Fix #6151: MatchError for imported java enum Values

When emitting annotations' arguments from the `DottyBackendInterface`,
the case when the argument value can be an `Ident` is not considered.
This commit generalises the `Select` case to `RefTree`, so that both
`Select` and `Ident` are considered.

Author: anatoliykmetyuk

compiler/src/dotty/tools/backend/jvm/DottyBackendInterface.scala

@@ -254,7 +254,7 @@ class DottyBackendInterface(outputDirectory: AbstractFile, val superCallsMap: Ma
         }
       case t: TypeApply if (t.fun.symbol == Predef_classOf) =>
         av.visit(name, t.args.head.tpe.classSymbol.denot.info.toTypeKind(bcodeStore)(innerClasesStore).toASMType)
-      case t: tpd.Select =>
+      case t: tpd.RefTree =>
         if (t.symbol.denot.owner.is(Flags.JavaEnum)) {
           val edesc = innerClasesStore.typeDescriptor(t.tpe.asInstanceOf[bcodeStore.int.Type]) // the class descriptor of the enumeration class.
           val evalue = t.symbol.name.mangledString // value the actual enumeration value.

tests/pos/i6151/Expect.java

@@ -0,0 +1 @@
+public enum Expect  { ExpectVal }

tests/pos/i6151/Outcome.java

@@ -0,0 +1 @@
+public @interface Outcome { Expect enm(); }

tests/pos/i6151/Test.scala

@@ -0,0 +1,3 @@
+import Expect._
+@Outcome(ExpectVal)
+class SimpleTest