A bit of style fixes here and there

Author: DarkDimius

src/dotty/tools/dotc/util/Attachment.scala

@@ -91,7 +91,7 @@ object Attachment {
     private[Attachment] var next: Link[_] = null
 
     final def pushAttachment[V](key: Key[V], value: V): Unit = {
-      assert(!getAttachment(key).isDefined, s"duplicate attachment for key $key")
+      assert(getAttachment(key).isEmpty, s"duplicate attachment for key $key")
       next = new Link(key, value, next)
     }
   }

test/dotty/partest/DPConsoleRunner.scala

@@ -120,7 +120,7 @@ extends SuiteRunner(testSourcePath, fileManager, updateCheck, failed, javaCmdPat
       echo(statusLine(state))
       if (!state.isOk && isDiffy) {
         val differ = bold(red("% ")) + "diff "
-        state.transcript.dropWhile(s => !(s startsWith differ)) foreach (echo(_))
+        state.transcript.dropWhile(s => !(s startsWith differ)) foreach (echo)
         // state.transcript find (_ startsWith differ) foreach (echo(_)) // original
       }
     }
@@ -248,7 +248,7 @@ class DPTestRunner(testFile: File, suiteRunner: DPSuiteRunner) extends nest.Runn
   // so we ignore groups (tests suffixed with _1 and _2)
   override def groupedFiles(sources: List[File]): List[List[File]] = {
     val grouped = sources groupBy (_.group)
-    val flatGroup = List(grouped.keys.toList.sorted.map({ k => grouped(k) sortBy (_.getName) }).flatten)
+    val flatGroup = List(grouped.keys.toList.sorted.flatMap { k => grouped(k) sortBy (_.getName) })
     try { // try/catch because of bug in partest that throws exception
       if (flatGroup != super.groupedFiles(sources))
         throw new java.lang.UnsupportedOperationException()

test/test/ContextEscapeDetector.java

@@ -1,6 +1,5 @@
 package test;
 
-import org.junit.runner.Description;
 import org.junit.runner.Result;
 import org.junit.runner.notification.RunListener;
 import org.junit.Assert;