`match_ref_pats` matching on macros like `unimplemented` there is nothing that can be dereferenced

[matthiaskrgr]

Using the following flags

--force-warn clippy::match_ref_pats

this code:

// check-pass

const FOO: &&&u32 = &&&42;

fn main() {
    match unimplemented!() {
        &&&42 => {
    match unimplemented!() {
        &&&42 => {},
        FOO => {},
        _ => {},
    }
},
        FOO => {
    match unimplemented!() {
        &&&42 => {},
        FOO => {},
        _ => {},
    }
},
        _ => {
    match unimplemented!() {
        &_ => {},
        &&&42 => {
    match unimplemented!() {
        &&&42 => {},
        FOO => {},
        _ => {},
    }
},
        _ => {},
    }
 },
    }
}

caused the following diagnostics:

    Checking _17cf102309ba325072c67c53efe4fb5e2d923828 v0.1.0 (/tmp/icemaker_global_tempdir.f0JXFBTcO4io/icemaker_clippyfix_tempdir.AjJtkmFC5tvf/_17cf102309ba325072c67c53efe4fb5e2d923828)
warning: you don't need to add `&` to all patterns
  --> src/main.rs:22:5
   |
22 | /     match unimplemented!() {
23 | |         &_ => {},
24 | |         &&&42 => {
25 | |     match unimplemented!() {
...  |
31 | |         _ => {},
32 | |     }
   | |_____^
   |
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#match_ref_pats
   = note: requested on the command line with `--force-warn clippy::match-ref-pats`
help: instead of prefixing all patterns with `&`, you can dereference the expression
   |
22 ~     match *unimplemented!() {
23 ~         _ => {},
24 ~         &&42 => {
   |

warning: `_17cf102309ba325072c67c53efe4fb5e2d923828` (bin "_17cf102309ba325072c67c53efe4fb5e2d923828") generated 1 warning (run `cargo clippy --fix --bin "_17cf102309ba325072c67c53efe4fb5e2d923828"` to apply 1 suggestion)
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.44s

However after applying these diagnostics, the resulting code:

// check-pass

const FOO: &&&u32 = &&&42;

fn main() {
    match unimplemented!() {
        &&&42 => {
    match unimplemented!() {
        &&&42 => {},
        FOO => {},
        _ => {},
    }
},
        FOO => {
    match unimplemented!() {
        &&&42 => {},
        FOO => {},
        _ => {},
    }
},
        _ => {
    match *unimplemented!() {
        _ => {},
        &&42 => {
    match unimplemented!() {
        &&&42 => {},
        FOO => {},
        _ => {},
    }
},
        _ => {},
    }
 },
    }
}

no longer compiled:

    Checking _17cf102309ba325072c67c53efe4fb5e2d923828 v0.1.0 (/tmp/icemaker_global_tempdir.f0JXFBTcO4io/icemaker_clippyfix_tempdir.AjJtkmFC5tvf/_17cf102309ba325072c67c53efe4fb5e2d923828)
error[E0614]: type `!` cannot be dereferenced
  --> src/main.rs:22:11
   |
22 |     match *unimplemented!() {
   |           ^^^^^^^^^^^^^^^^^ can't be dereferenced

For more information about this error, try `rustc --explain E0614`.
error: could not compile `_17cf102309ba325072c67c53efe4fb5e2d923828` (bin "_17cf102309ba325072c67c53efe4fb5e2d923828") due to 1 previous error
warning: build failed, waiting for other jobs to finish...
error: could not compile `_17cf102309ba325072c67c53efe4fb5e2d923828` (bin "_17cf102309ba325072c67c53efe4fb5e2d923828" test) due to 1 previous error

Version:

rustc 1.90.0-nightly (cc0a5b730 2025-07-31)
binary: rustc
commit-hash: cc0a5b73053c62a3df5f84b3ee85079c9b65fa87
commit-date: 2025-07-31
host: x86_64-unknown-linux-gnu
release: 1.90.0-nightly
LLVM version: 20.1.8