RootCauseunvalidated
it turns out that "synthesized three-way comparison" is used to compare each individual class member in a `=default`ed `operator`. Outcome: the synthesized three-way comparison happens twice: first for `a = m.x, b = n.x`, then for `a = m.y, b = n.y`.
267b740e-54c9-4729-b9f8-ab356ecb925e
it turns out that "synthesized three-way comparison" is used to compare each individual class member in a =defaulted operator. Outcome: the synthesized three-way comparison happens twice: first for a = m.x, b = n.x, then for a = m.y, b = n.y.