I\'ve a PHP library that uses a number of regular expressions featuring the \\P expressions for multibyte strings, e.g.
((((?:\\P{M}\\p{M}*)+?)|
Other than trying it, I think the only way is to use the pcretest command line tool, with the -C option (compile-time options):
bash-4.1.5$ pcretest -C
No UTF-8 support
No Unicode properties support
Newline sequence is LF
\R matches all Unicode newlines
Internal link size = 2
POSIX malloc threshold = 10
Default match limit = 10000000
Default recursion depth limit = 10000000
Match recursion uses stack