Generalize OverridingPairs to SymbolPairs.

Increases your chance of knowing what is going on in
OverridingPairs. Introduces some new abstractions which I
hope for your own sakes you will put to use in some way:

  RelativeTo: operations relative to a prefix
  SymbolPair: two symbols being compared for something, and
    the enclosing class where the comparison is being performed

Fixed a minor bug with access by accident by way of more
principled pair analysis. See run/private-override.scala.

Upgraded the error message issued on certain conflicts
to give the line numbers of both conflicting methods, as
opposed to just one and you go hunting.

1 files changed, 1 insertions, 5 deletions

diff --git a/test/files/neg/accesses.check b/test/files/neg/accesses.check
index db58af12ce..5a5e03233e 100644
--- a/test/files/neg/accesses.check
+++ b/test/files/neg/accesses.check
@@ -1,7 +1,3 @@
-accesses.scala:23: error: overriding method f2 in class A of type ()Unit;
- method f2 has weaker access privileges; it should not be private
-  private def f2(): Unit = ()
-              ^
 accesses.scala:24: error: overriding method f3 in class A of type ()Unit;
  method f3 has weaker access privileges; it should be at least protected
   private[p2] def f3(): Unit = ()
@@ -14,4 +10,4 @@ accesses.scala:26: error: overriding method f5 in class A of type ()Unit;
  method f5 has weaker access privileges; it should be at least protected[p1]
   protected[p2] def f5(): Unit
                     ^
-four errors found
+three errors found