[#264] Enable slice methods only for slice Payload; remove reinterpre…

…t cast

iceoryx2-ffi/cxx/include/iox2/publisher.hpp

@@ -65,7 +65,7 @@ class Publisher {
  /// [`Payload`].
  ///
  /// On failure it returns [`PublisherLoanError`] describing the failure.
- template <typename T = Payload, typename = std::enable_if<iox::IsSlice<T>::VALUE, T>>
+ template <typename T = Payload, typename = std::enable_if_t<iox::IsSlice<T>::VALUE, T>>
  auto
  loan_slice(uint64_t number_of_elements) -> iox::expected<SampleMut<S, Payload, UserHeader>, PublisherLoanError>;