c++ - move-assigning a std::map with an aligned value type segfaults -

the following code segfaults consistently me on clang 3.8 succeeds on clang 3.7. compile clang++ -std=c++14 -o2 test_case.cpp -o test_case in both cases. if compile optimisations off on clang 3.8 program runs completion.

i'm guessing compiler taking liberties when optimising - question is: compiler allowed optimise in way, or have found first compiler bug?

#include <iostream> #include <map>  struct __attribute__((aligned(16))) troublesome {   float s; };  int main() {   std::map<int, troublesome> m{{0, troublesome{}}};   std::map<int, troublesome> n{{1, troublesome{}}};   std::cout << "got here" << std::endl;  //  prints   m = std::move(n);  //  segfault happens here   std::cout << "got here too" << std::endl;  // here on old clang }