66 lines
2.6 KiB
Markdown
66 lines
2.6 KiB
Markdown
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---
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layout: post
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title: "git-merge stages"
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date: 2016-10-04 12:46:00
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tags: [git]
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published: true
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author:
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name: Gergely Polonkai
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email: gergely@polonkai.eu
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---
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This was a mail to my company’s internal Git mailing list, after I
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realised many colleagues can’t wrap their heads around merge
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conflicts.
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>Hello all,
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>
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>I just saw this on
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>the [git-users](https://groups.google.com/forum/#!forum/git-users)
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>list and thought it could help you when you bump into a merge
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>conflict. It is an excerpt from a mail by Konstantin Khomoutov (one
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>of the main contributors on the list), with a few modifications of
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>mine. Happy debugging :)
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>
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>>When a merge conflict is detected for a file, Git:
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>>
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>>1. Updates the entry for that file in the index to make it contain
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>> several so-called “stages”:
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>> * `0`: “Ours” version – that one which was there in this index entry
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>> before we begun to merge. At the beginning of the conflict, like
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>> right after the `git merge` or `git rebase` command this won’t
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>> exist (unless you had the file in the index, which you didn’t, did
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>> you?). When you resolve the conflict and use `git add
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>> my/conflicting/file.cc`, this will be the version added to the
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>> staging area (index), thus, the resolution of the conflict.
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>> * `1`: The version from the common ancestor commit, ie. the version
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>> of the file both of you modified.
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>> * `2`: The version from `HEAD`. During a merge, this is the current
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>> branch. During a rebase, this is the branch or commit you are
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>> rebasing onto, which usually will be `origin/develop`).
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>> * `3`: The version being merged, or the commit you are rebasing.
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>>2. Updates the file in the work tree to contain conflict markers and
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>> the conflicting chunks of text between them (and the text from the
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>> common ancestor if the `diff3` style of conflict markers was set).
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>>
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>>Now you can use the numbers in point 1 to access the different stages
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>>of the conflicting file. For example, to see the common ancestor (the
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>>version both of you modified), use
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>>
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>>```
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>>git show :1:my/conflicting/file.cc
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>>```
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>>
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>>Or, to see the difference between the two conflicting versions, try
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>>
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>>```
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>>git diff :2:my/conflicting/file.cc :3:my/conflicting/file.cc
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>>```
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>>
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>>**Note** that you can’t use the `:0:` stage *before* you stage your
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>>resolution with `git add`, and you can’t use the `:2:` and `:3:`
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>>stages *after* you staged the resolution.
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>>
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>>Fun fact: behind the scenes, these are the files (*revisions*) `git mergetool`
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>>accesses when it presents you the conflict visually.
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