[PATCH v4] histedit: make histedit aware of obsoletions not stored in state (issue4800)

[Kostia Balytskyi]

# HG changeset patch
# User Kostia Balytskyi <ikostia at fb.com>
# Date 1456227840 0
#      Tue Feb 23 11:44:00 2016 +0000
# Node ID 18e547e7742a2e54fc108748736d463262aabd38
# Parent  28e1694ca60056d609ae2c8e0ad5cb2891416ea3
histedit: make histedit aware of obsoletions not stored in state (issue4800)

Before this change, when histedit exited to interactive session (during edit
command for example), user could introduce obsolescence markers that would not
be known to histedit. For example, user could've amended one of the commits
(introducing an obsoletion change). The fact of this amendment would not be
stored in histedit's state file and later, when histedit would try to process
all the replacements that happened, one of the final successors (in its opinion)
would turn out to be hidden. This behavior is described in issue4800. This
commit fixes it.

diff --git a/hg b/hg
--- a/hg
+++ b/hg
@@ -39,5 +39,4 @@
 
 for fp in (sys.stdin, sys.stdout, sys.stderr):
     mercurial.util.setbinary(fp)
-
 mercurial.dispatch.run()
diff --git a/hgext/histedit.py b/hgext/histedit.py
--- a/hgext/histedit.py
+++ b/hgext/histedit.py
@@ -173,6 +173,7 @@
 import errno
 import os
 import sys
+import itertools
 
 from mercurial import bundle2
 from mercurial import cmdutil
@@ -1386,13 +1387,48 @@
                 hint=_('use "drop %s" to discard, see also: '
                        '"hg help -e histedit.config"') % missing[0][:12])
 
+def adjustreplacementsfrommarkers(repo, oldreplacements):
+    """Adjust replacements from obsolescense markers
+
+    Replacements structure is originally generated based on
+    histedit's state and does not account for changes that are
+    not recorded there. This function fixes that by adding
+    data read from obsolescense markers"""
+    if not obsolete.isenabled(repo, obsolete.createmarkersopt):
+        return oldreplacements
+
+    unfi = repo.unfiltered()
+    newreplacements = list(oldreplacements)
+    oldsuccs = itertools.imap(lambda r: r[1], oldreplacements)
+    # successors that have already been added to succstocheck once
+    seensuccs = set().union(*oldsuccs)
+    succstocheck = list(seensuccs)
+    while succstocheck:
+        n = succstocheck.pop()
+        try:
+            ctx = unfi[n]
+        except error.RepoError:
+            # node unknown locally, should be treated as replaced
+            newreplacements.append((n, ()))
+            continue
+
+        for marker in obsolete.successormarkers(ctx):
+            nsuccs = tuple(marker.succnodes())
+            newreplacements.append((n, nsuccs))
+            for nsucc in nsuccs:
+                if nsucc not in seensuccs:
+                    seensuccs.add(nsucc)
+                    succstocheck.append(nsucc)
+
+    return newreplacements
+
 def processreplacement(state):
     """process the list of replacements to return
 
     1) the final mapping between original and created nodes
     2) the list of temporary node created by histedit
     3) the list of new commit created by histedit"""
-    replacements = state.replacements
+    replacements = adjustreplacementsfrommarkers(state.repo, state.replacements)
     allsuccs = set()
     replaced = set()
     fullmapping = {}
diff --git a/tests/test-histedit-obsolete.t b/tests/test-histedit-obsolete.t
--- a/tests/test-histedit-obsolete.t
+++ b/tests/test-histedit-obsolete.t
@@ -14,6 +14,36 @@
   > rebase=
   > EOF
 
+Test that histedit learns about obsoletions not stored in histedit state
+  $ hg init boo
+  $ cd boo
+  $ echo a > a
+  $ hg ci -Am a
+  adding a
+  $ echo a > b
+  $ echo a > c
+  $ echo a > c
+  $ hg ci -Am b
+  adding b
+  adding c
+  $ echo a > d
+  $ hg ci -Am c
+  adding d
+  $ echo "pick `hg log -r 0 -T '{node|short}'`" > plan
+  $ echo "pick `hg log -r 2 -T '{node|short}'`" >> plan
+  $ echo "edit `hg log -r 1 -T '{node|short}'`" >> plan
+  $ hg histedit -r 'all()' --commands plan
+  Editing (1b2d564fad96), you may commit or record as needed now.
+  (hg histedit --continue to resume)
+  [1]
+  $ hg st
+  A b
+  A c
+  ? plan
+  $ hg commit --amend b
+  $ hg histedit --continue
+  $ cd ..
+
   $ hg init base
   $ cd base