@hauleth: For me it gives:
$ git config --global --set diff.elixir.xfuncname '^[ \t]*((def(macro|module|impl|guard|protocol)?p?|test)[ \t].*)$'
error: unknown option `set'
# here the git config usage is displayed
I think that it should be --add instead of --set.
My result:
$ git config --global --add diff.elixir.xfuncname '^[ \t]*((def(macro|module|impl|guard|protocol)?p?|test)[ \t].*)$'
$ git config --global --get diff.elixir.xfuncname
^[ \t]*((def(macro|module|impl|guard|protocol)?p?|test)[ \t].*)$
