Does this really break strict-aliasing rules?

Vote count:

0

When I compile this sample code using g++, I get this warning:

test.cpp:8:48: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]

The code:

#include <iostream>

int main(int argc, char ** argv) 
{
   alignas(int) char data[sizeof(int)];
   int *myInt = new(data) int;
   *myInt = 34;

   std::cout << *reinterpret_cast<int*>(data) << std::endl;
}

In this case, doesn't data alias an int, and therefore casting it back to an int would not violate strict aliasing rules? Or am I missing something here?

asked 1 min ago

Red Alert

1,877

Does this really break strict-aliasing rules?