Re: [PATCH v5 4/4] completion: fix zsh alias listing for subsection aliases

[Junio C Hamano <gitster@pobox.com>]

Jonatan Holmgren <jonatan@jontes.page> writes:

> The zsh completion function __git_zsh_cmd_alias() uses 'git config
> --get-regexp' to enumerate aliases and then strips the "alias." prefix
> from each key. For subsection-style aliases (alias.name.command), this
> leaves "name.command" as the completion candidate instead of just
> "name".
>
> The bash completion does not have this problem because it goes through
> 'git --list-cmds=alias', which calls list_aliases() in C and already
> handles both alias syntaxes correctly. However, zsh needs both the
> alias name and its value for descriptive completion, which
> --list-cmds=alias does not provide.

OK.  It is a natural question to ask why it is insufficient to use
what bash side happily uses, and the above gives a good explanation.

> Add a hidden --aliases-for-completion option to 'git help', following
> the existing --config-for-completion pattern. It outputs NUL-separated
> "name\nvalue" pairs using list_aliases(), which correctly resolves both
> the traditional (alias.name) and subsection (alias.name.command)
> formats. Update __git_zsh_cmd_alias() to use it.

Seeing that "--config-for-completion" is used for bash, I wonder if
it would be a good follow-up topic to rewrite the bash completion to
also use "--aliases-for-completion" (and possibly drop the need to
support "git --list-cmds=alias" command).  But that is clearly
outside the scope of this topic.

> ---

Missing sign-off.

>  builtin/help.c                        | 15 +++++++++++++++
>  contrib/completion/git-completion.zsh |  2 +-
>  2 files changed, 16 insertions(+), 1 deletion(-)
>
> diff --git a/builtin/help.c b/builtin/help.c
> index c09cbc8912..f02308a391 100644
> --- a/builtin/help.c
> +++ b/builtin/help.c
> @@ -54,6 +54,7 @@ static enum help_action {
>  	HELP_ACTION_DEVELOPER_INTERFACES,
>  	HELP_ACTION_CONFIG_FOR_COMPLETION,
>  	HELP_ACTION_CONFIG_SECTIONS_FOR_COMPLETION,
> +	HELP_ACTION_ALIASES_FOR_COMPLETION,
>  } cmd_mode;
>  
>  static char *html_path;
> @@ -90,6 +91,8 @@ static struct option builtin_help_options[] = {
>  		    HELP_ACTION_CONFIG_FOR_COMPLETION, PARSE_OPT_HIDDEN),
>  	OPT_CMDMODE_F(0, "config-sections-for-completion", &cmd_mode, "",
>  		    HELP_ACTION_CONFIG_SECTIONS_FOR_COMPLETION, PARSE_OPT_HIDDEN),
> +	OPT_CMDMODE_F(0, "aliases-for-completion", &cmd_mode, "",
> +		    HELP_ACTION_ALIASES_FOR_COMPLETION, PARSE_OPT_HIDDEN),
>  
>  	OPT_END(),
>  };
> @@ -691,6 +694,18 @@ int cmd_help(int argc,
>  			       help_format);
>  		list_config_help(SHOW_CONFIG_SECTIONS);
>  		return 0;
> +	case HELP_ACTION_ALIASES_FOR_COMPLETION: {
> +		struct string_list alias_list = STRING_LIST_INIT_DUP;
> +		opt_mode_usage(argc, "--aliases-for-completion",
> +			       help_format);
> +		list_aliases(&alias_list);
> +		string_list_sort(&alias_list);
> +		for (size_t i = 0; i < alias_list.nr; i++)
> +			printf("%s%c%s%c", alias_list.items[i].string, '\n',
> +			       (char *)alias_list.items[i].util, '\0');
> +		string_list_clear(&alias_list, 1);
> +		return 0;
> +	}
>  	case HELP_ACTION_CONFIG:
>  		opt_mode_usage(argc, "--config", help_format);
>  		setup_pager(the_repository);
> diff --git a/contrib/completion/git-completion.zsh b/contrib/completion/git-completion.zsh
> index f5877bd7a1..c32186a977 100644
> --- a/contrib/completion/git-completion.zsh
> +++ b/contrib/completion/git-completion.zsh
> @@ -202,7 +202,7 @@ __git_zsh_cmd_common ()
>  __git_zsh_cmd_alias ()
>  {
>  	local -a list
> -	list=(${${(0)"$(git config -z --get-regexp '^alias\.*')"}#alias.})
> +	list=(${(0)"$(git help --aliases-for-completion)"})
>  	list=(${(f)"$(printf "%s:alias for '%s'\n" ${(f@)list})"})
>  	_describe -t alias-commands 'aliases' list && _ret=0
>  }