type tick_type is (t0, t1, t2, t3, t4, t5, t6, t7);
signal tick: tick_type;
function nextTick(tick: tick_type) return tick_type is begin
-- return next logical value for tick
case tick is
when t0 => return t1; when t1 => return t2; when t2 => return t3;
when t3 => return t4; when t4 => return t5; when t5 => return t6;
when t6 => return t7; when others => return t0;
end case;
end function nextTick;

maxplus过不了 说是if和case语句中不能用 return

请帮忙改正