Proposed resolution:

This wording is relative to N4988.

1. Modify [cmp.alg] as indicated:

   (6.3) — Otherwise, if the expressions E == F, E < F, and F < E are all well-formed and each of `decltype(E == F)` and, decltype(E < F) , and decltype(F < E) models `boolean-testable`,

   
     E == F ? partial_ordering::equivalent :
     E < F  ? partial_ordering::less :
     F < E  ? partial_ordering::greater :
              partial_ordering::unordered
   

   except that `E` and `F` are evaluated only once.

[ 2024-10-02; Reflector poll ]

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

In the resolution of LWG 3465, F < E was required to be well-formed and implicitly convertible to `bool`. However, P2167R3 replaced the convertibility requirements with just "each of `decltype(E == F)` and decltype(E < F) models `boolean-testable`", which rendered the type of F < E underconstrained.