Implement reviewer suggestions

Author: odersky

compiler/src/dotty/tools/dotc/core/Types.scala

@@ -524,7 +524,7 @@ object Types {
     }
 
     /** The member with given `name` and required and/or excluded flags */
-    final def memberBasedOnFlags(name: Name, required: FlagConjunction, excluded: FlagSet)(implicit ctx: Context): Denotation = {
+    final def memberBasedOnFlags(name: Name, required: FlagConjunction = EmptyFlagConjunction, excluded: FlagSet = EmptyFlags)(implicit ctx: Context): Denotation = {
       // We need a valid prefix for `asSeenFrom`
       val pre = this match {
         case tp: ClassInfo => tp.appliedRef

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

@@ -1139,7 +1139,7 @@ trait Applications extends Compatibility { self: Typer with Dynamic =>
    *  result matching `resultType`?
    */
   def hasExtensionMethod(tp: Type, name: TermName, argType: Type, resultType: Type)(implicit ctx: Context) = {
-    val mbr = tp.member(name).suchThat(_.is(ExtensionMethod))
+    val mbr = tp.memberBasedOnFlags(name, required = allOf(ExtensionMethod))
     mbr.exists && isApplicable(tp.select(name, mbr), argType :: Nil, resultType)
   }
 
@@ -1645,7 +1645,7 @@ trait Applications extends Compatibility { self: Typer with Dynamic =>
 
   /** The typed application
    *
-   *   <nethodRef>(<receiver>)    or
+   *   <methodRef>(<receiver>)    or
    *   <methodRef>[<type-args>](<receiver>)
    *
    *  where <type-args> comes from `pt` if it is a PolyProto.

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

@@ -147,7 +147,7 @@ object Implicits {
                   tpw.derivesFrom(defn.Predef_Conforms) && ref.symbol != defn.Predef_conforms
               val hasExtensions = resType match {
                 case SelectionProto(name, _, _, _) =>
-                  tpw.member(name).hasAltWith(_.symbol.is(ExtensionMethod))
+                  tpw.memberBasedOnFlags(name, required = allOf(ExtensionMethod)).exists
                 case _ => false
               }
               val conversionKind =