Why this code wont work

fn ok<'lt> (first:&'lt mut &'lt str,sec:char)->&'lt str{
" "

fn main(){
let mut x="sun";
let z= ok(&mut x,' ' );

&'a mut T<'a> (where in this case T<'a> = &'a str) is almost always wrong, since it forces inner lifetime to be invariant - that is, to be unchangeable. Therefore, since x is &'static str, ok is called with 'static as generic parameter, and &mut x is essentially (in pseudocode) &'static mut x, which never expires and prohibits direct usage of x forever.


Recommend you read the book in my link as much as possible.


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