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trait_duplication_in_bounds checks path segments for trait items #8315

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Jan 24, 2022
Merged

trait_duplication_in_bounds checks path segments for trait items #8315

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58 changes: 30 additions & 28 deletions clippy_lints/src/trait_bounds.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,7 @@ use clippy_utils::source::{snippet, snippet_with_applicability};
use clippy_utils::{SpanlessEq, SpanlessHash};
use core::hash::{Hash, Hasher};
use if_chain::if_chain;
use rustc_data_structures::fx::{FxHashMap, FxHashSet};
use rustc_data_structures::fx::FxHashMap;
use rustc_data_structures::unhash::UnhashMap;
use rustc_errors::Applicability;
use rustc_hir::def::Res;
Expand Down Expand Up @@ -91,7 +91,7 @@ impl<'tcx> LateLintPass<'tcx> for TraitBounds {

fn check_trait_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx TraitItem<'tcx>) {
let Generics { where_clause, .. } = &item.generics;
let mut self_bounds_set = FxHashSet::default();
let mut self_bounds_map = FxHashMap::default();

for predicate in where_clause.predicates {
if_chain! {
Expand All @@ -108,27 +108,29 @@ impl<'tcx> LateLintPass<'tcx> for TraitBounds {
)
) = cx.tcx.hir().get_if_local(*def_id);
then {
if self_bounds_set.is_empty() {
if self_bounds_map.is_empty() {
for bound in self_bounds.iter() {
let Some((self_res, _)) = get_trait_res_span_from_bound(bound) else { continue };
self_bounds_set.insert(self_res);
let Some((self_res, self_segments, _)) = get_trait_info_from_bound(bound) else { continue };
self_bounds_map.insert(self_res, self_segments);
}
}

bound_predicate
.bounds
.iter()
.filter_map(get_trait_res_span_from_bound)
.for_each(|(trait_item_res, span)| {
if self_bounds_set.get(&trait_item_res).is_some() {
span_lint_and_help(
cx,
TRAIT_DUPLICATION_IN_BOUNDS,
span,
"this trait bound is already specified in trait declaration",
None,
"consider removing this trait bound",
);
.filter_map(get_trait_info_from_bound)
.for_each(|(trait_item_res, trait_item_segments, span)| {
if let Some(self_segments) = self_bounds_map.get(&trait_item_res) {
if SpanlessEq::new(cx).eq_path_segments(self_segments, trait_item_segments) {
span_lint_and_help(
cx,
TRAIT_DUPLICATION_IN_BOUNDS,
span,
"this trait bound is already specified in trait declaration",
None,
"consider removing this trait bound",
);
}
}
});
}
Expand All @@ -137,14 +139,6 @@ impl<'tcx> LateLintPass<'tcx> for TraitBounds {
}
}

fn get_trait_res_span_from_bound(bound: &GenericBound<'_>) -> Option<(Res, Span)> {
if let GenericBound::Trait(t, _) = bound {
Some((t.trait_ref.path.res, t.span))
} else {
None
}
}

impl TraitBounds {
fn check_type_repetition<'tcx>(self, cx: &LateContext<'tcx>, gen: &'tcx Generics<'_>) {
struct SpanlessTy<'cx, 'tcx> {
Expand Down Expand Up @@ -231,7 +225,7 @@ fn check_trait_bound_duplication(cx: &LateContext<'_>, gen: &'_ Generics<'_>) {
let res = param
.bounds
.iter()
.filter_map(get_trait_res_span_from_bound)
.filter_map(get_trait_info_from_bound)
.collect::<Vec<_>>();
map.insert(*ident, res);
}
Expand All @@ -245,10 +239,10 @@ fn check_trait_bound_duplication(cx: &LateContext<'_>, gen: &'_ Generics<'_>) {
if let Some(segment) = segments.first();
if let Some(trait_resolutions_direct) = map.get(&segment.ident);
then {
for (res_where, _) in bound_predicate.bounds.iter().filter_map(get_trait_res_span_from_bound) {
if let Some((_, span_direct)) = trait_resolutions_direct
for (res_where, _, _) in bound_predicate.bounds.iter().filter_map(get_trait_info_from_bound) {
if let Some((_, _, span_direct)) = trait_resolutions_direct
.iter()
.find(|(res_direct, _)| *res_direct == res_where) {
.find(|(res_direct, _, _)| *res_direct == res_where) {
span_lint_and_help(
cx,
TRAIT_DUPLICATION_IN_BOUNDS,
Expand All @@ -263,3 +257,11 @@ fn check_trait_bound_duplication(cx: &LateContext<'_>, gen: &'_ Generics<'_>) {
}
}
}

