diff --git a/compiler/rustc_expand/src/base.rs b/compiler/rustc_expand/src/base.rs
index 7fd891395fa0..427eee1a3c46 100644
--- a/compiler/rustc_expand/src/base.rs
+++ b/compiler/rustc_expand/src/base.rs
@@ -898,7 +898,7 @@ pub fn default(kind: SyntaxExtensionKind, edition: Edition) -> SyntaxExtension {
     fn get_collapse_debuginfo(sess: &Session, attrs: &[hir::Attribute], ext: bool) -> bool {
         let flag = sess.opts.cg.collapse_macro_debuginfo;
         let attr = if let Some(info) = find_attr!(attrs, CollapseDebugInfo(info) => info) {
-            info.clone()
+            *info
         } else if find_attr!(attrs, RustcBuiltinMacro { .. }) {
             CollapseMacroDebuginfo::Yes
         } else {
diff --git a/compiler/rustc_expand/src/config.rs b/compiler/rustc_expand/src/config.rs
index 71566407767c..9f40afa1861c 100644
--- a/compiler/rustc_expand/src/config.rs
+++ b/compiler/rustc_expand/src/config.rs
@@ -285,7 +285,7 @@ pub(crate) fn expand_cfg_attr(&self, cfg_attr: &Attribute, recursive: bool) -> V
 
         let Some((cfg_predicate, expanded_attrs)) = rustc_attr_parsing::parse_cfg_attr(
             cfg_attr,
-            &self.sess,
+            self.sess,
             self.features,
             self.lint_node_id,
         ) else {
@@ -422,7 +422,7 @@ pub(crate) fn maybe_emit_expr_attr_err(&self, attr: &Attribute) {
             && !attr.span.allows_unstable(sym::stmt_expr_attributes)
         {
             let mut err = feature_err(
-                &self.sess,
+                self.sess,
                 sym::stmt_expr_attributes,
                 attr.span,
                 msg!("attributes on expressions are experimental"),
diff --git a/compiler/rustc_expand/src/expand.rs b/compiler/rustc_expand/src/expand.rs
index 9f5a01452fdc..abdfe146c85a 100644
--- a/compiler/rustc_expand/src/expand.rs
+++ b/compiler/rustc_expand/src/expand.rs
@@ -1050,7 +1050,7 @@ fn gate_proc_macro_attr_item(&self, span: Span, item: &Annotatable) {
             return;
         }
         feature_err(
-            &self.cx.sess,
+            self.cx.sess,
             sym::proc_macro_hygiene,
             span,
             format!("custom attributes cannot be applied to {kind}"),
@@ -1085,7 +1085,7 @@ fn visit_item(&mut self, item: &'ast ast::Item) {
         }
 
         if !self.cx.ecfg.features.proc_macro_hygiene() {
-            annotatable.visit_with(&mut GateProcMacroInput { sess: &self.cx.sess });
+            annotatable.visit_with(&mut GateProcMacroInput { sess: self.cx.sess });
         }
     }
 
@@ -1474,7 +1474,7 @@ fn collect_use_tree_leaves(ut: &ast::UseTree, idents: &mut Vec<Ident>) {
                 }
             }
             let mut idents = Vec::new();
-            collect_use_tree_leaves(&ut, &mut idents);
+            collect_use_tree_leaves(ut, &mut idents);
             idents
         } else {
             self.kind.ident().into_iter().collect()
@@ -1482,7 +1482,7 @@ fn collect_use_tree_leaves(ut: &ast::UseTree, idents: &mut Vec<Ident>) {
     }
 
     fn as_target(&self) -> Target {
-        Target::from_ast_item(&*self)
+        Target::from_ast_item(self)
     }
 }
 
diff --git a/compiler/rustc_expand/src/mbe/diagnostics.rs b/compiler/rustc_expand/src/mbe/diagnostics.rs
index fd2e4e3ec39f..3de94d9830a7 100644
--- a/compiler/rustc_expand/src/mbe/diagnostics.rs
+++ b/compiler/rustc_expand/src/mbe/diagnostics.rs
@@ -323,9 +323,7 @@ pub(super) fn emit_frag_parse_err(
             } else if bindings_name.contains(&name) {
                 e.span_label(
                     parser.token.span,
-                    format!(
-                        "there is an macro metavariable with this name in another macro matcher"
-                    ),
+                    "there is an macro metavariable with this name in another macro matcher",
                 );
             } else if let Some(matched_name) =
                 rustc_span::edit_distance::find_best_match_for_name(&bindings_name[..], name, None)
@@ -343,7 +341,7 @@ pub(super) fn emit_frag_parse_err(
                     .collect::<Vec<_>>()
                     .join(", ");
 
