This partial specialization of is_void derives from bsl::true_type for when the (template parameter) t_TYPE is const void.
is_void
bsl::true_type
t_TYPE
const void
Declared in <bslmf_isvoid.h>
<bslmf_isvoid.h>
template<> struct is_void<void const> : true_type
true_type
true