Clippy lints / Restriction
Clippy lint · Restriction · checked with Clippy 0.1.99
clippy::clone_on_ref_ptr: Checks for usage of .clone() on a ref-counted pointer, (Rc, Arc, rc::Weak, or sync::Weak), and suggests calling Clone via unified function syntax instead (e.g., Rc::clone(foo))
What it meansChecks for usage of .clone() on a ref-counted pointer, (Rc, Arc, rc::Weak, or sync::Weak), and suggests calling Clone via unified function syntax instead (e.g., Rc::clone(foo)). It is in the restriction group and off by default.
Does it matter?
Calling .clone() on an Rc, Arc, or Weak can obscure the fact that only the pointer is being cloned, not the underlying data.
Lints that forbid language features for specific codebases (no unwrap, no indexing...). Off by default; pick them one by one, never the whole group.
How to fix it
Clippy does not fix this one automatically (its suggestion may change behaviour, so it only shows it). Change the code by hand:
Flagged
let x = Rc::new(1);
x.clone();
Write this instead
Rc::clone(&x);
Turn it off, or on
It is off by default. To use it, set it to warn or deny:
Whole crate (Cargo.toml)
[lints.clippy]
clone_on_ref_ptr = "warn"In code
#![warn(clippy::clone_on_ref_ptr)]One run
cargo clippy -- -W clippy::clone-on-ref-ptrThe [lints] table needs Rust 1.74 or newer. In a workspace, put it under [workspace.lints.clippy] and add [lints] workspace = true to each member.
Clippy's own documentation
What it does
Checks for usage of .clone() on a ref-counted pointer,
(Rc, Arc, rc::Weak, or sync::Weak), and suggests calling Clone via unified
function syntax instead (e.g., Rc::clone(foo)).
Why restrict this?
Calling .clone() on an Rc, Arc, or Weak
can obscure the fact that only the pointer is being cloned, not the underlying
data.
Example
let x = Rc::new(1);
x.clone();
Use instead:
Rc::clone(&x);
From the Clippy lint list (0.1.99), part of the Rust project, MIT or Apache-2.0. Official entry.
Related lints
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- expect_usedChecks for .expect() or .expect_err() calls on Results and .expect() call on Options
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- big_endian_bytesuse of `to_be_bytes`
- cfg_not_testcode is excluded from test builds
- cognitive_complexityWe used to think it measured how hard a method is to understand
- create_dircalling `std::fs::create_dir` where there may be a better way
- dbg_macroChecks for usage of the dbg! macro
All 847 Clippy lints · Rust compiler errors · Cargo.toml checker
Up next
Related lintclippy::unwrap_usedChecks for .unwrap() or .unwrap_err() calls on Results and .unwrap() call on OptionsRead it next →Did this answer your question?