Reduce # calls to simplify

Call simplify and interpolateTypeVars in the same situations.

Author: odersky

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

@@ -1807,11 +1807,12 @@ class Typer extends Namer
 
   /** Interpolate and simplify the type of the given tree. */
   protected def simplify(tree: Tree, pt: Type, locked: TypeVars)(implicit ctx: Context): tree.type = {
-    if (!tree.denot.isOverloaded) {
-      // for overloaded trees: resolve overloading before simplifying
-      if (tree.isDef || !tree.tpe.widen.isInstanceOf[MethodOrPoly])
-        interpolateTypeVars(tree, pt, locked)
-      tree.overwriteType(tree.tpe.simplified) // ??? can we move in?
+    if (tree.isDef || // always simplify types of definitions
+        !tree.denot.isOverloaded ||  // for overloaded trees: resolve overloading before simplifying
+        !tree.tpe.widen.isInstanceOf[MethodOrPoly]) // wait with simplifying until method is fully applied
+    {
+      interpolateTypeVars(tree, pt, locked)
+      tree.overwriteType(tree.tpe.simplified)
     }
     tree
   }