Re: [PATCH 2/3] branch: suggest how to undo a --set-upstream when given one branch

> This interface is error prone, and a better one (--set-upstream-to)
> exists. Suggest how to fix a --set-upstream invocation in case the
> user only gives one argument, which makes it likely that he meant to
> do the opposite, like with
>
>     git branch --set-upstream origin/master
>
> when they meant one of
>
>     git branch --set-upstream origin/master master
>     git branch --set-upstream-to origin/master
>
> Signed-off-by: Carlos Martín Nieto <cmn@elego.de>

>  builtin/branch.c |   22 ++++++++++++++++++++++
>  1 file changed, 22 insertions(+)
>
> diff --git a/builtin/branch.c b/builtin/branch.c
> index c886fc0..5551227 100644
> --- a/builtin/branch.c
> +++ b/builtin/branch.c
> @@ -864,10 +864,32 @@ int cmd_branch(int argc, const char **argv, const char *prefix)
>  		   info and making sure new_upstream is correct */
>  		create_branch(head, branch->name, new_upstream, 0, 0, 0, quiet, BRANCH_TRACK_OVERRIDE);
>  	} else if (argc > 0 && argc <= 2) {
> +		struct branch *branch = branch_get(argv[0]);
> +		const char *old_upstream = NULL;
> +		int branch_existed = 0;
> +
>  		if (kinds != REF_LOCAL_BRANCH)
>  			die(_("-a and -r options to 'git branch' do not make sense with a branch name"));
> +
> +		/* Save what argv[0] was pointing to so we can give
> +		   the --set-upstream-to hint */
> +		if (branch_has_merge_config(branch))
> +		  old_upstream = shorten_unambiguous_ref(branch->merge[0]->dst, 0);
> +
> +		branch_existed = ref_exists(branch->refname);
>  		create_branch(head, argv[0], (argc == 2) ? argv[1] : head,
>  			      force_create, reflog, 0, quiet, track);
> +
> +		if (argc == 1) {
> +			printf("If you wanted to make '%s' track '%s', do this:\n", head, argv[0]);
> +			if (branch_existed)
> +				printf(" $ git branch --set-upstream '%s' '%s'\n", argv[0], old_upstream);
> +			else
> +				printf(" $ git branch -d '%s'\n", argv[0]);
> +
> +			printf(" $ git branch --set-upstream-to '%s'\n", argv[0]);
> +		}
> +
>  	} else
>  		usage_with_options(builtin_branch_usage, options);