Boost C++ Libraries: Ticket #6060: Warning generated in SNC C++ compiler by use of __sync_fetch_and_add

attachment set

Tue, 25 Oct 2011 20:31:08 GMT

attachment → snc_warning.patch

Proposed change to fix warning

Peter Dimov — Tue, 25 Oct 2011 21:00:26 GMT

This is a problem with SNC. The prototype of __sync_fetch_and_add is

type __sync_fetch_and_add (type *ptr, type value, ...)

i.e. the second argument should be the same type as the first, which, in shared_ptr's code, is sp_int32_t, a signed integer.

Wed, 26 Oct 2011 12:59:06 GMT

I see. In any case, am I correct in seeing

__sync_fetch_and_add( pw, -1 );

and

__sync_fetch_and_sub( pw, 1 );

as interchangeable? Because if the change is correct, but cannot be incorporated into boost, I could keep it on my side and reapply it each time boost is updated. Thanks!

Peter Dimov — Mon, 07 Nov 2011 18:32:56 GMT

They should be interchangeable, but the first one has already been tested and the replacement has not, so I'm a bit reluctant to change it unconditionally. Have you tried reporting this as a problem to the SNC folks? I hear that they're quite responsive. If they don't want to eliminate the warning, we could add __sync_fetch_and_sub in an #ifdef __SNC__.

status changed; resolution set

Peter Dimov — Fri, 13 Dec 2013 22:26:17 GMT

status new → closed
resolution → wontfix

I'm closing this as too old and probably no longer relevant. Please reopen if this is not the case.