"use of moved value" when the control flow won't allow it?

Question

This is a minimal reproduction of the code I'm struggling with:

// real code struct is not just a string, and is not cloneable
struct NotCloneable(String);

fn outer() -> Result<NotCloneable, String> {
    let obj = NotCloneable(String::from("Hello, world!"));
    might_fail().map_err(|_| {
        // real code closure might return one of several errors, including an
        // error containing non-cloneable fields from struct
        obj.0
    })?;
    // the ? means that if we got to here, the closure never executed
    // ... yet this won't compile because it claims the closure moved obj
    Ok(obj)
}

fn might_fail() -> Result<(), ()> {
    Err(())
}

It fails to compile with:

error[E0382]: use of partially moved value: `obj`
  --> src/main.rs:16:8
   |
10 |     might_fail().map_err(|_| {
   |                          --- value partially moved into closure here
...
14 |         obj.0
   |         ----- variable partially moved due to use in closure
15 |     })?;
16 |     Ok(obj)
   |        ^^^ value used here after partial move
   |
   = note: partial move occurs because `obj.0` has type `String`, which does not implement the `Copy` trait

For more information about this error, try `rustc --explain E0382`.
error: could not compile `playground` due to previous error

Answer 1

After @Jmb's comment I also tried:

fn outer() -> Result<NotCloneable, String> {
    let obj = NotCloneable(String::from("Hello, world!"));
    match might_fail() {
        Ok(_) => Ok(()),
        Err(_) => Err(obj.0),
    }?;
    Ok(obj)
}

However, this fails to compile due the same error. What I did find is that if I explicitly early-return then it works:

fn outer() -> Result<NotCloneable, String> {
    let obj = NotCloneable(String::from("Hello, world!"));
    match might_fail() {
        Ok(_) => (),
        Err(_) => return Err(obj.0),
    };
    Ok(obj)
}

So it seems that whatever control flow analysis is happening is not smart enough to figure out that the capture is in an Err that is handled with an early return '?'.