# HG changeset patch
# User Pierre-Yves David <pierre-yves.david@octobus.net>
# Date 2021-05-04 12:18:06
# Node ID 6be2a7ca4b1d9e49f45d63a26126f0ed89c87aae
# Parent  9d1a8829f9593e69ede9f518aaf59918b455e59a

revlog: do not call Rust code if the index is not compatible with it

This will avoid hitting the TypeError we defined in the previous changesets.
This is the simplest fix but not the most elegant.

Ideally we would teach the Rust code to use any kind of revlog. However this is
an adventure for another time.

Differential Revision: https://phab.mercurial-scm.org/D10666

diff --git a/mercurial/revlog.py b/mercurial/revlog.py
--- a/mercurial/revlog.py
+++ b/mercurial/revlog.py
@@ -1063,7 +1063,7 @@ class revlog(object):
             checkrev(r)
         # and we're sure ancestors aren't filtered as well
 
-        if rustancestor is not None:
+        if rustancestor is not None and self.index.rust_ext_compat:
             lazyancestors = rustancestor.LazyAncestors
             arg = self.index
         else:
@@ -1150,7 +1150,7 @@ class revlog(object):
         if common is None:
             common = [nullrev]
 
-        if rustancestor is not None:
+        if rustancestor is not None and self.index.rust_ext_compat:
             return rustancestor.MissingAncestors(self.index, common)
         return ancestor.incrementalmissingancestors(self.parentrevs, common)
 
@@ -1370,7 +1370,7 @@ class revlog(object):
                 return self.index.headrevs()
             except AttributeError:
                 return self._headrevs()
-        if rustdagop is not None:
+        if rustdagop is not None and self.index.rust_ext_compat:
             return rustdagop.headrevs(self.index, revs)
         return dagop.headrevs(revs, self._uncheckedparentrevs)
 
diff --git a/mercurial/setdiscovery.py b/mercurial/setdiscovery.py
--- a/mercurial/setdiscovery.py
+++ b/mercurial/setdiscovery.py
@@ -274,6 +274,8 @@ class partialdiscovery(object):
         return sample
 
 
+pure_partialdiscovery = partialdiscovery
+
 partialdiscovery = policy.importrust(
     'discovery', member='PartialDiscovery', default=partialdiscovery
 )
@@ -434,9 +436,11 @@ def findcommonheads(
     hard_limit_sample = not (dynamic_sample or remote.limitedarguments)
 
     randomize = ui.configbool(b'devel', b'discovery.randomize')
-    disco = partialdiscovery(
-        local, ownheads, hard_limit_sample, randomize=randomize
-    )
+    if cl.index.rust_ext_compat:
+        pd = partialdiscovery
+    else:
+        pd = pure_partialdiscovery
+    disco = pd(local, ownheads, hard_limit_sample, randomize=randomize)
     if initial_head_exchange:
         # treat remote heads (and maybe own heads) as a first implicit sample
         # response