[temp.arg.template] Clean up wording for template template argument matching

source/templates.tex

@@ -1351,25 +1351,60 @@
 \end{example}
 
 \pnum
-A \grammarterm{template-argument} matches a template
+A template \grammarterm{template-argument} \tcode{A} matches a template
 \grammarterm{template-parameter} \tcode{P} when
-\tcode{P} is at least as specialized as the \grammarterm{template-argument} \tcode{A}.
-In this comparison, if \tcode{P} is unconstrained,
-the constraints on \tcode{A} are not considered.
-If \tcode{P} contains a template parameter pack, then \tcode{A} also matches \tcode{P}
+\tcode{P} is at least as specialized as \tcode{A},
+ignoring constraints on \tcode{A}
+if \tcode{P} is unconstrained.
+\tcode{P} is at least as specialized as \tcode{A}
+if, given the following rewrite to two function templates,
+the function template corresponding to \tcode{P}
+is at least as specialized as
+the function template corresponding to \tcode{A}
+according to the partial ordering rules
+for function templates\iref{temp.func.order}.
+Given an invented class template \tcode{X}
+with the \grammarterm{template-head} of \tcode{A} (including default arguments
+and \grammarterm{requires-clause}, if any):
+
+\begin{itemize}
+\item
+Each of the two function templates has the same template parameters
+and \grammarterm{requires-clause} (if any),
+respectively, as \tcode{P} or \tcode{A}.
+\item
+Each function template has a single function parameter
+whose type is a specialization of \tcode{X}
+with template arguments corresponding to the template parameters
+from the respective function template where,
+for each template parameter \tcode{PP}
+in the \grammarterm{template-head} of the function template,
+a corresponding template argument \tcode{AA} is formed.
+If \tcode{PP} declares a template parameter pack,
+then \tcode{AA} is the pack expansion \tcode{PP...}\iref{temp.variadic};
+otherwise, \tcode{AA} is the \grammarterm{id-expression} \tcode{PP}.
+\end{itemize}
+If the rewrite produces an invalid type,
+then \tcode{P} is not at least as specialized as \tcode{A}.
+
+\pnum
+If \tcode{P} contains a template parameter pack\iref{temp.variadic}, then
+\tcode{A} also matches \tcode{P}
 if each of \tcode{A}'s template parameters
 matches the corresponding template parameter in the
 \grammarterm{template-head} of \tcode{P}.
 Two template parameters match if they are of the same kind (type, non-type, template),
 for non-type \grammarterm{template-parameter}{s}, their types are
 equivalent\iref{temp.over.link}, and for template \grammarterm{template-parameter}{s},
 each of their corresponding \grammarterm{template-parameter}{s} matches, recursively.
-When \tcode{P}'s \grammarterm{template-head} contains a template parameter
-pack\iref{temp.variadic}, the template parameter pack will match zero or more template
+A template parameter pack
+in the \grammarterm{template-head} of \tcode{P}
+will match zero or more template
 parameters or template parameter packs in the \grammarterm{template-head} of
 \tcode{A} with the same type and form as the template parameter pack in \tcode{P}
 (ignoring whether those template parameters are template parameter packs).
 
+\pnum
 \begin{example}
 \begin{codeblock}
 template<class T> class A { @\commentellip@ };
@@ -1389,6 +1424,8 @@
 Z<D> zd;            // OK
 \end{codeblock}
 \end{example}
+
+\pnum
 \begin{example}
 \begin{codeblock}
 template <class T> struct eval;
@@ -1409,6 +1446,8 @@
 eval<E<int, float>> eE;         // error: \tcode{E} does not match \tcode{TT} in partial specialization
 \end{codeblock}
 \end{example}
+
+\pnum
 \begin{example}
 \begin{codeblock}
 template<typename T> concept C = requires (T t) { t.f(); };
@@ -1426,39 +1465,6 @@
 \end{codeblock}
 \end{example}
 
-\pnum
-A template \grammarterm{template-parameter} \tcode{P} is
-at least as specialized as a template \grammarterm{template-argument} \tcode{A}
-if, given the following rewrite to two function templates,
-the function template corresponding to \tcode{P}
-is at least as specialized as
-the function template corresponding to \tcode{A}
-according to the partial ordering rules
-for function templates\iref{temp.func.order}.
-Given an invented class template \tcode{X}
-with the \grammarterm{template-head} of \tcode{A} (including default arguments
-and \grammarterm{requires-clause}, if any):
-
-\begin{itemize}
-\item
-Each of the two function templates has the same template parameters
-and \grammarterm{requires-clause} (if any),
-respectively, as \tcode{P} or \tcode{A}.
-\item
-Each function template has a single function parameter
-whose type is a specialization of \tcode{X}
-with template arguments corresponding to the template parameters
-from the respective function template where,
-for each template parameter \tcode{PP}
-in the \grammarterm{template-head} of the function template,
-a corresponding template argument \tcode{AA} is formed.
-If \tcode{PP} declares a template parameter pack,
-then \tcode{AA} is the pack expansion \tcode{PP...}\iref{temp.variadic};
-otherwise, \tcode{AA} is the \grammarterm{id-expression} \tcode{PP}.
-\end{itemize}
-If the rewrite produces an invalid type,
-then \tcode{P} is not at least as specialized as \tcode{A}.
-
 \rSec1[temp.constr]{Template constraints}
 
 \rSec2[temp.constr.general]{General}