Git

Description

When specifying --tool=vimdiff in git mergetool Git will open Vim with a 4 windows layout distributed in the following way:

------------------------------------------
|             |           |              |
|   LOCAL     |   BASE    |   REMOTE     |
|             |           |              |
------------------------------------------
|                                        |
|                MERGED                  |
|                                        |
------------------------------------------

LOCAL, BASE and REMOTE are read-only buffers showing the contents of the conflicting file in specific commits ("commit you are merging into", "common ancestor commit" and "commit you are merging from" respectively)

MERGED is a writable buffer where you have to resolve the conflicts (using the other read-only buffers as a reference). Once you are done, save and exit Vim as usual (:wq) or, if you want to abort, exit using :cq.

Layout configuration

You can change the windows layout used by Vim by setting configuration variable mergetool.vimdiff.layout which accepts a string where the following separators have special meaning:

  • + is used to "open a new tab"

  • , is used to "open a new vertical split"

  • / is used to "open a new horizontal split"

  • @ is used to indicate which is the file containing the final version after solving the conflicts. If not present, MERGED will be used by default.

The precedence of the operators is this one (you can use parentheses to change it):

`@` > `+` > `/` > `,`

Let’s see some examples to understand how it works:

  • layout = "(LOCAL,BASE,REMOTE)/MERGED"

    This is exactly the same as the default layout we have already seen.

    Note that / has precedence over , and thus the parenthesis are not needed in this case. The next layout definition is equivalent:

    layout = "LOCAL,BASE,REMOTE / MERGED"

  • layout = "LOCAL,MERGED,REMOTE"

    If, for some reason, we are not interested in the BASE buffer.

    ------------------------------------------
|             |           |              |
|             |           |              |
|   LOCAL     |   MERGED  |   REMOTE     |
|             |           |              |
|             |           |              |
------------------------------------------

  • layout = "MERGED"

    Only the MERGED buffer will be shown. Note, however, that all the other ones are still loaded in vim, and you can access them with the "buffers" command.

    ------------------------------------------
|                                        |
|                                        |
|                 MERGED                 |
|                                        |
|                                        |
------------------------------------------

  • layout = "@LOCAL,REMOTE"

    When MERGED is not present in the layout, you must "mark" one of the buffers with an asterisk. That will become the buffer you need to edit and save after resolving the conflicts.

    ------------------------------------------
|                   |                    |
|                   |                    |
|                   |                    |
|     LOCAL         |    REMOTE          |
|                   |                    |
|                   |                    |
|                   |                    |
------------------------------------------

  • layout = "LOCAL,BASE,REMOTE / MERGED + BASE,LOCAL + BASE,REMOTE"

    Three tabs will open: the first one is a copy of the default layout, while the other two only show the differences between (BASE and LOCAL) and (BASE and REMOTE) respectively.

    ------------------------------------------
| <TAB #1> |  TAB #2  |  TAB #3  |       |
------------------------------------------
|             |           |              |
|   LOCAL     |   BASE    |   REMOTE     |
|             |           |              |
------------------------------------------
|                                        |
|                MERGED                  |
|                                        |
------------------------------------------
    ------------------------------------------
|  TAB #1  | <TAB #2> |  TAB #3  |       |
------------------------------------------
|                   |                    |
|                   |                    |
|                   |                    |
|     BASE          |    LOCAL           |
|                   |                    |
|                   |                    |
|                   |                    |
------------------------------------------
    ------------------------------------------
|  TAB #1  |  TAB #2  | <TAB #3> |       |
------------------------------------------
|                   |                    |
|                   |                    |
|                   |                    |
|     BASE          |    REMOTE          |
|                   |                    |
|                   |                    |
|                   |                    |
------------------------------------------

  • layout = "LOCAL,BASE,REMOTE / MERGED + BASE,LOCAL + BASE,REMOTE + (LOCAL/BASE/REMOTE),MERGED"

    Same as the previous example, but adds a fourth tab with the same information as the first tab, with a different layout.

    ---------------------------------------------
|  TAB #1  |  TAB #2  |  TAB #3  | <TAB #4> |
---------------------------------------------
|       LOCAL         |                     |
|---------------------|                     |
|       BASE          |        MERGED       |
|---------------------|                     |
|       REMOTE        |                     |
---------------------------------------------

    Note how in the third tab definition we need to use parenthesis to make , have precedence over /.

Variants

Instead of --tool=vimdiff, you can also use one of these other variants:

  • --tool=gvimdiff, to open gVim instead of Vim.

  • --tool=nvimdiff, to open Neovim instead of Vim.

When using these variants, in order to specify a custom layout you will have to set configuration variables mergetool.gvimdiff.layout and mergetool.nvimdiff.layout instead of mergetool.vimdiff.layout

In addition, for backwards compatibility with previous Git versions, you can also append 1, 2 or 3 to either vimdiff or any of the variants (ex: vimdiff3, nvimdiff1, etc…​) to use a predefined layout. In other words, using --tool=[g,n,]vimdiffx is the same as using --tool=[g,n,]vimdiff and setting configuration variable mergetool.[g,n,]vimdiff.layout to…​

  • x=1: "@LOCAL, REMOTE"

  • x=2: "LOCAL, MERGED, REMOTE"

  • x=3: "MERGED"

Example: using --tool=gvimdiff2 will open gvim with three columns (LOCAL, MERGED and REMOTE).

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