Deduces a FunctionRef wrapping a compile-time known member function.
Declared in <absl/functional/function_ref.h>
template<
class M,
class T,
MT::* Func,
class U>
FunctionRef<std::invoke_result_t<decltype(Func), U&>()>(
nontype_t<Func>,
U&&) -> FunctionRef<std::invoke_result_t<decltype(Func), U&>()>;