SI-5130, precision disappearing from refinement.

[backport]
Remove some code, win a prize.

Author: paulp

src/reflect/scala/reflect/internal/Types.scala

@@ -3592,12 +3592,6 @@ trait Types extends api.Types { self: SymbolTable =>
     val pre1 = pre match {
       case x: SuperType if sym1.isEffectivelyFinal || sym1.isDeferred =>
         x.thistpe
-      case _: CompoundType if sym1.isClass =>
-        // sharpen prefix so that it is maximal and still contains the class.
-        pre.parents.reverse dropWhile (_.member(sym1.name) != sym1) match {
-          case Nil         => pre
-          case parent :: _ => parent
-        }
       case _ => pre
     }
     if (pre eq pre1)                                TypeRef(pre, sym1, args)

test/files/pos/t5130.scala

@@ -0,0 +1,46 @@
+import scala.language.reflectiveCalls
+
+class A {
+  this_a =>
+
+  def b = new B
+  class B { def a: this_a.type = this_a }
+}
+trait A2 { def c = () }
+
+object Test {
+  val v1 = new A { def c = () }
+  val v2 = new A with A2 { }
+  val v3: A { def c: Unit } = null
+  def d1 = new A { def c = () }
+  def d2 = new A with A2 { }
+  def d3: A { def c: Unit } = null
+  var x1 = new A { def c = () }
+  var x2 = new A with A2 { }
+  var x3: A { def c: Unit } = null
+
+  def main(args: Array[String]): Unit = {
+    val mv1 = new A { def c = () }
+    val mv2 = new A with A2 { }
+    val mv3: A { def c: Unit } = null
+    def md1 = new A { def c = () }
+    def md2 = new A with A2 { }
+    def md3: A { def c: Unit } = null
+
+     v1.b.a.c
+     v2.b.a.c
+     v3.b.a.c
+     d1.b.a.c
+     d2.b.a.c
+     d3.b.a.c
+     x1.b.a.c
+     x2.b.a.c
+     x3.b.a.c
+    mv1.b.a.c
+    mv2.b.a.c
+    mv3.b.a.c
+    md1.b.a.c
+    md2.b.a.c
+    md3.b.a.c
+  }
+}