[Rd] The regular expressions in compareVersion()

[Yihui Xie]

Hi,

I guess the backslash should not be used as the separator for
strsplit() in compareVersion(), because the period in [.] is no longer
a metacharacter (no need to "escape" it using a backslash):
https://github.com/wch/r-source/blob/trunk/src/library/utils/R/packages.R#L866-L867

> compareVersion
function (a, b)
{
....
    a <- as.integer(strsplit(a, "[\\.-]")[[1L]])
    b <- as.integer(strsplit(b, "[\\.-]")[[1L]])
....
<environment: namespace:utils>

A similar regular expression problem also exists in the Sweave syntax
(for \Sexpr{}), and I have reported it once. It was fixed but the fix
was immediately reverted for some reason:
https://github.com/wch/r-source/commit/52b0a46e15136a7f9e4777e9960fdda6d84880c0

Regards,
Yihui
--
Yihui Xie <xieyihui at gmail.com>
Web: http://yihui.name