[Boost-bugs] [Boost C++ Libraries] #7499: call_once doesn't call even once

Subject: [Boost-bugs] [Boost C++ Libraries] #7499: call_once doesn't call even once
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2012-10-11 20:41:04

#7499: call_once doesn't call even once
------------------------------+---------------------------------------------
 Reporter:  kab@…             |       Owner:  anthonyw   
     Type:  Bugs              |      Status:  new        
Milestone:  To Be Determined  |   Component:  thread     
  Version:  Boost 1.52.0      |    Severity:  Showstopper
 Keywords:                    |  
------------------------------+---------------------------------------------
 In boost 1.52.0 beta1

 In boost/thread/pthread/once.hpp, near the head of the file, is the
 following conditional snippet:

 #ifdef SIG_ATOMIC_MAX
     typedef sig_atomic_t uintmax_atomic_t;
     ...
 #else
     ...
 #endif

 Well, sig_atomic_t may be a signed type, and in fact on the Linux system
 I'm testing on it is a typedef for int [suse12.1, but I suspect it doesn't
 really matter.]  POSIX says "Possibly volatile-qualified integer type
 ...".

 This led to boost::call_once never calling the function, because there is
 a comparison in call_once
   (epoch<this_thread_epoch)
 where I'm seeing values of 0 and -2 respectively for those variables, that
 doesn't go in the expected direction when uintmax_atomic_t is a signed
 type rather than the expected unsigned type.  I bet there are other places
 that get confused by this being an unexpectedly signed type.

 I'm working around this to continue my testing of 1.52beta1 by commenting
 out the offending conditional code and just using the code in the #else
 clause.

 The relevant code is new code, introduced since boost 1.51.  This is a
 serious regression that should be a blocker for the 1.52 release.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/7499>
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