diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6e0aaa25a7c..41a86e8ce51 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6063,6 +6063,7 @@ Released 2018-09-13
[`unused_result_ok`]: https://rust-lang.github.io/rust-clippy/master/index.html#unused_result_ok
[`unused_rounding`]: https://rust-lang.github.io/rust-clippy/master/index.html#unused_rounding
[`unused_self`]: https://rust-lang.github.io/rust-clippy/master/index.html#unused_self
+[`unused_trait_names`]: https://rust-lang.github.io/rust-clippy/master/index.html#unused_trait_names
[`unused_unit`]: https://rust-lang.github.io/rust-clippy/master/index.html#unused_unit
[`unusual_byte_groupings`]: https://rust-lang.github.io/rust-clippy/master/index.html#unusual_byte_groupings
[`unwrap_in_result`]: https://rust-lang.github.io/rust-clippy/master/index.html#unwrap_in_result
diff --git a/book/src/lint_configuration.md b/book/src/lint_configuration.md
index 78348797588..91159bc79c5 100644
--- a/book/src/lint_configuration.md
+++ b/book/src/lint_configuration.md
@@ -727,6 +727,7 @@ The minimum rust version that the project supports. Defaults to the `rust-versio
* [`uninlined_format_args`](https://rust-lang.github.io/rust-clippy/master/index.html#uninlined_format_args)
* [`unnecessary_lazy_evaluations`](https://rust-lang.github.io/rust-clippy/master/index.html#unnecessary_lazy_evaluations)
* [`unnested_or_patterns`](https://rust-lang.github.io/rust-clippy/master/index.html#unnested_or_patterns)
+* [`unused_trait_names`](https://rust-lang.github.io/rust-clippy/master/index.html#unused_trait_names)
* [`use_self`](https://rust-lang.github.io/rust-clippy/master/index.html#use_self)
diff --git a/clippy_config/src/conf.rs b/clippy_config/src/conf.rs
index 6c1dd232593..1765cf87d48 100644
--- a/clippy_config/src/conf.rs
+++ b/clippy_config/src/conf.rs
@@ -563,6 +563,7 @@ define_Conf! {
uninlined_format_args,
unnecessary_lazy_evaluations,
unnested_or_patterns,
+ unused_trait_names,
use_self,
)]
msrv: Msrv = Msrv::empty(),
diff --git a/clippy_config/src/msrvs.rs b/clippy_config/src/msrvs.rs
index a70effd6376..a6cba849922 100644
--- a/clippy_config/src/msrvs.rs
+++ b/clippy_config/src/msrvs.rs
@@ -49,6 +49,7 @@ msrv_aliases! {
1,36,0 { ITERATOR_COPIED }
1,35,0 { OPTION_COPIED, RANGE_CONTAINS }
1,34,0 { TRY_FROM }
+ 1,33,0 { UNDERSCORE_IMPORTS }
1,30,0 { ITERATOR_FIND_MAP, TOOL_ATTRIBUTES }
1,29,0 { ITER_FLATTEN }
1,28,0 { FROM_BOOL }
diff --git a/clippy_lints/src/declared_lints.rs b/clippy_lints/src/declared_lints.rs
index 824f57cece9..2b229d2fe6a 100644
--- a/clippy_lints/src/declared_lints.rs
+++ b/clippy_lints/src/declared_lints.rs
@@ -748,6 +748,7 @@ pub static LINTS: &[&crate::LintInfo] = &[
crate::unused_result_ok::UNUSED_RESULT_OK_INFO,
crate::unused_rounding::UNUSED_ROUNDING_INFO,
crate::unused_self::UNUSED_SELF_INFO,
+ crate::unused_trait_names::UNUSED_TRAIT_NAMES_INFO,
crate::unused_unit::UNUSED_UNIT_INFO,
crate::unwrap::PANICKING_UNWRAP_INFO,
crate::unwrap::UNNECESSARY_UNWRAP_INFO,
diff --git a/clippy_lints/src/lib.rs b/clippy_lints/src/lib.rs
index 3604090b68c..b21d3f8d09e 100644
--- a/clippy_lints/src/lib.rs
+++ b/clippy_lints/src/lib.rs
@@ -376,6 +376,7 @@ mod unused_peekable;
mod unused_result_ok;
mod unused_rounding;
mod unused_self;
+mod unused_trait_names;
mod unused_unit;
mod unwrap;
mod unwrap_in_result;
@@ -942,5 +943,6 @@ pub fn register_lints(store: &mut rustc_lint::LintStore, conf: &'static Conf) {
store.register_late_pass(move |_| Box::new(manual_div_ceil::ManualDivCeil::new(conf)));
