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cposixsetjmpucontext

Why was ucontext added to and then removed from POSIX?

As far as I know, ucontext offers something better then setjmp. But it's deprecated and now removed from the POSIX spec. So why did it appear and why was it removed?

Solution

  • The signature of makecontext from ucontext.h is:

    void makecontext(ucontext_t *ucp, void (*func)(),
       int argc, ...);

    Note that func uses an empty parenthesis as argument, but this is a deprecated feature in standard C:

    C11(ISO/IEC 9899:201x) §6.11.6 Function declarators

    The use of function declarators with empty parentheses (not prototype-format parameter type declarators) is an obsolescent feature.

    This is the reason it's deprecated (and somehow unfortunate).