Re: [PATCH 1/1] Warn about fast-forwarding of submodules during merge

[Stefan Beller <sbeller@google.com>]

On Thu, May 10, 2018 at 11:26 AM, Leif Middelschulte
<leif.middelschulte@gmail.com> wrote:
> From: Leif Middelschulte <Leif.Middelschulte@gmail.com>

Hi Leif!

thanks for following up with a patch!

> Warn the user about an automatically fast-forwarded submodule. The silent merge
> behavior was introduced by commit 68d03e4a6e44 ("Implement automatic fast-forward
> merge for submodules", 2010-07-07)).
>
> Signed-off-by: Leif Middelschulte <Leif.Middelschulte@gmail.com>
> ---
>  submodule.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/submodule.c b/submodule.c
> index 74d35b257..0198a72e6 100644
> --- a/submodule.c
> +++ b/submodule.c
> @@ -1817,10 +1817,12 @@ int merge_submodule(struct object_id *result, const char *path,
>         /* Case #1: a is contained in b or vice versa */
>         if (in_merge_bases(commit_a, commit_b)) {
>                 oidcpy(result, b);
> +               warning("Fast-forwarding submodule %s", path);
>                 return 1;
>         }
>         if (in_merge_bases(commit_b, commit_a)) {
>                 oidcpy(result, a);
> +               warning("Fast-forwarding submodule %s", path);
>                 return 1;
>         }

The code looks correct, however I think we can improve it.
(Originally I was just wondering if stderr is the right output,
which lead me to the thoughts below:)

Looking through the code of merge-recursive.c,
all the other merge outputs are done via 'output()'
that is able to buffer up the output as well as handles
the output for different verbosity settings.

So I would think we should make the output() function available
outside of merge-recursive.c. (and rename it to a be more concise
and descriptive in the global namespace) and make use of it.

Funnily we already have MERGE_WARNING in submodule.c
which outputs information for all the other cases. I would think
we ought to convert those to the output(), too.

Thanks,
Stefan