Re: [PATCH v8 05/14] merge-index: add a new way to invoke `git-merge-one-file'

From: Johannes Schindelin <johannes.schindelin@gmx.de>
Date: Aug 9, 2022, 21:36 UTC
Message-ID: <o759r3qn-nqn9-oq22-p90o-2nrn24085n80@tzk.qr>
In-Reply-To: <20220809185429.20098-6-alban.gruin@gmail.com>

Hi Alban,

On Tue, 9 Aug 2022, Alban Gruin wrote:

Show 5 quoted lines

> Since `git-merge-one-file' will be rewritten and libified, there may be
> cases where there is no executable named this way (ie. when git is
> compiled with `SKIP_DASHED_BUILT_INS' enabled).  This adds a new way to
> invoke this particular program even if it does not exist, by passing
> `--use=merge-one-file' to merge-index.  For now, it still forks.

I read up about Stolee's and Phillip's suggestion, and about Junio chiming in, but I have to point out that all the objections against special-casing `!strcmp(pgm, "git-merge-one-file`") share one fundamental flaw: they fail to acknowledge that we will _have_ to special-case this value once we turn `merge-one-file` into a built-in.

And the reason is: there might be scripts out there that expect `git merge-index git-merge-one-file [...]` to continue to work even when building Git with `SKIP_DASHED_BUILT_INS`.

In light of that, I would like to point out that we really _must_ revert to `if (!strcmp(pgm, "git-merge-one-file"))`, ie. to what v6 did (see https://lore.kernel.org/git/20201124115315.13311-7-alban.gruin@gmail.com/).

And since we must do that anyway, I do not see any need for the `--use` option at all, it just complicates the usage and does not really provide any benefit that I can see.

On the upside: skipping the `--use` option will dramatically simplify this patch.

Sorry for not catching this earlier.

Show 11 quoted lines

> diff --git a/Documentation/git-merge-index.txt b/Documentation/git-merge-index.txt
> [...]
> @@ -44,8 +44,9 @@ code.
>  Typically this is run with a script calling Git's imitation of
>  the 'merge' command from the RCS package.
>
> -A sample script called 'git merge-one-file' is included in the
> -distribution.
> +A sample script called 'git merge-one-file' used to be included in the
> +distribution. This program must now be called with
> +'--use=merge-one-file'.

It probably makes more sense to just drop this paragraph because we will no longer provide that sample script.

Thanks, Dscho