All index values and simd widths in subclause "Data-parallel types" use the type simd-size-type. Specifically, the NTTP of `std::datapar::resize` uses simd-size-type and `std::datapar::chunk` is "implemented" using `std::datapar::resize`.

For chunk<N>, N is of type `size_t` and needs to be converted to simd-size-type in the effects clause where it is passed to resize. The NTTP of chunk should use simd-size-type instead of `size_t`.