Fixup: definition of concept ThreeWayComparableWith

Author: jensmaurer

source/support.tex

@@ -4574,6 +4574,22 @@
   \libconcept{StrictTotallyOrdered}\iref{concept.stricttotallyordered}.
 \end{itemize}
 
+\begin{codeblock}
+template <typename T, typename U, typename Cat = partial_ordering>
+  concept ThreeWayComparableWith =
+    @\placeholdernc{weakly-equality-comparable-with}@<T, U> &&
+    (!ConvertibleTo<Cat, partial_ordering> || @\placeholdernc{partially-ordered-with}@<T, U>) &&
+    ThreeWayComparable<T, Cat> &&
+    ThreeWayComparable<U, Cat> &&
+    CommonReference<const remove_reference_t<T>&, const remove_reference_t<U>&> &&
+    ThreeWayComparable<
+      common_reference_t<const remove_reference_t<T>&, const remove_reference_t<U>&>, Cat> &&
+    requires(const remove_reference_t<T>& t, const remove_reference_t<U>& u) {
+      { t <=> u } -> @\placeholdernc{compares-as}@<Cat>;
+      { u <=> t } -> @\placeholdernc{compares-as}@<Cat>;
+    };
+\end{codeblock}
+
 \pnum
 Let \tcode{t} and \tcode{u} be lvalues
 of types \tcode{const remove_reference_t<T>} and