Tweaks to matches

1) Drop redundant signature comparison in overriding pairs
2) Abstract from repeated parameters when calculating matches

Author: odersky

src/dotty/tools/dotc/core/TypeApplications.scala

@@ -285,7 +285,7 @@ class TypeApplications(val self: Type) extends AnyVal {
    */
   def underlyingIfRepeated(isJava: Boolean)(implicit ctx: Context): Type =
     if (self.isRepeatedParam) {
-      val seqClass = if(isJava) defn.ArrayClass else defn.SeqClass
+      val seqClass = if (isJava) defn.ArrayClass else defn.SeqClass
       translateParameterized(defn.RepeatedParamClass, seqClass)
     }
     else self

src/dotty/tools/dotc/core/TypeComparer.scala

@@ -684,7 +684,7 @@ class TypeComparer(initctx: Context) extends DotClass with ConstraintHandling wi
     case formal1 :: rest1 =>
       formals2 match {
         case formal2 :: rest2 =>
-          (isSameType(formal1, formal2)
+          (isSameType(formal1.underlyingIfRepeated(isJava1), formal2.underlyingIfRepeated(isJava2))
             || isJava1 && (formal2 isRef ObjectClass) && (formal1 isRef AnyClass)
             || isJava2 && (formal1 isRef ObjectClass) && (formal2 isRef AnyClass)) &&
           matchingParams(rest1, rest2, isJava1, isJava2)

src/dotty/tools/dotc/transform/OverridingPairs.scala

@@ -39,12 +39,7 @@ object OverridingPairs {
      *  relative to <base>.this do
      */
     protected def matches(sym1: Symbol, sym2: Symbol): Boolean =
-      sym1.isType || {
-        val info1 = self.memberInfo(sym1)
-        val info2 = self.memberInfo(sym2)
-        info1.signature.sameParams(info2.signature) &&
-        info1.matches(info2)
-      }
+      sym1.isType || self.memberInfo(sym1).matches(self.memberInfo(sym2))
 
     /** The symbols that can take part in an overriding pair */
     private val decls = {