POSIX 1003.1 1996 Edition support--realtime stuff:
POSIX semaphores, message queues, shared memory, realtime clocks,
timers, signals (the metaconfig units mostly already exist for these)
- better shadow password support: see pp_sys.c:pp_gpwent()
+ PREFERABLY AS AN EXTENSION
UNIX98 support: reader-writer locks, realtime/asynchronous IO
+ PREFERABLY AS AN EXTENSION
IPv6 support: see RFC2292, RFC2553
+ PREFERABLY AS AN EXTENSION
+ there already is Socket6
Long doubles
figure out where the PV->NV->PV conversion gets it wrong at least
64-bit support
Configure probe for quad_t, uquad_t, and (argh) u_quad_t, they might
be in some systems the only thing working as quadtype and uquadtype.
+ more pain: long_long, u_long_long.
Locales
deprecate traditional/legacy locales?
(no metaconfig units yet for these).
Don't forget finitel(), fp_classl(), fp_class_l(), (yes, both do,
unfortunately, exist), and unorderedl().
+ PREFERABLY AS AN EXTENSION.
As of 5.6.1 there is cpp macro Perl_isnan().
fix the basic arithmetics (+ - * / %) to preserve IVness/UVness if
both arguments are IVs/UVs