CWG2379 Missing prohibition against constexpr in friend declaration

Author: Dawn Perchik

source/templates.tex

@@ -2967,8 +2967,9 @@
 \pnum
 When a friend declaration refers to a specialization of a function
 template, the function parameter declarations shall not include
-default arguments, nor shall the inline specifier be used in such a
-declaration.
+default arguments, nor shall
+the \tcode{inline}, \tcode{constexpr}, or \tcode{consteval} specifiers
+be used in such a declaration.
 
 \pnum
 A non-template friend declaration shall not have a \grammarterm{requires-clause}.