Avoid name table pollution with fresh existentials

During large compilations runs, the large numbers of globally unique
fresh names for existentials captured from prefixes of `asSeenFrom`.
is a) somewhat wasteful (all these names are interned in the name table)
, and, b) form a pathological case for the current implementation of
`Names#hashValue`, which leads to overfull hash-buckets in the name table.

`hashValue` should probably be improved, but my attempts to do so have
shown a small performance degradation in some benchmarks. So this commit
starts by being more frugal with these names, only uniquely naming
within an `asSeenFrom` operation.

References scala/scala-dev#246

5 files changed, 11 insertions, 11 deletions

diff --git a/test/files/neg/sabin2.check b/test/files/neg/sabin2.check
index aa0e8f734c..cd6fde4608 100644
--- a/test/files/neg/sabin2.check
+++ b/test/files/neg/sabin2.check
@@ -1,6 +1,6 @@
 sabin2.scala:22: error: type mismatch;
  found   : Test.Base#T
- required: _5.T where val _5: Test.Base
+ required: _1.T where val _1: Test.Base
    a.set(b.get()) // Error
               ^
 one error found
diff --git a/test/files/neg/t0764.check b/test/files/neg/t0764.check
index 830278e715..0c7cff1e1e 100644
--- a/test/files/neg/t0764.check
+++ b/test/files/neg/t0764.check
@@ -1,5 +1,5 @@
 t0764.scala:13: error: type mismatch;
- found   : Node{type T = _2.type} where val _2: Node{type T = NextType}
+ found   : Node{type T = _1.type} where val _1: Node{type T = NextType}
  required: Node{type T = Main.this.AType}
     (which expands to)  Node{type T = Node{type T = NextType}}
         new Main[AType]( (value: AType).prepend )
diff --git a/test/files/neg/t1010.check b/test/files/neg/t1010.check
index 2cc8f9d986..d412d8ac1e 100644
--- a/test/files/neg/t1010.check
+++ b/test/files/neg/t1010.check
@@ -1,6 +1,6 @@
 t1010.scala:14: error: type mismatch;
  found   : MailBox#Message
- required: _3.in.Message where val _3: Actor
+ required: _1.in.Message where val _1: Actor
    unstable.send(msg) // in.Message becomes unstable.Message, but that's ok since Message is a concrete type member
                  ^
 one error found
diff --git a/test/files/neg/t5120.check b/test/files/neg/t5120.check
index 34d4ebde31..b6a3cb96aa 100644
--- a/test/files/neg/t5120.check
+++ b/test/files/neg/t5120.check
@@ -6,7 +6,7 @@ t5120.scala:11: error: type mismatch;
 t5120.scala:25: error: type mismatch;
  found   : Thread
  required: h.T
-    (which expands to)  _2
+    (which expands to)  _1
   List(str, num).foreach(h => h.f1 = new Thread())
                                      ^
 two errors found
diff --git a/test/files/neg/t6829.check b/test/files/neg/t6829.check
index 274094f791..5ccd531be1 100644
--- a/test/files/neg/t6829.check
+++ b/test/files/neg/t6829.check
@@ -1,6 +1,6 @@
 t6829.scala:35: error: type mismatch;
  found   : AgentSimulation.this.state.type (with underlying type G#State)
- required: _9.State
+ required: _1.State
     lazy val actions: Map[G#Agent,G#Action] = agents.map(a => a -> a.chooseAction(state)).toMap
                                                                                   ^
 t6829.scala:45: error: trait AgentSimulation takes type parameters
@@ -17,32 +17,32 @@ t6829.scala:49: error: not found: value nextState
                                              ^
 t6829.scala:50: error: type mismatch;
  found   : s.type (with underlying type Any)
- required: _30.State where val _30: G
+ required: _1.State where val _1: G
         val r = rewards(agent).r(s,a,s2)
                                  ^
 t6829.scala:50: error: type mismatch;
  found   : a.type (with underlying type Any)
- required: _30.Action where val _30: G
+ required: _1.Action where val _1: G
         val r = rewards(agent).r(s,a,s2)
                                    ^
 t6829.scala:50: error: type mismatch;
  found   : s2.type (with underlying type Any)
- required: _30.State where val _30: G
+ required: _1.State where val _1: G
         val r = rewards(agent).r(s,a,s2)
                                      ^
 t6829.scala:51: error: type mismatch;
  found   : s.type (with underlying type Any)
- required: _25.State
+ required: _1.State
         agent.learn(s,a,s2,r): G#Agent
                     ^
 t6829.scala:51: error: type mismatch;
  found   : a.type (with underlying type Any)
- required: _25.Action
+ required: _1.Action
         agent.learn(s,a,s2,r): G#Agent
                       ^
 t6829.scala:51: error: type mismatch;
  found   : s2.type (with underlying type Any)
- required: _25.State
+ required: _1.State
         agent.learn(s,a,s2,r): G#Agent
                         ^
 t6829.scala:53: error: not found: value nextState