Rename TypeVarBinder --> InferredTypeTree

# Conflicts:
#	compiler/src/dotty/tools/dotc/typer/RefineTypes.scala

Author: odersky

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

@@ -699,10 +699,12 @@ object Trees {
       s"TypeTree${if (hasType) s"[$typeOpt]" else ""}"
   }
 
-  /** A type tree that defines a new type variable. Its type is always a TypeVar.
-   *  Every TypeVar is created as the type of one TypeVarBinder.
+  /** A type tree whose type is inferred. These trees appear in two contexts
+   *    - as an argument of a TypeApply. In that case its type is always a TypeVar
+   *    - as a (result-)type of an inferred ValDef or DefDef.
+   *  Every TypeVar is created as the type of one InferredTypeTree.
    */
-  class TypeVarBinder[-T >: Untyped](implicit @constructorOnly src: SourceFile) extends TypeTree[T]
+  class InferredTypeTree[-T >: Untyped](implicit @constructorOnly src: SourceFile) extends TypeTree[T]
 
   /** ref.type */
   case class SingletonTypeTree[-T >: Untyped] private[ast] (ref: Tree[T])(implicit @constructorOnly src: SourceFile)

compiler/src/dotty/tools/dotc/typer/Inferencing.scala

@@ -333,7 +333,7 @@ object Inferencing {
     @tailrec def boundVars(tree: Tree, acc: List[TypeVar]): List[TypeVar] = tree match {
       case Apply(fn, _) => boundVars(fn, acc)
       case TypeApply(fn, targs) =>
-        val tvars = targs.filter(_.isInstanceOf[TypeVarBinder[?]]).tpes.collect {
+        val tvars = targs.filter(_.isInstanceOf[InferredTypeTree[?]]).tpes.collect {
           case tvar: TypeVar
           if !tvar.isInstantiated &&
              ctx.typerState.ownedVars.contains(tvar) &&

compiler/src/dotty/tools/dotc/typer/ProtoTypes.scala

@@ -636,7 +636,7 @@ object ProtoTypes {
     def newTypeVars(tl: TypeLambda): List[TypeTree] =
       for (paramRef <- tl.paramRefs)
       yield {
-        val tt = TypeVarBinder().withSpan(owningTree.span)
+        val tt = InferredTypeTree().withSpan(owningTree.span)
         val tvar = TypeVar(paramRef, state)
         state.ownedVars += tvar
         tt.withType(tvar)

compiler/src/dotty/tools/dotc/typer/Typer.scala

@@ -3063,7 +3063,7 @@ class Typer extends Namer
             else Some(adapt(tree1, pt, locked))
           } { (_, _) => None
           }
-      case TypeApply(fn, args) if args.forall(_.isInstanceOf[TypeVarBinder[_]]) =>
+      case TypeApply(fn, args) if args.forall(_.isInstanceOf[InferredTypeTree[_]]) =>
         tryInsertImplicitOnQualifier(fn, pt, locked)
       case _ => None
   }