Hunting down an issue on the tracker

[RustyYato]

I also found this one, but it is from 2017 and stranded here on the user forums

Why are reads sometimes tolerated during mut borrows, and sometimes not?

Why would changing a field from a u8 to a reference make a borrow checking error go away??? This code contains a classic error -- using a value that's been mutably borrowed. playground link #![allow(dead_code)] pub struct Block<'a> { current: u8, unrelated: &'a u8, } fn f<'a>(_block: &mut Block<'a>, _u: u8) {} fn bump<'a>(block: &mut Block<'a>) { f(block, block.current); // ERROR } fn main() {} I understand why it's wrong. But then why does the exact same thing work fine if th…

Here's the git tracking issue,

borrowed referent of a `&T` sometimes incorrectly allowed