CWG2299 constexpr vararg functions

Author: Dawn Perchik

source/expressions.tex

@@ -5906,17 +5906,20 @@
 
 \item
 a relational\iref{expr.rel} or equality\iref{expr.eq}
-operator where the result is unspecified; or
+operator where the result is unspecified;
 
 \item
-a \grammarterm{throw-expression}\iref{expr.throw}.
+a \grammarterm{throw-expression}\iref{expr.throw}; or
+
+\item
+an invocation of the \tcode{va_arg} macro\iref{cstdarg.syn}.
 \end{itemize}
 
 If \tcode{e} satisfies the constraints of a core constant expression, but
 evaluation of \tcode{e} would evaluate an operation that has undefined behavior
-as specified in \ref{library} through \ref{\lastlibchapter} of this
-document, it is unspecified whether \tcode{e} is a core constant
-expression.
+as specified in \ref{library} through \ref{\lastlibchapter} of this document, or
+an invocation of the \tcode{va_start} macro\iref{cstdarg.syn},
+it is unspecified whether \tcode{e} is a core constant expression.
 
 \begin{example}
 \begin{codeblock}