Proposed resolution:

This wording is relative to N5032.

1. Modify [meta.reflection.layout] as indicated:

   struct member_offset {
     ptrdiff_t bytes;
     ptrdiff_t bits;
     constexpr ptrdiff_t total_bits() const noexcept;
     auto operator<=>(const member_offset&) const = default;
   };
   

   constexpr ptrdiff_t member_offset::total_bits() const noexcept;
   

   -1- Returns: `bytes * CHAR_BIT + bits`.

This member simply returns the result of integer calculations, which can be `noexcept`.