mergetool: include custom tools in '--tool-help'

>
> Signed-off-by: John Keeping <john@keeping.me.uk>
> ---
> After the recent changes to mergetool, do we want to do something like
> this as well, so that 'git mergetool --tool-help' will display any tools
> configured by the user/system administrator?
>
> This is on top of jk/mergetool.
>
>  git-mergetool--lib.sh | 29 +++++++++++++++++++++++++++++
>  1 file changed, 29 insertions(+)
>
> diff --git a/git-mergetool--lib.sh b/git-mergetool--lib.sh
> index 1d0fb12..f9a617c 100644
> --- a/git-mergetool--lib.sh
> +++ b/git-mergetool--lib.sh
> @@ -206,6 +206,29 @@ list_merge_tool_candidates () {
>  	esac
>  }
>  
> +# Adds tools from git-config to the available and unavailable lists.
> +# The tools are found in "$1.<tool>.cmd".
> +add_config_tools() {
> +	section=$1
> +
> +	eval $(git config --get-regexp $section'\..*\.cmd' |
> +		while read -r key value
> +		do
> +			tool=${key#mergetool.}
> +			tool=${tool%.cmd}
> +
> +			tool=$(echo "$tool" |sed -e 's/'\''/'\''\\'\'\''/g')
> +
> +			cmd=$(eval -- "set -- $value"; echo "$1")
> +			if type "$cmd" >/dev/null 2>&1
> +			then
> +				echo "available=\"\${available}\"'$tool'\"\$LF\""
> +			else
> +				echo "unavailable=\"\${unavailable}\"'$tool'\"\$LF\""
> +			fi
> +		done)
> +}
> +
>  show_tool_help () {
>  	unavailable= available= LF='
>  '
> @@ -223,6 +246,12 @@ show_tool_help () {
>  		fi
>  	done
>  
> +	add_config_tools mergetool
> +	if diff_mode
> +	then
> +		add_config_tools difftool
> +	fi
> +
>  	cmd_name=${TOOL_MODE}tool
>  	if test -n "$available"
>  	then

> John Keeping <john@keeping.me.uk> writes:
> 
> > 'git mergetool --tool-help' only lists builtin tools, not those that the
> > user has configured via a 'mergetool.<tool>.cmd' config value.  Fix this
> > by inspecting the tools configured in this way and adding them to the
> > available and unavailable lists before displaying them.
> 
> Although I am not a mergetool user, I would imagine that it would
> make sense to show it as available.
> 
> Just like "git help -a" lists subcommands in a way that can be easy
> to tell which ones are the standard ones and which ones are user
> customizations, this may want to give a similar distinction, though.
> I dunno.

> I think I'd want to do this with a suffix if at all, so the output would
> be like this:
>
>     'git mergetool --tool=<tool>' may be set to one of the following:
>
>             araxis
>             gvimdiff
>             gvimdiff2
>             mytool	(user-defined)
>             vimdiff
>             vimdiff2

> John Keeping <john@keeping.me.uk> writes:
>
>> I think I'd want to do this with a suffix if at all, so the output would
>> be like this:
>>
>>     'git mergetool --tool=<tool>' may be set to one of the following:
>>
>>             araxis
>>             gvimdiff
>>             gvimdiff2
>>             mytool    (user-defined)
>>             vimdiff
>>             vimdiff2
>
> That is fine by me, but the real users of mergetool please feel free
> to raise objections.