closes #3373, #3177: validity check of an impli...

closes #3373, #3177: validity check of an implicit value should consider
the value as well as its accessor review by odersky

3 files changed, 60 insertions, 4 deletions

diff --git a/src/compiler/scala/tools/nsc/typechecker/Implicits.scala b/src/compiler/scala/tools/nsc/typechecker/Implicits.scala
index 9a6c4cc401..862f9adaec 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Implicits.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Implicits.scala
@@ -520,7 +520,7 @@ self: Analyzer =>
      *   - the symbol's type is initialized
      *   - the symbol comes from a classfile
      *   - the symbol comes from a different sourcefile than the current one
-     *   - the symbol's definition comes before, and does not contain the closest enclosing definition,
+     *   - the symbol and the accessed symbol's definitions come before, and do not contain the closest enclosing definition, // see #3373
      *   - the symbol's definition is a val, var, or def with an explicit result type
      *  The aim of this method is to prevent premature cyclic reference errors
      *  by computing the types of only those implicits for which one of these
@@ -539,9 +539,15 @@ self: Analyzer =>
           case _ => true
         }
       }
-      def comesBefore(sym: Symbol, owner: Symbol) =
-        sym.pos.pointOrElse(0) < owner.pos.pointOrElse(Integer.MAX_VALUE) &&
-        !(owner.ownerChain contains sym)
+      def comesBefore(sym: Symbol, owner: Symbol) = {
+        val ownerPos = owner.pos.pointOrElse(Integer.MAX_VALUE)
+        sym.pos.pointOrElse(0) < ownerPos &&
+          if(sym isGetterOrSetter) {
+            val symAcc = sym.accessed // #3373
+            symAcc.pos.pointOrElse(0) < ownerPos &&
+            !(owner.ownerChain exists (o => (o eq sym) || (o eq symAcc))) // probably faster to iterate only once, don't feel like duplicating hasTransOwner for this case
+          } else !(owner hasTransOwner sym) // faster than owner.ownerChain contains sym
+      }
 
       sym.isInitialized ||
       sym.sourceFile == null ||
diff --git a/test/files/pos/t3177.scala b/test/files/pos/t3177.scala
new file mode 100644
index 0000000000..9f9528faec
--- /dev/null
+++ b/test/files/pos/t3177.scala
@@ -0,0 +1,39 @@
+trait InvariantFunctor[F[_]] {
+  def xmap[A, B](ma: F[A], f: A => B, g: B => A): F[B]
+}
+
+object InvariantFunctor {
+  import Endo._
+
+  implicit val EndoInvariantFunctor = new InvariantFunctor[Endo] {
+    def xmap[A, B](ma: Endo[A], f: A => B, g: B => A): Endo[B] = (b: B) => f(ma(g(b)))
+  }
+
+  // The definition about fails with:
+  // anon-type.scala:9: error: not found: value b
+  //       def xmap[A, B](ma: Endo[A], f: A => B, g: B => A): Endo[B] = (b: B) => f(ma(g(b)))
+  //                                                                                     ^
+  //   anon-type.scala:8: error: not found: type $anon
+  //     implicit val EndoInvariantFunctor = new InvariantFunctor[Endo] {
+  //                                         ^
+
+
+  // These both work:
+  // implicit val EndoInvariantFunctorAscribed: InvariantFunctor[Endo] = new InvariantFunctor[Endo] {
+  //   def xmap[A, B](ma: Endo[A], f: A => B, g: B => A): Endo[B] = (b: B) => f(ma(g(b)))
+  // }
+  //
+  // implicit val EndoInvariantFunctorStubbed = new InvariantFunctor[Endo] {
+  //   def xmap[A, B](ma: Endo[A], f: A => B, g: B => A): Endo[B] = error("stub")
+  // }
+}
+
+trait Endo[X]
+
+object Endo {
+  implicit def EndoTo[A](f: A => A): Endo[A] = new Endo[A] {
+    def apply(a: A) = f(a)
+  }
+
+  implicit def EndoFrom[A](e: Endo[A]): A => A = e.apply(_)
+}
\ No newline at end of file
diff --git a/test/files/pos/t3373.scala b/test/files/pos/t3373.scala
new file mode 100644
index 0000000000..b4af3610bb
--- /dev/null
+++ b/test/files/pos/t3373.scala
@@ -0,0 +1,11 @@
+class Entry(time: Long) {
+ def getTime: Long = time
+}
+
+object Test {
+  def extractTime(e: Entry) = e.getTime
+
+  implicit val orderEntries = new Ordering[Entry] {
+   def compare(first: Entry, second: Entry) = extractTime(first) compare extractTime(second)
+  }
+}
\ No newline at end of file