Proposed feature - Optionally generate gtags for gtags-visit-rootdir

[Earl Chew]

I recently had cause to look at gtags-visit-rootdir:

http://lists.gnu.org/archive/html/bug-global/2015-09/msg00021.html)

and it occurred to me that it would be useful if it was possible
to visit the rootdir, and generate gtags at the same time.

With this proposal, "C-c v" would visit the root directory, and
"C-u C-c v" would visit the root dir and generate gtags in that
directory.

Would this be a good feature to add ?

Earl