Device event stores a dangling pointer #4959
Description
In the group class, calls to async copies store the event on the stack and pass a pointer to it to the device event. The event is returned escaping a stack pointer.
https://github.com/intel/llvm/blob/sycl/sycl/include/CL/sycl/group.hpp#L294
https://github.com/intel/llvm/blob/sycl/sycl/include/CL/sycl/device_event.hpp#L32