bug#17945: 24.4.50; vc-git-annotate-command is too slow

[Óscar Fuentes]

Dmitry Gutov <dgutov@yandex.ru> writes:

> On 02/24/2015 07:57 PM, Glenn Morris wrote:
>
>> except vc-annotate-switches does not exist and would also
>> need to be added.
>
> I think this is only justified if we expect different backends'
> annotate command to receive the same options.

As the docstrings of vc-BACKEND-annotate-switches mention
vc-annotate-switches *and* vc-switches checks vc-annotate-switches, I
changed my mind again and implemented vc-annotate-switches with a caveat
on the docstring. Please review and suggest a better wording, if
necessary:

(defcustom vc-annotate-switches nil
  "A string or list of strings specifying switches for annotate under VC.
When running annotate under a given BACKEND, VC uses the first
non-nil value of `vc-BACKEND-annotate-switches', `vc-annotate-switches',
and `annotate-switches', in that order.  Since nil means to check the
next variable in the sequence, either of the first two may use
the value t to mean no switches at all.  `vc-annotate-switches'
should contain switches that are specific to version control, but
not specific to any particular backend.

As very few switches (if any) are used across different VC tools,
please consider using the specific `vc-BACKEND-annotate-switches'
for the backend you use."
  :type '(choice (const :tag "Unspecified" nil)
                 (const :tag "None" t)
                 (string :tag "Argument String")
                 (repeat :tag "Argument List" :value ("") string))
  :group 'vc
  :version "25.1")


> So far, only '-w' looks a likely candidate, albeit its descriptions
> are a bit different between Git and Hg. And it's not in e.g. Bzr.
>
> What if the user sets `vc-annotate-switches' to '-w', and then calls
> `vc-annotate' in a Bazaar repository, where it'll obviously lead to
> failure?
>
>> And for consistency, presumably all backends should
>> get the same treatment. Thanks.
>
> Probably. But I'd rather the present patch gets installed without too
> much delay.

I extended the vc-switches support to the rest of backends that
implement `vc-BACKEND-annotate-command', except rcs, that does some
complicated things (and I have no easy way of testing it.)

Once we agree on the resolution of the vc-annotate-switches issue, I'll
commit the changes.