Fix and add to tests

Author: odersky

compiler/src/dotty/tools/dotc/ast/TreeInfo.scala

@@ -824,7 +824,7 @@ trait TypedTreeInfo extends TreeInfo[Type] { self: Trees.Instance[Type] =>
     case _ => tree
   }
 
-  /** An extractor for eta expanded `mdef` an eta-expansion of a method reference? To recognize this, we use
+  /** Is `mdef` an eta-expansion of a method reference? To recognize this, we use
    *  the following criterion: A method definition is an eta expansion, if
    *  it contains at least one term paramter, the parameter has a zero extent span,
    *  and the right hand side is either an application or a closure with'

tests/neg/capt-wf.scala

@@ -13,7 +13,7 @@ def test(c: Cap, other: String): Unit =
   val x3a: () -> String = s1
   val s2 = () => if x1 == null then "" else "abc"
   val x4: C^{s2} = ??? // OK
-  val x5: C^{c, c} = ??? // error: redundant
+  val x5: C^{c, c} = ??? // error: redundant // error: redundant
   // val x6: C^{c}^{c} = ??? // would be syntax error
   val x7: Cap^{c} = ??? // error: redundant
   // val x8: C^{c}^{cap} = ??? // would be syntax error

tests/pos-custom-args/captures/pairs.scala

@@ -38,6 +38,10 @@ object Monomorphic2:
     def fst: Cap^{cap[Pair]} ->{x} Unit = x
     def snd: Cap^{cap[Pair]} ->{y} Unit = y
 
+  class Pair2(x: Cap => Unit, y: Cap => Unit):
+    def fst: Cap^{cap[Pair2]} => Unit = x
+    def snd: Cap^{cap[Pair2]} => Unit = y
+
   def test(c: Cap, d: Cap) =
     def f(x: Cap): Unit = if c == x then ()
     def g(x: Cap): Unit = if d == x then ()
@@ -46,3 +50,4 @@ object Monomorphic2:
     val x1c: Cap ->{c} Unit = x1
     val y1 = p.snd
     val y1c: Cap ->{d} Unit = y1
+