diff tests/test-revset2.t @ 35501:12a46ad67a3c

smartset: split generatorset classes to avoid cycle

I uncovered a cycle manifesting in a memory leak by running
`hgperfrevset '::tip'`. The cycle was due to generatorset.__init__
assigning a bound method to self.__contains__. Internet sleuthing
revealed that assigning a bound method to an instance attribute
always creates a cycle.

This commit creates two new variants of generatorset for the special
cases of ascending and descending generators. The special
implementations of __contains__ have been extracted to these classes
where they are defined as __contains__.

generatorset now implements __new__ and changes the spawned type to
one of the new classes if needed.

Differential Revision: https://phab.mercurial-scm.org/D1780

--- a/tests/test-revset2.t	Wed Dec 27 13:53:21 2017 -0600
+++ b/tests/test-revset2.t	Wed Dec 27 11:08:32 2017 -0700
@@ -152,7 +152,7 @@
   * set:
   <addset
     <baseset- [1, 3, 5]>,
-    <generatorset+>>
+    <generatorsetdesc+>>
   5
   3
   1
@@ -174,7 +174,7 @@
             (symbol '5'))))))
   * set:
   <addset+
-    <generatorset+>,
+    <generatorsetdesc+>,
     <baseset- [1, 3, 5]>>
   0
   1
@@ -927,7 +927,7 @@
       (symbol 'merge')
       None))
   * set:
-  <generatorset+>
+  <generatorsetasc+>
   6
   7