added wxS(); use it in a couple of places

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@50987 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

docs/latex/wx/function.tex

@@ -225,6 +225,7 @@ the corresponding topic.
 \helpref{wxRemoveFile}{wxremovefile}\\
 \helpref{wxRenameFile}{wxrenamefile}\\
 \helpref{wxRmdir}{wxrmdir}\\
+\helpref{wxS}{wxs}\\
 \helpref{wxSafeShowMessage}{wxsafeshowmessage}\\
 \helpref{wxSafeYield}{wxsafeyield}\\
 \helpref{wxSetClipboardData}{wxsetclipboarddata}\\
@@ -1696,6 +1697,25 @@ Returns \true if the pointer is either {\tt NULL} or points to an empty
 string, \false otherwise.
 
 
+\membersection{wxS}\label{wxs}
+
+\func{wxStringCharType}{wxS}{\param{char }{ch}}
+
+\func{const wxStringCharType *}{wxS}{\param{const char *}{s}}
+
+wxS is macro which can be used with character and string literals to either
+convert them to wide characters or strings in \texttt{wchar\_t}-based Unicode
+builds or keep them unchanged in UTF-8 builds. The use of this macro is
+optional as the translation will always be done at run-time even if there is a
+mismatch between the kind of the literal used and wxStringCharType used in the
+current build, but using it can be beneficial in performance-sensitive code to
+do the conversion at compile-time instead.
+
+\wxheading{See also}
+
+\helpref{wxT}{wxt}
+
+
 \membersection{::wxStrcmp}\label{wxstrcmp}
 
 \func{int}{wxStrcmp}{\param{const char *}{p1}, \param{const char *}{p2}}