Re: [PATCH] bash: support user-supplied completion scripts for user's git commands

> The bash completion script already provides support to complete
> aliases, options and refs for aliases (if the alias can be traced back
> to a supported git command by __git_aliased_command()), and the user's
> custom git commands, but it does not support the options of the user's
> custom git commands (of course; how could it know about the options of
> a custom git command?).  Users of such custom git commands could
> extend git's bash completion script by writing functions to support
> their commands, but they might have issues with it: they might not
> have the rights to modify a system-wide git completion script, and
> they will need to track and merge upstream changes in the future.
>
> This patch addresses this by providing means for users to supply
> custom completion scriplets for their custom git commands without
> modifying the main git bash completion script.
>
> Instead of having a huge hard-coded list of command-completion
> function pairs (in _git()), the completion script will figure out
> which completion function to call based on the command's name.  That
> is, when completing the options of 'git foo', the main completion
> script will check whether the function '_git_foo' is declared, and if
> declared, it will invoke that function to perform the completion.  If
> such a function is not declared, it will fall back to complete file
> names.  So, users will only need to provide this '_git_foo' completion
> function in a separate file, source that file, and it will be used the
> next time they press TAB after 'git foo '.
>
> There are two git commands (stage and whatchanged), for which the
> completion functions of other commands were used, therefore they
> got their own completion function.
>