-                e.span_label(parser.token.span, format!("macro metavariable not found"));
+                e.span_label(parser.token.span, "macro metavariable not found");
                 if !matched_rule_bindings_names.is_empty() {
                     e.note(format!("available metavariable names are: {msg}"));
                 }
diff --git a/compiler/rustc_expand/src/mbe/macro_parser.rs b/compiler/rustc_expand/src/mbe/macro_parser.rs
index 9c327c26849e..b8325e3ce775 100644
--- a/compiler/rustc_expand/src/mbe/macro_parser.rs
+++ b/compiler/rustc_expand/src/mbe/macro_parser.rs
@@ -199,8 +199,8 @@ fn inner(
                     let idx_seq = idx_first - 1;
                     inner(&seq.tts, locs, next_metavar, seq_depth + 1);
 
-                    if let Some(separator) = &seq.separator {
-                        locs.push(MatcherLoc::SequenceSep { separator: separator.clone() });
+                    if let Some(separator) = seq.separator {
+                        locs.push(MatcherLoc::SequenceSep { separator });
                         locs.push(MatcherLoc::SequenceKleeneOpAfterSep { idx_first });
                     } else {
                         locs.push(MatcherLoc::SequenceKleeneOpNoSep { op, idx_first });
diff --git a/compiler/rustc_expand/src/mbe/quoted.rs b/compiler/rustc_expand/src/mbe/quoted.rs
index eb874a27cece..a698db543759 100644
--- a/compiler/rustc_expand/src/mbe/quoted.rs
+++ b/compiler/rustc_expand/src/mbe/quoted.rs
@@ -214,7 +214,7 @@ fn parse_tree<'a>(
             // during parsing.
             let mut next = outer_iter.next();
             let mut iter_storage;
-            let mut iter: &mut TokenStreamIter<'_> = match next {
+            let iter: &mut TokenStreamIter<'_> = match next {
                 Some(tokenstream::TokenTree::Delimited(.., delim, tts)) if delim.skip() => {
                     iter_storage = tts.iter();
                     next = iter_storage.next();
@@ -284,7 +284,7 @@ fn parse_tree<'a>(
                     let sequence = parse(tts, part, sess, node_id, features, edition);
                     // Get the Kleene operator and optional separator
                     let (separator, kleene) =
-                        parse_sep_and_kleene_op(&mut iter, delim_span.entire(), sess);
+                        parse_sep_and_kleene_op(iter, delim_span.entire(), sess);
                     // Count the number of captured "names" (i.e., named metavars)
                     let num_captures =
                         if part.is_pattern() { count_metavar_decls(&sequence) } else { 0 };
diff --git a/compiler/rustc_expand/src/mbe/transcribe.rs b/compiler/rustc_expand/src/mbe/transcribe.rs
index dcf2cd1fa36a..7152ffcd9f30 100644
--- a/compiler/rustc_expand/src/mbe/transcribe.rs
+++ b/compiler/rustc_expand/src/mbe/transcribe.rs
@@ -396,7 +396,7 @@ fn transcribe_sequence<'tx, 'itp>(
                 // The first time we encounter the sequence we push it to the stack. It
                 // then gets reused (see the beginning of the loop) until we are done
                 // repeating.
-                tscx.stack.push(Frame::new_sequence(seq_rep, seq.separator.clone(), seq.kleene.op));
+                tscx.stack.push(Frame::new_sequence(seq_rep, seq.separator, seq.kleene.op));
             }
         }
     }
@@ -629,7 +629,7 @@ fn metavar_expr_concat<'tx>(
 ) -> PResult<'tx, TokenTree> {
     let dcx = tscx.psess.dcx();
     let mut concatenated = String::new();
-    for element in elements.into_iter() {
+    for element in elements {
         let symbol = match element {
             MetaVarExprConcatElem::Ident(elem) => elem.name,
             MetaVarExprConcatElem::Literal(elem) => *elem,
@@ -747,7 +747,7 @@ fn maybe_use_metavar_location(
         TokenTree::Token(Token { kind, span }, spacing) => {
             let span = metavar_span.with_ctxt(span.ctxt());
             with_metavar_spans(|mspans| mspans.insert(span, metavar_span));
-            TokenTree::Token(Token { kind: kind.clone(), span }, *spacing)
+            TokenTree::Token(Token { kind: *kind, span }, *spacing)
         }
         TokenTree::Delimited(dspan, dspacing, delimiter, tts) => {
             let open = metavar_span.with_ctxt(dspan.open.ctxt());
diff --git a/compiler/rustc_expand/src/module.rs b/compiler/rustc_expand/src/module.rs
index 79ab3cab22ce..a5799d64d1ea 100644
--- a/compiler/rustc_expand/src/module.rs
+++ b/compiler/rustc_expand/src/module.rs
@@ -75,7 +75,7 @@ pub(crate) fn parse_external_mod(
             Some(span),
         ));
         let (inner_attrs, items, inner_span) =
-            parser.parse_mod(exp!(Eof)).map_err(|err| ModError::ParserError(err))?;
+            parser.parse_mod(exp!(Eof)).map_err(ModError::ParserError)?;
         attrs.extend(inner_attrs);
         (items, inner_span, mp.file_path)
     };
diff --git a/compiler/rustc_expand/src/proc_macro.rs b/compiler/rustc_expand/src/proc_macro.rs
index 5b2482f5c1db..9aa8684677a9 100644
--- a/compiler/rustc_expand/src/proc_macro.rs
+++ b/compiler/rustc_expand/src/proc_macro.rs
@@ -232,7 +232,7 @@ fn enter<F, R>(ecx: &mut ExtCtxt<'_>, client: DeriveClient, f: F) -> R
     {
         // We need erasure to get rid of the lifetime
         let ctx = Self { expansion_ctx: ecx as *mut _ as *mut (), client };
-        DERIVE_EXPAND_CTX.set(&ctx, || f())
+        DERIVE_EXPAND_CTX.set(&ctx, f)
     }
 
