Multi tool use

How can I pattern match a tuple containing a &mut enum?

How can the code below be made to compile? It seems perfectly safe, but can't convince the compiler that it is.

The version matching *self gives the error: cannot move out of borrowed content on the line of the match

*self

cannot move out of borrowed content

The version matching self gives: use of moved value: *self

self

use of moved value: *self

enum Foo {
Foo1(u32),
Foo2(i16),
}

impl Foo {
fn bar(&mut self, y: u32) -> (u32, &mut Foo) {
match (*self, y) {
(Foo::Foo1(ref mut a), b) if (b == 5) => {
print!("is five");
*a = b + 42;

(b, self)
}

(Foo::Foo2(ref mut a), b) if (b == 5) => {
print!("is five");
*a = (b + 42) as i16;

(*a * b, self)
}

_ => {
print!("is not five!");
(y, self)
}
}
}
}


I feel like I would need a match arm such as the following, but it doesn't seem to be valid syntax:

(ref mut f @ Foo::Foo1, b) if (b == 5) => {
print!("is five");
f.0 = b + 42;
(b, f)
}


error[E0532]: expected unit struct/variant or constant, found tuple variant `Foo::Foo1`
--> src/main.rs:24:30
|
24 | (ref mut f @ Foo::Foo1, b) if (b == 5) => {
| ^^^^^^^^^ not a unit struct/variant or constant


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