rewriteutil: extract evolve code used to replace obsolete hashes in commits

The evolve command uses it, but there are core things like `phabsend` and
`rebase` that would also benefit.

Differential Revision: https://phab.mercurial-scm.org/D8948

mercurial/rewriteutil.py

@@ -1,72 +1,115 b''
 # rewriteutil.py - utility functions for rewriting changesets
 #
 # Copyright 2017 Octobus <[e-mail]>
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
 from __future__ import absolute_import
 
+import re
+
 from .i18n import _
 
 from . import (
     error,
     node,
     obsolete,
+    obsutil,
     revset,
+    scmutil,
 )
 
 
+sha1re = re.compile(br'\b[0-9a-f]{6,40}\b')
+
+
 def precheck(repo, revs, action=b'rewrite'):
     """check if revs can be rewritten
     action is used to control the error message.
 
     Make sure this function is called after taking the lock.
     """
     if node.nullrev in revs:
         msg = _(b"cannot %s null changeset") % action
         hint = _(b"no changeset checked out")
         raise error.Abort(msg, hint=hint)
 
     if len(repo[None].parents()) > 1:
         raise error.Abort(_(b"cannot %s while merging") % action)
 
     publicrevs = repo.revs(b'%ld and public()', revs)
     if publicrevs:
         msg = _(b"cannot %s public changesets") % action
         hint = _(b"see 'hg help phases' for details")
         raise error.Abort(msg, hint=hint)
 
     newunstable = disallowednewunstable(repo, revs)
     if newunstable:
         raise error.Abort(_(b"cannot %s changeset with children") % action)
 
 
 def disallowednewunstable(repo, revs):
     """Checks whether editing the revs will create new unstable changesets and
     are we allowed to create them.
 
     To allow new unstable changesets, set the config:
         `experimental.evolution.allowunstable=True`
     """
     allowunstable = obsolete.isenabled(repo, obsolete.allowunstableopt)
     if allowunstable:
         return revset.baseset()
     return repo.revs(b"(%ld::) - %ld", revs, revs)
 
 
 def skip_empty_successor(ui, command):
     empty_successor = ui.config(b'rewrite', b'empty-successor')
     if empty_successor == b'skip':
         return True
     elif empty_successor == b'keep':
         return False
     else:
         raise error.ConfigError(
             _(
                 b"%s doesn't know how to handle config "
                 b"rewrite.empty-successor=%s (only 'skip' and 'keep' are "
                 b"supported)"
             )
             % (command, empty_successor)
         )
+
+
+def update_hash_refs(repo, commitmsg):
+    """Replace all obsolete commit hashes in the message with the current hash.
+
+    If the obsolete commit was split or is divergent, the hash is not replaced
+    as there's no way to know which successor to choose.
+    """
+    cache = {}
+    sha1s = re.findall(sha1re, commitmsg)
+    unfi = repo.unfiltered()
+    for sha1 in sha1s:
+        fullnode = scmutil.resolvehexnodeidprefix(unfi, sha1)
+        if fullnode is None:
+            continue
+        ctx = unfi[fullnode]
+        if not ctx.obsolete():
+            continue
+
+        successors = obsutil.successorssets(repo, ctx.node(), cache=cache)
+
+        # We can't make any assumptions about how to update the hash if the
+        # cset in question was split or diverged.
+        if len(successors) == 1 and len(successors[0]) == 1:
+            newsha1 = node.hex(successors[0][0])
+            commitmsg = commitmsg.replace(sha1, newsha1[: len(sha1)])
+        else:
+            repo.ui.note(
+                _(
+                    b'The stale commit message reference to %s could '
+                    b'not be updated\n'
+                )
+                % sha1
+            )
+
+    return commitmsg