There is an ongoing discussion to unify unreturn attribute between C and
C++, making a compatible version, shared between languages. Instead of
picking C11-only approach here, switch back to __dead that wraps the
compiler extension for the same purpose.
This change makes this header more compatible with C++ and pre-C11.
Reference:
http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2410.pdf
Switch tss_t type from int to pthread_key_t (no functional change as
pthread_key_t was already typedefed as int).
Noted by <enh from Google>.
Use C11 _Noreturn in thrd_exit(3) instead of NetBSD specific __dead.
The former is documented in the standard as an attribute of thrd_exit(3),
the latter is more portable to pre-C11 compilers, however C11 thread
support library needs C11 compiler for TLS anyway. __dead made a little bit
more point 3 years ago than today as 3 years ago pre-C11 compilers were
more common.
C11 Thread support library is a portable threading C API between OSs,
similar to std::threads in the C++ world.
The library is implemented as a thin shim over POSIX interfaces.
NetBSD implements the API as a part of the POSIX threading library
(libpthread(3)).
C11 threads(3) are in the process of making them an integral part
of the POSIX standard. The interface has been implemented in major
OSs and used with stopgap libraries for older versions of them.
C11 threading library is already used (with a stopgap implementation)
in the NetBSD distribution in MESA.
Original implementation by myself from 2016.
ATF tests are new and cover almost all interfaces.
Proposed on tech-userlevel@.
