Ink Message must not be generic Warning

Question

on writing to: &mut AccountId, it throws warning to use explicit lifetime name needed here.

    #[ink(message)] 
    pub fn delegate(&mut self, to: &mut AccountId) {
        let caller = self.env().caller();
        let voters = self.voters.get(caller).unwrap_or_default();
        let voters_to = self.voters.get(*to).unwrap_or_default();
        assert!(!voters.voted, "You already voted.");

        assert!(*to != caller, "Self-delegation is disallowed");

        while voters_to.delegate != [0; 32].into() {
            *to = voters_to.delegate;
        }
    }

including lifetime, but it throws ink message must not be generic. I remove #[ink(message)] and it works fine and #[inline] as well

    #[ink(message)] 
    pub fn delegate<'a>(&mut self, to: &'a mut AccountId) {
        let caller = self.env().caller();
        let voters = self.voters.get(caller).unwrap_or_default();
        let voters_to = self.voters.get(*to).unwrap_or_default();
        assert!(!voters.voted, "You already voted.");

        assert!(*to != caller, "Self-delegation is disallowed");

        while voters_to.delegate != [0; 32].into() {
            *to = voters_to.delegate;
        }
    }

Anybody explain me why this is happening? Or am I doing something wrong?

Answer 1

You should change to: &'a mut AccountId to to: AccountId, and just use the AccountId directly in your ink! message.

Answer 2

You can not use references in [ink(message)].

I think you want this function to be public, so it needs to be [ink(message)]. You can just simply remove the reference of the parameter and work with its value.