clone-on-ref-ptr could suggest std::sync::Arc when Arc is not in scope #15258
Description
Using the following flags
--force-warn clippy::clone-on-ref-ptr
this code:
//@ run-pass
#![allow(unused_must_use)]
#![allow(deprecated)]
//@ needs-threads
//@ needs-subprocess
use std::{env, fmt, process, sync, thread};
struct SlowFmt(u32);
impl fmt::Debug for SlowFmt {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
thread::sleep_ms(3);
self.0.fmt(f)
}
}
fn do_print(x: u32) {
let x = SlowFmt(x);
println!("{:?}{:?}{:?}{:?}{:?}", x, x, x, x, x);
}
fn main(){
if env::args().count() == 2 {
let barrier = sync::Arc::new(sync::Barrier::new(2));
let tbarrier = barrier.clone();
let t = thread::spawn(move || {
tbarrier.wait();
do_print(1);
});
barrier.wait();
do_print(2);
t.join();
} else {
let this = env::args().next().unwrap();
let output = process::Command::new(this).arg("-").output().unwrap();
for line in String::from_utf8(output.stdout).unwrap().lines() {
match line.chars().next().unwrap() {
'1' => assert_eq!(line, "11111"),
'2' => assert_eq!(line, "22222"),
chr => panic!("unexpected character {:?}", chr)
}
}
}
}caused the following diagnostics:
Checking _atomic-print v0.1.0 (/tmp/icemaker_global_tempdir.ROAms2Xd0g8l/icemaker_clippyfix_tempdir.UiIt7ujO1kHB/_atomic-print)
warning: using `.clone()` on a ref-counted pointer
--> src/main.rs:26:24
|
26 | let tbarrier = barrier.clone();
| ^^^^^^^^^^^^^^^ help: try: `Arc::<std::sync::Barrier>::clone(&barrier)`
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#clone_on_ref_ptr
= note: requested on the command line with `--force-warn clippy::clone-on-ref-ptr`
warning: `_atomic-print` (bin "_atomic-print") generated 1 warning
Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.49s
However after applying these diagnostics, the resulting code:
//@ run-pass
#![allow(unused_must_use)]
#![allow(deprecated)]
//@ needs-threads
//@ needs-subprocess
use std::{env, fmt, process, sync, thread};
struct SlowFmt(u32);
impl fmt::Debug for SlowFmt {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
thread::sleep_ms(3);
self.0.fmt(f)
}
}
fn do_print(x: u32) {
let x = SlowFmt(x);
println!("{:?}{:?}{:?}{:?}{:?}", x, x, x, x, x);
}
fn main(){
if env::args().count() == 2 {
let barrier = sync::Arc::new(sync::Barrier::new(2));
let tbarrier = Arc::<std::sync::Barrier>::clone(&barrier);
let t = thread::spawn(move || {
tbarrier.wait();
do_print(1);
});
barrier.wait();
do_print(2);
t.join();
} else {
let this = env::args().next().unwrap();
let output = process::Command::new(this).arg("-").output().unwrap();
for line in String::from_utf8(output.stdout).unwrap().lines() {
match line.chars().next().unwrap() {
'1' => assert_eq!(line, "11111"),
'2' => assert_eq!(line, "22222"),
chr => panic!("unexpected character {:?}", chr)
}
}
}
}no longer compiled:
Checking _atomic-print v0.1.0 (/tmp/icemaker_global_tempdir.ROAms2Xd0g8l/icemaker_clippyfix_tempdir.UiIt7ujO1kHB/_atomic-print)
warning: error applying suggestions to `src/main.rs`
The full error message was:
> cannot replace slice of data that was already replaced
This likely indicates a bug in either rustc or cargo itself,
and we would appreciate a bug report! You're likely to see
a number of compiler warnings after this message which cargo
attempted to fix but failed. If you could open an issue at
https://github.com/rust-lang/rust-clippy/issues
quoting the full output of this command we'd be very appreciative!
Note that you may be able to make some more progress in the near-term
fixing code with the `--broken-code` flag
warning: failed to automatically apply fixes suggested by rustc to crate `_atomic_print`
after fixes were automatically applied the compiler reported errors within these files:
* src/main.rs
This likely indicates a bug in either rustc or cargo itself,
and we would appreciate a bug report! You're likely to see
a number of compiler warnings after this message which cargo
attempted to fix but failed. If you could open an issue at
https://github.com/rust-lang/rust-clippy/issues
quoting the full output of this command we'd be very appreciative!
Note that you may be able to make some more progress in the near-term
fixing code with the `--broken-code` flag
The following errors were reported:
error[E0433]: failed to resolve: use of undeclared type `Arc`
--> src/main.rs:26:24
|
26 | let tbarrier = Arc::<std::sync::Barrier>::clone(&barrier);
| ^^^ use of undeclared type `Arc`
|
help: consider importing one of these structs
|
8 + use crate::sync::Arc;
|
8 + use std::sync::Arc;
|
error: aborting due to 1 previous error
For more information about this error, try `rustc --explain E0433`.
Original diagnostics will follow.
error[E0433]: failed to resolve: use of undeclared type `Arc`
--> src/main.rs:26:24
|
26 | let tbarrier = Arc::<std::sync::Barrier>::clone(&barrier);
| ^^^ use of undeclared type `Arc`
|
help: consider importing one of these structs
|
8 + use crate::sync::Arc;
|
8 + use std::sync::Arc;
|
For more information about this error, try `rustc --explain E0433`.
error: could not compile `_atomic-print` (bin "_atomic-print" test) due to 1 previous error
warning: build failed, waiting for other jobs to finish...
warning: error applying suggestions to `src/main.rs`
The full error message was:
> cannot replace slice of data that was already replaced
This likely indicates a bug in either rustc or cargo itself,
and we would appreciate a bug report! You're likely to see
a number of compiler warnings after this message which cargo
attempted to fix but failed. If you could open an issue at
https://github.com/rust-lang/rust-clippy/issues
quoting the full output of this command we'd be very appreciative!
Note that you may be able to make some more progress in the near-term
fixing code with the `--broken-code` flag
warning: failed to automatically apply fixes suggested by rustc to crate `_atomic_print`
after fixes were automatically applied the compiler reported errors within these files:
* src/main.rs
This likely indicates a bug in either rustc or cargo itself,
and we would appreciate a bug report! You're likely to see
a number of compiler warnings after this message which cargo
attempted to fix but failed. If you could open an issue at
https://github.com/rust-lang/rust-clippy/issues
quoting the full output of this command we'd be very appreciative!
Note that you may be able to make some more progress in the near-term
fixing code with the `--broken-code` flag
The following errors were reported:
error[E0433]: failed to resolve: use of undeclared type `Arc`
--> src/main.rs:26:24
|
26 | let tbarrier = Arc::<std::sync::Barrier>::clone(&barrier);
| ^^^ use of undeclared type `Arc`
|
help: consider importing one of these structs
|
8 + use crate::sync::Arc;
|
8 + use std::sync::Arc;
|
error: aborting due to 1 previous error
For more information about this error, try `rustc --explain E0433`.
Original diagnostics will follow.
error: could not compile `_atomic-print` (bin "_atomic-print") due to 1 previous error
Version:
rustc 1.90.0-nightly (855e0fe46 2025-07-11)
binary: rustc
commit-hash: 855e0fe46e68d94e9f6147531b75ac2d488c548e
commit-date: 2025-07-11
host: x86_64-unknown-linux-gnu
release: 1.90.0-nightly
LLVM version: 20.1.7