222 lines
7.6 KiB
Text
222 lines
7.6 KiB
Text
git-rerere(1)
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=============
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NAME
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----
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git-rerere - Reuse recorded resolution of conflicted merges
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SYNOPSIS
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--------
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[verse]
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'git rerere' ['clear'|'forget' <pathspec>|'diff'|'remaining'|'status'|'gc']
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DESCRIPTION
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-----------
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In a workflow employing relatively long lived topic branches,
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the developer sometimes needs to resolve the same conflicts over
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and over again until the topic branches are done (either merged
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to the "release" branch, or sent out and accepted upstream).
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This command assists the developer in this process by recording
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conflicted automerge results and corresponding hand resolve results
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on the initial manual merge, and applying previously recorded
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hand resolutions to their corresponding automerge results.
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[NOTE]
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You need to set the configuration variable `rerere.enabled` in order to
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enable this command.
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COMMANDS
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--------
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Normally, 'git rerere' is run without arguments or user-intervention.
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However, it has several commands that allow it to interact with
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its working state.
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'clear'::
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Reset the metadata used by rerere if a merge resolution is to be
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aborted. Calling 'git am [--skip|--abort]' or 'git rebase [--skip|--abort]'
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will automatically invoke this command.
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'forget' <pathspec>::
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Reset the conflict resolutions which rerere has recorded for the current
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conflict in <pathspec>.
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'diff'::
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Display diffs for the current state of the resolution. It is
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useful for tracking what has changed while the user is resolving
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conflicts. Additional arguments are passed directly to the system
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'diff' command installed in PATH.
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'status'::
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Print paths with conflicts whose merge resolution rerere will record.
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'remaining'::
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Print paths with conflicts that have not been autoresolved by rerere.
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This includes paths whose resolutions cannot be tracked by rerere,
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such as conflicting submodules.
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'gc'::
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Prune records of conflicted merges that
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occurred a long time ago. By default, unresolved conflicts older
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than 15 days and resolved conflicts older than 60
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days are pruned. These defaults are controlled via the
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`gc.rerereUnresolved` and `gc.rerereResolved` configuration
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variables respectively.
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DISCUSSION
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----------
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When your topic branch modifies an overlapping area that your
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master branch (or upstream) touched since your topic branch
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forked from it, you may want to test it with the latest master,
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even before your topic branch is ready to be pushed upstream:
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------------
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o---*---o topic
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/
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o---o---o---*---o---o master
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------------
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For such a test, you need to merge master and topic somehow.
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One way to do it is to pull master into the topic branch:
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------------
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$ git switch topic
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$ git merge master
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o---*---o---+ topic
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/ /
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o---o---o---*---o---o master
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------------
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The commits marked with `*` touch the same area in the same
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file; you need to resolve the conflicts when creating the commit
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marked with `+`. Then you can test the result to make sure your
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work-in-progress still works with what is in the latest master.
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After this test merge, there are two ways to continue your work
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on the topic. The easiest is to build on top of the test merge
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commit `+`, and when your work in the topic branch is finally
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ready, pull the topic branch into master, and/or ask the
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upstream to pull from you. By that time, however, the master or
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the upstream might have been advanced since the test merge `+`,
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in which case the final commit graph would look like this:
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------------
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$ git switch topic
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$ git merge master
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$ ... work on both topic and master branches
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$ git switch master
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$ git merge topic
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o---*---o---+---o---o topic
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/ / \
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o---o---o---*---o---o---o---o---+ master
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------------
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When your topic branch is long-lived, however, your topic branch
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would end up having many such "Merge from master" commits on it,
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which would unnecessarily clutter the development history.
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Readers of the Linux kernel mailing list may remember that Linus
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complained about such too frequent test merges when a subsystem
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maintainer asked to pull from a branch full of "useless merges".
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As an alternative, to keep the topic branch clean of test
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merges, you could blow away the test merge, and keep building on
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top of the tip before the test merge:
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------------
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$ git switch topic
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$ git merge master
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$ git reset --hard HEAD^ ;# rewind the test merge
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$ ... work on both topic and master branches
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$ git switch master
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$ git merge topic
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o---*---o-------o---o topic
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/ \
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o---o---o---*---o---o---o---o---+ master
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------------
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This would leave only one merge commit when your topic branch is
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finally ready and merged into the master branch. This merge
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would require you to resolve the conflict, introduced by the
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commits marked with `*`. However, this conflict is often the
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same conflict you resolved when you created the test merge you
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blew away. 'git rerere' helps you resolve this final
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conflicted merge using the information from your earlier hand
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resolve.
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Running the 'git rerere' command immediately after a conflicted
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automerge records the conflicted working tree files, with the
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usual conflict markers `<<<<<<<`, `=======`, and `>>>>>>>` in
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them. Later, after you are done resolving the conflicts,
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running 'git rerere' again will record the resolved state of these
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files. Suppose you did this when you created the test merge of
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master into the topic branch.
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Next time, after seeing the same conflicted automerge,
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running 'git rerere' will perform a three-way merge between the
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earlier conflicted automerge, the earlier manual resolution, and
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the current conflicted automerge.
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If this three-way merge resolves cleanly, the result is written
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out to your working tree file, so you do not have to manually
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resolve it. Note that 'git rerere' leaves the index file alone,
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so you still need to do the final sanity checks with `git diff`
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(or `git diff -c`) and 'git add' when you are satisfied.
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As a convenience measure, 'git merge' automatically invokes
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'git rerere' upon exiting with a failed automerge and 'git rerere'
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records the hand resolve when it is a new conflict, or reuses the earlier hand
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resolve when it is not. 'git commit' also invokes 'git rerere'
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when committing a merge result. What this means is that you do
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not have to do anything special yourself (besides enabling
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the rerere.enabled config variable).
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In our example, when you do the test merge, the manual
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resolution is recorded, and it will be reused when you do the
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actual merge later with the updated master and topic branch, as long
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as the recorded resolution is still applicable.
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The information 'git rerere' records is also used when running
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'git rebase'. After blowing away the test merge and continuing
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development on the topic branch:
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------------
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o---*---o-------o---o topic
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/
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o---o---o---*---o---o---o---o master
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$ git rebase master topic
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o---*---o-------o---o topic
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/
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o---o---o---*---o---o---o---o master
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------------
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you could run `git rebase master topic`, to bring yourself
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up to date before your topic is ready to be sent upstream.
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This would result in falling back to a three-way merge, and it
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would conflict the same way as the test merge you resolved earlier.
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'git rerere' will be run by 'git rebase' to help you resolve this
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conflict.
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[NOTE] 'git rerere' relies on the conflict markers in the file to
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detect the conflict. If the file already contains lines that look the
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same as lines with conflict markers, 'git rerere' may fail to record a
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conflict resolution. To work around this, the `conflict-marker-size`
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setting in linkgit:gitattributes[5] can be used.
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GIT
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---
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Part of the linkgit:git[1] suite
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