From d88056c35ef8523afbd960a3927c71089d39d9f7 Mon Sep 17 00:00:00 2001
From: Nicholas Nethercote <n.nethercote@gmail.com>
Date: Wed, 23 Apr 2025 19:26:06 +1000
Subject: [PATCH 1/2] Derive `HashStable` for `DelimArgs`.

---
 compiler/rustc_ast/src/ast.rs | 14 +-------------
 1 file changed, 1 insertion(+), 13 deletions(-)

diff --git a/compiler/rustc_ast/src/ast.rs b/compiler/rustc_ast/src/ast.rs
index 1532ca77f713e..8986430141be4 100644
--- a/compiler/rustc_ast/src/ast.rs
+++ b/compiler/rustc_ast/src/ast.rs
@@ -1927,7 +1927,7 @@ impl AttrArgs {
 }
 
 /// Delimited arguments, as used in `#[attr()/[]/{}]` or `mac!()/[]/{}`.
-#[derive(Clone, Encodable, Decodable, Debug)]
+#[derive(Clone, Encodable, Decodable, Debug, HashStable_Generic)]
 pub struct DelimArgs {
     pub dspan: DelimSpan,
     pub delim: Delimiter, // Note: `Delimiter::Invisible` never occurs
@@ -1942,18 +1942,6 @@ impl DelimArgs {
     }
 }
 
-impl<CTX> HashStable<CTX> for DelimArgs
-where
-    CTX: crate::HashStableContext,
-{
-    fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
-        let DelimArgs { dspan, delim, tokens } = self;
-        dspan.hash_stable(ctx, hasher);
-        delim.hash_stable(ctx, hasher);
-        tokens.hash_stable(ctx, hasher);
-    }
-}
-
 /// Represents a macro definition.
 #[derive(Clone, Encodable, Decodable, Debug, HashStable_Generic)]
 pub struct MacroDef {

From 7fe6bc57f5c9f1e40f82b4eefb4391149bc752e8 Mon Sep 17 00:00:00 2001
From: Nicholas Nethercote <n.nethercote@gmail.com>
Date: Wed, 23 Apr 2025 20:10:49 +1000
Subject: [PATCH 2/2] Use `clone` to clone `DelimArgs` in two places.

---
 compiler/rustc_ast_lowering/src/lib.rs     | 2 +-
 compiler/rustc_attr_parsing/src/context.rs | 8 ++------
 2 files changed, 3 insertions(+), 7 deletions(-)

diff --git a/compiler/rustc_ast_lowering/src/lib.rs b/compiler/rustc_ast_lowering/src/lib.rs
index c40987541f4a5..d23cf6cb2f1de 100644
--- a/compiler/rustc_ast_lowering/src/lib.rs
+++ b/compiler/rustc_ast_lowering/src/lib.rs
@@ -916,7 +916,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
     }
 
     fn lower_delim_args(&self, args: &DelimArgs) -> DelimArgs {
-        DelimArgs { dspan: args.dspan, delim: args.delim, tokens: args.tokens.clone() }
+        args.clone()
     }
 
     /// Lower an associated item constraint.
diff --git a/compiler/rustc_attr_parsing/src/context.rs b/compiler/rustc_attr_parsing/src/context.rs
index 63597b37cb5ee..55c3df003fe16 100644
--- a/compiler/rustc_attr_parsing/src/context.rs
+++ b/compiler/rustc_attr_parsing/src/context.rs
@@ -3,7 +3,7 @@ use std::collections::BTreeMap;
 use std::ops::Deref;
 use std::sync::LazyLock;
 
-use rustc_ast::{self as ast, DelimArgs};
+use rustc_ast as ast;
 use rustc_attr_data_structures::AttributeKind;
 use rustc_errors::{DiagCtxtHandle, Diagnostic};
 use rustc_feature::Features;
@@ -315,11 +315,7 @@ impl<'sess> AttributeParser<'sess> {
     fn lower_attr_args(&self, args: &ast::AttrArgs, lower_span: impl Fn(Span) -> Span) -> AttrArgs {
         match args {
             ast::AttrArgs::Empty => AttrArgs::Empty,
-            ast::AttrArgs::Delimited(args) => AttrArgs::Delimited(DelimArgs {
-                dspan: args.dspan,
-                delim: args.delim,
-                tokens: args.tokens.clone(),
-            }),
+            ast::AttrArgs::Delimited(args) => AttrArgs::Delimited(args.clone()),
             // This is an inert key-value attribute - it will never be visible to macros
             // after it gets lowered to HIR. Therefore, we can extract literals to handle
             // nonterminals in `#[doc]` (e.g. `#[doc = $e]`).