🚀 go-pugleaf

alexr@msil.sps.mot.COM (Alex Rezinsky) wrote:

|>
|>        Hi all,
|>
|>Can I use setjmp/longjmp routines in C++ environment (g++ compiler)?
|>Do they save/restore C++ environment correctly?
|>Does longjmp call default destructors?

In theory you can use setjmp/longjmp, in C++, but they are very
restricted.  From the September draft 18.7:

	The function signature longjmp(jmp_buf jbuf, int val) has more
	restricted behavior in this International 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.

In practice, this is so restrictive that I would say that these macros
are not usable in C++.  Use exceptions instead.

I expect that most compilers will not destroy auto objects when
longjmp() is called unless they actually implement setjmp/longjmp with
exceptions.

Michael M Rubenstein

In <9512171357.AA03464@msil.sps.mot.com>, alexr@msil.sps.mot.COM (Alex Rezinsky) writes:
>
>        Hi all,
>
>Can I use setjmp/longjmp routines in C++ environment (g++ compiler)?
>Do they save/restore C++ environment correctly?
>Does longjmp call default destructors?
>
>Thanks,
>Alex

Alex;
	Yes, you can use setjmp/longjmp. No, you shouldn't. They do not
call destructors, and in fact, unless used very carefully, are almost
guaranteed to mess up memory. Exception handling will address these
problems, but I don't know of any compilers currently implementing
exception handling according to the standard.