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Auto merge of #10727 - john-h-k:lint/dup-auto-traits, r=Manishearth

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Extend `trait_duplication_in_bounds` to cover trait objects

This PR extends `trait_duplication_in_bounds` to cover trait objects.

Currently,
```rs
fn foo(_a: &(dyn Any + Send + Send)) {}
```

generates no warnings. With this PR, it will complain about a duplicate trait and can remove it

Moved from rust-lang/rust#110991

changelog: [`trait_duplication_in_bounds`]: warn on duplicate trait object constraints
This commit is contained in:
bors 2023-05-09 13:46:18 +00:00
commit 77e4d7a839
4 changed files with 92 additions and 11 deletions
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59
clippy_lints/src/trait_bounds.rs
View File

@ -37,12 +37,12 @@
#[clippy::version = "1.38.0"]
pub TYPE_REPETITION_IN_BOUNDS,
nursery,
"types are repeated unnecessary in trait bounds use `+` instead of using `T: _, T: _`"
"types are repeated unnecessarily in trait bounds, use `+` instead of using `T: _, T: _`"
}
declare_clippy_lint! {
/// ### What it does
/// Checks for cases where generics are being used and multiple
/// Checks for cases where generics or trait objects are being used and multiple
/// syntax specifications for trait bounds are used simultaneously.
///
/// ### Why is this bad?
@ -167,6 +167,61 @@ fn check_trait_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx TraitItem<'tc
}
}
}
fn check_ty(&mut self, cx: &LateContext<'tcx>, ty: &'tcx Ty<'tcx>) {
if_chain! {
if let TyKind::Ref(.., mut_ty) = &ty.kind;
if let TyKind::TraitObject(bounds, ..) = mut_ty.ty.kind;
if bounds.len() > 2;
then {
// Build up a hash of every trait we've seen
// When we see a trait for the first time, add it to unique_traits
// so we can later use it to build a string of all traits exactly once, without duplicates
let mut seen_def_ids = FxHashSet::default();
let mut unique_traits = Vec::new();
// Iterate the bounds and add them to our seen hash
// If we haven't yet seen it, add it to the fixed traits
for bound in bounds.iter() {
let Some(def_id) = bound.trait_ref.trait_def_id() else { continue; };
let new_trait = seen_def_ids.insert(def_id);
if new_trait {
unique_traits.push(bound);
}
}
// If the number of unique traits isn't the same as the number of traits in the bounds,
// there must be 1 or more duplicates
if bounds.len() != unique_traits.len() {
let mut bounds_span = bounds[0].span;
for bound in bounds.iter().skip(1) {
bounds_span = bounds_span.to(bound.span);
}
let fixed_trait_snippet = unique_traits
.iter()
.filter_map(|b| snippet_opt(cx, b.span))
.collect::<Vec<_>>()
.join(" + ");
span_lint_and_sugg(
cx,
TRAIT_DUPLICATION_IN_BOUNDS,
bounds_span,
"this trait bound is already specified in trait declaration",
"try",
fixed_trait_snippet,
Applicability::MaybeIncorrect,
);
}
}
}
}
}
impl TraitBounds {

10
tests/ui/trait_duplication_in_bounds.fixed
View File

@ -2,6 +2,8 @@
#![deny(clippy::trait_duplication_in_bounds)]
#![allow(unused)]
use std::any::Any;
fn bad_foo<T: Clone + Copy, U: Clone + Copy>(arg0: T, argo1: U) {
unimplemented!();
}
@ -109,4 +111,12 @@ fn qualified_path<T: std::clone::Clone + foo::Clone>(arg0: T) {
unimplemented!();
}
fn good_trait_object(arg0: &(dyn Any + Send)) {
unimplemented!();
}
fn bad_trait_object(arg0: &(dyn Any + Send)) {
unimplemented!();
}
fn main() {}

10
tests/ui/trait_duplication_in_bounds.rs
View File

@ -2,6 +2,8 @@
#![deny(clippy::trait_duplication_in_bounds)]
#![allow(unused)]
use std::any::Any;
fn bad_foo<T: Clone + Clone + Clone + Copy, U: Clone + Copy>(arg0: T, argo1: U) {
unimplemented!();
}
@ -109,4 +111,12 @@ fn qualified_path<T: std::clone::Clone + Clone + foo::Clone>(arg0: T) {
unimplemented!();
}
fn good_trait_object(arg0: &(dyn Any + Send)) {
unimplemented!();
}
fn bad_trait_object(arg0: &(dyn Any + Send + Send)) {
unimplemented!();
}
fn main() {}

24
tests/ui/trait_duplication_in_bounds.stderr
View File

@ -1,5 +1,5 @@
error: these bounds contain repeated elements
--> $DIR/trait_duplication_in_bounds.rs:5:15
--> $DIR/trait_duplication_in_bounds.rs:7:15
|
LL | fn bad_foo<T: Clone + Clone + Clone + Copy, U: Clone + Copy>(arg0: T, argo1: U) {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `Clone + Copy`
@ -11,46 +11,52 @@ LL | #![deny(clippy::trait_duplication_in_bounds)]
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: these where clauses contain repeated elements
--> $DIR/trait_duplication_in_bounds.rs:11:8
--> $DIR/trait_duplication_in_bounds.rs:13:8
|
LL | T: Clone + Clone + Clone + Copy,
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `Clone + Copy`
error: these bounds contain repeated elements
--> $DIR/trait_duplication_in_bounds.rs:39:26
--> $DIR/trait_duplication_in_bounds.rs:41:26
|
LL | trait BadSelfTraitBound: Clone + Clone + Clone {
| ^^^^^^^^^^^^^^^^^^^^^ help: try: `Clone`
error: these where clauses contain repeated elements
--> $DIR/trait_duplication_in_bounds.rs:46:15
--> $DIR/trait_duplication_in_bounds.rs:48:15
|
LL | Self: Clone + Clone + Clone;
| ^^^^^^^^^^^^^^^^^^^^^ help: try: `Clone`
error: these bounds contain repeated elements
--> $DIR/trait_duplication_in_bounds.rs:60:24
--> $DIR/trait_duplication_in_bounds.rs:62:24
|
LL | trait BadTraitBound<T: Clone + Clone + Clone + Copy, U: Clone + Copy> {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `Clone + Copy`
error: these where clauses contain repeated elements
--> $DIR/trait_duplication_in_bounds.rs:67:12
--> $DIR/trait_duplication_in_bounds.rs:69:12
|
LL | T: Clone + Clone + Clone + Copy,
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `Clone + Copy`
error: these bounds contain repeated elements
--> $DIR/trait_duplication_in_bounds.rs:100:19
--> $DIR/trait_duplication_in_bounds.rs:102:19
|
LL | fn bad_generic<T: GenericTrait<u64> + GenericTrait<u32> + GenericTrait<u64>>(arg0: T) {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `GenericTrait<u64> + GenericTrait<u32>`
error: these bounds contain repeated elements
--> $DIR/trait_duplication_in_bounds.rs:108:22
--> $DIR/trait_duplication_in_bounds.rs:110:22
|
LL | fn qualified_path<T: std::clone::Clone + Clone + foo::Clone>(arg0: T) {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `std::clone::Clone + foo::Clone`
error: aborting due to 8 previous errors
error: this trait bound is already specified in trait declaration
--> $DIR/trait_duplication_in_bounds.rs:118:33
|
LL | fn bad_trait_object(arg0: &(dyn Any + Send + Send)) {
| ^^^^^^^^^^^^^^^^^ help: try: `Any + Send`
error: aborting due to 9 previous errors