...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
Unless otherwise specified, the lifetime of arguments to initiating functions shall be treated as follows:
— If the parameter has a pointer type or has a type of lvalue reference to non-const, the implementation may assume the validity of the pointee or referent, respectively, until the completion handler is invoked. [Note: In other words, the program must guarantee the validity of the argument until the completion handler is invoked. —end note]
— Otherwise, the implementation must not assume the validity of the argument after the initiating function completes. [Note: In other words, the program is not required to guarantee the validity of the argument after the initiating function completes. —end note] The implementation may make copies of the argument, and all copies shall be destroyed no later than immediately after invocation of the completion handler.