CWG3102 Update list of void contexts

Editorial note:
* Changed "requires expression" to \grammarterm{requires-expression}.
  Only the latter form seems to be in use.

Author: eisenwave

source/basic.tex

@@ -5602,20 +5602,23 @@
 is an incomplete type that cannot be completed; such a type has
 an empty set of values. It is used as the return
 type for functions that do not return a value.
-An expression of type \cv{}~\keyword{void} shall
-be used only as
+\begin{note}
+An expression of type \cv{}~\keyword{void} can be used as
 \begin{itemize}
 \item an expression statement\iref{stmt.expr},
 \item the expression in a \keyword{return} statement\iref{stmt.return}
 for a function with the return type \cv{}~\keyword{void},
 \item an operand of a comma expression\iref{expr.comma},
+\item the operand of a parenthesized expression\iref{expr.prim.paren},
+\item a requirement in a \grammarterm{requires-expression}\iref{expr.prim.req.general},
 \item the second or third operand of \tcode{?:}\iref{expr.cond},
 \item the operand of a \keyword{typeid} expression\iref{expr.typeid},
 \item the operand of a \keyword{noexcept} operator\iref{expr.unary.noexcept},
 \item the operand of a \keyword{decltype} specifier\iref{dcl.type.decltype}, or
 \item the operand of an explicit conversion to type
 \cv{}~\keyword{void}\iref{expr.type.conv,expr.static.cast,expr.cast}.
 \end{itemize}
+\end{note}
 
 \pnum
 The types denoted by \cv~\tcode{std::nullptr_t} are distinct types.