From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E10E3C4321E for ; Fri, 2 Dec 2022 16:16:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233811AbiLBQQU (ORCPT ); Fri, 2 Dec 2022 11:16:20 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53112 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233796AbiLBQPx (ORCPT ); Fri, 2 Dec 2022 11:15:53 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2EB1CD96A9; Fri, 2 Dec 2022 08:15:46 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id CBBF1B821E8; Fri, 2 Dec 2022 16:15:44 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4E3E4C433C1; Fri, 2 Dec 2022 16:15:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1669997743; bh=dtOQU49yR7LQiDxvwc6HHhk83pUumrESygYwXplYSi8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dgXNifwtz8f9FEDXONTfj3cn2QJYnm8teZte4lQpJxMPea8wUtXyATIgmMeKzTcc5 YrYJkdjvYKOSt+76f5eHIO1KRmO/Q5YLnq3bNhL4V1oRk3vebFIXrkYseYbKXSQhc/ QkLxtKZLmMnoq7K0UXyxEITHuUHw/Yyf0lpXKPYSvs8Pn71MKjqfd+6kE4l/dRTaIG xIL++tc8A2qgNGZ4SPkuxeE2MHXsVLvV4fV8/AsVb8wWxVXNd2EFu4+MKoDz0ncjtK zu+T16cjFD/nu2Jh7uD6HM4JGWLVgpvf5ae3S1TVPsbRhaMqlKGdu7ijHIwhVNePcz 3qdx+Dx684TjA== From: ojeda@kernel.org To: Miguel Ojeda , Wedson Almeida Filho , Alex Gaynor , Boqun Feng , Gary Guo , =?UTF-8?q?Bj=C3=B6rn=20Roy=20Baron?= Cc: rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, patches@lists.linux.dev, Finn Behrens Subject: [PATCH v2 05/28] rust: macros: add `concat_idents!` proc macro Date: Fri, 2 Dec 2022 17:14:36 +0100 Message-Id: <20221202161502.385525-6-ojeda@kernel.org> In-Reply-To: <20221202161502.385525-1-ojeda@kernel.org> References: <20221202161502.385525-1-ojeda@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: rust-for-linux@vger.kernel.org From: Björn Roy Baron This macro provides similar functionality to the unstable feature `concat_idents` without having to rely on it. For instance: let x_1 = 42; let x_2 = concat_idents!(x, _1); assert!(x_1 == x_2); It has different behavior with respect to macro hygiene. Unlike the unstable `concat_idents!` macro, it allows, for example, referring to local variables by taking the span of the second macro as span for the output identifier. Signed-off-by: Björn Roy Baron Reviewed-by: Finn Behrens [Reworded, adapted for upstream and applied latest changes] Signed-off-by: Miguel Ojeda --- rust/macros/concat_idents.rs | 23 +++++++++++++++++++ rust/macros/lib.rs | 44 ++++++++++++++++++++++++++++++++++++ 2 files changed, 67 insertions(+) create mode 100644 rust/macros/concat_idents.rs diff --git a/rust/macros/concat_idents.rs b/rust/macros/concat_idents.rs new file mode 100644 index 000000000000..7e4b450f3a50 --- /dev/null +++ b/rust/macros/concat_idents.rs @@ -0,0 +1,23 @@ +// SPDX-License-Identifier: GPL-2.0 + +use proc_macro::{token_stream, Ident, TokenStream, TokenTree}; + +use crate::helpers::expect_punct; + +fn expect_ident(it: &mut token_stream::IntoIter) -> Ident { + if let Some(TokenTree::Ident(ident)) = it.next() { + ident + } else { + panic!("Expected Ident") + } +} + +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"); + let res = Ident::new(&format!("{a}{b}"), b.span()); + TokenStream::from_iter([TokenTree::Ident(res)]) +} diff --git a/rust/macros/lib.rs b/rust/macros/lib.rs index 91764bfb1f89..15555e7ff487 100644 --- a/rust/macros/lib.rs +++ b/rust/macros/lib.rs @@ -2,6 +2,7 @@ //! Crate for all kernel procedural macros. +mod concat_idents; mod helpers; mod module; @@ -70,3 +71,46 @@ use proc_macro::TokenStream; pub fn module(ts: TokenStream) -> TokenStream { module::module(ts) } + +/// Concatenate two identifiers. +/// +/// This is useful in macros that need to declare or reference items with names +/// starting with a fixed prefix and ending in a user specified name. The resulting +/// identifier has the span of the second argument. +/// +/// # Examples +/// +/// ```ignore +/// use kernel::macro::concat_idents; +/// +/// macro_rules! pub_no_prefix { +/// ($prefix:ident, $($newname:ident),+) => { +/// $(pub(crate) const $newname: u32 = kernel::macros::concat_idents!($prefix, $newname);)+ +/// }; +/// } +/// +/// pub_no_prefix!( +/// binder_driver_return_protocol_, +/// BR_OK, +/// BR_ERROR, +/// BR_TRANSACTION, +/// BR_REPLY, +/// BR_DEAD_REPLY, +/// BR_TRANSACTION_COMPLETE, +/// BR_INCREFS, +/// BR_ACQUIRE, +/// BR_RELEASE, +/// BR_DECREFS, +/// BR_NOOP, +/// BR_SPAWN_LOOPER, +/// BR_DEAD_BINDER, +/// BR_CLEAR_DEATH_NOTIFICATION_DONE, +/// BR_FAILED_REPLY +/// ); +/// +/// assert_eq!(BR_OK, binder_driver_return_protocol_BR_OK); +/// ``` +#[proc_macro] +pub fn concat_idents(ts: TokenStream) -> TokenStream { + concat_idents::concat_idents(ts) +} -- 2.38.1