Query methods in api.Symbols for Java flags

Adds query methods to the public reflection API for querying the
JAVA_ENUM and JAVA_ANNOTATION flags.

Didn't include JAVA_DEFAULTMETHOD because it does not correspond
to a real java classfile flag (just a non-abstract method in an
interface), and we want to clean the usage of this flag before adding
it to a public API.

The flags themselfs are not added to the reflection API. A comment in
api/FlagSets.scala says:

    Q: I have a pretty flag. Can I put it here?
    A: Only if there's a tree that cannot be built without it.
       If you want to put a flag here so that it can be tested
       against, introduce an `isXXX` method in one of the api.Symbols
       classes instead.

Author: lrytz

src/reflect/scala/reflect/api/FlagSets.scala

@@ -173,6 +173,7 @@ trait FlagSets { self: Universe =>
      *  - the enum's class
      *  - enum constants
      **/
+    @deprecated("Use `isJavaEnum` on the corresponding symbol instead.", since = "2.11.8")
     val ENUM: FlagSet
 
     /** Flag indicating that tree represents a parameter of the primary constructor of some class

src/reflect/scala/reflect/api/Symbols.scala

@@ -504,6 +504,18 @@ trait Symbols { self: Universe =>
      */
     def isImplicit: Boolean
 
+    /** Does this symbol represent a java enum class or a java enum value?
+      *
+      *  @group Tests
+      */
+    def isJavaEnum: Boolean
+
+    /** Does this symbol represent a java annotation interface?
+      *
+      *  @group Tests
+      */
+    def isJavaAnnotation: Boolean
+
     /******************* helpers *******************/
 
     /** Provides an alternate if symbol is a NoSymbol.

src/reflect/scala/reflect/internal/Symbols.scala

@@ -102,6 +102,9 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
     def isPrivateThis = (this hasFlag PRIVATE) && (this hasFlag LOCAL)
     def isProtectedThis = (this hasFlag PROTECTED) && (this hasFlag LOCAL)
 
+    def isJavaEnum: Boolean = hasJavaEnumFlag
+    def isJavaAnnotation: Boolean = hasJavaAnnotationFlag
+
     def newNestedSymbol(name: Name, pos: Position, newFlags: Long, isClass: Boolean): Symbol = name match {
       case n: TermName => newTermSymbol(n, pos, newFlags)
       case n: TypeName => if (isClass) newClassSymbol(n, pos, newFlags) else newNonClassSymbol(n, pos, newFlags)

test/junit/scala/tools/nsc/symtab/FlagsTest.scala

@@ -86,4 +86,11 @@ class FlagsTest {
 
     assertEquals(withFlagMask(AllFlags)(sym.setFlag(lateFlags).flags), lateFlags | lateable)
   }
+
+  @Test
+  def javaClassMirrorAnnotationFlag(): Unit = {
+    import scala.reflect.runtime.universe._
+    val dep = typeOf[java.lang.Deprecated].typeSymbol
+    assertTrue(dep.isJavaAnnotation && dep.isJava)
+  }
 }