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.

10 files changed, 35 insertions, 24 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
diff --git a/test/files/neg/accesses2.check b/test/files/neg/accesses2.check
new file mode 100644
index 0000000000..554a7b4c81
--- /dev/null
+++ b/test/files/neg/accesses2.check
@@ -0,0 +1,4 @@
+accesses2.scala:5: error: class B1 needs to be abstract, since method f2 in class A of type ()Int is not defined
+  class B1 extends A {
+        ^
+one error found
diff --git a/test/files/neg/accesses2.scala b/test/files/neg/accesses2.scala
new file mode 100644
index 0000000000..c7640f84b5
--- /dev/null
+++ b/test/files/neg/accesses2.scala
@@ -0,0 +1,11 @@
+package p2 {
+  abstract class A {
+    private[p2] def f2(): Int
+  }
+  class B1 extends A {
+    private def f2(): Int = 1
+  }
+  abstract class B2 extends A {
+    private def f2(): Int = 1
+  }
+}
diff --git a/test/files/neg/t0259.check b/test/files/neg/t0259.check
index 24e35e6176..8c15d98419 100644
--- a/test/files/neg/t0259.check
+++ b/test/files/neg/t0259.check
@@ -1,6 +1,6 @@
 t0259.scala:4: error: double definition:
-constructor TestCase3:(groups: String*)test.TestCase3 and
-constructor TestCase3:(groups: (String, Int)*)test.TestCase3 at line 3
+constructor TestCase3: (groups: (String, Int)*)test.TestCase3 at line 3 and
+constructor TestCase3: (groups: String*)test.TestCase3 at line 4
 have same type after erasure: (groups: Seq)test.TestCase3
   def this( groups: String*) = this()
       ^
diff --git a/test/files/neg/t3653.check b/test/files/neg/t3653.check
index ac6e2ca9dc..ad68e29fb4 100644
--- a/test/files/neg/t3653.check
+++ b/test/files/neg/t3653.check
@@ -1,7 +1,7 @@
 t3653.scala:3: error: double definition:
-method x:(implicit x: Int)Int and
-method x:(i: Int)Int at line 2
-have same type after erasure: (x: Int)Int
+def x(i: Int): Int at line 2 and
+def x(implicit x: Int): Int at line 3
+have same type after erasure: (i: Int)Int
    def x(implicit x: Int) = 5
        ^
 one error found
diff --git a/test/files/neg/t588.check b/test/files/neg/t588.check
index f8b5516fdc..ff08f77a6f 100644
--- a/test/files/neg/t588.check
+++ b/test/files/neg/t588.check
@@ -1,13 +1,13 @@
 t588.scala:3: error: double definition:
-method visit:(f: Int => String)Boolean and
-method visit:(f: Int => Unit)Boolean at line 2
+def visit(f: Int => Unit): Boolean at line 2 and
+def visit(f: Int => String): Boolean at line 3
 have same type after erasure: (f: Function1)Boolean
   def visit(f: Int => String): Boolean
       ^
 t588.scala:10: error: double definition:
-method f:(brac: Test.this.TypeB)Unit and
-method f:(node: Test.this.TypeA)Unit at line 9
-have same type after erasure: (brac: Test#TraitA)Unit
+def f(node: Test.this.TypeA): Unit at line 9 and
+def f(brac: Test.this.TypeB): Unit at line 10
+have same type after erasure: (node: Test#TraitA)Unit
   def f(brac : TypeB) : Unit;
       ^
 two errors found
diff --git a/test/files/neg/t6443c.check b/test/files/neg/t6443c.check
index 7cf8d23f4b..7b7f419f6c 100644
--- a/test/files/neg/t6443c.check
+++ b/test/files/neg/t6443c.check
@@ -1,6 +1,6 @@
 t6443c.scala:16: error: double definition:
-method foo:(d: B.D)(a: Any)(d2: d.type)Unit and
-method foo:(d: B.D)(a: Any, d2: d.type)Unit at line 11
+def foo(d: B.D)(a: Any,d2: d.type): Unit at line 11 and
+def foo(d: B.D)(a: Any)(d2: d.type): Unit at line 16
 have same type after erasure: (d: B.D, a: Object, d2: B.D)Unit
   def foo(d: D)(a: Any)(d2: d.type): Unit = ()
       ^
diff --git a/test/files/neg/t663.check b/test/files/neg/t663.check
index 40161fb3e3..633e27ee12 100644
--- a/test/files/neg/t663.check
+++ b/test/files/neg/t663.check
@@ -1,7 +1,7 @@
 t663.scala:11: error: name clash between defined and inherited member:
-method asMatch:(m: Test.this.Node)Any and
-method asMatch:(node: Test.this.Matchable)Any in trait MatchableImpl
-have same type after erasure: (m: test.Test#NodeImpl)Object
+def asMatch(node: Test.this.Matchable): Any in trait MatchableImpl and
+def asMatch(m: Test.this.Node): Any at line 11
+have same type after erasure: (node: test.Test#NodeImpl)Object
     def asMatch(m : Node) : Any = {
         ^
 one error found
diff --git a/test/files/neg/valueclasses-doubledefs.check b/test/files/neg/valueclasses-doubledefs.check
index 556d7a0900..ec513aca6b 100644
--- a/test/files/neg/valueclasses-doubledefs.check
+++ b/test/files/neg/valueclasses-doubledefs.check
@@ -1,6 +1,6 @@
 valueclasses-doubledefs.scala:5: error: double definition:
-method apply:(x: Meter)String and
-method apply:(x: Double)String at line 4
+def apply(x: Double): String at line 4 and
+def apply(x: Meter): String at line 5
 have same type after erasure: (x: Double)String
  def apply(x: Meter) = x.toString
      ^
diff --git a/test/files/neg/valueclasses-pavlov.check b/test/files/neg/valueclasses-pavlov.check
index 031589edad..17102a0c68 100644
--- a/test/files/neg/valueclasses-pavlov.check
+++ b/test/files/neg/valueclasses-pavlov.check
@@ -1,6 +1,6 @@
 valueclasses-pavlov.scala:8: error: double definition:
-method foo:(x: Box2)String and
-method foo:(x: String)String at line 7
+def foo(x: String): String at line 7 and
+def foo(x: Box2): String at line 8
 have same type after erasure: (x: String)String
   def foo(x: Box2) = "foo(Box2): ok"
       ^