filemerge: add support for partial conflict resolution by external tool
A common class of merge conflicts is in imports/#includes/etc. It's
relatively easy to write a tool that can resolve these conflicts,
perhaps by naively just unioning the statements and leaving any
cleanup to other tools to do later [1]. Such specialized tools cannot
generally resolve all conflicts in a file, of course. Let's therefore
call them "partial merge tools". Note that the internal simplemerge
algorithm is such a partial merge tool - one that only resolves
trivial "conflicts" where one side is unchanged or both sides change
in the same way.
One can also imagine having smarter language-aware partial tools that
merge the AST. It may be useful for such tools to interactively let
the user resolve any conflicts it can't resolve itself. However,
having the option of implementing it as a partial merge tool means
that the developer doesn't *need* to create a UI for it. Instead, the
user can resolve any remaining conflicts with their regular merge tool
(e.g. `:merge3` or `meld).
We don't currently have a way to let the user define such partial
merge tools. That's what this patch addresses. It lets the user
configure partial merge tools to run. Each tool can be configured to
run only on files matching certain patterns (e.g. "*.py"). The tool
takes three inputs (local, base, other) and resolves conflicts by
updating these in place. For example, let's say the inputs are these:
base:
```
import sys
def main():
print('Hello')
```
local:
```
import os
import sys
def main():
print('Hi')
```
other:
```
import re
import sys
def main():
print('Howdy')
```
A partial merge tool could now resolve the conflicting imports by
replacing the import statements in *all* files by the following
snippet, while leaving the remainder of the files unchanged.
```
import os
import re
import sys
```
As a result, simplemerge and any regular merge tool that runs after
the partial merge tool(s) will consider the imports to be
non-conflicting and will only present the conflict in `main()` to the
user.
Differential Revision: https://phab.mercurial-scm.org/D12356
Check that obsolete properly strip heads
$ cat >> $HGRCPATH << EOF
> [phases]
> # public changeset are not obsolete
> publish=false
> [command-templates]
> log='{node|short} ({phase}) {desc|firstline}\n'
> [experimental]
> evolution.createmarkers=True
> EOF
$ mkcommit() {
> echo "$1" > "$1"
> hg add "$1"
> hg ci -m "add $1"
> }
$ getid() {
> hg id --debug -ir "desc('$1')"
> }
$ hg init remote
$ cd remote
$ mkcommit base
$ hg phase --public .
$ cd ..
$ cp -R remote base
$ hg clone remote local
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd local
New head replaces old head
==========================
setup
(we add the 1 flags to prevent bumped error during the test)
$ mkcommit old
$ hg push
pushing to $TESTTMP/remote
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
$ hg up -q '.^'
$ mkcommit new
created new head
$ hg debugobsolete --flags 1 `getid old` `getid new`
1 new obsolescence markers
obsoleted 1 changesets
$ hg log -G --hidden
@ 71e3228bffe1 (draft) add new
|
| x c70b08862e08 (draft) add old
|/
o b4952fcf48cf (public) add base
$ cp -R ../remote ../backup1
old exists remotely as draft. It is obsoleted by new that we now push.
Push should not warn about creating new head
$ hg push
pushing to $TESTTMP/remote
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files (+1 heads)
old head is now public (public local version)
=============================================
setup
$ rm -fr ../remote
$ cp -R ../backup1 ../remote
$ hg -R ../remote phase --public c70b08862e08
$ hg pull -v
pulling from $TESTTMP/remote
searching for changes
no changes found
1 local changesets published
$ hg log -G --hidden
@ 71e3228bffe1 (draft) add new
|
| o c70b08862e08 (public) add old
|/
o b4952fcf48cf (public) add base
Abort: old will still be an head because it's public.
$ hg push
pushing to $TESTTMP/remote
searching for changes
abort: push creates new remote head 71e3228bffe1
(merge or see 'hg help push' for details about pushing new heads)
[20]
old head is now public (public remote version)
==============================================
TODO: Not implemented yet.
