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Check for clone-on-copy in argument positions

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Earlier if arguments to method calls matched the above pattern they were
not reported. This patch ensures such arguments are checked as well.

Fixes #5436
This commit is contained in:
Rabi Guha 2020-04-09 19:20:09 +05:30
parent c25f26d4ca
commit 183c4abb22
3 changed files with 37 additions and 15 deletions
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5
clippy_lints/src/methods/mod.rs
View File

@ -1947,9 +1947,10 @@ fn lint_clone_on_copy(cx: &LateContext<'_, '_>, expr: &hir::Expr<'_>, arg: &hir:
match &cx.tcx.hir().get(parent) {
hir::Node::Expr(parent) => match parent.kind {
// &*x is a nop, &x.clone() is not
hir::ExprKind::AddrOf(..) |
hir::ExprKind::AddrOf(..) => return,
// (*x).func() is useless, x.clone().func() can work in case func borrows mutably
hir::ExprKind::MethodCall(..) => return,
hir::ExprKind::MethodCall(_, _, parent_args) if expr.hir_id == parent_args[0].hir_id => return,
_ => {},
},
hir::Node::Stmt(stmt) => {

9
tests/ui/unnecessary_clone.rs
View File

@ -13,6 +13,10 @@ impl SomeTrait for SomeImpl {}
fn main() {}
fn is_ascii(ch: char) -> bool {
ch.is_ascii()
}
fn clone_on_copy() {
42.clone();
@ -27,6 +31,11 @@ fn clone_on_copy() {
let mut x = 43;
let _ = &x.clone(); // ok, getting a ref
'a'.clone().make_ascii_uppercase(); // ok, clone and then mutate
is_ascii('z'.clone());
// Issue #5436
let mut vec = Vec::new();
vec.push(42.clone());
}
fn clone_on_ref_ptr() {

38
tests/ui/unnecessary_clone.stderr
View File

@ -1,5 +1,5 @@
error: using `clone` on a `Copy` type
--> $DIR/unnecessary_clone.rs:17:5
--> $DIR/unnecessary_clone.rs:21:5
|
LL | 42.clone();
| ^^^^^^^^^^ help: try removing the `clone` call: `42`
@ -7,19 +7,31 @@ LL | 42.clone();
= note: `-D clippy::clone-on-copy` implied by `-D warnings`
error: using `clone` on a `Copy` type
--> $DIR/unnecessary_clone.rs:21:5
--> $DIR/unnecessary_clone.rs:25:5
|
LL | (&42).clone();
| ^^^^^^^^^^^^^ help: try dereferencing it: `*(&42)`
error: using `clone` on a `Copy` type
--> $DIR/unnecessary_clone.rs:24:5
--> $DIR/unnecessary_clone.rs:28:5
|
LL | rc.borrow().clone();
| ^^^^^^^^^^^^^^^^^^^ help: try dereferencing it: `*rc.borrow()`
error: using `clone` on a `Copy` type
--> $DIR/unnecessary_clone.rs:34:14
|
LL | is_ascii('z'.clone());
| ^^^^^^^^^^^ help: try removing the `clone` call: `'z'`
error: using `clone` on a `Copy` type
--> $DIR/unnecessary_clone.rs:38:14
|
LL | vec.push(42.clone());
| ^^^^^^^^^^ help: try removing the `clone` call: `42`
error: using `.clone()` on a ref-counted pointer
--> $DIR/unnecessary_clone.rs:39:5
--> $DIR/unnecessary_clone.rs:48:5
|
LL | rc.clone();
| ^^^^^^^^^^ help: try this: `Rc::<bool>::clone(&rc)`
@ -27,43 +39,43 @@ LL | rc.clone();
= note: `-D clippy::clone-on-ref-ptr` implied by `-D warnings`
error: using `.clone()` on a ref-counted pointer
--> $DIR/unnecessary_clone.rs:42:5
--> $DIR/unnecessary_clone.rs:51:5
|
LL | arc.clone();
| ^^^^^^^^^^^ help: try this: `Arc::<bool>::clone(&arc)`
error: using `.clone()` on a ref-counted pointer
--> $DIR/unnecessary_clone.rs:45:5
--> $DIR/unnecessary_clone.rs:54:5
|
LL | rcweak.clone();
| ^^^^^^^^^^^^^^ help: try this: `Weak::<bool>::clone(&rcweak)`
error: using `.clone()` on a ref-counted pointer
--> $DIR/unnecessary_clone.rs:48:5
--> $DIR/unnecessary_clone.rs:57:5
|
LL | arc_weak.clone();
| ^^^^^^^^^^^^^^^^ help: try this: `Weak::<bool>::clone(&arc_weak)`
error: using `.clone()` on a ref-counted pointer
--> $DIR/unnecessary_clone.rs:52:33
--> $DIR/unnecessary_clone.rs:61:33
|
LL | let _: Arc<dyn SomeTrait> = x.clone();
| ^^^^^^^^^ help: try this: `Arc::<SomeImpl>::clone(&x)`
error: using `clone` on a `Copy` type
--> $DIR/unnecessary_clone.rs:56:5
--> $DIR/unnecessary_clone.rs:65:5
|
LL | t.clone();
| ^^^^^^^^^ help: try removing the `clone` call: `t`
error: using `clone` on a `Copy` type
--> $DIR/unnecessary_clone.rs:58:5
--> $DIR/unnecessary_clone.rs:67:5
|
LL | Some(t).clone();
| ^^^^^^^^^^^^^^^ help: try removing the `clone` call: `Some(t)`
error: using `clone` on a double-reference; this will copy the reference instead of cloning the inner type
--> $DIR/unnecessary_clone.rs:64:22
--> $DIR/unnecessary_clone.rs:73:22
|
LL | let z: &Vec<_> = y.clone();
| ^^^^^^^^^
@ -79,10 +91,10 @@ LL | let z: &Vec<_> = &std::vec::Vec<i32>::clone(y);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: using `clone` on a `Copy` type
--> $DIR/unnecessary_clone.rs:100:20
--> $DIR/unnecessary_clone.rs:109:20
|
LL | let _: E = a.clone();
| ^^^^^^^^^ help: try dereferencing it: `*****a`
error: aborting due to 12 previous errors
error: aborting due to 14 previous errors