NB CA 378 (C++20 CD): Remove constrained non-template functions

Author: Dawn Perchik

source/declarations.tex

@@ -2174,7 +2174,7 @@
 The optional \grammarterm{requires-clause}\iref{temp} in an
 \grammarterm{init-declarator} or \grammarterm{member-declarator}
 shall not be present when the declarator does not declare a
-function\iref{dcl.fct}.
+templated function\iref{dcl.fct}.
 %
 \indextext{trailing requires-clause@trailing \textit{requires-clause}|see{\textit{requires-clause}, trailing}}%
 When present after a declarator, the \grammarterm{requires-clause}
@@ -2187,9 +2187,11 @@
 %
 \begin{example}
 \begin{codeblock}
-void f1(int a) requires true;               // OK
-auto f2(int a) -> bool requires true;       // OK
-auto f3(int a) requires true -> bool;       // error: \grammarterm{requires-clause} precedes \grammarterm{trailing-return-type}
+void f1(int a) requires true;               // error: non-templated function
+template<typename T>
+  auto f2(T a) -> bool requires true;       // OK
+template<typename T>
+  auto f3(T a) requires true -> bool;       // error: \grammarterm{requires-clause} precedes \grammarterm{trailing-return-type}
 void (*pf)() requires true;                 // error: constraint on a variable
 void g(int (*)() requires true);            // error: constraint on a \grammarterm{parameter-declaration}
 

source/expressions.tex

@@ -1324,12 +1324,14 @@
 is ill-formed.
 \begin{example}
 \begin{codeblock}
-void f(int) requires false;
+template<typename T> struct A {
+  static void f(int) requires false;
+}
 
 void g() {
-  f(0);                         // error: cannot call \tcode{f}
-  void (*p1)(int) = f;          // error: cannot take the address of \tcode{f}
-  decltype(f)* p2 = nullptr;    // error: the type \tcode{decltype(f)} is invalid
+  A<int>::f(0);                         // error: cannot call \tcode{f}
+  void (*p1)(int) = A<int>::f;          // error: cannot take the address of \tcode{f}
+  decltype(A<int>::f)* p2 = nullptr;    // error: the type \tcode{decltype(A<int>::f)} is invalid
 }
 \end{codeblock}
 In each case, the constraints of \tcode{f} are not satisfied.

source/templates.tex

@@ -1647,7 +1647,7 @@
 
 \pnum
 A template declaration\iref{temp}
-or function declaration\iref{dcl.fct}
+or templated function declaration\iref{dcl.fct}
 can be constrained by the use of a \grammarterm{requires-clause}.
 This allows the specification of constraints for that declaration as
 an expression:
@@ -1666,7 +1666,7 @@
 
 \pnum
 \indextext{constraint!associated|see{associated constraints}}%
-A template's \defn{associated constraints} are defined as follows:
+A declaration's \defn{associated constraints} are defined as follows:
 
 \begin{itemize}
 \item If there are no introduced \grammarterm{constraint-expression}{s},