LWG3974 mdspan::operator[] should not copy OtherIndexTypes

Author: burblebee

source/containers.tex

@@ -21473,7 +21473,7 @@
 is \tcode{true}.
 Equivalent to:
 \begin{codeblock}
-return operator[](as_const(indices[P])...);
+return operator[](extents_type::@\exposid{index-cast}@(as_const(indices[P]))...);
 \end{codeblock}
 \end{itemdescr}