Occasional "cannot move out" error (E0505) when adding a match guard

[bytefall]

Given the following snippet:

struct State {
    val: u8,
    xy: bool,
}

struct Test {
    vec: Vec<State>,
}

impl Test {
    fn new() -> Self {
        Test { vec: Vec::new() }
    }
    
    fn get_mut(&mut self, id: usize) -> Result<&mut u8, Option<&mut State>> {
        match self.vec.get_mut(id) {
            Some(State { ref mut val, ref xy }) /*if true*/ => Ok(val),
            other => Err(other),
        }
    }
}

This compiles just fine. Now uncomment the if true match guard and compile fails:

error[E0505]: cannot move out of `_` because it is borrowed
  --> src/lib.rs:18:13
   |
15 |     fn get_mut(&mut self, id: usize) -> Result<&mut u8, Option<&mut State>> {
   |                - let's call the lifetime of this reference `'1`
16 |         match self.vec.get_mut(id) {
17 |             Some(State { ref mut val, ref xy }) if true => Ok(val),
   |                          -----------                       ------- returning this value requires that borrow lasts for `'1`
   |                          |
   |                          borrow of value occurs here
18 |             other => Err(other),
   |             ^^^^^ move out of value occurs here

Why does the insignificant match guard affect the borrowck?

Tested both on stable 1.38.0 and 1.40.0-nightly (032a53a 2019-10-03).

[bytefall]

This issue became a warning since rustc 1.34.0-nightly (00aae71 2019-02-25):

rustup run nightly-2019-02-26 cargo build

warning[E0505]: cannot move out of `_` because it is borrowed
  --> src\main.rs:18:13
   |
15 |     fn get_mut(&mut self, id: usize) -> Result<&mut u8, Option<&mut State>> {
   |                - let's call the lifetime of this reference `'1`
16 |         match self.vec.get_mut(id) {
17 |             Some(State { ref mut val, ref xy }) if true => Ok(val),
   |                          -----------                       ------- returning this value requires that borrow lasts for `'1`
   |                          |
   |                          borrow of value occurs here
18 |             other => Err(other),
   |             ^^^^^ move out of value occurs here
   |
   = warning: this error has been downgraded to a warning for backwards compatibility with previous releases
   = warning: this represents potential undefined behavior in your code and this warning will become a hard error in the future

Looks like #57609 has affected this issue.

[RodBurman]

Using the current latest toolchain:

% cargo -v -V  
cargo 1.85.0 (d73d2caf9 2024-12-31)
release: 1.85.0
commit-hash: d73d2caf9e41a39daf2a8d6ce60ec80bf354d2a7
commit-date: 2024-12-31
host: aarch64-apple-darwin
libgit2: 1.8.1 (sys:0.19.0 vendored)
libcurl: 8.7.1 (sys:0.4.74+curl-8.9.0 system ssl:(SecureTransport) LibreSSL/3.3.6)
ssl: OpenSSL 1.1.1w  11 Sep 2023
os: Mac OS 15.3.1 [64-bit]

The given snippet compiles as stated (but with several warnings), until the "if true" is uncommented , which then gives:

% cargo build  
   Compiling cantmvout v0.1.0 (/Users/rod/code/rust/triage/cantmvout)
error[E0505]: cannot move out of value because it is borrowed
  --> src/lib.rs:18:13
   |
15 |     fn get_mut(&mut self, id: usize) -> Result<&mut u8, Option<&mut State>> {
   |                - let's call the lifetime of this reference `'1`
16 |         match self.vec.get_mut(id) {
17 |             Some(State { ref mut val, ref _xy }) if true => Ok(val),
   |                          -----------                        ------- returning this value requires that borrow lasts for `'1`
   |                          |
   |                          borrow of value occurs here
18 |             other => Err(other),
   |             ^^^^^ move out of value occurs here

For more information about this error, try `rustc --explain E0505`.
error: could not compile `cantmvout` (lib) due to 1 previous error

Note I changed xy to _xy to prevent unused variable warnings.

After more than 5 years and with a presumably stable error is it time to close this issue?