From 197b444407b86b1990f4051b1cb28181e45eb965 Mon Sep 17 00:00:00 2001
From: Yuri Astrakhan <YuriAstrakhan@gmail.com>
Date: Tue, 16 Jul 2024 17:45:22 -0400
Subject: [PATCH] Ignore underscore-prefixed args for needless_pass_by_value
lint
When a user explicitly tags a param as unused (yet?), there is no need to raise another lint on it.
---
clippy_lints/src/needless_pass_by_value.rs | 15 ++++++++-------
tests/ui/needless_pass_by_value.rs | 12 ++++++++----
tests/ui/needless_pass_by_value.stderr | 10 +++++-----
3 files changed, 21 insertions(+), 16 deletions(-)
diff --git a/clippy_lints/src/needless_pass_by_value.rs b/clippy_lints/src/needless_pass_by_value.rs
index f2e00cef7e9..4b86db33fde 100644
--- a/clippy_lints/src/needless_pass_by_value.rs
+++ b/clippy_lints/src/needless_pass_by_value.rs
@@ -129,7 +129,7 @@ impl<'tcx> LateLintPass<'tcx> for NeedlessPassByValue {
})
.collect::<Vec<_>>();
- // Collect moved variables and spans which will need dereferencings from the
+ // Collect moved variables and spans which will need dereferencing from the
// function body.
let MovedVariablesCtxt { moved_vars } = {
let mut ctx = MovedVariablesCtxt::default();
@@ -148,12 +148,13 @@ impl<'tcx> LateLintPass<'tcx> for NeedlessPassByValue {
return;
}
- // Ignore `self`s.
- if idx == 0 {
- if let PatKind::Binding(.., ident, _) = arg.pat.kind {
- if ident.name == kw::SelfLower {
- continue;
- }
+ // Ignore `self`s and params whose variable name starts with an underscore
+ if let PatKind::Binding(.., ident, _) = arg.pat.kind {
+ if idx == 0 && ident.name == kw::SelfLower {
+ continue;
+ }
+ if ident.name.as_str().starts_with('_') {
+ continue;
}
}
diff --git a/tests/ui/needless_pass_by_value.rs b/tests/ui/needless_pass_by_value.rs
index 14cba5a7eb5..9408b8c948f 100644
--- a/tests/ui/needless_pass_by_value.rs
+++ b/tests/ui/needless_pass_by_value.rs
@@ -84,7 +84,7 @@ trait Serialize {}
impl<'a, T> Serialize for &'a T where T: Serialize {}
impl Serialize for i32 {}
-fn test_blanket_ref<T: Foo, S: Serialize>(_foo: T, _serializable: S) {}
+fn test_blanket_ref<T: Foo, S: Serialize>(vals: T, serializable: S) {}
//~^ ERROR: this argument is passed by value, but not consumed in the function body
fn issue_2114(s: String, t: String, u: Vec<i32>, v: Vec<i32>) {
@@ -116,7 +116,7 @@ impl<T: Serialize, U> S<T, U> {
) {
}
- fn baz(&self, _u: U, _s: Self) {}
+ fn baz(&self, uu: U, ss: Self) {}
//~^ ERROR: this argument is passed by value, but not consumed in the function body
//~| ERROR: this argument is passed by value, but not consumed in the function body
}
@@ -162,13 +162,13 @@ fn test_destructure_copy(x: CopyWrapper, y: CopyWrapper, z: CopyWrapper) {
// The following 3 lines should not cause an ICE. See #2831
trait Bar<'a, A> {}
impl<'b, T> Bar<'b, T> for T {}
-fn some_fun<'b, S: Bar<'b, ()>>(_item: S) {}
+fn some_fun<'b, S: Bar<'b, ()>>(items: S) {}
//~^ ERROR: this argument is passed by value, but not consumed in the function body
// Also this should not cause an ICE. See #2831
trait Club<'a, A> {}
impl<T> Club<'static, T> for T {}
-fn more_fun(_item: impl Club<'static, i32>) {}
+fn more_fun(items: impl Club<'static, i32>) {}
//~^ ERROR: this argument is passed by value, but not consumed in the function body
fn is_sync<T>(_: T)
@@ -177,6 +177,10 @@ where
{
}
+struct Obj(String);
+
+fn prefix_test(_unused_with_prefix: Obj) {}
+
fn main() {
// This should not cause an ICE either
// https://github.com/rust-lang/rust-clippy/issues/3144
diff --git a/tests/ui/needless_pass_by_value.stderr b/tests/ui/needless_pass_by_value.stderr
index 827a200ba68..dce28186ff8 100644
--- a/tests/ui/needless_pass_by_value.stderr
+++ b/tests/ui/needless_pass_by_value.stderr
@@ -46,7 +46,7 @@ LL | fn test_destructure(x: Wrapper, y: Wrapper, z: Wrapper) {
error: this argument is passed by value, but not consumed in the function body
--> tests/ui/needless_pass_by_value.rs:87:49
|
-LL | fn test_blanket_ref<T: Foo, S: Serialize>(_foo: T, _serializable: S) {}
+LL | fn test_blanket_ref<T: Foo, S: Serialize>(vals: T, serializable: S) {}
| ^ help: consider taking a reference instead: `&T`
error: this argument is passed by value, but not consumed in the function body
@@ -106,13 +106,13 @@ LL | t: String,
error: this argument is passed by value, but not consumed in the function body
--> tests/ui/needless_pass_by_value.rs:119:23
|
-LL | fn baz(&self, _u: U, _s: Self) {}
+LL | fn baz(&self, uu: U, ss: Self) {}
| ^ help: consider taking a reference instead: `&U`
error: this argument is passed by value, but not consumed in the function body
--> tests/ui/needless_pass_by_value.rs:119:30
|
-LL | fn baz(&self, _u: U, _s: Self) {}
+LL | fn baz(&self, uu: U, ss: Self) {}
| ^^^^ help: consider taking a reference instead: `&Self`
error: this argument is passed by value, but not consumed in the function body
@@ -166,13 +166,13 @@ LL | struct CopyWrapper(u32);
error: this argument is passed by value, but not consumed in the function body
--> tests/ui/needless_pass_by_value.rs:165:40
|
-LL | fn some_fun<'b, S: Bar<'b, ()>>(_item: S) {}
+LL | fn some_fun<'b, S: Bar<'b, ()>>(items: S) {}
| ^ help: consider taking a reference instead: `&S`
error: this argument is passed by value, but not consumed in the function body
--> tests/ui/needless_pass_by_value.rs:171:20
|
-LL | fn more_fun(_item: impl Club<'static, i32>) {}
+LL | fn more_fun(items: impl Club<'static, i32>) {}
| ^^^^^^^^^^^^^^^^^^^^^^^ help: consider taking a reference instead: `&impl Club<'static, i32>`
error: aborting due to 22 previous errors