Guess the style on the region; don't install it.
Every line of code in the region is examined and values for the following two
variables are guessed:
* `c-basic-offset', and
* the indentation values of the various syntactic symbols in
`c-offsets-alist'.
The guessed values are put into `c-guess-guessed-basic-offset' and
`c-guess-guessed-offsets-alist'.
Frequencies of use are taken into account when guessing, so minor
inconsistencies in the indentation style shouldn't produce wrong guesses.
If given a prefix argument (or if the optional argument ACCUMULATE is
non-nil) then the previous examination is extended, otherwise a new
guess is made from scratch.
Note that the larger the region to guess in, the slower the guessing.
So you can limit the region with `c-guess-region-max'.
(fn START END &optional ACCUMULATE)