unamend: error out when running on merge commit

It's better to error out than to produce a bad commit. We do that same
in `hg uncommit`. I haven't looked into how much work it is to make
them work instead.

Differential Revision: https://phab.mercurial-scm.org/D12087

hgext/uncommit.py

@@ -1,316 +1,318 b''
 # uncommit - undo the actions of a commit
 #
 # Copyright 2011 Peter Arrenbrecht <[e-mail]>
 #                Logilab SA        <[e-mail]>
 #                Pierre-Yves David <[e-mail]>
 #                Patrick Mezard <[e-mail]>
 # Copyright 2016 Facebook, Inc.
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
 """uncommit part or all of a local changeset (EXPERIMENTAL)
 
 This command undoes the effect of a local commit, returning the affected
 files to their uncommitted state. This means that files modified, added or
 removed in the changeset will be left unchanged, and so will remain modified,
 added and removed in the working directory.
 """
 
 from __future__ import absolute_import
 
 from mercurial.i18n import _
 
 from mercurial import (
     cmdutil,
     commands,
     context,
     copies as copiesmod,
     error,
     obsutil,
     pathutil,
     pycompat,
     registrar,
     rewriteutil,
     scmutil,
 )
 
 cmdtable = {}
 command = registrar.command(cmdtable)
 
 configtable = {}
 configitem = registrar.configitem(configtable)
 
 configitem(
     b'experimental',
     b'uncommitondirtywdir',
     default=False,
 )
 configitem(
     b'experimental',
     b'uncommit.keep',
     default=False,
 )
 
 # Note for extension authors: ONLY specify testedwith = 'ships-with-hg-core' for
 # extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
 # be specifying the version(s) of Mercurial they are tested with, or
 # leave the attribute unspecified.
 testedwith = b'ships-with-hg-core'
 
 
 def _commitfiltered(
     repo, ctx, match, keepcommit, message=None, user=None, date=None
 ):
     """Recommit ctx with changed files not in match. Return the new
     node identifier, or None if nothing changed.
     """
     base = ctx.p1()
     # ctx
     initialfiles = set(ctx.files())
     exclude = {f for f in initialfiles if match(f)}
 
     # No files matched commit, so nothing excluded
     if not exclude:
         return None
 
     # return the p1 so that we don't create an obsmarker later
     if not keepcommit:
         return ctx.p1().node()
 
     files = initialfiles - exclude
     # Filter copies
     copied = copiesmod.pathcopies(base, ctx)
     copied = {
         dst: src for dst, src in pycompat.iteritems(copied) if dst in files
     }
 
     def filectxfn(repo, memctx, path, contentctx=ctx, redirect=()):
         if path not in contentctx:
             return None
         fctx = contentctx[path]
         mctx = context.memfilectx(
             repo,
             memctx,
             fctx.path(),
             fctx.data(),
             fctx.islink(),
             fctx.isexec(),
             copysource=copied.get(path),
         )
         return mctx
 
     if not files:
         repo.ui.status(_(b"note: keeping empty commit\n"))
 
     if message is None:
         message = ctx.description()
     if not user:
         user = ctx.user()
     if not date:
         date = ctx.date()
 
     new = context.memctx(
         repo,
         parents=[base.node(), repo.nullid],
         text=message,
         files=files,
         filectxfn=filectxfn,
         user=user,
         date=date,
         extra=ctx.extra(),
     )
     return repo.commitctx(new)
 
 
 @command(
     b'uncommit',
     [
         (b'', b'keep', None, _(b'allow an empty commit after uncommitting')),
         (
             b'',
             b'allow-dirty-working-copy',
             False,
             _(b'allow uncommit with outstanding changes'),
         ),
         (b'n', b'note', b'', _(b'store a note on uncommit'), _(b'TEXT')),
     ]
     + commands.walkopts
     + commands.commitopts
     + commands.commitopts2
     + commands.commitopts3,
     _(b'[OPTION]... [FILE]...'),
     helpcategory=command.CATEGORY_CHANGE_MANAGEMENT,
 )
 def uncommit(ui, repo, *pats, **opts):
     """uncommit part or all of a local changeset
 
     This command undoes the effect of a local commit, returning the affected
     files to their uncommitted state. This means that files modified or
     deleted in the changeset will be left unchanged, and so will remain
     modified in the working directory.
 
