The attached sample program was taken from a real-world program with the data structures obfuscated and simplified. Both in the sample program and our product, std::sort hangs when qSort doesn't hang.

The issue came to our attention when one of our customers reported our product hanging. Replacing the std::sort call with a qSort call fixed the issue for our customer.

However, it is my understanding that we're supposed to favor std::sort over qSort in new development.