diff --git a/clippy_lints/src/loops.rs b/clippy_lints/src/loops.rs
index ae1aa66be5c..9020b47a146 100644
--- a/clippy_lints/src/loops.rs
+++ b/clippy_lints/src/loops.rs
@@ -1497,7 +1497,7 @@ struct MutatePairDelegate<'a, 'tcx> {
     span_high: Option<Span>,
 }
 
-impl<'a, 'tcx> Delegate<'tcx> for MutatePairDelegate<'a, 'tcx> {
+impl<'tcx> Delegate<'tcx> for MutatePairDelegate<'_, 'tcx> {
     fn consume(&mut self, _: &PlaceWithHirId<'tcx>, _: ConsumeMode) {}
 
     fn borrow(&mut self, cmt: &PlaceWithHirId<'tcx>, bk: ty::BorrowKind) {
@@ -1525,7 +1525,7 @@ impl<'a, 'tcx> Delegate<'tcx> for MutatePairDelegate<'a, 'tcx> {
     }
 }
 
-impl<'a, 'tcx> MutatePairDelegate<'a, 'tcx> {
+impl MutatePairDelegate<'_, '_> {
     fn mutation_span(&self) -> (Option<Span>, Option<Span>) {
         (self.span_low, self.span_high)
     }
@@ -2292,7 +2292,7 @@ struct HasBreakOrReturnVisitor {
     has_break_or_return: bool,
 }
 
-impl<'a, 'tcx> Visitor<'tcx> for HasBreakOrReturnVisitor {
+impl<'tcx> Visitor<'tcx> for HasBreakOrReturnVisitor {
     type Map = Map<'tcx>;
 
     fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
diff --git a/clippy_lints/src/suspicious_trait_impl.rs b/clippy_lints/src/suspicious_trait_impl.rs
index a9e6fa329c0..cf71c3144a2 100644
--- a/clippy_lints/src/suspicious_trait_impl.rs
+++ b/clippy_lints/src/suspicious_trait_impl.rs
@@ -184,7 +184,7 @@ struct BinaryExprVisitor {
     in_binary_expr: bool,
 }
 
-impl<'a, 'tcx> Visitor<'tcx> for BinaryExprVisitor {
+impl<'tcx> Visitor<'tcx> for BinaryExprVisitor {
     type Map = Map<'tcx>;
 
     fn visit_expr(&mut self, expr: &'tcx hir::Expr<'_>) {
diff --git a/clippy_lints/src/trivially_copy_pass_by_ref.rs b/clippy_lints/src/trivially_copy_pass_by_ref.rs
index 8e0cb94317a..146ac4b09d5 100644
--- a/clippy_lints/src/trivially_copy_pass_by_ref.rs
+++ b/clippy_lints/src/trivially_copy_pass_by_ref.rs
@@ -58,7 +58,7 @@ pub struct TriviallyCopyPassByRef {
     limit: u64,
 }
 
-impl<'a, 'tcx> TriviallyCopyPassByRef {
+impl<'tcx> TriviallyCopyPassByRef {
     pub fn new(limit: Option<u64>, target: &SessionConfig) -> Self {
         let limit = limit.unwrap_or_else(|| {
             let bit_width = u64::from(target.ptr_width);
diff --git a/clippy_lints/src/utils/sugg.rs b/clippy_lints/src/utils/sugg.rs
index 73758b7eeb7..e919b1522d8 100644
--- a/clippy_lints/src/utils/sugg.rs
+++ b/clippy_lints/src/utils/sugg.rs
@@ -509,7 +509,7 @@ fn indentation<T: LintContext>(cx: &T, span: Span) -> Option<String> {
 }
 
 /// Convenience extension trait for `DiagnosticBuilder`.
-pub trait DiagnosticBuilderExt<'a, T: LintContext> {
+pub trait DiagnosticBuilderExt<T: LintContext> {
     /// Suggests to add an attribute to an item.
     ///
     /// Correctly handles indentation of the attribute and item.
@@ -556,7 +556,7 @@ pub trait DiagnosticBuilderExt<'a, T: LintContext> {
     fn suggest_remove_item(&mut self, cx: &T, item: Span, msg: &str, applicability: Applicability);
 }
 
-impl<'a, 'b, 'c, T: LintContext> DiagnosticBuilderExt<'c, T> for rustc_errors::DiagnosticBuilder<'b> {
+impl<T: LintContext> DiagnosticBuilderExt<T> for rustc_errors::DiagnosticBuilder<'_> {
     fn suggest_item_with_attr<D: Display + ?Sized>(
         &mut self,
         cx: &T,
diff --git a/src/driver.rs b/src/driver.rs
index 10f56fb2070..3d12436e9af 100644
--- a/src/driver.rs
+++ b/src/driver.rs
@@ -8,6 +8,8 @@
 // FIXME: switch to something more ergonomic here, once available.
 // (Currently there is no way to opt into sysroot crates without `extern crate`.)
 #[allow(unused_extern_crates)]
+extern crate rustc_data_structures;
+#[allow(unused_extern_crates)]
 extern crate rustc_driver;
 #[allow(unused_extern_crates)]
 extern crate rustc_errors;
@@ -97,7 +99,7 @@ impl rustc_driver::Callbacks for ClippyCallbacks {
 #[allow(clippy::find_map, clippy::filter_map)]
 fn describe_lints() {
     use lintlist::{Level, Lint, ALL_LINTS, LINT_LEVELS};
-    use std::collections::HashSet;
+    use rustc_data_structures::fx::FxHashSet;
 
     println!(
         "
@@ -141,7 +143,7 @@ Available lint options:
 
     let scoped = |x: &str| format!("clippy::{}", x);
 
-    let lint_groups: HashSet<_> = lints.iter().map(|lint| lint.group).collect();
+    let lint_groups: FxHashSet<_> = lints.iter().map(|lint| lint.group).collect();
 
     println!("Lint checks provided by clippy:\n");
     println!("    {}  {:7.7}  meaning", padded("name"), "default");