     If no files are specified, the commit will be pruned, unless --keep is
     given.
     """
     cmdutil.check_note_size(opts)
     cmdutil.resolve_commit_options(ui, opts)
     opts = pycompat.byteskwargs(opts)
 
     with repo.wlock(), repo.lock():
 
         st = repo.status()
         m, a, r, d = st.modified, st.added, st.removed, st.deleted
         isdirtypath = any(set(m + a + r + d) & set(pats))
         allowdirtywcopy = opts[
             b'allow_dirty_working_copy'
         ] or repo.ui.configbool(b'experimental', b'uncommitondirtywdir')
         if not allowdirtywcopy and (not pats or isdirtypath):
             cmdutil.bailifchanged(
                 repo,
                 hint=_(b'requires --allow-dirty-working-copy to uncommit'),
             )
         old = repo[b'.']
         rewriteutil.precheck(repo, [old.rev()], b'uncommit')
         if len(old.parents()) > 1:
             raise error.InputError(_(b"cannot uncommit merge changeset"))
 
         match = scmutil.match(old, pats, opts)
 
         # Check all explicitly given files; abort if there's a problem.
         if match.files():
             s = old.status(old.p1(), match, listclean=True)
             eligible = set(s.added) | set(s.modified) | set(s.removed)
 
             badfiles = set(match.files()) - eligible
 
             # Naming a parent directory of an eligible file is OK, even
             # if not everything tracked in that directory can be
             # uncommitted.
             if badfiles:
                 badfiles -= {f for f in pathutil.dirs(eligible)}
 
             for f in sorted(badfiles):
                 if f in s.clean:
                     hint = _(
                         b"file was not changed in working directory parent"
                     )
                 elif repo.wvfs.exists(f):
                     hint = _(b"file was untracked in working directory parent")
                 else:
                     hint = _(b"file does not exist")
 
                 raise error.InputError(
                     _(b'cannot uncommit "%s"') % scmutil.getuipathfn(repo)(f),
                     hint=hint,
                 )
 
         with repo.transaction(b'uncommit'):
             if not (opts[b'message'] or opts[b'logfile']):
                 opts[b'message'] = old.description()
             message = cmdutil.logmessage(ui, opts)
 
             keepcommit = pats
             if not keepcommit:
                 if opts.get(b'keep') is not None:
                     keepcommit = opts.get(b'keep')
                 else:
                     keepcommit = ui.configbool(
                         b'experimental', b'uncommit.keep'
                     )
             newid = _commitfiltered(
                 repo,
                 old,
                 match,
                 keepcommit,
                 message=message,
                 user=opts.get(b'user'),
                 date=opts.get(b'date'),
             )
             if newid is None:
                 ui.status(_(b"nothing to uncommit\n"))
                 return 1
 
             mapping = {}
             if newid != old.p1().node():
                 # Move local changes on filtered changeset
                 mapping[old.node()] = (newid,)
             else:
                 # Fully removed the old commit
                 mapping[old.node()] = ()
 
             with repo.dirstate.parentchange():
                 scmutil.movedirstate(repo, repo[newid], match)
 
             scmutil.cleanupnodes(repo, mapping, b'uncommit', fixphase=True)
 
 
 def predecessormarkers(ctx):
     """yields the obsolete markers marking the given changeset as a successor"""
     for data in ctx.repo().obsstore.predecessors.get(ctx.node(), ()):
         yield obsutil.marker(ctx.repo(), data)
 
 
 @command(
     b'unamend',
     [],
     helpcategory=command.CATEGORY_CHANGE_MANAGEMENT,
     helpbasic=True,
 )
 def unamend(ui, repo, **opts):
     """undo the most recent amend operation on a current changeset
 
     This command will roll back to the previous version of a changeset,
     leaving working directory in state in which it was before running
     `hg amend` (e.g. files modified as part of an amend will be
     marked as modified `hg status`)
     """
 
     unfi = repo.unfiltered()
     with repo.wlock(), repo.lock(), repo.transaction(b'unamend'):
 
         # identify the commit from which to unamend
         curctx = repo[b'.']
 
         rewriteutil.precheck(repo, [curctx.rev()], b'unamend')
+        if len(curctx.parents()) > 1:
+            raise error.InputError(_(b"cannot unamend merge changeset"))
 
         # identify the commit to which to unamend
         markers = list(predecessormarkers(curctx))
         if len(markers) != 1:
             e = _(b"changeset must have one predecessor, found %i predecessors")
             raise error.InputError(e % len(markers))
 
         prednode = markers[0].prednode()
         predctx = unfi[prednode]
 
