Proposed resolution:

This wording is relative to N4901.

1. Modify [stdatomic.h.syn], header <stdatomic.h> synopsis, as indicated:

   [Drafting Note: The editor is kindly requested to reorder these "atomic_fetch_KEY" declarations to match the other synopses in Clause [atomics]: add, sub, and, or, xor.]

   […]
   using std::atomic_fetch_or;                    // see below
   using std::atomic_fetch_or_explicit;           // see below
   using std::atomic_fetch_xor;                   // see below
   using std::atomic_fetch_xor_explicit;          // see below
   using std::atomic_fetch_and;                   // see below
   using std::atomic_fetch_and_explicit;          // see below
   […]
   

[ 2022-07-25 Approved at July 2022 virtual plenary. Status changed: Ready → WP. ]

[ 2022-07-15; LWG telecon: move to Ready ]

[ 2022-03-04; Reflector poll ]

Set status to Tentatively Ready after eight votes in favour during reflector poll.

[ 2022-02-09; Jonathan comments and provides wording ]

C++20 [atomics.syn] has both of them, too, so it should definitely be in the common subset.

C17 subclause 7.17.7.5 provides atomic_fetch_xor and atomic_fetch_xor_explicit. stdatomic.h in the working draft (N4901) does not.