Re: [PATCH] doc: clarify usage of XDG_CONFIG_HOME config file

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

Yaroslav Halchenko <yoh@onerussian.com> writes:

> It always read it for non--global
> ...
> and it doesn't read it for --global
> ...
> unless ~/.gitconfig is missing

Yes, this dates back to 21cf3227 ("config: read (but not write) from
$XDG_CONFIG_HOME/git/config file", 2012-06-22), around the time back
when we added support to use xdg locations and doing so without breaking
existing users.

Taken together with a later commit in the same series 0e8593dc
("config: write to $XDG_CONFIG_HOME/git/config file when
appropriate", 2012-06-22), which says:

    config: write to $XDG_CONFIG_HOME/git/config file when appropriate
    
    Teach git to write to $XDG_CONFIG_HOME/git/config if
    
     - it already exists,
     - $HOME/.gitconfig file doesn't, and
     - The --global option is used.
    
    Otherwise, write to $HOME/.gitconfig when the --global option is
    given, as before.
    
    If the user doesn't create $XDG_CONFIG_HOME/git/config, there is
    absolutely no change. Users can use this new file only if they want.
    
    If $XDG_CONFIG_HOME is either not set or empty, $HOME/.config/git/config
    will be used.
    
    Advice for users who often come back to an old version of Git: you
    shouldn't create this file.

the plan is to have either one of these and not both at the same
time.  A user who wants to live in xdg world (and wants to avoid
cluttering $HOME with .many-files) can do so by creating an empty
one there, and all writes from there on go to the xdg world; as
there will no $HOME/.gitconfig created, the read side attempting to
read from it does not matter.  Other users get $HOME/.gitconfig when
running "config --global" to write for the first time, or users who
have been using Git from olden days already have $HOME/.gitconfig,
and no write goes to xdg world, so again the read side attempting to
read from there does not matter, either.

Perhaps a doc update needs to clarify these.

Thanks.