don't use implicit wxString->char*/wchar_t* conversion, it will not be available in wxUSE_STL build in the future

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@46391 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/common/txtstrm.cpp

@@ -416,7 +416,8 @@ void wxTextOutputStream::WriteString(const wxString& string)
     }
 
 #if wxUSE_UNICODE
-    wxCharBuffer buffer = m_conv->cWC2MB(out, out.length(), &len);
+    // FIXME-UTF8: use wxCharBufferWithLength if/when we have it
+    wxCharBuffer buffer = m_conv->cWC2MB(out.wc_str(), out.length(), &len);
     m_output.Write(buffer, len);
 #else
     m_output.Write(out.c_str(), out.length() );