Alias for T if B is true, otherwise F (equivalent to std::conditional_t<B, T, F>)
T
B
true
F
std::conditional_t<B, T, F>
Declared in <mp-units/ext/type_traits.h>
<mp-units/ext/type_traits.h>
template< bool B, typename T, typename F> using conditional = /* implementation-defined */::type<T, F>;