[temp.res] Convert note to footnote to avoid breaking up flow,

add back introductory sentence for the template validity rule,
and fix formatting of example.

Author: zygoloid

source/templates.tex

@@ -4078,9 +4078,9 @@
 \begin{itemize}
 \item \grammarterm{simple-declaration} or a \grammarterm{function-definition} in namespace scope,
 \item \grammarterm{member-declaration},
-\item \grammarterm{parameter-declaration} in a \grammarterm{member-declaration},
-unless that \grammarterm{parameter-declaration} appears in a default argument
-\begin{note} This includes friend function declarations. \end{note},
+\item \grammarterm{parameter-declaration} in a \grammarterm{member-declaration}%
+\footnote{This includes friend function declarations.},
+unless that \grammarterm{parameter-declaration} appears in a default argument,
 \item \grammarterm{parameter-declaration} in a \grammarterm{declarator}
 of a function or function template declaration
 whose \grammarterm{declarator-id} is qualified,
@@ -4113,13 +4113,14 @@
 \begin{example}
 \begin{codeblock}
 template<class T> T::R f();             // OK, return type of a function declaration at global scope
-template<class T> void f(T::R);         // ill-formed (no diagnostic required), attempt to declare a \tcode{void} variable template
+template<class T> void f(T::R);         // ill-formed (no diagnostic required), attempt to declare
+                                        // a \tcode{void} variable template
 template<class T> struct S {
   using Ptr = PtrTraits<T>::Ptr;        // OK, in a \grammarterm{defining-type-id}
   T::R f(T::P p) {                      // OK, class scope
     return static_cast<T::R>(p);        // OK, \grammarterm{type-id} of a \tcode{static_cast}
   }
-  auto g() -> S<T*>::Ptr;               // OK, \grammarterm{trailing-return-type}
+  auto g() -> S<T*>::Ptr;               // OK, \grammarterm{trailing-return-type}
 };
 template<typename T> void f() {
   void (*pf)(T::X);                     // variable \tcode{pf} of type \tcode{void*} initialized with \tcode{T::X}
@@ -4174,9 +4175,10 @@
 \pnum
 \indextext{checking!syntax}%
 \indextext{checking!point of error}%
+The validity of a template may be checked prior to any instantiation.
 \begin{note}
 Knowing which names are type names allows the syntax of every template
-to be checked.
+to be checked in this way.
 \end{note}
 The program is ill-formed, no diagnostic required, if: