Tamito Kajiyama
efd774ce5a
The reported crash was confirmed as a segmentation fault in std::sort(). The cause of the crash was traced down to a binary comparison function that was not satisfying the so-called strict weak ordering requirements of the C++ standard sorting function. Specifically, the comparison operator has to return false when two objects are equivalent (i.e., comp(a, a) must be false), but that requirement was not met. Since the binary comparison operator in question could be a user-defined Python function, here a safety measure is implemented in the C++ layer to make sure the aforementioned requirement is always satisfied.