Re: [RFC PATCH] config: teach `repo_config()` to allow `repo` to be NULL

> The `repo` value can be NULL if a builtin command is run outside
> any repository. The current implementation of `repo_config()` will
> fail if `repo` is NULL.
>
> If the `repo` is NULL the `repo_config()` can ignore the repository
> configuration but it should read the other configuration sources like
> the system-side configuration instead of failing.
>
> Teach the `repo_config()` to allow `repo` to be NULL by calling the
> `read_very_early_config()` which read config but only enumerate system
> and global settings.
>
> Suggested-by: Junio C Hamano <gitster@pobox.com>
> Mentored-by: Christian Couder <chriscool@tuxfamily.org>
> Signed-off-by: Usman Akinyemi <usmanakinyemi202@gmail.com>
> ---
>  config.c | 4 ++++
>  config.h | 3 +++
>  2 files changed, 7 insertions(+)

> diff --git a/config.c b/config.c
> index 36f76fafe5..c5181fd23b 100644
> --- a/config.c
> +++ b/config.c
> @@ -2526,6 +2526,10 @@ void repo_config_clear(struct repository *repo)
>  
>  void repo_config(struct repository *repo, config_fn_t fn, void *data)
>  {
> +	if (!repo) {
> +		read_very_early_config(fn, data);
> +		return;
> +	}
>  	git_config_check_init(repo);
>  	configset_iter(repo->config, fn, data);
>  }
> diff --git a/config.h b/config.h
> index 5c730c4f89..1e5b22dfc4 100644
> --- a/config.h
> +++ b/config.h
> @@ -219,6 +219,9 @@ void read_very_early_config(config_fn_t cb, void *data);
>   * repo-specific one; by overwriting, the higher-priority repo-specific
>   * value is left at the end).
>   *
> + * In cases where the repository variable is NULL, repo_config() will
> + * call read_early_config().
> + *
>   * Unlike git_config_from_file(), this function respects includes.
>   */
>  void repo_config(struct repository *r, config_fn_t fn, void *);