support inherent impls and trait impls

clippy_lints/src/implied_bounds_in_impls.rs

@@ -1,11 +1,14 @@
 use clippy_utils::diagnostics::span_lint_and_then;
 use clippy_utils::source::snippet;
+use rustc_errors::{Applicability, SuggestionStyle};
 use rustc_hir::def_id::LocalDefId;
 use rustc_hir::intravisit::FnKind;
-use rustc_hir::{Body, FnDecl, FnRetTy, GenericArg, GenericBound, ItemKind, TraitBoundModifier, TyKind};
+use rustc_hir::{
+    Body, FnDecl, FnRetTy, GenericArg, GenericBound, ImplItem, ImplItemKind, ItemKind, TraitBoundModifier, TraitItem,
+    TraitItemKind, TyKind,
+};
 use rustc_hir_analysis::hir_ty_to_ty;
 use rustc_lint::{LateContext, LateLintPass};
-use rustc_errors::{Applicability, SuggestionStyle};
 use rustc_middle::ty::{self, ClauseKind, TyCtxt};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::Span;
@@ -94,16 +97,7 @@ fn is_same_generics(
         })
 }
 
-impl LateLintPass<'_> for ImpliedBoundsInImpls {
-    fn check_fn(
-        &mut self,
-        cx: &LateContext<'_>,
-        _: FnKind<'_>,
-        decl: &FnDecl<'_>,
-        _: &Body<'_>,
-        _: Span,
-        _: LocalDefId,
-    ) {
+fn check(cx: &LateContext<'_>, decl: &FnDecl<'_>) {
     if let FnRetTy::Return(ty) = decl.output
         &&let TyKind::OpaqueDef(item_id, ..) = ty.kind
         && let item = cx.tcx.hir().item(item_id)
@@ -158,7 +152,7 @@ fn check_fn(
                 span_lint_and_then(
                     cx, IMPLIED_BOUNDS_IN_IMPLS,
                     poly_trait.span,
-                        &format!("this bound is already specified as the supertrait of `{}`", implied_by),
+                    &format!("this bound is already specified as the supertrait of `{implied_by}`"),
                     |diag| {
                         // If we suggest removing a bound, we may also need extend the span
                         // to include the `+` token, so we don't end up with something like `impl + B`
@@ -181,5 +175,28 @@ fn check_fn(
             }
         }
     }
+}
+
+impl LateLintPass<'_> for ImpliedBoundsInImpls {
+    fn check_fn(
+        &mut self,
+        cx: &LateContext<'_>,
+        _: FnKind<'_>,
+        decl: &FnDecl<'_>,
+        _: &Body<'_>,
+        _: Span,
+        _: LocalDefId,
+    ) {
+        check(cx, decl);
+    }
+    fn check_trait_item(&mut self, cx: &LateContext<'_>, item: &TraitItem<'_>) {
+        if let TraitItemKind::Fn(sig, ..) = &item.kind {
+            check(cx, sig.decl);
+        }
+    }
+    fn check_impl_item(&mut self, cx: &LateContext<'_>, item: &ImplItem<'_>) {
+        if let ImplItemKind::Fn(sig, ..) = &item.kind {
+            check(cx, sig.decl);
+        }
     }
 }

tests/ui/implied_bounds_in_impls.fixed

@@ -49,9 +49,7 @@ fn generics_same() -> impl GenericSubtrait<(), i32, ()> {}
 
 trait SomeTrait {
     // Check that it works in trait declarations.
-    fn f() -> impl DerefMut<Target = u8> {
-        Box::new(0)
-    }
+    fn f() -> impl DerefMut<Target = u8>;
 }
 struct SomeStruct;
 impl SomeStruct {

tests/ui/implied_bounds_in_impls.rs

@@ -49,20 +49,18 @@ fn generics_same() -> impl GenericTrait<i32> + GenericSubtrait<(), i32, ()> {}
 
 trait SomeTrait {
     // Check that it works in trait declarations.
-    fn f() -> impl Deref + DerefMut<Target = u8> {
-        Box::new(0)
-    }
+    fn f() -> impl Deref + DerefMut<Target = u8>;
 }
 struct SomeStruct;
 impl SomeStruct {
     // Check that it works in inherent impl blocks.
-    fn f() -> impl DerefMut<Target = u8> {
+    fn f() -> impl Deref + DerefMut<Target = u8> {
         Box::new(123)
     }
 }
 impl SomeTrait for SomeStruct {
     // Check that it works in trait impls.
-    fn f() -> impl DerefMut<Target = u8> {
+    fn f() -> impl Deref + DerefMut<Target = u8> {
         Box::new(42)
     }
 }

tests/ui/implied_bounds_in_impls.stderr

@@ -86,6 +86,18 @@ LL + fn generics_same() -> impl GenericSubtrait<(), i32, ()> {}
 error: this bound is already specified as the supertrait of `DerefMut<Target = u8>`
   --> $DIR/implied_bounds_in_impls.rs:52:20
    |
+LL |     fn f() -> impl Deref + DerefMut<Target = u8>;
+   |                    ^^^^^
+   |
+help: try removing this bound
+   |
+LL -     fn f() -> impl Deref + DerefMut<Target = u8>;
+LL +     fn f() -> impl DerefMut<Target = u8>;
+   |
+
+error: this bound is already specified as the supertrait of `DerefMut<Target = u8>`
+  --> $DIR/implied_bounds_in_impls.rs:57:20
+   |
 LL |     fn f() -> impl Deref + DerefMut<Target = u8> {
    |                    ^^^^^
    |
@@ -95,5 +107,17 @@ LL -     fn f() -> impl Deref + DerefMut<Target = u8> {
 LL +     fn f() -> impl DerefMut<Target = u8> {
    |
 
-error: aborting due to 8 previous errors
+error: this bound is already specified as the supertrait of `DerefMut<Target = u8>`
+  --> $DIR/implied_bounds_in_impls.rs:63:20
+   |
+LL |     fn f() -> impl Deref + DerefMut<Target = u8> {
+   |                    ^^^^^
+   |
+help: try removing this bound
+   |
+LL -     fn f() -> impl Deref + DerefMut<Target = u8> {
+LL +     fn f() -> impl DerefMut<Target = u8> {
+   |
+
+error: aborting due to 10 previous errors