     /// Accesses the thread local value of the derive expansion context.
diff --git a/compiler/rustc_expand/src/proc_macro_server.rs b/compiler/rustc_expand/src/proc_macro_server.rs
index 037afbb9f550..cb7d62ce191e 100644
--- a/compiler/rustc_expand/src/proc_macro_server.rs
+++ b/compiler/rustc_expand/src/proc_macro_server.rs
@@ -110,9 +110,8 @@ fn from_internal(stream: TokenStream) -> Self {
         // Estimate the capacity as `stream.len()` rounded up to the next power
         // of two to limit the number of required reallocations.
         let mut trees = Vec::with_capacity(stream.len().next_power_of_two());
-        let mut iter = stream.iter();
 
-        while let Some(tree) = iter.next() {
+        for tree in stream.iter() {
             let (Token { kind, span }, joint) = match tree.clone() {
                 tokenstream::TokenTree::Delimited(span, _, mut delim, mut stream) => {
                     // In `mk_delimited` we avoid nesting invisible delimited
diff --git a/compiler/rustc_expand/src/stats.rs b/compiler/rustc_expand/src/stats.rs
index 00f1c11044e0..0d60141f274e 100644
--- a/compiler/rustc_expand/src/stats.rs
+++ b/compiler/rustc_expand/src/stats.rs
@@ -152,7 +152,7 @@ pub(crate) fn update_macro_stats(
     }
 
     // The recorded size is the difference between the input and the output.
-    let entry = ecx.macro_stats.entry((name, macro_kind)).or_insert(MacroStat::default());
+    let entry = ecx.macro_stats.entry((name, macro_kind)).or_default();
     entry.uses += 1;
     entry.lines += num_lines;
     entry.bytes += num_bytes;