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
Testing changing branch on commits
==================================
Setup
$ cat >> $HGRCPATH << EOF
> [alias]
> glog = log -G -T "{rev}:{node|short} {desc}\n{branch} ({bookmarks})"
> [experimental]
> evolution = createmarkers
> [extensions]
> rebase=
> EOF
$ hg init repo
$ cd repo
$ for ch in a b c d e; do echo foo >> $ch; hg ci -Aqm "Added "$ch; done
$ hg glog
@ 4:aa98ab95a928 Added e
| default ()
o 3:62615734edd5 Added d
| default ()
o 2:28ad74487de9 Added c
| default ()
o 1:29becc82797a Added b
| default ()
o 0:18d04c59bb5d Added a
default ()
$ hg branches
default 4:aa98ab95a928
Try without passing a new branch name
$ hg branch -r .
abort: no branch name specified for the revisions
[10]
Setting an invalid branch name
$ hg branch -r . a:b
abort: ':' cannot be used in a name
[10]
$ hg branch -r . tip
abort: the name 'tip' is reserved
[10]
$ hg branch -r . 1234
abort: cannot use an integer as a name
[10]
Change on non-linear set of commits
$ hg branch -r 2 -r 4 foo
abort: cannot change branch of non-linear revisions
[10]
Change in middle of the stack (linear commits)
$ hg branch -r 1::3 foo
abort: cannot change branch of changeset, as that will orphan 1 descendants
(see 'hg help evolution.instability')
[10]
Change with dirty working directory
$ echo bar > a
$ hg branch -r . foo
abort: uncommitted changes
[20]
$ hg revert --all
reverting a
Change on empty revision set
$ hg branch -r 'draft() - all()' foo
abort: empty revision set
[10]
Changing branch on linear set of commits from head
Without obsmarkers
$ hg branch -r 3:4 foo --config experimental.evolution=!
changed branch on 2 changesets
saved backup bundle to $TESTTMP/repo/.hg/strip-backup/62615734edd5-e86bd13a-branch-change.hg
$ hg glog
@ 4:3938acfb5c0f Added e
| foo ()
o 3:9435da006bdc Added d
| foo ()
o 2:28ad74487de9 Added c
| default ()
o 1:29becc82797a Added b
| default ()
o 0:18d04c59bb5d Added a
default ()
$ hg branches
foo 4:3938acfb5c0f
default 2:28ad74487de9 (inactive)
With obsmarkers
$ hg branch -r 3::4 bar
changed branch on 2 changesets
$ hg glog
@ 6:7c1991464886 Added e
| bar ()
o 5:1ea05e93925f Added d
| bar ()
o 2:28ad74487de9 Added c
| default ()
o 1:29becc82797a Added b
| default ()
o 0:18d04c59bb5d Added a
default ()
$ hg branches
bar 6:7c1991464886
default 2:28ad74487de9 (inactive)
Change branch name to an existing branch
$ hg branch -r . default
abort: a branch of the same name already exists
[10]
Changing on a branch head which is not topological head
$ hg branch -r 2 stable
abort: cannot change branch of changeset, as that will orphan 2 descendants
(see 'hg help evolution.instability')
[10]
Enabling the allowunstable config and trying to change branch on a branch head
which is not a topological head
$ echo "[experimental]" >> .hg/hgrc
$ echo "evolution.allowunstable=yes" >> .hg/hgrc
$ hg branch -r 2 foo
changed branch on 1 changesets
2 new orphan changesets
Changing branch of an obsoleted changeset
$ hg branch -r 4 foobar
abort: hidden revision '4' was rewritten as: 7c1991464886
(use --hidden to access hidden revisions)
[10]
$ hg branch -r 4 --hidden foobar
abort: cannot change branch of 3938acfb5c0f, as that creates content-divergence with 7c1991464886
(add --verbose for details or see 'hg help evolution.instability')
[10]
Make sure bookmark movement is correct
$ hg bookmark b1
$ hg glog -r '.^::'
@ 6:7c1991464886 Added e
| bar (b1)
* 5:1ea05e93925f Added d
| bar ()
~
$ hg branch -r '(.^)::' wat --debug
changing branch of '1ea05e93925f806d875a2163f9b76764be644636' from 'bar' to 'wat'
committing files:
d
committing manifest
committing changelog
new node id is 343660ccab7400da637bd6a211d07f413536d718
changing branch of '7c19914648869f5b02fc7fed31ddee9783fdd680' from 'bar' to 'wat'
committing files:
e
committing manifest
committing changelog
new node id is de1404b45a69f8cc6437d7679033ee33e9efb4ba
moving bookmarks ['b1'] from 7c19914648869f5b02fc7fed31ddee9783fdd680 to de1404b45a69f8cc6437d7679033ee33e9efb4ba
resolving manifests
branchmerge: False, force: False, partial: False
ancestor: 7c1991464886, local: 7c1991464886+, remote: de1404b45a69
starting 4 threads for background file closing (?)
changed branch on 2 changesets
updating the branch cache
invalid branch cache (served): tip differs
invalid branch cache (served.hidden): tip differs
$ hg glog -r '(.^)::'
@ 9:de1404b45a69 Added e
| wat (b1)
* 8:343660ccab74 Added d
| wat ()
~
Make sure phase handling is correct
$ echo foo >> bar
$ hg ci -Aqm "added bar" --secret
1 new orphan changesets
$ hg glog -r .
@ 10:8ad1294c1660 added bar
| wat (b1)
~
$ hg branch -r . secret
changed branch on 1 changesets
$ hg phase -r .
11: secret
$ hg branches
secret 11:38a9b2d53f98
foo 7:8a4729a5e2b8
wat 9:de1404b45a69 (inactive)
default 1:29becc82797a (inactive)
$ hg branch
secret
Changing branch of another head, different from one on which we are
$ hg glog
@ 11:38a9b2d53f98 added bar
| secret (b1)
* 9:de1404b45a69 Added e
| wat ()
* 8:343660ccab74 Added d
| wat ()
| o 7:8a4729a5e2b8 Added c
| | foo ()
x | 2:28ad74487de9 Added c
|/ default ()
o 1:29becc82797a Added b
| default ()
o 0:18d04c59bb5d Added a
default ()
$ hg branch
secret
$ hg branch -r 7 foobar
changed branch on 1 changesets
The current branch must be preserved
$ hg branch
secret
Changing branch on multiple heads at once
$ hg rebase -s 8 -d 12 --keepbranches -q
$ hg rebase -s 14 -d 1 --keepbranches -q
$ hg branch -r 0: stable
changed branch on 6 changesets
$ hg glog
@ 23:6a5ddbcfb870 added bar
| stable (b1)
o 22:baedc6e98a67 Added e
| stable ()
| o 21:99ac7bf8aad1 Added d
| | stable ()
| o 20:0ecb4d39c4bd Added c
|/ stable ()
o 19:fd45b986b109 Added b
| stable ()
o 18:204d2769eca2 Added a
stable ()
$ hg branches
stable 23:6a5ddbcfb870
$ hg branch
stable
Changing to same branch is no-op
$ hg branch -r 19::21 stable
changed branch on 0 changesets
Changing branch name to existing branch name if the branch of parent of root of
revs is same as the new branch name
$ hg branch -r 20::21 bugfix
changed branch on 2 changesets
$ hg glog
o 25:714defe1cf34 Added d
| bugfix ()
o 24:98394def28fc Added c
| bugfix ()
| @ 23:6a5ddbcfb870 added bar
| | stable (b1)
| o 22:baedc6e98a67 Added e
|/ stable ()
o 19:fd45b986b109 Added b
| stable ()
o 18:204d2769eca2 Added a
stable ()
$ hg branch -r 24:25 stable
changed branch on 2 changesets
$ hg glog
o 27:4ec342341562 Added d
| stable ()
o 26:83f48859c2de Added c
| stable ()
| @ 23:6a5ddbcfb870 added bar
| | stable (b1)
| o 22:baedc6e98a67 Added e
|/ stable ()
o 19:fd45b986b109 Added b
| stable ()
o 18:204d2769eca2 Added a
stable ()
Changing branch of a merge commit
$ hg branch -q ghi
$ echo f > f
$ hg ci -qAm 'Added f'
$ hg up -q 27
$ hg branch -q jkl
$ echo g > g
$ hg ci -qAm 'Added g'
$ hg glog -r 'heads(:)'
@ 29:6bc1c6c2c9da Added g
| jkl ()
~
o 28:2f1019bd29d2 Added f
| ghi (b1)
~
$ hg branch -q default
$ hg merge -r 28
4 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ hg branch -r . abcd
abort: outstanding uncommitted merge
[20]
$ hg ci -m "Merge commit"
$ hg glog -r 'parents(.)::'
@ 30:4d56e6b1eb6b Merge commit
|\ default ()
| o 29:6bc1c6c2c9da Added g
| | jkl ()
| ~
o 28:2f1019bd29d2 Added f
| ghi (b1)
~
$ hg branch -r . ghi
0 files updated, 0 files merged, 4 files removed, 0 files unresolved
changed branch on 1 changesets
$ hg branch -r . jkl
changed branch on 1 changesets
$ hg branch -r . default
changed branch on 1 changesets
$ hg branch -r . stable
abort: a branch of the same name already exists
[10]
$ hg branch -r . stable --force
changed branch on 1 changesets
$ hg branches
stable 34:d1c2addda4a2
jkl 29:6bc1c6c2c9da (inactive)
ghi 28:2f1019bd29d2 (inactive)
Changing branch on public changeset
$ hg phase -r . -p
$ hg branch -r . def
abort: cannot change branch of public changesets: d1c2addda4a2
(see 'hg help phases' for details)
[10]
Merge commit with conflicts, with evolution and without
$ mklozenge() {
> echo foo > a
> hg ci -qAm foo
> echo bar > a
> hg ci -qm bar
> hg up -q '.^'
> echo baz > a
> hg ci -qm baz
> hg merge -q -t :local
> echo neither > a
> hg ci -qm neither
> }
$ cd ..
$ hg init merge-with-evolution
$ cd merge-with-evolution
$ mklozenge
$ hg branch -r '(.^)::' abc
changed branch on 2 changesets
$ hg glog
@ 5:c07fa8b34d54 neither
|\ abc ()
| o 4:f2aa51777cc9 baz
| | abc ()
o | 1:2e33c4f0856b bar
|/ default ()
o 0:91cfb6004abf foo
default ()
$ hg cat a
neither
$ cd ..
$ hg init merge-without-evolution
$ cd merge-without-evolution
$ mklozenge
$ cat > .hg/hgrc << EOF
> [experimental]
> evolution = no
> evolution.allowunstable = no
> EOF
$ hg branch -r '(.^)::' abc
changed branch on 2 changesets
saved backup bundle to $TESTTMP/merge-without-evolution/.hg/strip-backup/9a3a2af368f4-8db1a361-branch-change.hg
$ hg glog
@ 3:c07fa8b34d54 neither
|\ abc ()
| o 2:f2aa51777cc9 baz
| | abc ()
o | 1:2e33c4f0856b bar
|/ default ()
o 0:91cfb6004abf foo
default ()
$ hg cat a
neither