Struct update syntax doesn't reborrow mut references

When using struct update syntax to copy a struct's &mut fields, the compiler will complain about the field being moved, even though it could logically be reborrowed.

Here's a minimal example:

struct Foobar<'a> {
    s: &'a str,
}

// Works fine
fn take_foobar(foobar: Foobar<'_>) {
    let foobar2 = Foobar {
        ..foobar
    };
    dbg!(foobar.s);
}

struct FoobarMut<'a> {
    s: &'a mut str,
}

// COMPILE ERROR - error[E0382]: use of moved value: `foobar.s`
fn take_foobar_mut(foobar: FoobarMut<'_>) {
    let foobar2 = FoobarMut {
        ..foobar
    };
    dbg!(foobar.s);
}

(Playground link)

I'm not familiar with compiler internals, but from a very rough guess, this doesn't seem like a use-case that would need architectural changes to handle. If we replace the use of struct update syntax with copying the individual fields, the code works fine:

fn take_foobar_mut_2(foobar: FoobarMut<'_>) {
    let foobar2 = FoobarMut {
        s: foobar.s
    };
    dbg!(foobar.s);
}

Meta

rustc 1.78.0 (9b00956e5 2024-04-29)
binary: rustc
commit-hash: 9b00956e56009bab2aa15d7bff10916599e3d6d6
commit-date: 2024-04-29
host: x86_64-unknown-linux-gnu
release: 1.78.0
LLVM version: 18.1.2

Start by reproducing the minimal Rust examples with rustc 1.78.0 or the linked Playground, comparing struct update syntax with explicit field initialization. Trace the rustc entry point for struct updates and borrow/move checking; done means the FoobarMut example compiles without E0382.