Re: [BUG?] 'git rebase --update-refs --whitespace=fix' incompatible, but not enforced

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

Hi Stolee

On 18/01/2023 15:51, Derrick Stolee wrote:
> On 1/17/2023 5:02 PM, Philippe Blain wrote:
> Subject: [PATCH] rebase: die for both --apply and --update-refs
> 
> The --apply backend is not compatible with the --update-refs option,
> which requires the interactive backend. Without any warning, users
> running 'git rebase --whitespace=fix' with --update-refs (or
> rebase.updateRefs=true in their config) will realize that their non-HEAD
> branches did not come along for the ride.

I think that for other options such as "--exec" that require the "merge" 
backend we call imply_merge() and then have some code that will error 
out if there are also options that require the "apply" backend. Is it 
possible to do that here?

> Fix this with a die() message in the presence of both options. Since we
> cannot distinguish between the --update-refs option and the config
> option at this point, do an extra check to see if --update-refs was
> implied by the config and present a helpful warning to use
> --no-update-refs.
> 
> It is possible that users might want to be able to use options such as
> --whitespace=fix with rebase.updateRefs=true in their config without
> explicitly adding --no-update-refs. However, it is probably safest to
> require them to explicitly opt-in to that behavior. Users with the
> config option likely expect that their refs will be automatically
> updated and this will help warn them that the action they are doing is
> likely destructive to their branch organization.

I agree that requiring an explicit --no-update-refs in that case is best.

Best Wishes

Phillip

> Reported-by: Philippe Blain <levraiphilippeblain@gmail.com>
> Signed-off-by: Derrick Stolee <derrickstolee@github.com>
> ---
>   builtin/rebase.c              | 21 +++++++++++++++++++++
>   t/t3404-rebase-interactive.sh | 12 ++++++++++++
>   2 files changed, 33 insertions(+)
> 
> diff --git a/builtin/rebase.c b/builtin/rebase.c
> index 1481c5b6a5b..5330258c865 100644
> --- a/builtin/rebase.c
> +++ b/builtin/rebase.c
> @@ -1247,6 +1247,27 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
>   		die(_("The --edit-todo action can only be used during "
>   		      "interactive rebase."));
>   
> +	/* Check for arguments that imply --apply before checking --apply itself. */
> +	if (options.update_refs) {
> +		const char *incompatible = NULL;
> +		if (options.git_am_opts.nr)
> +			incompatible = options.git_am_opts.v[0];
> +		else if (options.type == REBASE_APPLY)
> +			incompatible = "--apply";
> +
> +		if (incompatible) {
> +			int from_config = 0;
> +			if (!git_config_get_bool("rebase.updaterefs", &from_config) &&
> +			    from_config) {
> +				warning(_("you have 'rebase.updateRefs' enabled in your config, "
> +					  "but it is incompatible with one or more options;"));
> +				warning(_("run again with '--no-update-refs' to resolve the issue"));
> +			}
> +			die(_("options '%s' and '%s' cannot be used together"),
> +			    "--upate-refs", incompatible);
> +		}
> +	}
> +
>   	if (trace2_is_enabled()) {
>   		if (is_merge(&options))
>   			trace2_cmd_mode("interactive");
> diff --git a/t/t3404-rebase-interactive.sh b/t/t3404-rebase-interactive.sh
> index 462cefd25df..8681c8a07f8 100755
> --- a/t/t3404-rebase-interactive.sh
> +++ b/t/t3404-rebase-interactive.sh
> @@ -2123,6 +2123,18 @@ test_expect_success '--update-refs: check failed ref update' '
>   	test_cmp expect err.trimmed
>   '
>   
> +test_expect_success '--apply options are incompatible with --update-refs' '
> +	for opt in "--whitespace=fix" "-C1" "--apply"
> +	do
> +		test_must_fail git rebase "$opt" --update-refs HEAD~1 2>err &&
> +		grep "options '\''--upate-refs'\'' and '\''$opt'\'' cannot be used together" err &&
> +
> +		test_must_fail git -c rebase.updateRefs=true rebase "$opt" HEAD~1 2>err &&
> +		grep "options '\''--upate-refs'\'' and '\''$opt'\'' cannot be used together" err &&
> +		grep "you have '\''rebase.updateRefs'\'' enabled" err || return 1
> +	done
> +'
> +
>   # This must be the last test in this file
>   test_expect_success '$EDITOR and friends are unchanged' '
>   	test_editor_unchanged