CWG2643 Completing a pointer to array of unknown bound

Fixes NB US 039 (C++23 CD).

Author: burblebee

source/basic.tex

@@ -4666,9 +4666,14 @@
 can be an array of unknown bound and therefore be incomplete at one
 point in a translation unit and complete later on; the array types at
 those two points (``array of unknown bound of \tcode{T}'' and ``array of
-\tcode{N} \tcode{T}'') are different types. The type of a pointer to array of
-unknown bound, or of a type defined by a \keyword{typedef} declaration to
-be an array of unknown bound, cannot be completed.
+\tcode{N} \tcode{T}'') are different types.
+\begin{note}
+The type of a pointer or reference to array of unknown bound
+permanently points to or refers to an incomplete type.
+An array of unknown bound named by a \keyword{typedef} declaration
+permanently refers to an incomplete type.
+In either case, the array type cannot be completed.
+\end{note}
 \begin{example}
 \indextext{type!example of incomplete}%
 \begin{codeblock}