Rich Map woes

M.scala

class M {
  type AnyIterableOps[+A, Repr] = collection.IterableOps[A, Any, Repr]
  def richMap[K, V, CC <: collection.MapOps[K, V, AnyIterableOps, CC]] = ()
  
  def foo(m: scala.collection.immutable.Map[String, String]): AnyIterableOps[(String, String), scala.collection.immutable.Map[String, String]] = m
  
  richMap[Int, String, scala.collection.immutable.Map[Int, String]]

  
}

out.log

./build/quick/bin/scalac -d /tmp /tmp/map.scala -explaintypes
Nothing <: Int?
true
Nothing <: String?
  Nothing <: String?
  true
true
Nothing <: scala.collection.immutable.Map[Int,String]?
true
Int <: Any?
true
String <: Any?
true
scala.collection.immutable.Map[Int,String] <: scala.collection.MapOps[Int,String,M.this.AnyIterableOps,scala.collection.immutable.Map[Int,String]]?
  scala.collection.MapOps[Int,String,[_, _]scala.collection.immutable.Map[_,_],scala.collection.immutable.Map[Int,String]] <: scala.collection.MapOps[Int,String,M.this.AnyIterableOps,scala.collection.immutable.Map[Int,String]]?
    [_, _]scala.collection.immutable.Map[_,_] <: M.this.AnyIterableOps?
      scala.collection.immutable.Map[_,_] <: M.this.AnyIterableOps[_,_]?
        scala.collection.immutable.Map[_,_] <: scala.collection.IterableOps[_,Any,_]?
          scala.collection.IterableOps[(_, _),[_]scala.collection.immutable.Iterable[_],scala.collection.immutable.Map[_,_]] <: scala.collection.IterableOps[_,Any,_]?
            (_, _) <: _?
              (_, _) <: Nothing?
              false
            false
          false
        false
      false
    false
  false
false
/tmp/map.scala:9: error: type arguments [Int,String,scala.collection.immutable.Map[Int,String]] do not conform to method richMap's type parameter bounds [K,V,CC <: scala.collection.MapOps[K,V,M.this.AnyIterableOps,CC]]
  richMap[Int, String, scala.collection.immutable.Map[Int, String]]
         ^
1 error

scalac.patch

diff --git a/src/reflect/scala/reflect/internal/Types.scala b/src/reflect/scala/reflect/internal/Types.scala
index 1cefcf355d..4ae40687c2 100644
--- a/src/reflect/scala/reflect/internal/Types.scala
+++ b/src/reflect/scala/reflect/internal/Types.scala
@@ -98,6 +98,7 @@ trait Types
   import statistics._
 
   private[this] var explainSwitch = false
+  final def explainSwitchEnabled = explainSwitch
   @unused private final val emptySymbolSet = immutable.Set.empty[Symbol]
 
   @unused private final val breakCycles = settings.breakCycles.value
@@ -817,8 +818,7 @@ trait Types
       if (settings.areStatisticsEnabled) stat_<:<(that)
       else {
         (this eq that) ||
-        (if (explainSwitch) explain("<:", isSubType(_: Type, _: Type), this, that)
-         else isSubType(this, that))
+        (isSubType(this, that))
       }
     }
 
diff --git a/src/reflect/scala/reflect/internal/tpe/TypeComparers.scala b/src/reflect/scala/reflect/internal/tpe/TypeComparers.scala
index 92357d0e0e..9cc8e91999 100644
--- a/src/reflect/scala/reflect/internal/tpe/TypeComparers.scala
+++ b/src/reflect/scala/reflect/internal/tpe/TypeComparers.scala
@@ -265,6 +265,10 @@ trait TypeComparers {
   }
 
   def isSubType(tp1: Type, tp2: Type, depth: Depth = Depth.AnyDepth): Boolean = try {
+    if (explainSwitchEnabled) explain("<:", isSubTypeUnexplained(_: Type, _: Type, depth), tp1, tp2)
+    else isSubTypeUnexplained(tp1, tp2, depth)
+  }
+  def isSubTypeUnexplained(tp1: Type, tp2: Type, depth: Depth = Depth.AnyDepth): Boolean = try {
     subsametypeRecursions += 1
 
     //OPT cutdown on Function0 allocation