Note that there is no guarantee that the return value of C<SvPV()> is
equal to C<SvPVX(sv)>, or that C<SvPVX(sv)> contains valid data, or that
-successive calls to C<SvPV(sv)) will return the same pointer value each
+successive calls to C<SvPV(sv)> will return the same pointer value each
time. This is due to the way that things like overloading and
Copy-On-Write are handled. In these cases, the return value may point to
a temporary buffer or similar. If you absolutely need the SvPVX field to