From 05c5df56824aaf931aef617827589bb0f3936ffa Mon Sep 17 00:00:00 2001
From: Caleb Cartwright <caleb.cartwright@outlook.com>
Date: Thu, 11 May 2023 21:51:41 -0500
Subject: [PATCH] refactor: use by-ref TokenTree iterator to avoid a few clones

---
 compiler/rustc_builtin_macros/src/concat_idents.rs | 2 +-
 compiler/rustc_builtin_macros/src/trace_macros.rs  | 2 +-
 compiler/rustc_lint/src/builtin.rs                 | 8 ++++----
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/compiler/rustc_builtin_macros/src/concat_idents.rs b/compiler/rustc_builtin_macros/src/concat_idents.rs
index 8c737f043237e..ee56d45c9c826 100644
--- a/compiler/rustc_builtin_macros/src/concat_idents.rs
+++ b/compiler/rustc_builtin_macros/src/concat_idents.rs
@@ -19,7 +19,7 @@ pub fn expand_concat_idents<'cx>(
     }
 
     let mut res_str = String::new();
-    for (i, e) in tts.into_trees().enumerate() {
+    for (i, e) in tts.trees().enumerate() {
         if i & 1 == 1 {
             match e {
                 TokenTree::Token(Token { kind: token::Comma, .. }, _) => {}
diff --git a/compiler/rustc_builtin_macros/src/trace_macros.rs b/compiler/rustc_builtin_macros/src/trace_macros.rs
index cc5ae6894e6fe..9c98723e1f43f 100644
--- a/compiler/rustc_builtin_macros/src/trace_macros.rs
+++ b/compiler/rustc_builtin_macros/src/trace_macros.rs
@@ -8,7 +8,7 @@ pub fn expand_trace_macros(
     sp: Span,
     tt: TokenStream,
 ) -> Box<dyn base::MacResult + 'static> {
-    let mut cursor = tt.into_trees();
+    let mut cursor = tt.trees();
     let mut err = false;
     let value = match &cursor.next() {
         Some(TokenTree::Token(token, _)) if token.is_keyword(kw::True) => true,
diff --git a/compiler/rustc_lint/src/builtin.rs b/compiler/rustc_lint/src/builtin.rs
index 3025cce7ba7e5..b1c45eaf601e5 100644
--- a/compiler/rustc_lint/src/builtin.rs
+++ b/compiler/rustc_lint/src/builtin.rs
@@ -1882,8 +1882,8 @@ declare_lint_pass!(
 struct UnderMacro(bool);
 
 impl KeywordIdents {
-    fn check_tokens(&mut self, cx: &EarlyContext<'_>, tokens: TokenStream) {
-        for tt in tokens.into_trees() {
+    fn check_tokens(&mut self, cx: &EarlyContext<'_>, tokens: &TokenStream) {
+        for tt in tokens.trees() {
             match tt {
                 // Only report non-raw idents.
                 TokenTree::Token(token, _) => {
@@ -1944,10 +1944,10 @@ impl KeywordIdents {
 
 impl EarlyLintPass for KeywordIdents {
     fn check_mac_def(&mut self, cx: &EarlyContext<'_>, mac_def: &ast::MacroDef) {
-        self.check_tokens(cx, mac_def.body.tokens.clone());
+        self.check_tokens(cx, &mac_def.body.tokens);
     }
     fn check_mac(&mut self, cx: &EarlyContext<'_>, mac: &ast::MacCall) {
-        self.check_tokens(cx, mac.args.tokens.clone());
+        self.check_tokens(cx, &mac.args.tokens);
     }
     fn check_ident(&mut self, cx: &EarlyContext<'_>, ident: Ident) {
         self.check_ident_token(cx, UnderMacro(false), ident);