         # add an extra so that we get a new hash
         # note: allowing unamend to undo an unamend is an intentional feature
         extras = predctx.extra()
         extras[b'unamend_source'] = curctx.hex()
 
         def filectxfn(repo, ctx_, path):
             try:
                 return predctx.filectx(path)
             except KeyError:
                 return None
 
         # Make a new commit same as predctx
         newctx = context.memctx(
             repo,
             parents=(predctx.p1(), predctx.p2()),
             text=predctx.description(),
             files=predctx.files(),
             filectxfn=filectxfn,
             user=predctx.user(),
             date=predctx.date(),
             extra=extras,
         )
         newprednode = repo.commitctx(newctx)
         newpredctx = repo[newprednode]
         dirstate = repo.dirstate
 
         with dirstate.parentchange():
             scmutil.movedirstate(repo, newpredctx)
 
         mapping = {curctx.node(): (newprednode,)}
         scmutil.cleanupnodes(repo, mapping, b'unamend', fixphase=True)

tests/test-unamend.t

@@ -1,450 +1,447 b''
 Test for command `hg unamend` which lives in uncommit extension
 ===============================================================
 
   $ cat >> $HGRCPATH << EOF
   > [alias]
   > glog = log -G -T '{rev}:{node|short}  {desc}'
   > [experimental]
   > evolution = createmarkers, allowunstable
   > evolution.allowdivergence = true
   > [extensions]
   > rebase =
   > amend =
   > uncommit =
   > EOF
 
 Repo Setup
 
   $ hg init repo
   $ cd repo
   $ for ch in a b c d e f g h; do touch $ch; echo "foo" >> $ch; hg ci -Aqm "Added "$ch; done
 
   $ hg glog
   @  7:ec2426147f0e  Added h
   |
   o  6:87d6d6676308  Added g
   |
   o  5:825660c69f0c  Added f
   |
   o  4:aa98ab95a928  Added e
   |
   o  3:62615734edd5  Added d
   |
   o  2:28ad74487de9  Added c
   |
   o  1:29becc82797a  Added b
   |
   o  0:18d04c59bb5d  Added a
   
 Trying to unamend when there was no amend done
 
   $ hg unamend
   abort: changeset must have one predecessor, found 0 predecessors
   [10]
 
 Unamend on clean wdir and tip
 
   $ echo "bar" >> h
   $ hg amend
 
   $ hg exp
   # HG changeset patch
   # User test
   # Date 0 0
   #      Thu Jan 01 00:00:00 1970 +0000
   # Node ID c9fa1a715c1b7661c0fafb362a9f30bd75878d7d
   # Parent  87d6d66763085b629e6d7ed56778c79827273022
   Added h
   
   diff -r 87d6d6676308 -r c9fa1a715c1b h
   --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
   +++ b/h	Thu Jan 01 00:00:00 1970 +0000
   @@ -0,0 +1,2 @@
   +foo
   +bar
 
   $ hg glog --hidden
   @  8:c9fa1a715c1b  Added h
   |
   | x  7:ec2426147f0e  Added h
   |/
   o  6:87d6d6676308  Added g
   |
   o  5:825660c69f0c  Added f
   |
   o  4:aa98ab95a928  Added e
   |
   o  3:62615734edd5  Added d
   |
   o  2:28ad74487de9  Added c
   |
   o  1:29becc82797a  Added b
   |
   o  0:18d04c59bb5d  Added a
   
   $ hg unamend
   $ hg glog --hidden
   @  9:46d02d47eec6  Added h
   |
   | x  8:c9fa1a715c1b  Added h
   |/
   | x  7:ec2426147f0e  Added h
   |/
   o  6:87d6d6676308  Added g
   |
   o  5:825660c69f0c  Added f
   |
   o  4:aa98ab95a928  Added e
   |
   o  3:62615734edd5  Added d
   |
   o  2:28ad74487de9  Added c
   |
   o  1:29becc82797a  Added b
   |
   o  0:18d04c59bb5d  Added a
   
   $ hg diff
   diff -r 46d02d47eec6 h
   --- a/h	Thu Jan 01 00:00:00 1970 +0000
   +++ b/h	Thu Jan 01 00:00:00 1970 +0000
   @@ -1,1 +1,2 @@
    foo
   +bar
 
