# HG changeset patch
# User Martin von Zweigbergk <martinvonz@google.com>
# Date 1552373832 25200
# Node ID cfcb7eedc6664f79b4f8a02c478be0d5a55cacfd
# Parent  90f94231db5d050747d089845703463b1e6bde68
evolve: use merge.update() for resolving phase divergence

Iterating over the manifest when tree manifests and narrowness is in
play produces entries for paths outside the narrowspec that represent
trees. For example, if the tests/ directory of the hg repo was not in
the narrowspec (and the hg repo was using tree manifests, which it
doesn't), then there would be a "tests/" entry in the manifest. The
merge code deals with some of these cases. For example, it's valid to
do a merge if only the local side changes directories outside the
narrowspec. That allows rebasing a local commit onto a public commit
that had changes to the excluded paths to work.

However, _resolvephasedivergent() was iterating of the manifests,
which resulted in crashes for some of our users when they tried to
resolve phase-divergent commits (actually content-divergent commits
that became phase-divergent after the intermediate rebase). We can fix
that by relying on merge.update(), since that already handles this
case.

diff -r 90f94231db5d -r cfcb7eedc666 hgext3rd/evolve/evolvecmd.py
--- a/hgext3rd/evolve/evolvecmd.py	Wed Apr 10 23:19:29 2019 +0530
+++ b/hgext3rd/evolve/evolvecmd.py	Mon Mar 11 23:57:12 2019 -0700
@@ -276,43 +276,22 @@
     newid = None
     replacementnode = None
 
-    # Create the new commit context
-    files = set()
-    copied = copies.pathcopies(prec, bumped)
-    precmanifest = prec.manifest().copy()
-    # 3.3.2 needs a list.
-    # future 3.4 don't detect the size change during iteration
-    # this is fishy
-    for key, val in list(bumped.manifest().iteritems()):
-        precvalue = precmanifest.get(key, None)
-        if precvalue is not None:
-            del precmanifest[key]
-        if precvalue != val:
-            files.add(key)
-    files.update(precmanifest)  # add missing files
-
-    # commit it
-    if files: # something to commit!
-        def filectxfn(repo, ctx, path):
-            if path in bumped:
-                fctx = bumped[path]
-                flags = fctx.flags()
-                mctx = compat.memfilectx(repo, ctx, fctx, flags, copied, path)
-                return mctx
-            return None
+    # Create the new commit context. This is done by applying the changes from
+    # the precursor to the bumped node onto the precursor. This is effectively
+    # like reverting to the bumped node.
+    wctx = context.overlayworkingctx(repo)
+    wctx.setbase(prec)
+    merge.update(repo, bumped.node(), ancestor=prec, mergeancestor=True,
+                 branchmerge=True, force=False, wc=wctx)
+    if not wctx.isempty():
         text = '%s update to %s:\n\n' % (TROUBLES['PHASEDIVERGENT'], prec)
         text += bumped.description()
-
-        new = context.memctx(repo,
-                             parents=[prec.node(), nodemod.nullid],
-                             text=text,
-                             files=files,
-                             filectxfn=filectxfn,
-                             user=bumped.user(),
-                             date=bumped.date(),
-                             extra=bumped.extra())
-
-        newid = repo.commitctx(new)
+        memctx = wctx.tomemctx(text,
+                               parents=(prec.node(), nodemod.nullid),
+                               date=bumped.date(),
+                               extra=bumped.extra(),
+                               user=bumped.user())
+        newid = repo.commitctx(memctx)
         replacementnode = newid
     if newid is None:
         repo.ui.status(_('no changes to commit\n'))