cleaned up addEvidenceParams a bit

implemented my own feedback from
https://codereview.scala-lang.org/fisheye/cru/SR-1022#CFR-23393

no review

1 files changed, 8 insertions, 12 deletions

diff --git a/src/compiler/scala/tools/nsc/ast/parser/TreeBuilder.scala b/src/compiler/scala/tools/nsc/ast/parser/TreeBuilder.scala
index bf305ffc97..f65481e29a 100644
--- a/src/compiler/scala/tools/nsc/ast/parser/TreeBuilder.scala
+++ b/src/compiler/scala/tools/nsc/ast/parser/TreeBuilder.scala
@@ -596,22 +596,18 @@ abstract class TreeBuilder {
     AppliedTypeTree(rootScalaDot(newTypeName("Function" + argtpes.length)), argtpes ::: List(restpe))
 
   /** Append implicit parameter section if `contextBounds` nonempty */
-  def addEvidenceParams(owner: Name, vparamss: List[List[ValDef]], contextBounds: List[Tree]): List[List[ValDef]] =
+  def addEvidenceParams(owner: Name, vparamss: List[List[ValDef]], contextBounds: List[Tree]): List[List[ValDef]] = {
     if (contextBounds.isEmpty) vparamss
     else {
       val mods = Modifiers(if (owner.isTypeName) PARAMACCESSOR | LOCAL | PRIVATE else PARAM)
       def makeEvidenceParam(tpt: Tree) = ValDef(mods | IMPLICIT, freshTermName(nme.EVIDENCE_PARAM_PREFIX), tpt, EmptyTree)
       val evidenceParams = contextBounds map makeEvidenceParam
-      if (vparamss.isEmpty)
-        List(evidenceParams)
-      else {
-        val lastParams = vparamss(vparamss.size - 1)
-        if (!lastParams.isEmpty && (lastParams(0).mods hasFlag IMPLICIT))
-          // append lastParams to evidenceParams
-          (vparamss take (vparamss.size - 1)) ::: List(evidenceParams ::: lastParams)
-        else
-          vparamss ::: List(evidenceParams)
-      }
-  }
 
+      val vparamssLast = if(vparamss.nonEmpty) vparamss.last else Nil
+      if(vparamssLast.nonEmpty && vparamssLast.head.mods.hasFlag(IMPLICIT))
+        vparamss.init ::: List(evidenceParams ::: vparamssLast)
+      else
+        vparamss ::: List(evidenceParams)
+    }
+  }
 }