diff --git a/compiler/rustc_hir_typeck/src/check.rs b/compiler/rustc_hir_typeck/src/check.rs
index 3feb23d3481..2b3678d9875 100644
--- a/compiler/rustc_hir_typeck/src/check.rs
+++ b/compiler/rustc_hir_typeck/src/check.rs
@@ -264,7 +264,7 @@ fn check_lang_start_fn<'tcx>(
         let fn_generic = generics.param_at(0, tcx);
         let generic_ty = tcx.mk_ty_param(fn_generic.index, fn_generic.name);
         let expected_fn_sig =
-            tcx.mk_fn_sig([].iter(), &generic_ty, false, hir::Unsafety::Normal, Abi::Rust);
+            tcx.mk_fn_sig([].into_iter(), generic_ty, false, hir::Unsafety::Normal, Abi::Rust);
         let expected_ty = tcx.mk_fn_ptr(Binder::dummy(expected_fn_sig));
 
         // we emit the same error to suggest changing the arg no matter what's wrong with the arg
diff --git a/compiler/rustc_hir_typeck/src/generator_interior/mod.rs b/compiler/rustc_hir_typeck/src/generator_interior/mod.rs
index 3f61a1a83e5..d0a66acd5a1 100644
--- a/compiler/rustc_hir_typeck/src/generator_interior/mod.rs
+++ b/compiler/rustc_hir_typeck/src/generator_interior/mod.rs
@@ -312,7 +312,7 @@ pub fn resolve_interior<'a, 'tcx>(
 
     // Extract type components to build the witness type.
     let type_list = fcx.tcx.mk_type_list(type_causes.iter().map(|cause| cause.ty));
-    let bound_vars = fcx.tcx.mk_bound_variable_kinds(bound_vars.iter());
+    let bound_vars = fcx.tcx.mk_bound_variable_kinds(bound_vars.into_iter());
     let witness =
         fcx.tcx.mk_generator_witness(ty::Binder::bind_with_vars(type_list, bound_vars.clone()));
 
diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
index a28e236d860..7b144d478e0 100644
--- a/compiler/rustc_middle/src/ty/context.rs
+++ b/compiler/rustc_middle/src/ty/context.rs
@@ -2387,7 +2387,7 @@ impl<'tcx> TyCtxt<'tcx> {
                 .unwrap_or_else(|| {
                     bug!("No bound vars found for {}", self.hir().node_to_string(id))
                 })
-                .iter(),
+                .into_iter(),
         )
     }
 
diff --git a/compiler/rustc_symbol_mangling/src/typeid/typeid_itanium_cxx_abi.rs b/compiler/rustc_symbol_mangling/src/typeid/typeid_itanium_cxx_abi.rs
index fb8695e7eaf..c2eccbcbc3c 100644
--- a/compiler/rustc_symbol_mangling/src/typeid/typeid_itanium_cxx_abi.rs
+++ b/compiler/rustc_symbol_mangling/src/typeid/typeid_itanium_cxx_abi.rs
@@ -781,8 +781,8 @@ fn transform_ty<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>, options: TransformTyOptio
                 let output = transform_ty(tcx, fn_sig.skip_binder().output(), options);
                 ty = tcx.mk_fn_ptr(ty::Binder::bind_with_vars(
                     tcx.mk_fn_sig(
-                        parameters.iter(),
-                        &output,
+                        parameters.into_iter(),
+                        output,
                         fn_sig.c_variadic(),
                         fn_sig.unsafety(),
                         fn_sig.abi(),
diff --git a/compiler/rustc_trait_selection/src/solve/trait_goals.rs b/compiler/rustc_trait_selection/src/solve/trait_goals.rs
index 0921fb5756d..d12e5f797fb 100644
--- a/compiler/rustc_trait_selection/src/solve/trait_goals.rs
+++ b/compiler/rustc_trait_selection/src/solve/trait_goals.rs
@@ -359,7 +359,7 @@ impl<'tcx> assembly::GoalKind<'tcx> for TraitPredicate<'tcx> {
                     let b_last_ty = b_tys.last().unwrap();
 
                     // Substitute just the tail field of B., and require that they're equal.
-                    let unsized_a_ty = tcx.mk_tup(a_rest_tys.iter().chain([b_last_ty]));
+                    let unsized_a_ty = tcx.mk_tup(a_rest_tys.iter().chain([b_last_ty]).copied());
                     let mut nested_goals = ecx.infcx.eq(goal.param_env, unsized_a_ty, b_ty)?;
 
                     // Similar to ADTs, require that the rest of the fields are equal.
diff --git a/compiler/rustc_ty_utils/src/abi.rs b/compiler/rustc_ty_utils/src/abi.rs
index 8b32c0119e0..76ecb86efb8 100644
--- a/compiler/rustc_ty_utils/src/abi.rs
+++ b/compiler/rustc_ty_utils/src/abi.rs
@@ -141,8 +141,8 @@ fn fn_sig_for_fn_abi<'tcx>(
 
             ty::Binder::bind_with_vars(
                 tcx.mk_fn_sig(
-                    [env_ty, resume_ty].iter(),
-                    &ret_ty,
+                    [env_ty, resume_ty].into_iter(),
+                    ret_ty,
                     false,
                     hir::Unsafety::Normal,
                     rustc_target::spec::abi::Abi::Rust,
diff --git a/compiler/rustc_type_ir/src/lib.rs b/compiler/rustc_type_ir/src/lib.rs
index cb28731681b..d3c0a410bfc 100644
--- a/compiler/rustc_type_ir/src/lib.rs
+++ b/compiler/rustc_type_ir/src/lib.rs
@@ -127,17 +127,6 @@ impl<T, R> InternIteratorElement<T, R> for T {
     }
 }
 
-impl<'a, T, R> InternIteratorElement<T, R> for &'a T
-where
-    T: Clone + 'a,
-{
-    type Output = R;
-    fn intern_with<I: Iterator<Item = Self>, F: FnOnce(&[T]) -> R>(iter: I, f: F) -> Self::Output {
-        // This code isn't hot.
-        f(&iter.cloned().collect::<SmallVec<[_; 8]>>())
-    }
-}
-
 impl<T, R, E> InternIteratorElement<T, R> for Result<T, E> {
     type Output = Result<R, E>;
     fn intern_with<I: Iterator<Item = Self>, F: FnOnce(&[T]) -> R>(