Re: [PATCH v3] submodule merge: update conflict error message

From: Glen Choo <chooglen@google.com>
Date: Jun 30, 2022, 20:35 UTC
Message-ID: <kl6l35flubx8.fsf@chooglen-macbookpro.roam.corp.google.com>
In-Reply-To: <20220629224059.1016645-1-calvinwan@google.com>

Hi! I have a suggestion for the output text; I haven't looked closely at the code changes.

Calvin Wan <calvinwan@google.com> writes:

>  Changes since v2:
>  [...]
>  Changes since v1:
>  [...]

I notice that this is all above the "---", i.e. this becomes part of the commit message when "git am"-ed. Intentional?

Show 25 quoted lines

> If git detects a possible merge resolution, the following is printed:
>
> --------
>
> Failed to merge submodule sub, but a possible merge resolution exists:
>     <commit> Merge branch '<branch1>' into <branch2>
>
>
> If this is correct simply add it to the index for example
> by using:
>
>   git update-index --cacheinfo 160000 <commit> "<submodule>"
>
> which will accept this suggestion.
>
> CONFLICT (submodule): Merge conflict in <submodule>
> Recursive merging with submodules is currently not supported.
> To manually complete the merge:
>  - go to submodule (<submodule>), and either update the submodule to a possible commit above or merge commit <commit>
>  - come back to superproject, and `git add <submodule>` to record the above merge 
>  - resolve any other conflicts in the superproject
>  - commit the resulting index in the superproject
> Automatic merge failed; fix conflicts and then commit the result.
>
> --------

I'm hesitant to recommend a plumbing command like "git update-index" to the user, especially if the user is one who needs help resolving a submodule merge conflict. I also believe this would be the first time we recommend "git update-index".

To do this using only porcelain commands, maybe:

   git -C <submodule> checkout <commit> &&
   git add <submodule>

(Though this might need to be broken up into two commands because I'm not sure if we ever include "&&" in a help message. I'm guessing we don't for portability reasons?)

Show 18 quoted lines

> If git detects multiple possible merge resolutions, the following is printed:
>
> --------
>
> Failed to merge submodule sub, but multiple possible merges exist:
>     <commit> Merge branch '<branch1>' into <branch2>
>     <commit> Merge branch '<branch1>' into <branch3>
>
> CONFLICT (submodule): Merge conflict in <submodule>
> Recursive merging with submodules is currently not supported.
> To manually complete the merge:
>  - go to submodule (<submodule>), and either update the submodule to a possible commit above or merge commit <commit>
>  - come back to superproject, and `git add <submodule>` to record the above merge 
>  - resolve any other conflicts in the superproject
>  - commit the resulting index in the superproject
> Automatic merge failed; fix conflicts and then commit the result.
>
> -------

For consistency, perhaps include the "here's how to use the suggestion" instructions here as well?