In the following example, Dropper contains a mutable reference and a destructor that uses that reference. The compiler thinks that Dropper's drop code runs when reassigning to the variable v. But since here the value is already moved and v is basically just an empty slot, that shouldn't haben and as such I would expect that I can reuse the variable.
It works if I create a new let binding, but in my actual use case that doesn't work because I want to reassign in a loop.
fn main() {
let mut s = "hi".to_string();
let mut v = Dropper(&mut s);
drop(v);
// error: first borrow might be used here, when `v` is dropped
// second mutable borrow occurs here
v = Dropper(&mut s);
}
struct Dropper<'a>(&'a mut String);
impl Drop for Dropper<'_> {
fn drop(&mut self) {
self.0.push_str("dropped!");
}
}Meta
rustc --version --verbose:
rustc 1.50.0 (cb75ad5db 2021-02-10)
binary: rustc
commit-hash: cb75ad5db02783e8b0222fee363c5f63f7e2cf5b
commit-date: 2021-02-10
host: x86_64-pc-windows-msvc
release: 1.50.0
In the following example,
Droppercontains a mutable reference and a destructor that uses that reference. The compiler thinks thatDropper's drop code runs when reassigning to the variablev. But since here the value is already moved andvis basically just an empty slot, that shouldn't haben and as such I would expect that I can reuse the variable.It works if I create a new let binding, but in my actual use case that doesn't work because I want to reassign in a loop.
Meta
rustc --version --verbose: