Same as the other unpoint overloads, for t_TP *volatile&.
unpoint
t_TP *volatile&
Declared in <bslmf_invokeresult.h>
<bslmf_invokeresult.h>
template<class t_TP> static t_TP& unpoint(t_TP volatile*&) requires !bsl::is_void<t_TP>::value;