Unfortunately swap context requires saving and restoring the signal mask, which, at least on Linux, requires a syscall so it is going to be at least a hundred times slower than an hand rolled implementation.
replyAlso, although not likely to be removed anytime soon from existing systems, POSIX has declared the context API obsolescent a while ago (it might actually no longer be part of the standard).
Signal mask? What century are we in?
replyIt can be safely ignored for the vast majority of apps. If you're using multithreading (quite likely if you're doing coroutines), then signals are not a good fit anyway.
Aside from the fact that the signal mask is still relevant in 2026 and even for multithreaded programs, that doesn't have anything to do with the fact that POSIX requires swapcontext to preserve it.
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