SV *
Perl_newSVsv(pTHX_ register SV *const old)
{
    dVAR;
    register SV *sv;

    if (!old)
	return NULL;
    if (SvTYPE(old) == SVTYPEMASK) {
	Perl_ck_warner_d(aTHX_ packWARN(WARN_INTERNAL), "semi-panic: attempt to dup freed string");
	return NULL;
    }
    new_SV(sv);
    /* SV_GMAGIC is the default for sv_setv()
       SV_NOSTEAL prevents TEMP buffers being, well, stolen, and saves games
       with SvTEMP_off and SvTEMP_on round a call to sv_setsv.  */
    sv_setsv_flags(sv, old, SV_GMAGIC | SV_NOSTEAL);
    return sv;
}