Add regression test (scala#16857)

Closes scala#16008

Author: nicolasstucki

tests/pos-macros/i16008/Macro_1.scala

@@ -0,0 +1,24 @@
+import scala.quoted.*
+
+enum MyEnum0:
+  case Marked
+  case Marked2(i: Int)
+
+trait MyMarker
+
+enum MyEnum(val value: String):
+  case Marked extends MyEnum("marked") with MyMarker
+  case Marked2(i: Int) extends MyEnum("marked") with MyMarker
+
+inline def enumMacro: Unit = ${ enumMacroExpr }
+
+private def enumMacroExpr(using Quotes): Expr[Unit] =
+  import quotes.reflect.*
+  assert(TypeRepr.of[MyEnum0].typeSymbol.flags.is(Flags.Enum))
+  assert(TypeRepr.of[MyEnum0.Marked.type].termSymbol.flags.is(Flags.Enum))
+  assert(TypeRepr.of[MyEnum0.Marked2].typeSymbol.flags.is(Flags.Enum))
+  assert(TypeRepr.of[MyEnum].typeSymbol.flags.is(Flags.Enum))
+  assert(TypeRepr.of[MyEnum.Marked.type].termSymbol.flags.is(Flags.Enum))
+  assert(TypeRepr.of[MyEnum.Marked2].typeSymbol.flags.is(Flags.Enum))
+
+  '{}

tests/pos-macros/i16008/Test_2.scala

@@ -0,0 +1 @@
+def test = enumMacro