# HG changeset patch
# User Yuya Nishihara <yuya@tcha.org>
# Date 2017-06-18 08:16:02
# Node ID c7da57bbae96ebdc8435fb33b57a2e0f98f936b1
# Parent  b9e2269aeff89ee5ff8665a8537d852d2dadab1a

dagop: comment why revancestors() doesn't heapify input revs at once

I wondered why we're doing this complicated stuff without noticing the input
revs may be iterated lazily in descending order. c1f666e27345 showed why.

diff --git a/mercurial/dagop.py b/mercurial/dagop.py
--- a/mercurial/dagop.py
+++ b/mercurial/dagop.py
@@ -26,6 +26,9 @@ def _genrevancestors(repo, revs, followf
     else:
         cut = None
     cl = repo.changelog
+
+    # load input revs lazily to heap so earlier revisions can be yielded
+    # without fully computing the input revs
     revs.sort(reverse=True)
     irevs = iter(revs)
     h = []