https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92426
--- Comment #3 from Cameron <dacamara.cameron at gmail dot com> --- (In reply to W E Brown from comment #2) > 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." My mistake, I over simplified the example. There should have been a #include <compare> in both cases.
