Dear SG12,

CC: Herb Sutter

As we limber up to the Cologne mailing deadline, here is draft 1 of a
proposal to add stackable, thread local, signal guards to the C++
standard library. It will be submitted for SG12 to review at Cologne.

A signal guard allows one to recover from a hardware exception during a
guarded piece of code e.g. SIGFPE, SIGSEGV, and so on. The guard acts on
the local thread, rather than globally. And they can be stacked, one
inside another.

They also can guard against OOM and termination, which may be useful for
Herbceptions' proposed OOM handling changes.

A reference library implementation is linked, it's been in production
for over a year now, and has proven quite popular with many people as it
abstracts away lots of annoying implementation specifics.

Comments welcome.

Niall