http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46914
Summary: std::atomic<int*>::exchange(...) doesn't store correct value. Product: gcc Version: 4.4.3 Status: UNCONFIRMED Severity: normal Priority: P3 Component: libstdc++ AssignedTo: unassig...@gcc.gnu.org ReportedBy: frts...@hotmail.com Run the following to compile the program below. $ g++ -std=c++0x ./test.cpp -o test.tsk //test.cpp #include <iostream> #include <stdatomic.h> int main(int argc, char **argv) { int *a = new int(10); std::cout << "a = " << a << " *a = " << *a << std::endl; std::atomic<int*> x(a); int *ptr = x; std::cout << "ptr = " << ptr << " *ptr " << *ptr << std::endl; int *b = new int(11); std::cout << "b = " << b << " *b = " << *b << std::endl; std::cout << "x.exchange(b) = " << x.exchange(b) << std::endl; ptr = x; std::cout << "ptr = " << ptr << " *ptr " << *ptr << std::endl; int *c = new int(12); std::cout << "c = " << c << " *c = " << *c << std::endl; std::cout << "x.exchange(c) = " << x.exchange(c) << std::endl; ptr = x; std::cout << "ptr = " << ptr << " *ptr " << *ptr << std::endl; return 0; } $ g++ --version g++ (Ubuntu 4.4.3-4ubuntu5) 4.4.3 Copyright (C) 2009 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. It runs and gives the following result. ./test.tsk a = 0x9b9c008 *a = 10 ptr = 0x9b9c008 *ptr 10 b = 0x9b9c018 *b = 11 x.exchange(b) = 0x9b9c008 ptr = 0x1ec71b *ptr -388381823 c = 0x9b9c028 *c = 12 x.exchange(c) = 0x1ec71b ptr = 0x1ec71b *ptr -388381823 After "x" is initialized with "a", it doesn't store the new value correctly in its "exchange" member function.