If a function argument is described as being an array,
the pointer actually passed to the function shall have a value such that all
address computations and accesses to objects (that would be valid if the
pointer did point to the first element of such an array) are in fact valid.
If a function argument is bound to an rvalue reference parameter, the implementation may
assume that this parameter is a unique reference to this argument,
except that the argument passed to a move assignment operator may be
a reference to *this ([lib.types.movedfrom]).
If a program casts
an lvalue to an xvalue while passing that lvalue to a library function
(e.g., by calling the function with the argument std::move(x)), the program
is effectively asking that function to treat that lvalue as a temporary object.
is free to optimize away aliasing checks which would possibly be needed if the argument was