A bug from drop

[lengyijun]

struct S;
impl S{
    fn foo(&mut self){}
}

struct T<'a>(&'a S);

impl<'a> Drop for T<'a>{
    fn drop(&mut self){}
}

fn main() {
    let mut s=S;
    let t=T(&s);
    s.foo();
}

Inspired by rust-lang/rust#70797
The Drop of T makes polonius failed.
It's related to eager drop: rust-lang/lang-team#86
Is it a bug?