merge: deprecate accessing update results by index

Now that we have named attributes, let's convert the code base to use
them. We also add deprecation warnings so legacy consumers are aware
of their transgressions.

``stats.unresolvedcount`` is much easier to read than ``stats[3]``,
don't you think?

Differential Revision: https://phab.mercurial-scm.org/D2694

hgext/histedit.py

@@ -499,7 +499,7 b' class histeditaction(object):'
         hg.update(repo, self.state.parentctxnode, quietempty=True)
         stats = applychanges(repo.ui, repo, rulectx, {})
         repo.dirstate.setbranch(rulectx.branch())
-        if stats and stats[3] > 0:
+        if stats.unresolvedcount:
             buf = repo.ui.popbuffer()
             repo.ui.write(buf)
             raise error.InterventionRequired(

hgext/rebase.py

@@ -525,7 +525,7 b' class rebaseruntime(object):'
                 with ui.configoverride(overrides, 'rebase'):
                     stats = rebasenode(repo, rev, p1, base, self.collapsef,
                                        dest, wctx=self.wctx)
-                    if stats[3] > 0:
+                    if stats.unresolvedcount > 0:
                         if self.inmemory:
                             raise error.InMemoryMergeConflictsError()
                         else:

mercurial/commands.py

@@ -629,7 +629,7 b' def _dobackout(ui, repo, node=None, rev='
             repo.setparents(op1, op2)
             dsguard.close()
             hg._showstats(repo, stats)
-            if stats[3]:
+            if stats.unresolvedcount:
                 repo.ui.status(_("use 'hg resolve' to retry unresolved "
                                  "file merges\n"))
                 return 1
@@ -2311,7 +2311,7 b' def _dograft(ui, repo, *revs, **opts):'
             finally:
                 repo.ui.setconfig('ui', 'forcemerge', '', 'graft')
             # report any conflicts
-            if stats[3] > 0:
+            if stats.unresolvedcount > 0:
                 # write out state for --continue
                 nodelines = [repo[rev].hex() + "\n" for rev in revs[pos:]]
                 repo.vfs.write('graftstate', ''.join(nodelines))

mercurial/hg.py

@@ -749,7 +749,7 b' def clone(ui, peeropts, source, dest=Non'
     return srcpeer, destpeer
 
 def _showstats(repo, stats, quietempty=False):
-    if quietempty and not any(stats):
+    if quietempty and stats.isempty():
         return
     repo.ui.status(_("%d files updated, %d files merged, "
                      "%d files removed, %d files unresolved\n") % (
@@ -770,9 +770,9 b' def update(repo, node, quietempty=False,'
     """update the working directory to node"""
     stats = updaterepo(repo, node, False, updatecheck=updatecheck)
     _showstats(repo, stats, quietempty)
-    if stats[3]:
+    if stats.unresolvedcount:
         repo.ui.status(_("use 'hg resolve' to retry unresolved file merges\n"))
-    return stats[3] > 0
+    return stats.unresolvedcount > 0
 
 # naming conflict in clone()
 _update = update
@@ -783,7 +783,7 b' def clean(repo, node, show_stats=True, q'
     repo.vfs.unlinkpath('graftstate', ignoremissing=True)
     if show_stats:
         _showstats(repo, stats, quietempty)
-    return stats[3] > 0
+    return stats.unresolvedcount > 0
 
 # naming conflict in updatetotally()
 _clean = clean
@@ -882,12 +882,12 b' def merge(repo, node, force=None, remind'
                                 labels=labels)
 
     _showstats(repo, stats)
-    if stats[3]:
+    if stats.unresolvedcount:
         repo.ui.status(_("use 'hg resolve' to retry unresolved file merges "
                          "or 'hg merge --abort' to abandon\n"))
     elif remind and not abort:
         repo.ui.status(_("(branch merge, don't forget to commit)\n"))
-    return stats[3] > 0
+    return stats.unresolvedcount > 0
 
 def _incoming(displaychlist, subreporecurse, ui, repo, source,
         opts, buffered=False):

mercurial/merge.py

@@ -1483,9 +1483,15 b' class updateresult(object):'
     removedcount = attr.ib()
     unresolvedcount = attr.ib()
 
+    def isempty(self):
+        return (not self.updatedcount and not self.mergedcount
+                and not self.removedcount and not self.unresolvedcount)
+
     # TODO remove container emulation once consumers switch to new API.
 
     def __getitem__(self, x):
+        util.nouideprecwarn('access merge.update() results by name instead of '
+                            'index', '4.6', 2)
         if x == 0:
             return self.updatedcount
         elif x == 1:
@@ -1498,6 +1504,8 b' class updateresult(object):'
             raise IndexError('can only access items 0-3')
 
     def __len__(self):
+        util.nouideprecwarn('access merge.update() results by name instead of '
+                            'index', '4.6', 2)
         return 4
 
 def applyupdates(repo, actions, wctx, mctx, overwrite, labels=None):
@@ -2164,7 +2172,8 b' def update(repo, node, branchmerge, forc'
         sparse.prunetemporaryincludes(repo)
 
     if not partial:
-        repo.hook('update', parent1=xp1, parent2=xp2, error=stats[3])
+        repo.hook('update', parent1=xp1, parent2=xp2,
+                  error=stats.unresolvedcount)
     return stats
 
 def graft(repo, ctx, pctx, labels, keepparent=False):