Comment by strenholme

Not POSIX/C99 worship as much as the very practical issue that a lot of C code which used to compile just fine stopped compiling once compilers defaulted to using C23. To use POSIX calls while compiling with -std=c99 (so I don’t have to update my code should C29 or what not come out) one needs to declare, for each .c file which uses a POSIX call, the version of POSIX the C file is compatible with.