4 files changed, 8 insertions, 7 deletions
diff --git a/src/librustdoc/clean/auto_trait.rs b/src/librustdoc/clean/auto_trait.rs
index 60d6c33f81a..7b58312a5ed 100644
--- a/src/librustdoc/clean/auto_trait.rs
+++ b/src/librustdoc/clean/auto_trait.rs
@@ -341,7 +341,7 @@ impl<'a, 'tcx> AutoTraitFinder<'a, 'tcx> {
             .collect()
     }
 
-    fn make_final_bounds<'b, 'c, 'cx>(
+    fn make_final_bounds(
         &self,
         ty_to_bounds: FxHashMap<Type, FxHashSet<GenericBound>>,
         ty_to_fn: FxHashMap<Type, (Option<PolyTrait>, Option<Type>)>,
diff --git a/src/librustdoc/clean/mod.rs b/src/librustdoc/clean/mod.rs
index a717ef20a84..e44c35b55ff 100644
--- a/src/librustdoc/clean/mod.rs
+++ b/src/librustdoc/clean/mod.rs
@@ -1298,7 +1298,7 @@ impl Clean<Constant> for hir::ConstArg {
     }
 }
 
-impl<'tcx> Clean<Lifetime> for ty::GenericParamDef {
+impl Clean<Lifetime> for ty::GenericParamDef {
     fn clean(&self, _cx: &DocContext<'_>) -> Lifetime {
         Lifetime(self.name.to_string())
     }
@@ -2039,7 +2039,7 @@ impl<'a, A: Copy> Clean<FnDecl> for (&'a hir::FnDecl, A)
     }
 }
 
-impl<'a, 'tcx> Clean<FnDecl> for (DefId, ty::PolyFnSig<'tcx>) {
+impl<'tcx> Clean<FnDecl> for (DefId, ty::PolyFnSig<'tcx>) {
     fn clean(&self, cx: &DocContext<'_>) -> FnDecl {
         let (did, sig) = *self;
         let mut names = if cx.tcx.hir().as_local_hir_id(did).is_some() {
@@ -2276,7 +2276,7 @@ impl Clean<Item> for hir::ImplItem {
     }
 }
 
-impl<'tcx> Clean<Item> for ty::AssocItem {
+impl Clean<Item> for ty::AssocItem {
     fn clean(&self, cx: &DocContext<'_>) -> Item {
         let inner = match self.kind {
             ty::AssocKind::Const => {
@@ -3174,7 +3174,7 @@ impl Clean<Item> for hir::StructField {
     }
 }
 
-impl<'tcx> Clean<Item> for ty::FieldDef {
+impl Clean<Item> for ty::FieldDef {
     fn clean(&self, cx: &DocContext<'_>) -> Item {
         Item {
             name: Some(self.ident.name).clean(cx),
@@ -3342,7 +3342,7 @@ impl Clean<Item> for doctree::Variant {
     }
 }
 
-impl<'tcx> Clean<Item> for ty::VariantDef {
+impl Clean<Item> for ty::VariantDef {
     fn clean(&self, cx: &DocContext<'_>) -> Item {
         let kind = match self.ctor_kind {
             CtorKind::Const => VariantKind::CLike,
diff --git a/src/librustdoc/html/render.rs b/src/librustdoc/html/render.rs
index 3555e2e7498..36270682059 100644
--- a/src/librustdoc/html/render.rs
+++ b/src/librustdoc/html/render.rs
@@ -1764,7 +1764,7 @@ impl DocFolder for Cache {
     }
 }
 
-impl<'a> Cache {
+impl Cache {
     fn generics(&mut self, generics: &clean::Generics) {
         for param in &generics.params {
             match param.kind {
diff --git a/src/librustdoc/lib.rs b/src/librustdoc/lib.rs
index ffe277ae50b..3b4d65352a3 100644
--- a/src/librustdoc/lib.rs
+++ b/src/librustdoc/lib.rs
@@ -1,5 +1,6 @@
 #![deny(rust_2018_idioms)]
 #![deny(internal)]
+#![deny(unused_lifetimes)]
 
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/",
        html_playground_url = "https://play.rust-lang.org/")]