Spiced up the irrefutability tests a bit.

test/files/neg/t5589neg.check

@@ -1,30 +1,37 @@
-t5589neg.scala:24: error: constructor cannot be instantiated to expected type;
+t5589neg.scala:2: warning: `withFilter' method does not yet exist on Either.RightProjection[Int,String], using `filter' method instead
+  def f5(x: Either[Int, String])        = for ((y1, y2: String) <- x.right) yield ((y1, y2))
+                                                                     ^
+t5589neg.scala:2: error: constructor cannot be instantiated to expected type;
  found   : (T1, T2)
  required: String
   def f5(x: Either[Int, String])        = for ((y1, y2: String) <- x.right) yield ((y1, y2))
                                                ^
-t5589neg.scala:25: error: constructor cannot be instantiated to expected type;
+t5589neg.scala:3: warning: `withFilter' method does not yet exist on Either.RightProjection[Int,String], using `filter' method instead
+  def f6(x: Either[Int, String])        = for ((y1, y2: Any) <- x.right) yield ((y1, y2))
+                                                                  ^
+t5589neg.scala:3: error: constructor cannot be instantiated to expected type;
  found   : (T1, T2)
  required: String
   def f6(x: Either[Int, String])        = for ((y1, y2: Any) <- x.right) yield ((y1, y2))
                                                ^
-t5589neg.scala:26: error: constructor cannot be instantiated to expected type;
+t5589neg.scala:4: error: constructor cannot be instantiated to expected type;
  found   : (T1,)
  required: (String, Int)
   def f7(x: Either[Int, (String, Int)]) = for (y1 @ Tuple1(y2) <- x.right) yield ((y1, y2))
                                                     ^
-t5589neg.scala:26: error: not found: value y2
+t5589neg.scala:4: error: not found: value y2
   def f7(x: Either[Int, (String, Int)]) = for (y1 @ Tuple1(y2) <- x.right) yield ((y1, y2))
                                                                                        ^
-t5589neg.scala:27: error: constructor cannot be instantiated to expected type;
+t5589neg.scala:5: error: constructor cannot be instantiated to expected type;
  found   : (T1, T2, T3)
  required: (String, Int)
   def f8(x: Either[Int, (String, Int)]) = for ((y1, y2, y3) <- x.right) yield ((y1, y2))
                                                ^
-t5589neg.scala:27: error: not found: value y1
+t5589neg.scala:5: error: not found: value y1
   def f8(x: Either[Int, (String, Int)]) = for ((y1, y2, y3) <- x.right) yield ((y1, y2))
                                                                                 ^
-t5589neg.scala:27: error: not found: value y2
+t5589neg.scala:5: error: not found: value y2
   def f8(x: Either[Int, (String, Int)]) = for ((y1, y2, y3) <- x.right) yield ((y1, y2))
                                                                                     ^
+two warnings found
 7 errors found

test/files/neg/t5589neg.scala

@@ -1,26 +1,4 @@
 class A {
-  // First three compile.
-  def f1(x: Either[Int, String])        = x.right map (y => y)
-  def f2(x: Either[Int, String])        = for (y <- x.right) yield y
-  def f3(x: Either[Int, (String, Int)]) = x.right map { case (y1, y2) => (y1, y2) }
-  // Last one fails.
-  def f4(x: Either[Int, (String, Int)]) = for ((y1, y2) <- x.right) yield ((y1, y2))
-/**
-./a.scala:5: error: constructor cannot be instantiated to expected type;
- found   : (T1, T2)
- required: Either[Nothing,(String, Int)]
-  def f4(x: Either[Int, (String, Int)]) = for ((y1, y2) <- x.right) yield ((y1, y2))
-                                               ^
-./a.scala:5: error: not found: value y1
-  def f4(x: Either[Int, (String, Int)]) = for ((y1, y2) <- x.right) yield ((y1, y2))
-                                                                            ^
-./a.scala:5: error: not found: value y2
-  def f4(x: Either[Int, (String, Int)]) = for ((y1, y2) <- x.right) yield ((y1, y2))
-                                                                                ^
-three errors found
-**/
-
-
   def f5(x: Either[Int, String])        = for ((y1, y2: String) <- x.right) yield ((y1, y2))
   def f6(x: Either[Int, String])        = for ((y1, y2: Any) <- x.right) yield ((y1, y2))
   def f7(x: Either[Int, (String, Int)]) = for (y1 @ Tuple1(y2) <- x.right) yield ((y1, y2))

test/files/neg/t5589neg2.check

@@ -0,0 +1,9 @@
+t5589neg2.scala:7: error: constructor cannot be instantiated to expected type;
+ found   : (T1, T2)
+ required: String
+    for (((((a, (b, (c, (d1, d2)))), es), fs), gs) <- x) yield (d :: es).mkString(", ") // not ok
+                        ^
+t5589neg2.scala:7: error: not found: value d
+    for (((((a, (b, (c, (d1, d2)))), es), fs), gs) <- x) yield (d :: es).mkString(", ") // not ok
+                                                                ^
+two errors found

test/files/neg/t5589neg2.scala

@@ -0,0 +1,13 @@
+class A {
+  def f1(x: List[((((Int, (Double, (Float, String))), List[String]), List[Int]), List[Float])]) = {
+    for (((((a, (b, (c, d))), es), fs), gs) <- x) yield (d :: es).mkString(", ") // ok
+  }
+
+  def f2(x: List[((((Int, (Double, (Float, String))), List[String]), List[Int]), List[Float])]) = {
+    for (((((a, (b, (c, (d1, d2)))), es), fs), gs) <- x) yield (d :: es).mkString(", ") // not ok
+  }
+
+  def f3(x: List[((((Int, (Double, (Float, String))), List[String]), List[Int]), List[Float])]) = {
+    for (((((a, (b, _)), es), fs), gs) <- x) yield (es ::: fs).mkString(", ") // ok
+  }
+}