Function luaK_setoneret

third-party/lua-5.5.0/src/lcode.c:792–803

** Fix an expression to return one result. ** If expression is not a multi-ret expression (function call or ** vararg), it already returns one result, so nothing needs to be done. ** Function calls become VNONRELOC expressions (as its result comes ** fixed in the base register of the call), while vararg expressions ** become VRELOC (as OP_VARARG puts its results where it wants). ** (Calls are crea

** to be fixed.)
*/
void luaK_setoneret (FuncState *fs, expdesc *e) {
  if (e->k == VCALL) {  /* expression is an open function call? */
    /* already returns 1 value */
    lua_assert(GETARG_C(getinstruction(fs, e)) == 2);
    e->k = VNONRELOC;  /* result has fixed position */
    e->u.info = GETARG_A(getinstruction(fs, e));
  }
  else if (e->k == VVARARG) {
    SETARG_C(getinstruction(fs, e), 2);
    e->k = VRELOC;  /* can relocate its simple result */
  }
}

/*
** Change a vararg parameter into a regular local variable