CWG2697 Deduction guides using abbreviated function syntax

Author: burblebee

source/templates.tex

@@ -2413,7 +2413,10 @@
 The same restrictions apply
 to the \grammarterm{parameter-declaration-clause}
 of a deduction guide
-as in a function declaration\iref{dcl.fct}.
+as in a function declaration\iref{dcl.fct},
+except that a generic parameter type placeholder\iref{dcl.spec.auto}
+shall not appear in the \grammarterm{parameter-declaration-clause} of
+a deduction guide.
 The \grammarterm{simple-template-id}
 shall name a class template specialization.
 The \grammarterm{template-name}