fn get_trait_info_from_bound<'a>(bound: &'a GenericBound<'_>) -> Option<(Res, &'a [PathSegment<'a>], Span)> {
if let GenericBound::Trait(t, _) = bound {
Some((t.trait_ref.path.res, t.trait_ref.path.segments, t.span))
} else {
None
}
}
22 changes: 22 additions & 0 deletions tests/ui/trait_duplication_in_bounds.rs
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Original file line number Diff line number Diff line change
@@ -1,5 +1,6 @@
#![deny(clippy::trait_duplication_in_bounds)]

use std::collections::BTreeMap;
use std::ops::{Add, AddAssign, Div, DivAssign, Mul, MulAssign, Sub, SubAssign};

fn bad_foo<T: Clone + Default, Z: Copy>(arg0: T, arg1: Z)
Expand Down Expand Up @@ -73,4 +74,25 @@ impl U for Life {
fn f() {}
}

// should not warn
trait Iter: Iterator {
fn into_group_btreemap<K, V>(self) -> BTreeMap<K, Vec<V>>
where
Self: Iterator<Item = (K, V)> + Sized,
K: Ord + Eq,
{
unimplemented!();
}
}

struct Foo {}

trait FooIter: Iterator<Item = Foo> {
fn bar()
where
Self: Iterator<Item = Foo>,
{
}
}

fn main() {}
24 changes: 16 additions & 8 deletions tests/ui/trait_duplication_in_bounds.stderr
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
error: this trait bound is already specified in the where clause
--> $DIR/trait_duplication_in_bounds.rs:5:15
--> $DIR/trait_duplication_in_bounds.rs:6:15
|
LL | fn bad_foo<T: Clone + Default, Z: Copy>(arg0: T, arg1: Z)
| ^^^^^
Expand All @@ -12,52 +12,60 @@ LL | #![deny(clippy::trait_duplication_in_bounds)]
= help: consider removing this trait bound

error: this trait bound is already specified in the where clause
--> $DIR/trait_duplication_in_bounds.rs:5:23
--> $DIR/trait_duplication_in_bounds.rs:6:23
|
LL | fn bad_foo<T: Clone + Default, Z: Copy>(arg0: T, arg1: Z)
| ^^^^^^^
|
= help: consider removing this trait bound

error: this trait bound is already specified in trait declaration
--> $DIR/trait_duplication_in_bounds.rs:34:15
--> $DIR/trait_duplication_in_bounds.rs:35:15
|
LL | Self: Default;
| ^^^^^^^
|
= help: consider removing this trait bound

error: this trait bound is already specified in trait declaration
--> $DIR/trait_duplication_in_bounds.rs:48:15
--> $DIR/trait_duplication_in_bounds.rs:49:15
|
LL | Self: Default + Clone;
| ^^^^^^^
|
= help: consider removing this trait bound

error: this trait bound is already specified in trait declaration
--> $DIR/trait_duplication_in_bounds.rs:54:15
--> $DIR/trait_duplication_in_bounds.rs:55:15
|
LL | Self: Default + Clone;
| ^^^^^^^
|
= help: consider removing this trait bound

error: this trait bound is already specified in trait declaration
--> $DIR/trait_duplication_in_bounds.rs:54:25
--> $DIR/trait_duplication_in_bounds.rs:55:25
|
LL | Self: Default + Clone;
| ^^^^^
|
= help: consider removing this trait bound

error: this trait bound is already specified in trait declaration
--> $DIR/trait_duplication_in_bounds.rs:57:15
--> $DIR/trait_duplication_in_bounds.rs:58:15
|
LL | Self: Default;
| ^^^^^^^
|
= help: consider removing this trait bound

error: aborting due to 7 previous errors
error: this trait bound is already specified in trait declaration
--> $DIR/trait_duplication_in_bounds.rs:93:15
|
LL | Self: Iterator<Item = Foo>,
| ^^^^^^^^^^^^^^^^^^^^
|
= help: consider removing this trait bound

error: aborting due to 8 previous errors