https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92426
--- Comment #2 from W E Brown <webrown.cpp at gmail dot com> --- Please note that the submitted test program seems not to meet the #include requirement as articulated in N4835 clause [expr.spaceship] p10: "10 The five comparison category types (17.11.2) (the types std::strong_ordering, std::strong_equality, std::weak_ordering, std::weak_equality, and std::partial_ordering) are not predefined; if the header <compare> (17.11.1) is not included prior to a use of such a class type – even an implicit use in which the type is not named (e.g., via the auto specifier (9.2.8.5) in a defaulted three-way comparison (11.11.3) or use of the built-in operator) – the program is ill-formed."