   $ hg exp
   # HG changeset patch
   # User test
   # Date 0 0
   #      Thu Jan 01 00:00:00 1970 +0000
   # Node ID 46d02d47eec6ca096b8dcab3f8f5579c40c3dd9a
   # Parent  87d6d66763085b629e6d7ed56778c79827273022
   Added h
   
   diff -r 87d6d6676308 -r 46d02d47eec6 h
   --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
   +++ b/h	Thu Jan 01 00:00:00 1970 +0000
   @@ -0,0 +1,1 @@
   +foo
 
   $ hg status
   M h
 
   $ hg log -r . -T '{extras % "{extra}\n"}' --config alias.log=log
   branch=default
   unamend_source=c9fa1a715c1b7661c0fafb362a9f30bd75878d7d
 
 Using unamend to undo an unamed (intentional)
 
   $ hg unamend
   $ hg exp
   # HG changeset patch
   # User test
   # Date 0 0
   #      Thu Jan 01 00:00:00 1970 +0000
   # Node ID 850ddfc1bc662997ec6094ada958f01f0cc8070a
   # Parent  87d6d66763085b629e6d7ed56778c79827273022
   Added h
   
   diff -r 87d6d6676308 -r 850ddfc1bc66 h
   --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
   +++ b/h	Thu Jan 01 00:00:00 1970 +0000
   @@ -0,0 +1,2 @@
   +foo
   +bar
   $ hg diff
 
 Unamend on a dirty working directory
 
   $ echo "bar" >> a
   $ hg amend
   $ echo "foobar" >> a
   $ echo "bar" >> b
   $ hg status
   M a
   M b
 
   $ hg unamend
 
   $ hg status
   M a
   M b
 
   $ hg diff
   diff -r ec338db45d51 a
   --- a/a	Thu Jan 01 00:00:00 1970 +0000
   +++ b/a	Thu Jan 01 00:00:00 1970 +0000
   @@ -1,1 +1,3 @@
    foo
   +bar
   +foobar
   diff -r ec338db45d51 b
   --- a/b	Thu Jan 01 00:00:00 1970 +0000
   +++ b/b	Thu Jan 01 00:00:00 1970 +0000
   @@ -1,1 +1,2 @@
    foo
   +bar
 
 Unamending an added file
 
   $ hg ci -m "Added things to a and b"
   $ echo foo > bar
   $ hg add bar
   $ hg amend
 
   $ hg unamend
   $ hg status
   A bar
 
   $ hg revert --all
   forgetting bar
 
 Unamending a removed file
 
   $ hg remove a
   $ hg amend
 
   $ hg unamend
   $ hg status
   R a
   ? bar
 
   $ hg revert --all
   undeleting a
 
 Unamending an added file with dirty wdir status
 
   $ hg add bar
   $ hg amend
   $ echo bar >> bar
   $ hg status
   M bar
 
   $ hg unamend
   $ hg status
   A bar
   $ hg diff
   diff -r 7f79409af972 bar
   --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
   +++ b/bar	Thu Jan 01 00:00:00 1970 +0000
   @@ -0,0 +1,2 @@
   +foo
   +bar
 
   $ hg revert --all
   forgetting bar
   $ rm bar
 
 Unamending in middle of a stack
 
   $ hg glog
   @  19:7f79409af972  Added things to a and b
   |
   o  12:ec338db45d51  Added h
   |
   o  6:87d6d6676308  Added g
   |
   o  5:825660c69f0c  Added f
   |
   o  4:aa98ab95a928  Added e
   |
   o  3:62615734edd5  Added d
   |
   o  2:28ad74487de9  Added c
   |
   o  1:29becc82797a  Added b
   |
   o  0:18d04c59bb5d  Added a
   
   $ hg up 5
   2 files updated, 0 files merged, 2 files removed, 0 files unresolved
   $ echo bar >> f
   $ hg amend
   3 new orphan changesets
   $ hg rebase -s 6 -d . -q
 
   $ hg glog
   o  23:03ddd6fc5af1  Added things to a and b
   |
   o  22:3e7b64ee157b  Added h
   |
   o  21:49635b68477e  Added g
   |
   @  20:93f0e8ffab32  Added f
   |
   o  4:aa98ab95a928  Added e
   |
   o  3:62615734edd5  Added d
   |
   o  2:28ad74487de9  Added c
   |
   o  1:29becc82797a  Added b
   |
   o  0:18d04c59bb5d  Added a
   
