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2021-03-13mergetool: do not enable hideResolved by defaultLibravatar Jonathan Nieder1-1/+1
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>
2021-02-09mergetool: add per-tool support and overrides for the hideResolved flagLibravatar Seth House1-0/+5
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>
2021-02-09mergetool: add hideResolved configurationLibravatar Seth House1-0/+10
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.html https://github.com/whiteinge/eseth/blob/c884424769fffb05d87afb33b2cf80cecb4044c3/2020/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>
2020-09-16mergetool: allow auto-merge for meld to follow the vim-diff behaviorLibravatar Lin Sun1-0/+10
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>
2018-10-29config.txt: move mergetool.* to a separate fileLibravatar Nguyễn Thái Ngọc Duy1-0/+53
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>