Re: How are VC switches supposed to work?

[Stefan Monnier]

> VC switches don't work as they are documented to work.
> If someone can confirm that they work correctly, I will try to update
> the many incorrect pieces of documentation. If on the other hand the
> documentation is correct then the code needs fixing.

> The documentation says that switches are appended. For example:

> C-h v vc-diff-switches
> C-h f vc-cvs-register
> The Emacs manual "Examining And Comparing Old Revisions"

> all say that it works, eg, as: vc-cvs-diff-switches +
> vc-diff-switches + diff-switches.


> In practice, (almost) everywhere uses the vc-switches function to
> process switches. This does no appending, it simply returns the first
> non-nil element.

> For example:

> (setq vc-cvs-diff-switches "-a"
>       vc-diff-switches "-b"
>       diff-switches "-c")

> (vc-switches 'CVS 'diff)
> -> '("-a")

> The situation was basically the same (ie inconsistent) in Emacs 22 AFAICS.

I can't remember all the details, but I do remember that appending is
not good enough because you may have switches in diff-switches that are
not accepted by some backends.


        Stefan