SI-7624 Fix -feature warnings and build with -feature

I added a language.existential import to LazyCombiner.scala which
should not be necessary, but causes a spurious warning otherwise:

    scala/src/library/scala/collection/parallel/mutable/LazyCombiner.scala:33:
    warning: the existential type
        scala.collection.parallel.mutable.LazyCombiner[_$1,_$2,_$3] forSome {
          type _$1; type _$2; type _$3 <: scala.collection.generic.Growable[_$1] with scala.collection.generic.Sizing },
    which cannot be expressed by wildcards, should be enabled by making the implicit value scala.language.existentials visible.
    if (other.isInstanceOf[LazyCombiner[_, _, _]]) {
                       ^

I created ticket SI-7750 to track this issue.

1 files changed, 1 insertions, 0 deletions

diff --git a/src/xml/scala/xml/Elem.scala b/src/xml/scala/xml/Elem.scala
index 484cf98744..e9b87e516c 100755
--- a/src/xml/scala/xml/Elem.scala
+++ b/src/xml/scala/xml/Elem.scala
@@ -37,6 +37,7 @@ object Elem {
   }
 
   import scala.sys.process._
+  import scala.language.implicitConversions
   /** Implicitly convert a [[scala.xml.Elem]] into a
     * [[scala.sys.process.ProcessBuilder]]. This is done by obtaining the text
     * elements of the element, trimming spaces, and then converting the result