Subject: Re: [PATCH v5 1/2] branch: accept multiple upstream branches for tracking

From: Ævar Arnfjörð Bjarmason <[email-masked]>
Date: Tue, 07 Dec 2021 09:57:22 +0100

On Mon, Dec 06 2021, Josh Steadmon wrote:

> Add a new static variant of install_branch_config() that accepts
> multiple remote branch names for tracking. This will be used in an
> upcoming commit that enables inheriting the tracking configuration from
> a parent branch.
>
> Currently, all callers of install_branch_config() pass only a single
> remote. Make install_branch_config() a small wrapper around
> install_branch_config_multiple_remotes() so that existing callers do not
> need to be changed.
>
> Signed-off-by: Josh Steadmon <[email-masked]>
> ---
>  branch.c | 120 ++++++++++++++++++++++++++++++++++++++++---------------
>  1 file changed, 87 insertions(+), 33 deletions(-)
>
> diff --git a/branch.c b/branch.c
> index 7a88a4861e..1aabef4de0 100644
> --- a/branch.c
> +++ b/branch.c
> @@ -55,19 +55,24 @@ N_("\n"
>  "the remote tracking information by invoking\n"
>  "\"git branch --set-upstream-to=%s%s%s\".");
>  
> -int install_branch_config(int flag, const char *local, const char *origin, const char *remote)
> +static int install_branch_config_multiple_remotes(int flag, const char *local, const char *origin,
> +		struct string_list *remotes)
>  {
>  	const char *shortname = NULL;
>  	struct strbuf key = STRBUF_INIT;
> -	int rebasing = should_setup_rebase(origin);
> -
> -	if (skip_prefix(remote, "refs/heads/", &shortname)
> -	    && !strcmp(local, shortname)
> -	    && !origin) {
> -		warning(_("Not setting branch %s as its own upstream."),
> -			local);
> -		return 0;
> -	}
> +	int i, rebasing = should_setup_rebase(origin);
> +
> +	if (remotes->nr < 1)
> +		BUG("must provide at least one remote for branch config");

Since it's unsigned IMO this would be clearer: if (!remotes->nr)

> +
> +	if (!origin)
> +		for (i = 0; i < remotes->nr; i++)
> +			if (skip_prefix(remotes->items[i].string, "refs/heads/", &shortname)

For this and others, since you don't use the [i] for anything except
getting the current item using for_each_string_list_item() would be
better.

Partially a nit, partially that I've got another WIP
soon-to-be-submitted topic to fix overflow bugs in that API, and not
having "int i" etc. hardcoded in various places
helps. I.e. for_each_string_list_item() is future-proof.

> +			    && !strcmp(local, shortname)) {
> +				warning(_("Not setting branch %s as its own upstream."),

Better to quote '%s', also s/Not/not/ (lower-case) for all error/warning/die etc.

> +					local);
> +				return 0;
> +			}
>  
>  	strbuf_addf(&key, "branch.%s.remote", local);
>  	if (git_config_set_gently(key.buf, origin ? origin : ".") < 0)
> @@ -75,8 +80,17 @@ int install_branch_config(int flag, const char *local, const char *origin, const
>  
>  	strbuf_reset(&key);
>  	strbuf_addf(&key, "branch.%s.merge", local);
> -	if (git_config_set_gently(key.buf, remote) < 0)
> +	/*
> +	 * We want to overwrite any existing config with all the branches in
> +	 * "remotes". Override any existing config with the first branch, but if
> +	 * more than one is provided, use CONFIG_REGEX_NONE to preserve what
> +	 * we've written so far.
> +	 */
> +	if (git_config_set_gently(key.buf, remotes->items[0].string) < 0)
>  		goto out_err;
> +	for (i = 1; i < remotes->nr; i++)
> +		if (git_config_set_multivar_gently(key.buf, remotes->items[i].string, CONFIG_REGEX_NONE, 0) < 0)
> +			goto out_err;
>  
>  	if (rebasing) {
>  		strbuf_reset(&key);
> @@ -87,29 +101,62 @@ int install_branch_config(int flag, const char *local, const char *origin, const
>  	strbuf_release(&key);
>  
>  	if (flag & BRANCH_CONFIG_VERBOSE) {
> -		if (shortname) {
> -			if (origin)
> -				printf_ln(rebasing ?
> -					  _("Branch '%s' set up to track remote branch '%s' from '%s' by rebasing.") :
> -					  _("Branch '%s' set up to track remote branch '%s' from '%s'."),
> -					  local, shortname, origin);
> -			else
> -				printf_ln(rebasing ?
> -					  _("Branch '%s' set up to track local branch '%s' by rebasing.") :
> -					  _("Branch '%s' set up to track local branch '%s'."),
> -					  local, shortname);
> +		int plural = remotes->nr > 1;

This....

