Question

Is it safe to use longjmp and setjmp in C++ on linux/gcc with regards to the following?

1. Exception handling (I’m not implementing exception handling using longjmp/setjmp. I want to know what side effects longjmp/setjmp will have on standard exception handling)
2. *this pointer
3. Signals
4. Smart pointers (boost’s shared and intrusive pointers)
5. Anything else you can think of.

Answer 1

setjmp()/longjmp() completely subvert stack unwinding and therefore exception handling as well as RAII (destructors in general).

From 18.7/4 “Other runtime support” in the standard:

If any automatic objects would be destroyed by a thrown exception transferring
control to another (destination) point in the program, then a call to longjmp(jbuf, val) at the throw point that transfers control to the same (destination) point has undefined behavior.

So the bottom line is that setjmp()/longjmp() do not play well in C++.