Closed
Description
At first, I thought this was a bug in two-phase borrows, but I realize now that this example does not fall into the subset that @pnkfelix and I identified. That said, I wonder if it should? Try it on play:
#![feature(nll)]
struct Foo<'a> {
x: &'a u32,
}
impl<'a> Foo<'a> {
fn method(&mut self, value: &u32) {
}
}
fn main() {
let mut f = &mut Foo { x: &22 };
Foo::method(f, f.x)
}This gives:
error[E0502]: cannot borrow `*f.x` as immutable because it is also borrowed as mutable
--> src/main.rs:15:20
|
15 | Foo::method(f, f.x)
| - ^^^ immutable borrow occurs here
| |
| mutable borrow occurs here
I wonder if we should expand to auto-refs on any method argument? I think they all have the same character as self.foo(), and those would preserve the self.foo(..) => Foo::foo(self, ..) transformation more faithfully.
cc @rust-lang/wg-compiler-nll