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 templating for rebase command
Setup
$ cat >> $HGRCPATH <<EOF
> [extensions]
> rebase=
> [experimental]
> evolution=createmarkers
> EOF
$ hg init repo
$ cd repo
$ for ch in a b c d; do echo foo > $ch; hg commit -Aqm "Added "$ch; done
$ hg log -G -T "{rev}:{node|short} {desc}"
@ 3:62615734edd5 Added d
|
o 2:28ad74487de9 Added c
|
o 1:29becc82797a Added b
|
o 0:18d04c59bb5d Added a
Getting the JSON output for nodechanges
$ hg rebase -s 2 -d 0 -q -Tjson
[
{
"nodechanges": {"28ad74487de9599d00d81085be739c61fc340652": ["849767420fd5519cf0026232411a943ed03cc9fb"], "62615734edd52f06b6fb9c2beb429e4fe30d57b8": ["df21b32134ba85d86bca590cbe9b8b7cbc346c53"]}
}
]
$ hg log -G -T "{rev}:{node|short} {desc}"
@ 5:df21b32134ba Added d
|
o 4:849767420fd5 Added c
|
| o 1:29becc82797a Added b
|/
o 0:18d04c59bb5d Added a
$ hg rebase -s 1 -d 5 -q -T "{nodechanges|json}"
{"29becc82797a4bc11ec8880b58eaecd2ab3e7760": ["d9d6773efc831c274eace04bc13e8e6412517139"]} (no-eol)
$ hg log -G -T "{rev}:{node|short} {desc}"
o 6:d9d6773efc83 Added b
|
@ 5:df21b32134ba Added d
|
o 4:849767420fd5 Added c
|
o 0:18d04c59bb5d Added a
$ hg rebase -s 6 -d 4 -q -T "{nodechanges % '{oldnode}:{newnodes % ' {node} '}'}"
d9d6773efc831c274eace04bc13e8e6412517139: f48cd65c6dc3d2acb55da54402a5b029546e546f (no-eol)
$ hg log -G -T "{rev}:{node|short} {desc}"
o 7:f48cd65c6dc3 Added b
|
| @ 5:df21b32134ba Added d
|/
o 4:849767420fd5 Added c
|
o 0:18d04c59bb5d Added a
$ hg rebase -s 7 -d 5 -q --keep -T "{nodechanges % '{oldnode}:{newnodes % ' {node} '}'}"
f48cd65c6dc3d2acb55da54402a5b029546e546f: 6f7dda91e55e728fb798f3e44dbecf0ebaa83267 (no-eol)
$ hg log -G -T "{rev}:{node|short} {desc}"
o 8:6f7dda91e55e Added b
|
| o 7:f48cd65c6dc3 Added b
| |
@ | 5:df21b32134ba Added d
|/
o 4:849767420fd5 Added c
|
o 0:18d04c59bb5d Added a
Respects command-templates.oneline-summary
$ hg rebase -r 7 -d 8 -n --config command-templates.oneline-summary='rev: {rev}'
starting dry-run rebase; repository will not be changed
rebasing rev: 7
note: not rebasing rev: 7, its destination already has all its changes
dry-run rebase completed successfully; run without -n/--dry-run to perform this rebase
command-templates.oneline-summary.rebase overrides
$ hg rebase -r 7 -d 8 -n \
> --config command-templates.oneline-summary='global: {rev}' \
> --config command-templates.oneline-summary.rebase='override: {rev}'
starting dry-run rebase; repository will not be changed
rebasing override: 7
note: not rebasing override: 7, its destination already has all its changes
dry-run rebase completed successfully; run without -n/--dry-run to perform this rebase
check namespaces and coloring (labels)
$ hg tag -l -r 7 my-tag
$ hg rebase -r 7 -d 8 -n
starting dry-run rebase; repository will not be changed
rebasing 7:f48cd65c6dc3 my-tag "Added b"
note: not rebasing 7:f48cd65c6dc3 my-tag "Added b", its destination already has all its changes
dry-run rebase completed successfully; run without -n/--dry-run to perform this rebase
$ hg bookmark -r 7 my-bookmark
$ hg rebase -r 7 -d 8 -n
starting dry-run rebase; repository will not be changed
rebasing 7:f48cd65c6dc3 my-bookmark my-tag "Added b"
note: not rebasing 7:f48cd65c6dc3 my-bookmark my-tag "Added b", its destination already has all its changes
dry-run rebase completed successfully; run without -n/--dry-run to perform this rebase
$ hg rebase -r 7 -d 8 -n --color=debug
[ ui.status|starting dry-run rebase; repository will not be changed]
[ ui.status|rebasing [oneline-summary.changeset|7:f48cd65c6dc3] [oneline-summary.bookmarks|my-bookmark] [oneline-summary.tags|my-tag] "[oneline-summary.desc|Added b]"]
[ ui.warning|note: not rebasing [oneline-summary.changeset|7:f48cd65c6dc3] [oneline-summary.bookmarks|my-bookmark] [oneline-summary.tags|my-tag] "[oneline-summary.desc|Added b]", its destination already has all its changes]
[ ui.status|dry-run rebase completed successfully; run without -n/--dry-run to perform this rebase]