Re: [PATCH v8 3/3] rebase: add a config option for --rebase-merges

[Phillip Wood <phillip.wood123@gmail.com>]

Hi Alex

On 20/03/2023 05:59, Alex Henrie wrote:
> The purpose of the new option is to accommodate users who would like
> --rebase-merges to be on by default and to facilitate turning on
> --rebase-merges by default without configuration in a future version of
> Git.
> 
> Name the new option rebase.rebaseMerges, even though it is a little
> redundant, for consistency with the name of the command line option and
> to be clear when scrolling through values in the [rebase] section of
> .gitconfig.
> 
> Support setting rebase.rebaseMerges to the nonspecific value "true" for
> users who don't need to or don't want to learn about the difference
> between rebase-cousins and no-rebase-cousins.
> 
> Make --rebase-merges without an argument on the command line override
> any value of rebase.rebaseMerges in the configuration, for consistency
> with other command line flags with optional arguments that have an
> associated config option.

Hurray! Thanks for re-rolling. I've left a couple of comments below, I 
had hoped this would be the final version but I've realized that the way 
you've rearranged the error handling for apply and merge options is not 
a good idea (see below). Apart from that I'm happy.

> Signed-off-by: Alex Henrie <alexhenrie24@gmail.com>
> ---
>   Documentation/config/rebase.txt        | 10 ++++
>   Documentation/git-rebase.txt           |  3 +-
>   builtin/rebase.c                       | 81 ++++++++++++++++++--------
>   t/t3422-rebase-incompatible-options.sh | 17 ++++++
>   t/t3430-rebase-merges.sh               | 34 +++++++++++
>   5 files changed, 121 insertions(+), 24 deletions(-)
> 
> diff --git a/Documentation/config/rebase.txt b/Documentation/config/rebase.txt
> index f19bd0e040..afaf6dad99 100644
> --- a/Documentation/config/rebase.txt
> +++ b/Documentation/config/rebase.txt
> @@ -67,3 +67,13 @@ rebase.rescheduleFailedExec::
>   
>   rebase.forkPoint::
>   	If set to false set `--no-fork-point` option by default.
> +
> +rebase.rebaseMerges::
> +	Whether and how to set the `--rebase-merges` option by default. Can
> +	be `rebase-cousins`, `no-rebase-cousins`, or a boolean. Setting to
> +	true or to `no-rebase-cousins` is equivalent to
> +	`--rebase-merges=no-rebase-cousins`, setting to `rebase-cousins` is
> +	equivalent to `--rebase-merges=rebase-cousins`, and setting to false is
> +	equivalent to `--no-rebase-merges`. Passing `--rebase-merges` on the
> +	command line, with or without an argument, overrides any
> +	`rebase.rebaseMerges` configuration.

Sounds good

> [...]   
> +	if (!strcmp(var, "rebase.rebasemerges")) {
> +		opts->config_rebase_merges = git_parse_maybe_bool(value);
> +		if (opts->config_rebase_merges < 0) {
> +			opts->config_rebase_merges = 1;
> +			parse_rebase_merges_value(opts, value);
> +		} else
> +			opts->rebase_cousins = 0;

The "else" clause should have braces because the "if" cause requires 
them (see Documentation/CodingGuidelines). I don't think it is worth 
re-rolling just for this though.

> [...]   
> +static int parse_opt_rebase_merges(const struct option *opt, const char *arg, int unset)
> +{
> +	struct rebase_options *options = opt->value;
> +
> +	options->rebase_merges = !unset;
> +	options->rebase_cousins = 0;

This makes --rebase-merges without an option override 
rebase.rebaseMerges - good.

 > [...]
> @@ -1514,13 +1542,15 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
>   				break;
>   
>   		if (i >= 0 || options.type == REBASE_APPLY) {
> -			if (is_merge(&options))
> -				die(_("apply options and merge options "
> -					  "cannot be used together"));

This isn't a new change but having thought about it I'm not sure moving 
this code is a good idea. If the user runs

	git -c rebase.updateRefs=true rebase --whitespace=fix --exec "make test"

then instead of getting an message saying that they cannot use apply and 
merge options together they'll get a message suggesting they pass 
--no-update-refs which wont fix the problem for them.

> -			else if (options.autosquash == -1 && options.config_autosquash == 1)
> +			if (options.autosquash == -1 && options.config_autosquash == 1)
>   				die(_("apply options are incompatible with rebase.autoSquash.  Consider adding --no-autosquash"));
> +			else if (options.rebase_merges == -1 && options.config_rebase_merges == 1)
> +				die(_("apply options are incompatible with rebase.rebaseMerges.  Consider adding --no-rebase-merges"));
>   			else if (options.update_refs == -1 && options.config_update_refs == 1)
>   				die(_("apply options are incompatible with rebase.updateRefs.  Consider adding --no-update-refs"));
> +			else if (is_merge(&options))
> +				die(_("apply options and merge options "
> +					  "cannot be used together"));
>   			else
>   				options.type = REBASE_APPLY;
>   		}

Best Wishes

Phillip