store.register_late_pass(|_| Box::new(manual_is_power_of_two::ManualIsPowerOfTwo));
store.register_late_pass(|_| Box::new(non_zero_suggestions::NonZeroSuggestions));
+ store.register_late_pass(move |_| Box::new(unused_trait_names::UnusedTraitNames::new(conf)));
// add lints here, do not remove this comment, it's used in `new_lint`
}
diff --git a/clippy_lints/src/unused_trait_names.rs b/clippy_lints/src/unused_trait_names.rs
new file mode 100644
index 00000000000..c1cf58dcfce
--- /dev/null
+++ b/clippy_lints/src/unused_trait_names.rs
@@ -0,0 +1,94 @@
+use clippy_config::msrvs::{self, Msrv};
+use clippy_config::Conf;
+use clippy_utils::diagnostics::span_lint_and_sugg;
+use clippy_utils::is_from_proc_macro;
+use clippy_utils::source::snippet_opt;
+use rustc_errors::Applicability;
+use rustc_hir::def::{DefKind, Res};
+use rustc_hir::{Item, ItemKind, UseKind};
+use rustc_lint::{LateContext, LateLintPass, LintContext as _};
+use rustc_middle::lint::in_external_macro;
+use rustc_middle::ty::Visibility;
+use rustc_session::impl_lint_pass;
+use rustc_span::symbol::kw;
+
+declare_clippy_lint! {
+ /// ### What it does
+ /// Checks for `use Trait` where the Trait is only used for its methods and not referenced by a path directly.
+ ///
+ /// ### Why is this bad?
+ /// Traits imported that aren't used directly can be imported anonymously with `use Trait as _`.
+ /// It is more explicit, avoids polluting the current scope with unused names and can be useful to show which imports are required for traits.
+ ///
+ /// ### Example
+ /// ```no_run
+ /// use std::fmt::Write;
+ ///
+ /// fn main() {
+ /// let mut s = String::new();
+ /// let _ = write!(s, "hello, world!");
+ /// println!("{s}");
+ /// }
+ /// ```
+ /// Use instead:
+ /// ```no_run
+ /// use std::fmt::Write as _;
+ ///
+ /// fn main() {
+ /// let mut s = String::new();
+ /// let _ = write!(s, "hello, world!");
+ /// println!("{s}");
+ /// }
+ /// ```
+ #[clippy::version = "1.83.0"]
+ pub UNUSED_TRAIT_NAMES,
+ restriction,
+ "use items that import a trait but only use it anonymously"
+}
+
+pub struct UnusedTraitNames {
+ msrv: Msrv,
+}
+
+impl UnusedTraitNames {
+ pub fn new(conf: &'static Conf) -> Self {
+ Self {
+ msrv: conf.msrv.clone(),
+ }
+ }
+}
+
+impl_lint_pass!(UnusedTraitNames => [UNUSED_TRAIT_NAMES]);
+
+impl<'tcx> LateLintPass<'tcx> for UnusedTraitNames {
+ fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'tcx>) {
+ if self.msrv.meets(msrvs::UNDERSCORE_IMPORTS)
+ && !in_external_macro(cx.sess(), item.span)
+ && let ItemKind::Use(path, UseKind::Single) = item.kind
+ // Ignore imports that already use Underscore
+ && item.ident.name != kw::Underscore
+ // Only check traits
+ && let Some(Res::Def(DefKind::Trait, _)) = path.res.first()
+ && cx.tcx.maybe_unused_trait_imports(()).contains(&item.owner_id.def_id)
+ // Only check this import if it is visible to its module only (no pub, pub(crate), ...)
+ && let module = cx.tcx.parent_module_from_def_id(item.owner_id.def_id)
+ && cx.tcx.visibility(item.owner_id.def_id) == Visibility::Restricted(module.to_def_id())
+ && let Some(last_segment) = path.segments.last()
+ && let Some(snip) = snippet_opt(cx, last_segment.ident.span)
+ && !is_from_proc_macro(cx, &last_segment.ident)
+ {
+ let complete_span = last_segment.ident.span.to(item.ident.span);
+ span_lint_and_sugg(
+ cx,
+ UNUSED_TRAIT_NAMES,
+ complete_span,
+ "importing trait that is only used anonymously",
+ "use",
+ format!("{snip} as _"),
+ Applicability::MachineApplicable,
+ );
+ }
+ }
+
+ extract_msrv_attr!(LateContext);
+}