LWG4426 Clarify what meta::reflect_constant_string considers a string literal

Author: eisenwave

source/meta.tex

@@ -3401,8 +3401,8 @@
 \pnum
 Let $V$ be the pack of values of type \tcode{CharT}
 whose elements are the corresponding elements of \tcode{r},
-except that if \tcode{r} refers to a string literal object,
-then $V$ does not include the trailing null terminator of \tcode{r}.
+except that if \tcode{r} is a reference to a string literal object,
+then $V$ does not include the terminating \unicode{0000}{null} character of \tcode{r}.
 
 \pnum
 Let $P$ be the template parameter object\iref{temp.param}