[over.match.class.deduct] Fix failure to handle the case where a

deducible alias template's defining-type-id contains a
nested-name-specifier (or 'typename' or 'template' keywords).

Author: zygoloid

source/declarations.tex

@@ -1387,7 +1387,7 @@
 The \grammarterm{nested-name-specifier}, if any, shall be non-dependent and
 the \grammarterm{template-name} shall name a deducible template.
 A \defnadj{deducible}{template} is either a class template or
-an alias template whose \grammarterm{defining-type-id} is of the form
+is an alias template whose \grammarterm{defining-type-id} is of the form
 \begin{ncsimplebnf}
 \opt{\keyword{typename}} \opt{nested-name-specifier} \opt{\keyword{template}} simple-template-id
 \end{ncsimplebnf}

source/overloading.tex

@@ -1572,18 +1572,24 @@
 
 \pnum
 When resolving a placeholder for a deduced class type\iref{dcl.type.simple}
-where the \grammarterm{template-name} names an alias template \tcode{A}
-whose \grammarterm{defining-type-id}
-is a \grammarterm{simple-template-id} \tcode{B<L>},
-the guides of \tcode{A} are the set of functions or function templates
+where the \grammarterm{template-name} names an alias template \tcode{A},
+the \grammarterm{defining-type-id} must be of the form
+\begin{ncsimplebnf}
+\opt{\keyword{typename}} \opt{nested-name-specifier} \opt{\keyword{template}} simple-template-id
+\end{ncsimplebnf}
+as specified in \ref{dcl.type.simple}.
+The guides of \tcode{A} are the set of functions or function templates
 formed as follows.
-For each function or function template \tcode{f} in the guides of \tcode{B},
+For each function or function template \tcode{f} in the guides of
+the template named by the \grammarterm{simple-template-id}
+of the \grammarterm{defining-type-id},
 form a function or function template \tcode{f'}
 according to the following procedure and add it to the set:
 \begin{itemize}
 \item
   Deduce the template arguments of the return type of \tcode{f}
-  from \tcode{B<L>} according to the process in \ref{temp.deduct.type}
+  from the \grammarterm{defining-type-id} of \tcode{A}
+  according to the process in \ref{temp.deduct.type}
   with the exception that deduction does not fail
   if not all template arguments are deduced.
   Let \tcode{g} denote the result of substituting