> +		int all_shortnames = 1;
> +		const char *msg_fmt;
> +		struct strbuf ref_string = STRBUF_INIT;
> +
> +		for (i = 0; i < remotes->nr; i++)
> +			if (skip_prefix(remotes->items[i].string, "refs/heads/", &shortname)) {
> +				strbuf_addf(&ref_string, "'%s', ", shortname);
> +			} else {
> +				all_shortnames = 0;
> +				strbuf_addf(&ref_string, "'%s', ", remotes->items[i].string);
> +			}
> +		/* The last two characters are an extraneous ", ", so trim those. */
> +		strbuf_setlen(&ref_string, ref_string.len - 2);

languages RTL in around way wrong the be to going is thing of sort This.

:)

We deal with this in most other places by just formatting a list of
branches. E.g. in the ambiguous object output:

    https://lore.kernel.org/git/[email-masked]/

> +
> +		if (all_shortnames && origin) {
> +			if (rebasing && plural)
> +				msg_fmt = "Branch '%s' set up to track remote branches %s from '%s' by rebasing.";
> +			else if (rebasing && !plural)
> +				msg_fmt = "Branch '%s' set up to track remote branch %s from '%s' by rebasing.";
> +			else if (!rebasing && plural)
> +				msg_fmt = "Branch '%s' set up to track remote branches %s from '%s'.";
> +			else if (!rebasing && !plural)
> +				msg_fmt = "Branch '%s' set up to track remote branch %s from '%s'.";

...and this is hardcoding plural rules used in English that don't apply
in a lot of other languages...

> +
> +			printf_ln(_(msg_fmt), local, ref_string, origin);
>  		} else {
> -			if (origin)
> -				printf_ln(rebasing ?
> -					  _("Branch '%s' set up to track remote ref '%s' by rebasing.") :
> -					  _("Branch '%s' set up to track remote ref '%s'."),
> -					  local, remote);
> -			else
> -				printf_ln(rebasing ?
> -					  _("Branch '%s' set up to track local ref '%s' by rebasing.") :
> -					  _("Branch '%s' set up to track local ref '%s'."),
> -					  local, remote);
> +			if (all_shortnames && !origin && rebasing && plural)
> +				msg_fmt = "Branch '%s' set up to track local branches %s by rebasing.";
> +			if (all_shortnames && !origin && rebasing && !plural)
> +				msg_fmt = "Branch '%s' set up to track local branch %s by rebasing.";
> +			if (all_shortnames && !origin && !rebasing && plural)
> +				msg_fmt = "Branch '%s' set up to track local branches %s.";
> +			if (all_shortnames && !origin && !rebasing && !plural)
> +				msg_fmt = "Branch '%s' set up to track local branch %s.";
> +			if (!all_shortnames && origin && rebasing && plural)
> +				msg_fmt = "Branch '%s' set up to track remote refs %s by rebasing.";
> +			if (!all_shortnames && origin && rebasing && !plural)
> +				msg_fmt = "Branch '%s' set up to track remote ref %s by rebasing.";
> +			if (!all_shortnames && origin && !rebasing && plural)
> +				msg_fmt = "Branch '%s' set up to track remote refs %s.";
> +			if (!all_shortnames && origin && !rebasing && !plural)
> +				msg_fmt = "Branch '%s' set up to track remote ref %s.";
> +			if (!all_shortnames && !origin && rebasing && plural)
> +				msg_fmt = "Branch '%s' set up to track local refs %s by rebasing.";
> +			if (!all_shortnames && !origin && rebasing && !plural)
> +				msg_fmt = "Branch '%s' set up to track local ref %s by rebasing.";
> +			if (!all_shortnames && !origin && !rebasing && plural)
> +				msg_fmt = "Branch '%s' set up to track local refs %s.";
> +			if (!all_shortnames && !origin && !rebasing && !plural)
> +				msg_fmt = "Branch '%s' set up to track local ref %s.";

...in English you've got one dog, then dogs, so == 1 and >1, but in
various other languages it's:

    git grep Plural-Forms -- po

Anyway, this is easily solved, and even with less verbosity, see:

    git grep -E -W '\bQ_\('

For examples of how to use the magic of libintl to do this for you.

> +
> +			printf_ln(_(msg_fmt), local, ref_string);

...also s/Branch/branch/ for all of them/.

>  		}
> +
> +		strbuf_release(&ref_string);
>  	}
>  
>  	return 0;
> @@ -121,11 +168,18 @@ int install_branch_config(int flag, const char *local, const char *origin, const
>  	advise(_(tracking_advice),
>  	       origin ? origin : "",
>  	       origin ? "/" : "",
> -	       shortname ? shortname : remote);
> +	       remotes->items[0].string);
>  
>  	return -1;
>  }
>  
> +int install_branch_config(int flag, const char *local, const char *origin, const char *remote) {

nit: overly long line..
> +	struct string_list remotes = STRING_LIST_INIT_DUP;

nit: an extra \n after variable decls...

> +	string_list_append(&remotes, remote);
> +	return install_branch_config_multiple_remotes(flag, local, origin, &remotes);
> +	string_list_clear(&remotes, 0);
> +}
> +
>  /*
>   * This is called when new_ref is branched off of orig_ref, and tries
>   * to infer the settings for branch.<new_ref>.{remote,merge} from the