 
   $ hg --config experimental.evolution=createmarkers unamend
   abort: cannot unamend changeset, as that will orphan 3 descendants
   (see 'hg help evolution.instability')
   [10]
 
   $ hg unamend
   3 new orphan changesets
 
 Trying to unamend a public changeset
 
   $ hg up -C 23
   5 files updated, 0 files merged, 0 files removed, 0 files unresolved
   $ hg phase -r . -p
   1 new phase-divergent changesets
   $ hg unamend
   abort: cannot unamend public changesets: 03ddd6fc5af1
   (see 'hg help phases' for details)
   [10]
 
 Testing whether unamend retains copies or not
 
   $ hg status
 
   $ hg mv a foo
 
   $ hg ci -m "Moved a to foo"
   $ hg exp --git
   # HG changeset patch
   # User test
   # Date 0 0
   #      Thu Jan 01 00:00:00 1970 +0000
   # Node ID cfef290346fbee5126313d7e1aab51d877679b09
   # Parent  03ddd6fc5af19e028c44a2fd6d790dd22712f231
   Moved a to foo
   
   diff --git a/a b/foo
   rename from a
   rename to foo
 
   $ hg mv b foobar
   $ hg diff --git
   diff --git a/b b/foobar
   rename from b
   rename to foobar
   $ hg amend
 
   $ hg exp --git
   # HG changeset patch
   # User test
   # Date 0 0
   #      Thu Jan 01 00:00:00 1970 +0000
   # Node ID eca050985275bb271ce3092b54e56ea5c85d29a3
   # Parent  03ddd6fc5af19e028c44a2fd6d790dd22712f231
   Moved a to foo
   
   diff --git a/a b/foo
   rename from a
   rename to foo
   diff --git a/b b/foobar
   rename from b
   rename to foobar
 
   $ hg mv c wat
   $ hg unamend
 
   $ hg verify -v
   repository uses revlog format 1
   checking changesets
   checking manifests
   crosschecking files in changesets and manifests
   checking files
   checked 28 changesets with 16 changes to 11 files
 
 Retained copies in new prdecessor commit
 
   $ hg exp --git
   # HG changeset patch
   # User test
   # Date 0 0
   #      Thu Jan 01 00:00:00 1970 +0000
   # Node ID 552e3af4f01f620f88ca27be1f898316235b736a
   # Parent  03ddd6fc5af19e028c44a2fd6d790dd22712f231
   Moved a to foo
   
   diff --git a/a b/foo
   rename from a
   rename to foo
 
 Retained copies in working directoy
 
   $ hg diff --git
   diff --git a/b b/foobar
   rename from b
   rename to foobar
   diff --git a/c b/wat
   rename from c
   rename to wat
   $ hg revert -qa
   $ rm foobar wat
 
 Rename a->b, then amend b->c. After unamend, should look like b->c.
 
   $ hg co -q 0
   $ hg mv a b
   $ hg ci -qm 'move to a b'
   $ hg mv b c
   $ hg amend
   $ hg unamend
   $ hg st --copies --change .
   A b
     a
   R a
   $ hg st --copies
   A c
     b
   R b
   $ hg revert -qa
   $ rm c
 
 Rename a->b, then amend b->c, and working copy change c->d. After unamend, should look like b->d
 
   $ hg co -q 0
   $ hg mv a b
   $ hg ci -qm 'move to a b'
   warning: commit already existed in the repository!
   $ hg mv b c
   $ hg amend
   warning: commit already existed in the repository!
   $ hg mv c d
   $ hg unamend
   $ hg st --copies --change .
   A b
     a
   R a
   $ hg st --copies
   A d
     b
   R b
 
 Try to unamend a merge
 
   $ cd ..
   $ hg init merge
   $ cd merge
   $ echo initial > initial
   $ hg ci -Aqm initial
   $ echo left > left
   $ hg ci -Aqm left
   $ hg co -q 0
   $ echo right > right
   $ hg ci -Aqm right
   $ hg merge -q 1
   $ hg ci -m merge
   $ echo accidental > initial
   $ hg st --rev 1 --rev .
   A right
   $ hg st --rev 2 --rev .
   A left
   $ hg amend
   $ hg unamend
-  $ hg st --rev 1 --rev .
-  A right
-  R left (known-bad-output !)
-  $ hg st --rev 2 --rev .
-  A left (missing-correct-output !)
+  abort: cannot unamend merge changeset
+  [10]