# setup
#
# $ rm -fr ../remote
# $ cp -R ../backup1 ../remote
# $ hg -R ../remote phase --public c70b08862e08
# $ hg phase --draft --force c70b08862e08
# $ hg log -G --hidden
# @ 71e3228bffe1 (draft) add new
# |
# | x c70b08862e08 (draft) add old
# |/
# o b4952fcf48cf (public) add base
#
#
#
# Abort: old will still be an head because it's public.
#
# $ hg push
# pushing to $TESTTMP/remote
# searching for changes
# abort: push creates new remote head 71e3228bffe1!
# (merge or see 'hg help push' for details about pushing new heads)
# [255]
old head is obsolete but replacement is not pushed
==================================================
setup
$ rm -fr ../remote
$ cp -R ../backup1 ../remote
$ hg phase --draft --force '(0::) - 0'
$ hg up -q '.^'
$ mkcommit other
created new head
$ hg log -G --hidden
@ d7d41ccbd4de (draft) add other
|
| o 71e3228bffe1 (draft) add new
|/
| x c70b08862e08 (draft) add old
|/
o b4952fcf48cf (public) add base
old exists remotely as draft. It is obsoleted by new but we don't push new.
Push should abort on new head
$ hg push -r 'desc("other")'
pushing to $TESTTMP/remote
searching for changes
abort: push creates new remote head d7d41ccbd4de
(merge or see 'hg help push' for details about pushing new heads)
[20]
Both precursors and successors are already know remotely. Descendant adds heads
===============================================================================
setup. (The obsolete marker is known locally only
$ cd ..
$ rm -rf local
$ hg clone remote local
updating to branch default
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd local
$ mkcommit old
old already tracked!
nothing changed
[1]
$ hg up -q '.^'
$ mkcommit new
created new head
$ hg push -f
pushing to $TESTTMP/remote
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files (+1 heads)
$ mkcommit desc1
$ hg up -q '.^'
$ mkcommit desc2
created new head
$ hg debugobsolete `getid old` `getid new`
1 new obsolescence markers
obsoleted 1 changesets
$ hg log -G --hidden
@ 5fe37041cc2b (draft) add desc2
|
| o a3ef1d111c5f (draft) add desc1
|/
o 71e3228bffe1 (draft) add new
|
| x c70b08862e08 (draft) add old
|/
o b4952fcf48cf (public) add base
$ hg log -G --hidden -R ../remote
o 71e3228bffe1 (draft) add new
|
| o c70b08862e08 (draft) add old
|/
@ b4952fcf48cf (public) add base
$ cp -R ../remote ../backup2
Push should not warn about adding new heads. We create one, but we'll delete
one anyway.
$ hg push
pushing to $TESTTMP/remote
searching for changes
adding changesets
adding manifests
adding file changes
added 2 changesets with 2 changes to 2 files (+1 heads)
Remote head is unknown but obsoleted by a local changeset
=========================================================
setup
$ rm -fr ../remote
$ cp -R ../backup1 ../remote
$ cd ..
$ rm -rf local
$ hg clone remote local -r 0
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
new changesets b4952fcf48cf
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd local
$ mkcommit new
$ hg -R ../remote id --debug -r tip
c70b08862e0838ea6d7c59c85da2f1ed6c8d67da tip
$ hg id --debug -r tip
71e3228bffe1886550777233d6c97bb5a6b2a650 tip
$ hg debugobsolete c70b08862e0838ea6d7c59c85da2f1ed6c8d67da 71e3228bffe1886550777233d6c97bb5a6b2a650
1 new obsolescence markers
$ hg log -G --hidden
@ 71e3228bffe1 (draft) add new
|
o b4952fcf48cf (public) add base
$ hg log -G --hidden -R ../remote
o c70b08862e08 (draft) add old
|
@ b4952fcf48cf (public) add base
We do not have enought data to take the right decision, we should fail
$ hg push
pushing to $TESTTMP/remote
searching for changes
remote has heads on branch 'default' that are not known locally: c70b08862e08
abort: push creates new remote head 71e3228bffe1
(pull and merge or see 'hg help push' for details about pushing new heads)
[20]
Pulling the missing data makes it work
$ hg pull
pulling from $TESTTMP/remote
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files (+1 heads)
(1 other changesets obsolete on arrival)
(run 'hg heads' to see heads)
$ hg push
pushing to $TESTTMP/remote
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files (+1 heads)
Old head is pruned without parent data and new unrelated head added
===================================================================
setup
$ cd ..
$ rm -R remote local
$ cp -R backup1 remote
$ hg clone remote local -qr c70b08862e08
$ cd local
$ hg up -q '.^'
$ mkcommit new-unrelated
created new head
$ hg debugobsolete `getid old`
1 new obsolescence markers
obsoleted 1 changesets
$ hg log -G --hidden
@ 350a93b716be (draft) add new-unrelated
|
| x c70b08862e08 (draft) add old
|/
o b4952fcf48cf (public) add base
$ hg push
pushing to $TESTTMP/remote
searching for changes
abort: push creates new remote head 350a93b716be
(merge or see 'hg help push' for details about pushing new heads)
[20]