@@ -6400,12 +6400,15 @@
 
 \pnum
 A defaulted comparison operator function\iref{over.binary}
-for some class \tcode{C}
 shall be a non-template function
-that is
+that
 \begin{itemize}
 \item
-a non-static member or friend of \tcode{C} and
+is a non-static member or friend of some class \tcode{C},
+
+\item
+is defined as defaulted in \tcode{C} or in
+a context where \tcode{C} is complete, and
 
 \item
 either has
@@ -6414,13 +6417,27 @@
 where the implicit object parameter (if any) is considered to be
 the first parameter.
 \end{itemize}
+Such a comparison operator function is termed
+\indextext{operator!defaulted comparison operator function}%
+a defaulted comparison operator function for class \tcode{C}.
 Name lookups in the implicit definition\iref{dcl.fct.def.default}
 of a comparison operator function
 are performed from a context equivalent to
 its \grammarterm{function-body}.
 A definition of a comparison operator as
 defaulted that appears in a class shall be the first declaration
 of that function.
+\begin{example}
+\begin{codeblock}
+struct S;
+bool operator==(S, S) = default;                    // error: \tcode{S} is not complete
+struct S {
+  friend bool operator==(S, const S&) = default;    // error: parameters of different types
+};
+enum E { };
+bool operator==(E, E) = default;                    // error: not a member or friend of a class
+\end{codeblock}
+\end{example}
 
 \pnum
 A defaulted \tcode{<=>} or \tcode{==} operator function for class \tcode{C}
 
@@ -6403,9 +6403,9 @@
 is called an \defnx{explicitly-defaulted}{definition!function!explicitly-defaulted} definition.
 A function that is explicitly defaulted shall
 \begin{itemize}
-\item be a special member function or
-a comparison operator function\iref{over.binary}, and
-\item not have default arguments.
+\item be a special member function\iref{special} or
+a comparison operator function\iref{over.binary, class.compare.default}, and
+\item not have default arguments\iref{dcl.fct.default}.
 \end{itemize}
 
 \pnum