Create def with closure extractor in TreeInfo

Author: nicolasstucki

compiler/src/dotty/tools/dotc/ast/TreeInfo.scala

@@ -534,9 +534,18 @@ trait TypedTreeInfo extends TreeInfo[Type] { self: Trees.Instance[Type] =>
     }
   }
 
+  /** An extractor for closures with their def contained in a block. */
+  object closureWithDef {
+    def unapply(tree: Tree): Option[(DefDef, Closure)] = tree match {
+      case Block((meth @ DefDef(nme.ANON_FUN, _, _, _, _)) :: Nil, closure: Closure) =>
+        Some(meth, closure)
+      case _ => None
+    }
+  }
+
   /** If tree is a closure, its body, otherwise tree itself */
   def closureBody(tree: Tree)(implicit ctx: Context): Tree = tree match {
-    case Block((meth @ DefDef(nme.ANON_FUN, _, _, _, _)) :: Nil, Closure(_, _, _)) => meth.rhs
+    case closureWithDef(meth, _) => meth.rhs
     case _ => tree
   }
 

compiler/src/dotty/tools/dotc/core/quoted/PickledQuotes.scala

@@ -126,7 +126,7 @@ object PickledQuotes {
     val x1 = SyntheticValDef(NameKinds.UniqueName.fresh("x".toTermName), x)
     def x1Ref() = ref(x1.symbol)
     def rec(f: Tree): Tree = f match {
-      case Block((ddef: DefDef) :: Nil, _: Closure) =>
+      case closureWithDef(ddef, _) =>
         new TreeMap() {
           private val paramSym = ddef.vparamss.head.head.symbol
           override def transform(tree: tpd.Tree)(implicit ctx: Context): tpd.Tree = tree match {