Subj : Re: Can C++ local static objects be made thread safe?
To   : comp.programming.threads
From : Marcin 'Qrczak' Kowalczyk
Date : Sat Feb 19 2005 01:58 pm

gniccolai@yahoo.com (Giancarlo Niccolai) writes:

> Then the problem remain the same as with the mutexes; pthread_once
> just atomically initializes some internal mutex, or other blocking
> thing, but semantically doesn't move our problem of deadlocking code
> that has been safe by itself before...

The point is that it has *not* been safe before. Recursive
initialization of static locals has never been correct C++.

--------
bool done = false;

void test();

class C {
public:
   C() {
      if (!done) {
         done = true;
         test();
      }
   }
};

void test() {
   static C x;
}

int main(void) {
   test();
}
--------

The result (gcc 4):

terminate called after throwing an instance of '__gnu_cxx::recursive_init'
  what():  N9__gnu_cxx14recursive_initE

Would you complain to authors of GCC that this doesn't work? I guess I
know what they would answer :-)

-- 
   __("<         Marcin Kowalczyk
   \__/       qrczak@knm.org.pl
    ^^     http://qrnik.knm.org.pl/~qrczak/

.