CWG2819 Cast from null pointer value in a constant expression

Author: burblebee

source/expressions.tex

@@ -7601,7 +7601,9 @@
 from a prvalue \tcode{P} of type ``pointer to \cv{}~\keyword{void}''
 to a type ``\cvqual{cv1} pointer to  \tcode{T}'',
 where  \tcode{T} is not \cvqual{cv2}~\keyword{void},
-unless \tcode{P} points to an object whose type is similar to \tcode{T};
+unless \tcode{P}
+is a null pointer value or
+points to an object whose type is similar to \tcode{T};
 
 \item
 a \keyword{reinterpret_cast}\iref{expr.reinterpret.cast};