remove_volatile_t is an alias to the return type of the bsl::remove_volatile meta-function. Note, that the remove_volatile_t avoids the ::type suffix and typename prefix when we want to use the result of the meta-function in templates.
Declared in <bslmf_removevolatile.h>
template<class t_TYPE>
using remove_volatile_t = remove_volatile<t_TYPE>::type;