mergetools: add new conflict marker format with diffs in
I use 3-way conflict markers. Often when I resolve them, I manually
compare one the base with one side and apply the differences to the
other side. That can be hard when the conflict marker is large. This
patch introduces a new type of conflict marker, which I'm hoping will
make it easier to resolve conflicts.
The new format uses `<<<<<<<` and `>>>>>>>` to open and close the
markers, just like our existing 2-way and 3-way conflict
markers. Instead of having 2 or 3 snapshots (left+right or
left+base+right), it has a sequence of diffs. A diff looks like this:
```
------- base
+++++++ left
a
-b
+c
d
```
A diff that adds one side ("diff from nothing") has a `=======` header
instead and does not have have `+` prefixed on its lines. A regular
3-way merge can be viewed as adding one side plus a diff between the
base and the other side. It thus has two ways of being represented,
depending on which side is being diffed:
```
<<<<<<<
======= left
contents
on
left
------- base
+++++++ right
contents
on
-left
+right
>>>>>>>
```
or
```
<<<<<<<
------- base
+++++++ left
contents
on
-right
+left
======= right
contents
on
right
>>>>>>>
```
I've made it so the new merge tool tries to pick a version that has
the most common lines (no difference in the example above).
I've called the new tool "mergediff" to stick to the convention of
starting with "merge" if the tool tries a regular 3-way merge.
The idea came from my pet VCS (placeholder name `jj`), which has
support for octopus merges and other ways of ending up with merges of
more than 3 versions. I wanted to be able to represent such conflicts
in the working copy and therefore thought of this format (although I
have not yet implemented it in my VCS). I then attended a meeting with
Larry McVoy, who said BitKeeper has an option (`bk smerge -g`) for
showing a similar format, which reminded me to actually attempt this
in Mercurial.
Differential Revision: https://phab.mercurial-scm.org/D9551
== New Features ==
* `hg purge`/`hg clean` can now delete ignored files instead of
untracked files, with the new -i flag.
* `hg pull` now has a `--confirm` flag to prompt before applying changes.
Config option `pull.confirm` is also added for that.
* `hg log` now defaults to using an '%' symbol for commits involved
in unresolved merge conflicts. That includes unresolved conflicts
caused by e.g. `hg update --merge` and `hg graft`. '@' still takes
precedence, so what used to be marked '@' still is.
* New `conflictlocal()` and `conflictother()` revsets return the
commits that are being merged, when there are conflicts. Also works
for conflicts caused by e.g. `hg graft`.
* `hg copy --forget` can be used to unmark a file as copied.
* The `format.revlog-compression` configuration entry now accept a list. The
first available option will be used. for example setting::
[format]
revlog-compression=zstd, zlib
Will use `zstd` compression for new repositories is available, and will
simply fall back to `zlib` if not.
* `hg debugmergestate` output is now templated, which may be useful
e.g. for IDEs that want to help the user resolve merge conflicts.
== New Experimental Features ==
* `hg copy` now supports a `--at-rev` argument to mark files as
copied in the specified commit. It only works with `--after` for
now (i.e., it's only useful for marking files copied using non-hg
`cp` as copied).
* Use `hg copy --forget --at-rev REV` to unmark already committed
copies.
== Bug Fixes ==
* Fix server exception when concurrent pushes delete the same bookmark
* Prevent pushes of divergent bookmarks (foo@remote)
* The push error "remote repository changed while pushing - please
try again" now only happens when a concurrent push changed related
heads (instead of when a concurrent pushed any revision).
== Backwards Compatibility Changes ==
* When `hg rebase` pauses for merge conflict resolution, the working
copy will no longer have the rebased node as a second parent. You
can use the new `conflictparents()` revset for finding the other
parent during a conflict.
* `hg rebase` now accepts repeated `--source` and `--base`
arguments. For example, `hg rebase --source 'A + B'` is equivalent
to `hg rebase --source A --source B`. This is a
backwards-incompatible change because it will break overriding an
alias `myrebase = rebase --source A` by `hg myrebase --source B`
(it will now rebase `(A + B)::` instead of `B::`).
* `hg recover` does not verify the validity of the whole repository
anymore. You can pass `--verify` or call `hg verify` if necessary.
* `hg debugmergestate` output format changed. Let us know if that is
causing you problems and we'll roll it back.
* Resolved merge conflicts are now cleared by `hg commit` even if the
working copy has no changes.
== Internal API Changes ==
* The deprecated `ui.progress()` has now been deleted. Please use
`ui.makeprogress()` instead.
* `hg.merge()` now takes a `ctx` instead of the previous `repo` and
`node` arguments.
* `hg.merge()` has lost its `abort` argument. Please call
`hg.abortmerge()` directly instead.
* `hg.merge()` has lost its `mergeforce` argument. It should have
only ever been called with the same value as the `force` argument.
* The `*others` argument of `cmdutil.check_incompatible_arguments()`
changed from being varargs argument to being a single collection.