LWG4242 ranges::distance does not work with volatile iterators

Author: burblebee

source/iterators.tex

@@ -3068,7 +3068,13 @@
 \begin{itemdescr}
 \pnum
 \effects
-Equivalent to: \tcode{return last - static_cast<const decay_t<I>\&>(first);}
+Equivalent to:
+\begin{codeblock}
+if constexpr (!is_array_v<remove_reference_t<I>>)
+  return last - first;
+else
+  return last - static_cast<decay_t<I>>(first);
+\end{codeblock}
 \end{itemdescr}
 
 \indexlibraryglobal{distance}%