    res.flatten
+}