Support release-size releaseMode in Scala Native (#2754)

Co-authored-by: Tobias Roeser <le.petit.fou@web.de>

Pull request: #2754

contrib/bloop/src/mill/contrib/bloop/BloopImpl.scala

@@ -248,6 +248,7 @@ class BloopImpl(ev: () => Evaluator, wd: os.Path) extends ExternalModule { outer
                 case ReleaseMode.Debug => BloopConfig.LinkerMode.Debug
                 case ReleaseMode.ReleaseFast => BloopConfig.LinkerMode.Release
                 case ReleaseMode.ReleaseFull => BloopConfig.LinkerMode.Release
+                case ReleaseMode.ReleaseSize => BloopConfig.LinkerMode.Release
               },
               gc = m.nativeGC(),
               targetTriple = m.nativeTarget(),

scalanativelib/src/mill/scalanativelib/api/ScalaNativeApi.scala

@@ -18,15 +18,23 @@ object LTO {
 
 sealed abstract class ReleaseMode(val value: String)
 object ReleaseMode {
-  val values = Seq(Debug, ReleaseFast, ReleaseFull)
+  val values = Seq(Debug, ReleaseFast, ReleaseFull, ReleaseSize)
 
   case object Debug extends ReleaseMode("debug")
   case object ReleaseFast extends ReleaseMode("release-fast")
   case object ReleaseFull extends ReleaseMode("release-full")
 
+  /**
+   * Optimizes output binary size and still have relatively fast runtime performance.
+   *  Equivalent to `-Oz` switch of `clang`.
+   *  Since Scala Native 0.4.10
+   */
+  case object ReleaseSize extends ReleaseMode("release-size")
+
   implicit val rwDebug: ReadWriter[Debug.type] = macroRW[Debug.type]
   implicit val rwReleaseFast: ReadWriter[ReleaseFast.type] = macroRW[ReleaseFast.type]
   implicit val rwReleaseFull: ReadWriter[ReleaseFull.type] = macroRW[ReleaseFull.type]
+  implicit val rwReleaseSize: ReadWriter[ReleaseSize.type] = macroRW[ReleaseSize.type]
   implicit val rw: ReadWriter[ReleaseMode] = macroRW[ReleaseMode]
 }