When 98ea309b3f (mergetool: add hideResolved configuration,
2021-02-09) introduced the mergetool.hideResolved setting to reduce
the clutter in viewing non-conflicted sections of files in a
mergetool, it enabled it by default, explaining:
No adverse effects were noted in a small survey of popular mergetools[1]
so this behavior defaults to `true`.
In practice, alas, adverse effects do appear. A few issues:
1. No indication is shown in the UI that the base, local, and remote
versions shown have been modified by additional resolution. This
is inherent in the design: the idea of mergetool.hideResolved is to
convince a mergetool that expects pristine local, base, and remote
files to show partially resolved verisons of those files instead;
there is no additional source of information accessible to the
mergetool to see where the resolution has happened.
(By contrast, a mergetool generating the partial resolution from
conflict markers for itself would be able to hilight the resolved
sections with a different color.)
A user accustomed to seeing the files without partial resolution
gets no indication that this behavior has changed when they upgrade
Git.
2. If the computed merge did not line up the files correctly (for
example due to repeated sections in the file), the partially
resolved files can be misleading and do not have enough information
to reconstruct what happened and compute the correct merge result.
3. Resolving a conflict can involve information beyond the textual
conflict. For example, if the local and remote versions added
overlapping functionality in different ways, seeing the full
unresolved versions of each alongside the base gives information
about each side's intent that makes it possible to come up with a
resolution that combines those two intents. By contrast, when
starting with partially resolved versions of those files, one can
produce a subtly wrong resolution that includes redundant extra
code added by one side that is not needed in the approach taken
on the other.
All that said, a user wanting to focus on textual conflicts with
reduced clutter can still benefit from mergetool.hideResolved=true as
a way to deemphasize sections of the code that resolve cleanly without
requiring any changes to the invoked mergetool. The caveats described
above are reduced when the user has explicitly turned this on, because
then the user is aware of them.
Flip the default to 'false'.
Reported-by: Dana Dahlstrom <dahlstrom@google.com>
Helped-by: Seth House <seth@eseth.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Add a per-tool override flag so that users may enable the flag for one
tool and disable it for another by setting
`mergetool.<tool>.hideResolved` to `false`.
In addition, the author or maintainer of a mergetool may optionally
override the default `hideResolved` value for that mergetool. If the
`mergetools/<tool>` shell script contains a `hide_resolved_enabled`
function it will be called when the mergetool is invoked and the return
value will be used as the default for the `hideResolved` flag.
hide_resolved_enabled () {
return 1
}
Disabling may be desirable if the mergetool wants or needs access to the
original, unmodified 'LOCAL' and 'REMOTE' versions of the conflicted
file. For example:
- A tool may use a custom conflict resolution algorithm and prefer to
ignore the results of Git's conflict resolution.
- A tool may want to visually compare/constrast the version of the file
from before the merge (saved to 'LOCAL', 'REMOTE', and 'BASE') with
Git's conflict resolution results (saved to 'MERGED').
Helped-by: Johannes Sixt <j6t@kdbg.org>
Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Seth House <seth@eseth.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The purpose of a mergetool is to help the user resolve any conflicts
that Git cannot automatically resolve. If there is a conflict that must
be resolved manually Git will write a file named MERGED which contains
everything Git was able to resolve by itself and also everything that it
was not able to resolve wrapped in conflict markers.
One way to think of MERGED is as a two- or three-way diff. If each
"side" of the conflict markers is separately extracted an external tool
can represent those conflicts as a side-by-side diff.
However many mergetools instead diff LOCAL and REMOTE both of which
contain versions of the file from before the merge. Since the conflicts
Git resolved automatically are not present it forces the user to
manually re-resolve those conflicts. Some mergetools also show MERGED
but often only for reference and not as the focal point to resolve the
conflicts.
This adds a `mergetool.hideResolved` flag that will overwrite LOCAL and
REMOTE with each corresponding "side" of a conflicted file and thus hide
all conflicts that Git was able to resolve itself. Overwriting these
files will immediately benefit any mergetool that uses them without
requiring any changes to the tool.
No adverse effects were noted in a small survey of popular mergetools[1]
so this behavior defaults to `true`. However it can be globally disabled
by setting `mergetool.hideResolved` to `false`.
[1] https://www.eseth.org/2020/mergetools.htmlc884424769/2020/mergetools.md
Original-implementation-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Seth House <seth@eseth.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Make the mergetool used with "meld" backend behave similarly to "vimdiff" by
telling it to auto-merge non-conflicting parts and highlight the conflicting
parts when `mergetool.meld.useAutoMerge` is configured with `true`, or `auto`
for detecting the `--auto-merge` option automatically.
Helped-by: Đoàn Trần Công Danh <congdanhqx@gmail.com>
Helped-by: David Aguilar <davvid@gmail.com>
Signed-off-by: Lin Sun <lin.sun@zoom.us>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
