In priority order:
- msvc: __debugbreak()
- clang: __builtin_debugtrap()
- linux (and probably some other posix-ish systems): raise(SIGTRAP)
- gcc x86: asm("int3; nop")
- otherwise: you're out of luck, just abort()/__builtin_trap()
catch infinite-loop
But I did think about how it could work. It could work by peridically sampling the instructions the current thread is running and detect trivial infinite loops that way.
With more effort more complicated infinite loops could be detected, but in the end not all, due to the halting problem.
edit: Actually maybe halting problem is not (theoretically) involved if you have a lot of memory: take snapshots every after every instruction. Once you take a snapshot you have already taken previously, you have found a loop. However you would still might need to somehow account for (emulate and include in snapshot?) or disallow external IO, such as time of day.
I have to admit I didn't try it out though. Maybe this changed in the meantime and it is not needed anymore.
// Q: Why is there a __nop() before __debugbreak()?
// A: VS' debug engine has a bug where it will silently swallow explicit
// breakpoint interrupts when single-step debugging either line-by-line or
// over call instructions. This can hide legitimate reasons to trap. Asserts
// for example, which can appear as if the did not fire, leaving a programmer
// unknowingly debugging an undefined process.