Re: [PATCH v3 5/6] config: add `git_die_config()` to the config-set API

> Add `git_die_config` that dies printing the line number and the file name
> of the highest priority value for the configuration variable `key`.
> 
> It has usage in non-callback based config value retrieval where we can
> raise an error and die if there is a semantic error.
> For example,
> 
> 	if (!git_config_get_value(key, &value)) {
> 		/* NULL values not allowed */
> 		if (!value)
> 			git_config_die(key);
> 		else
> 			/* do work */
> 	}
> 
> Signed-off-by: Tanay Abhra <tanayabh@gmail.com>
> ---
> Note: git_config_get_string() calls git_config_get_string_const(),
> so no need to check for whether to die or not, as it is done by
> git_config_get_string_const().
> 
>  Documentation/technical/api-config.txt |  5 +++++
>  cache.h                                |  1 +
>  config.c                               | 24 ++++++++++++++++++++++--
>  3 files changed, 28 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/technical/api-config.txt b/Documentation/technical/api-config.txt
> index 815c1ee..e7ec7cc 100644
> --- a/Documentation/technical/api-config.txt
> +++ b/Documentation/technical/api-config.txt
> @@ -155,6 +155,11 @@ as well as retrieval for the queried variable, including:
>  	Similar to `git_config_get_string`, but expands `~` or `~user` into
>  	the user's home directory when found at the beginning of the path.
>  
> +`void git_die_config(const char *key)`::
> +
> +	Dies printing the line number and the file name of the highest
> +	priority value for the configuration variable `key`.
> +
>  See test-config.c for usage examples.
>  
>  Value Parsing Helpers
> diff --git a/cache.h b/cache.h
> index 93bdbab..8512225 100644
> --- a/cache.h
> +++ b/cache.h
> @@ -1406,6 +1406,7 @@ extern int git_config_get_bool(const char *key, int *dest);
>  extern int git_config_get_bool_or_int(const char *key, int *is_bool, int *dest);
>  extern int git_config_get_maybe_bool(const char *key, int *dest);
>  extern int git_config_get_pathname(const char *key, const char **dest);
> +extern void git_die_config(const char *key);
>  
>  extern int committer_ident_sufficiently_given(void);
>  extern int author_ident_sufficiently_given(void);
> diff --git a/config.c b/config.c
> index 2ce3318..136ee9c 100644
> --- a/config.c
> +++ b/config.c
> @@ -1505,8 +1505,12 @@ const struct string_list *git_config_get_value_multi(const char *key)
>  
>  int git_config_get_string_const(const char *key, const char **dest)
>  {
> +	int ret;
>  	git_config_check_init();
> -	return git_configset_get_string_const(&the_config_set, key, dest);
> +	ret = git_configset_get_string_const(&the_config_set, key, dest);
> +	if (ret < 0)
> +		git_die_config(key);
> +	return ret;
>  }
>  
>  int git_config_get_string(const char *key, char **dest)
> @@ -1547,10 +1551,26 @@ int git_config_get_maybe_bool(const char *key, int *dest)
>  
>  int git_config_get_pathname(const char *key, const char **dest)
>  {
> +	int ret;
>  	git_config_check_init();
> -	return git_configset_get_pathname(&the_config_set, key, dest);
> +	ret = git_configset_get_pathname(&the_config_set, key, dest);
> +	if (ret < 0)
> +		git_die_config(key);
> +	return ret;
>  }
>  
> +void git_die_config(const char *key)
> +{
> +	const struct string_list *values;
> +	struct key_value_info *kv_info;
> +	values = git_config_get_value_multi(key);
> +	kv_info = values->items[values->nr - 1].util;
> +	if (!kv_info->linenr)
> +		die("unable to parse command-line config");
> +	else
> +		die("bad config file line %d in %s",kv_info->linenr, kv_info->filename);

> + }
> +
>  /*
>   * Find all the stuff for git_config_set() below.
>   */
>