freebsd
Perfer sys/cdefs.h __unreachable over the builtin
The __builtin_unreachable macro provided by Clang and GCC is a hint to the compiler used for optimization. The programs work fine even if the compiler doesn't support it. The sys/cdefs.h has had __unreachable for 9 years (commit 732b31de5d9244bd1cc98192e09ee1881e9f55e9). It expands to the builtin if it is available. In the rare case that it is unsupported it expands to a null statement so compilation does not fail.
@bsdimp @emaste ISO C 23 N2826 adds the function-like macro unreachable() to stddef.h. Can I submit a separate patch proposing that change? I'm not sure if it is something left up to the GCC/Clang people to include with their headers though...
this needs one commit per subsystem.
Oops, my bad. Split into three commits, one for each program.
Landed this... go ahead and start to implement the c23 defined macro if you can do it w/o problems on older C compilers.
