linux-kernel - [PATCH 07/11] rust: macros: convert `concat

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Message-ID: <20251211185805.2835633-8-gary@kernel.org>
Date: Thu, 11 Dec 2025 18:56:47 +0000
From: Gary Guo <gary@...nel.org>
To: Miguel Ojeda <ojeda@...nel.org>,
	Boqun Feng <boqun.feng@...il.com>,
	Gary Guo <gary@...yguo.net>,
	Björn Roy Baron <bjorn3_gh@...tonmail.com>,
	Benno Lossin <lossin@...nel.org>,
	Andreas Hindborg <a.hindborg@...nel.org>,
	Alice Ryhl <aliceryhl@...gle.com>,
	Trevor Gross <tmgross@...ch.edu>,
	Danilo Krummrich <dakr@...nel.org>,
	Fiona Behrens <me@...enk.dev>,
	Guilherme Giacomo Simoes <trintaeoitogc@...il.com>,
	José Expósito <jose.exposito89@...il.com>,
	Tamir Duberstein <tamird@...il.com>
Cc: rust-for-linux@...r.kernel.org,
	David Gow <davidgow@...gle.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH 07/11] rust: macros: convert `concat_idents!` to use `syn`

From: Gary Guo <gary@...yguo.net>

This eliminates the need for `expect_punct` helper.

Signed-off-by: Gary Guo <gary@...yguo.net>
---
 rust/macros/concat_idents.rs | 39 ++++++++++++++++++++++++------------
 rust/macros/helpers.rs       | 14 +------------
 rust/macros/lib.rs           |  4 ++--
 3 files changed, 29 insertions(+), 28 deletions(-)

diff --git a/rust/macros/concat_idents.rs b/rust/macros/concat_idents.rs
index 12cb231c3d715..47b6add378d2c 100644
--- a/rust/macros/concat_idents.rs
+++ b/rust/macros/concat_idents.rs
@@ -1,23 +1,36 @@
 // SPDX-License-Identifier: GPL-2.0
 
-use proc_macro2::{token_stream, Ident, TokenStream, TokenTree};
+use proc_macro2::{
+    Ident,
+    TokenStream,
+    TokenTree, //
+};
+use syn::{
+    parse::{
+        Parse,
+        ParseStream, //
+    },
+    Result,
+    Token, //
+};
 
-use crate::helpers::expect_punct;
+pub(crate) struct Input {
+    a: Ident,
+    _comma: Token![,],
+    b: Ident,
+}
 
-fn expect_ident(it: &mut token_stream::IntoIter) -> Ident {
-    if let Some(TokenTree::Ident(ident)) = it.next() {
-        ident
-    } else {
-        panic!("Expected Ident")
+impl Parse for Input {
+    fn parse(input: ParseStream<'_>) -> Result<Self> {
+        Ok(Self {
+            a: input.parse()?,
+            _comma: input.parse()?,
+            b: input.parse()?,
+        })
     }
 }
 
-pub(crate) fn concat_idents(ts: TokenStream) -> TokenStream {
-    let mut it = ts.into_iter();
-    let a = expect_ident(&mut it);
-    assert_eq!(expect_punct(&mut it), ',');
-    let b = expect_ident(&mut it);
-    assert!(it.next().is_none(), "only two idents can be concatenated");
+pub(crate) fn concat_idents(Input { a, b, .. }: Input) -> TokenStream {
     let res = Ident::new(&format!("{a}{b}"), b.span());
     TokenStream::from_iter([TokenTree::Ident(res)])
 }
diff --git a/rust/macros/helpers.rs b/rust/macros/helpers.rs
index 754c827cc21e1..adfa60d8f42d8 100644
--- a/rust/macros/helpers.rs
+++ b/rust/macros/helpers.rs
@@ -1,10 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0
 
-use proc_macro2::{
-    token_stream,
-    TokenStream,
-    TokenTree, //
-};
+use proc_macro2::TokenStream;
 use quote::ToTokens;
 use syn::{
     parse::{
@@ -16,14 +12,6 @@
     Result, //
 };
 
-pub(crate) fn expect_punct(it: &mut token_stream::IntoIter) -> char {
-    if let TokenTree::Punct(punct) = it.next().expect("Reached end of token stream for Punct") {
-        punct.as_char()
-    } else {
-        panic!("Expected Punct");
-    }
-}
-
 /// A string literal that is required to have ASCII value only.
 pub(crate) struct AsciiLitStr(LitStr);
 
diff --git a/rust/macros/lib.rs b/rust/macros/lib.rs
index 870a42d41ac91..bb2dfd4a4dafc 100644
--- a/rust/macros/lib.rs
+++ b/rust/macros/lib.rs
@@ -283,8 +283,8 @@ pub fn fmt(input: TokenStream) -> TokenStream {
 /// assert_eq!(BR_OK, binder_driver_return_protocol_BR_OK);
 /// ```
 #[proc_macro]
-pub fn concat_idents(ts: TokenStream) -> TokenStream {
-    concat_idents::concat_idents(ts.into()).into()
+pub fn concat_idents(input: TokenStream) -> TokenStream {
+    concat_idents::concat_idents(parse_macro_input!(input)).into()
 }
 
 /// Paste identifiers together.
-- 
2.51.2