vc-switches

vc-switches is an autoloaded compiled Lisp function in `vc.el'.

(vc-switches BACKEND OP)

Return a list of vc-BACKEND switches for operation OP.
BACKEND is a symbol such as `CVS', which will be downcased.
OP is a symbol such as `diff'.

In decreasing order of preference, return the value of:
vc-BACKEND-OP-switches (e.g. `vc-cvs-diff-switches');
vc-OP-switches (e.g. `vc-diff-switches'); or, in the case of
diff only, `diff-switches'.

If the chosen value is not a string or a list, return nil.
This is so that you may set, e.g. `vc-svn-diff-switches' to t in order
to override the value of `vc-diff-switches' and `diff-switches'.