diff --git a/compiler/rustc_const_eval/src/interpret/visitor.rs b/compiler/rustc_const_eval/src/interpret/visitor.rs
index fc21ad1f1834b..32f35933bbf78 100644
--- a/compiler/rustc_const_eval/src/interpret/visitor.rs
+++ b/compiler/rustc_const_eval/src/interpret/visitor.rs
@@ -21,7 +21,7 @@ pub trait ValueVisitor<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>>: Sized {
     /// `read_discriminant` can be hooked for better error messages.
     #[inline(always)]
     fn read_discriminant(&mut self, v: &Self::V) -> InterpResult<'tcx, VariantIdx> {
-        Ok(self.ecx().read_discriminant(&v.to_op(self.ecx())?)?)
+        self.ecx().read_discriminant(&v.to_op(self.ecx())?)
     }
 
     /// This function provides the chance to reorder the order in which fields are visited for
diff --git a/compiler/rustc_driver_impl/src/lib.rs b/compiler/rustc_driver_impl/src/lib.rs
index 65c7aed3f1078..44f414dc49994 100644
--- a/compiler/rustc_driver_impl/src/lib.rs
+++ b/compiler/rustc_driver_impl/src/lib.rs
@@ -600,10 +600,8 @@ fn show_md_content_with_pager(content: &str, color: ColorConfig) {
     let mut print_formatted = if pager_name == "less" {
         cmd.arg("-r");
         true
-    } else if ["bat", "catbat", "delta"].iter().any(|v| *v == pager_name) {
-        true
     } else {
-        false
+        ["bat", "catbat", "delta"].iter().any(|v| *v == pager_name)
     };
 
     if color == ColorConfig::Never {
diff --git a/compiler/rustc_query_system/src/dep_graph/serialized.rs b/compiler/rustc_query_system/src/dep_graph/serialized.rs
index fcf46be6e6f5a..5aedc37adc9f5 100644
--- a/compiler/rustc_query_system/src/dep_graph/serialized.rs
+++ b/compiler/rustc_query_system/src/dep_graph/serialized.rs
@@ -69,7 +69,7 @@ const DEP_NODE_PAD: usize = DEP_NODE_SIZE - 1;
 const DEP_NODE_WIDTH_BITS: usize = DEP_NODE_SIZE / 2;
 
 /// Data for use when recompiling the **current crate**.
-#[derive(Debug)]
+#[derive(Debug, Default)]
 pub struct SerializedDepGraph {
     /// The set of all DepNodes in the graph
     nodes: IndexVec<SerializedDepNodeIndex, DepNode>,
@@ -88,18 +88,6 @@ pub struct SerializedDepGraph {
     index: Vec<UnhashMap<PackedFingerprint, SerializedDepNodeIndex>>,
 }
 
-impl Default for SerializedDepGraph {
-    fn default() -> Self {
-        SerializedDepGraph {
-            nodes: Default::default(),
-            fingerprints: Default::default(),
-            edge_list_indices: Default::default(),
-            edge_list_data: Default::default(),
-            index: Default::default(),
-        }
-    }
-}
-
 impl SerializedDepGraph {
     #[inline]
     pub fn edge_targets_from(
diff --git a/compiler/rustc_resolve/src/imports.rs b/compiler/rustc_resolve/src/imports.rs
index d271519a8a385..bd0d08a9df93f 100644
--- a/compiler/rustc_resolve/src/imports.rs
+++ b/compiler/rustc_resolve/src/imports.rs
@@ -1048,12 +1048,8 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                             initial_binding.res()
                         });
                         let res = binding.res();
-                        let has_ambiguity_error = this
-                            .ambiguity_errors
-                            .iter()
-                            .filter(|error| !error.warning)
-                            .next()
-                            .is_some();
+                        let has_ambiguity_error =
+                            this.ambiguity_errors.iter().any(|error| !error.warning);
                         if res == Res::Err || has_ambiguity_error {
                             this.tcx
                                 .sess
diff --git a/compiler/rustc_ty_utils/src/needs_drop.rs b/compiler/rustc_ty_utils/src/needs_drop.rs
index 6dcbc4470e607..ad7a52d8c4700 100644
--- a/compiler/rustc_ty_utils/src/needs_drop.rs
+++ b/compiler/rustc_ty_utils/src/needs_drop.rs
@@ -20,8 +20,7 @@ fn needs_drop_raw<'tcx>(tcx: TyCtxt<'tcx>, query: ty::ParamEnvAnd<'tcx, Ty<'tcx>
     let adt_has_dtor =
         |adt_def: ty::AdtDef<'tcx>| adt_def.destructor(tcx).map(|_| DtorType::Significant);
     let res = drop_tys_helper(tcx, query.value, query.param_env, adt_has_dtor, false)
-        .filter(filter_array_elements(tcx, query.param_env))
-        .next()
+        .find(filter_array_elements(tcx, query.param_env))
         .is_some();
 
     debug!("needs_drop_raw({:?}) = {:?}", query, res);
@@ -56,8 +55,7 @@ fn has_significant_drop_raw<'tcx>(
         adt_consider_insignificant_dtor(tcx),
         true,
     )
-    .filter(filter_array_elements(tcx, query.param_env))
-    .next()
+    .find(filter_array_elements(tcx, query.param_env))
     .is_some();
     debug!("has_significant_drop_raw({:?}) = {:?}", query, res);
     res
diff --git a/src/librustdoc/clean/mod.rs b/src/librustdoc/clean/mod.rs
index 34d81f51f76e6..5350489305258 100644
--- a/src/librustdoc/clean/mod.rs
+++ b/src/librustdoc/clean/mod.rs
@@ -1589,7 +1589,7 @@ fn first_non_private<'tcx>(
     path: &hir::Path<'tcx>,
 ) -> Option<Path> {
     let target_def_id = path.res.opt_def_id()?;
-    let (parent_def_id, ident) = match &path.segments[..] {
+    let (parent_def_id, ident) = match &path.segments {
         [] => return None,
         // Relative paths are available in the same scope as the owner.
         [leaf] => (cx.tcx.local_parent(hir_id.owner.def_id), leaf.ident),
diff --git a/src/librustdoc/clean/utils.rs b/src/librustdoc/clean/utils.rs
index 8388f722a7f1a..2a74f3b86580c 100644
--- a/src/librustdoc/clean/utils.rs
+++ b/src/librustdoc/clean/utils.rs
@@ -498,7 +498,7 @@ pub(crate) fn has_doc_flag(tcx: TyCtxt<'_>, did: DefId, flag: Symbol) -> bool {
 /// Set by `bootstrap::Builder::doc_rust_lang_org_channel` in order to keep tests passing on beta/stable.
 pub(crate) const DOC_RUST_LANG_ORG_CHANNEL: &str = env!("DOC_RUST_LANG_ORG_CHANNEL");
 pub(crate) static DOC_CHANNEL: Lazy<&'static str> =
-    Lazy::new(|| DOC_RUST_LANG_ORG_CHANNEL.rsplit("/").filter(|c| !c.is_empty()).next().unwrap());
+    Lazy::new(|| DOC_RUST_LANG_ORG_CHANNEL.rsplit("/").find(|c| !c.is_empty()).unwrap());
 
 /// Render a sequence of macro arms in a format suitable for displaying to the user
 /// as part of an item declaration.