From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9ED8453D0B3; Wed, 23 Sep 2026 14:07:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790172436; cv=none; b=LtHNUs3I2vjPSBAzT4Jw2Qh7goPwnlw1y14XkBHihQ3mKMb/iD0ofTbi2pRerVwpXmC5sqRIqh/C6AbzieSbNvVaI73GiXMCcvGqZy3N8AGozz2EHvmNoAWspW1ZHWnfoCAPVi+35uwJYqnDCPfBCNf6TzLTv7QPqc1VO4iBLss= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790172436; c=relaxed/simple; bh=DVmg1Qw+UJvOzq9bmew3Kfr7VsO1+wfWT4VU/mAKc84=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=jCMcDpfFMgFOmUBlhMGB1loioxyV5UtoTAnFUBmhW0tJuH7t9PLgyXBvqshEtw1G2HqB/JU7wQHi31eJQPNjANVkPz1wGqE2t+Bmt0mqLDQK9q8ync8C5LlmY8XWPIBkeSs3NCiYL9y3EWpSXz6/TFeYnUHEx7Rz5VPdsAGbdX8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=R/B+oYmm; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="R/B+oYmm" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1CCB21F000FF; Wed, 23 Sep 2026 14:07:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790172432; bh=PvQPNZtEOwJUljthFnc90/Uq2bva5cJfHgJ0X/p1BpI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:Reply-To; b=R/B+oYmmcbYDaz5llw4lgl5ohLejcCIAyjQvBitxYIozAs2rRaiUUd6N66hkwUycx FM1ZV4/xtIp60tW4OBnNOYfdxKcXpiaIdGxyPlDs4Im0liwxdOcFLawzgiPd8+aFbd VLTWNrs5tlT//6C7Xg0Kej3lKrk/x8k4nA3HvJiavezP/35mmV2pZxuIhs/WDKQNk+ JDYH1K8Hto+TaNP6dDyu97qwhCyhV9gYfdan4MsEdAXNRuzuB72w+qOkfsSJResibI yO91VqpBeBTwH4TJDgRlH3f3Wdc8oo6ynG2S0f2mogjAiX9ntlcIk35xjg550NRUTq wMmW/2gYPO48A== From: Gary Guo To: Benno Lossin , Gary Guo , Miguel Ojeda , Boqun Feng , =?UTF-8?q?Bj=C3=B6rn=20Roy=20Baron?= , Andreas Hindborg , Alice Ryhl , Trevor Gross , Danilo Krummrich , Daniel Almeida , Tamir Duberstein , Alexandre Courbot , =?UTF-8?q?Onur=20=C3=96zkan?= Cc: rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 2/3] rust: pin-init: internal: make `DiagCtxt` available inside parser Date: Wed, 23 Sep 2026 15:06:14 +0100 Message-ID: <20260923140618.1978181-2-gary@kernel.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260923140618.1978181-1-gary@kernel.org> References: <20260923140618.1978181-1-gary@kernel.org> Reply-To: Gary Guo Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Gary Guo Currently, there is a split between `syn::Error` and pin-init's custom `DiagCtxt`. Parsing has no access to `DiagCtxt` and therefore cannot report diagnostics without failing the parse. Bridge the gap by making the `DiagCtxt` available inside parsers using `thread_local!`. `parse_macro_input!` returns error as token stream directly, so it is no longer suitable when the parsing is moved inside `DiagCtxt` closure. Add a `From for ErrorGuaranteed` implementation so `?` can be used to add a `syn::Error` into the current diagnostic context and obtain a `ErrorGuaranteed`. Clean up the handler of using `<-` inside tuple expression as a demonstration of the usefulness of having `DiagCtxt` access inside `Parse`. Signed-off-by: Gary Guo --- rust/pin-init/internal/src/diagnostics.rs | 84 ++++++++++++++++++----- rust/pin-init/internal/src/init.rs | 41 ++++------- rust/pin-init/internal/src/lib.rs | 32 +++++---- 3 files changed, 96 insertions(+), 61 deletions(-) diff --git a/rust/pin-init/internal/src/diagnostics.rs b/rust/pin-init/internal/src/diagnostics.rs index c42f1095ab10..efdcf45f40cf 100644 --- a/rust/pin-init/internal/src/diagnostics.rs +++ b/rust/pin-init/internal/src/diagnostics.rs @@ -1,32 +1,68 @@ // SPDX-License-Identifier: Apache-2.0 OR MIT +use std::cell::RefCell; use std::fmt::Display; +use std::marker::PhantomData; use proc_macro2::TokenStream; use quote::{quote, quote_spanned}; use syn::{spanned::Spanned, Error}; -pub(crate) struct DiagCtxt(TokenStream); +pub(crate) struct DiagCtxt(PhantomData<*mut ()>); pub(crate) struct ErrorGuaranteed(()); +struct DiagCtxtData { + diag: TokenStream, +} + +thread_local! { + static DIAGNOSTICS: RefCell> = const { RefCell::new(None) }; +} + +// Allows `syn::Error` to be emitted into the current diagnostic context with just `?`. +impl From for ErrorGuaranteed { + fn from(error: syn::Error) -> Self { + DIAGNOSTICS.with_borrow_mut(|data| { + data.as_mut() + .unwrap() + .diag + .extend(error.into_compile_error()); + }); + Self(()) + } +} + impl DiagCtxt { - pub(crate) fn error(&mut self, span: impl Spanned, msg: impl Display) -> ErrorGuaranteed { - let error = Error::new(span.span(), msg); - self.0.extend(error.into_compile_error()); - ErrorGuaranteed(()) + pub(crate) fn error(&self, span: impl Spanned, msg: impl Display) -> ErrorGuaranteed { + Error::new(span.span(), msg).into() } - pub(crate) fn warn(&mut self, span: impl Spanned, msg: impl Display) { + pub(crate) fn warn(&self, span: impl Spanned, msg: impl Display) { // Have the message start on a new line for visual clarity. let msg = format!("\n{}", msg); - self.0.extend(quote_spanned!(span.span() => - // Approximate using deprecated warning while `proc_macro_diagnostic` is unstable. - const _: () = { - #[deprecated = #msg] - const fn warn() {} - warn(); - }; - )); + DIAGNOSTICS.with_borrow_mut(|data| { + data.as_mut() + .unwrap() + .diag + .extend(quote_spanned!(span.span() => + // Approximate using deprecated warning while `proc_macro_diagnostic` is + // unstable. + const _: () = { + #[deprecated = #msg] + const fn warn() {} + warn(); + }; + )) + }); + } + + /// Execute the provided function with the current diagnostic context. + pub(crate) fn current(f: impl FnOnce(&DiagCtxt) -> R) -> R { + DIAGNOSTICS.with_borrow(|data| { + assert!(data.is_some(), "No active `DiagCtxt`"); + }); + + f(&DiagCtxt(PhantomData)) } fn with( @@ -34,16 +70,26 @@ fn with( merge_diag: impl FnOnce(TokenStream, TokenStream) -> TokenStream, convert_diag: impl FnOnce(TokenStream) -> TokenStream, ) -> TokenStream { - let mut dcx = Self(TokenStream::new()); - match f(&mut dcx) { + DIAGNOSTICS.with_borrow_mut(|data| { + assert!(data.is_none(), "`DiagCtxt` cannot be nested"); + *data = Some(DiagCtxtData { + diag: TokenStream::new(), + }); + }); + + let result = f(&mut DiagCtxt(PhantomData)); + + let data = DIAGNOSTICS.with_borrow_mut(|data| data.take().unwrap()); + + match result { Ok(stream) => { - if dcx.0.is_empty() { + if data.diag.is_empty() { stream } else { - merge_diag(stream, dcx.0) + merge_diag(stream, data.diag) } } - Err(ErrorGuaranteed(())) => convert_diag(dcx.0), + Err(ErrorGuaranteed(())) => convert_diag(data.diag), } } diff --git a/rust/pin-init/internal/src/init.rs b/rust/pin-init/internal/src/init.rs index 1d2db93dd33d..b60feb68b65f 100644 --- a/rust/pin-init/internal/src/init.rs +++ b/rust/pin-init/internal/src/init.rs @@ -44,9 +44,6 @@ pub(crate) enum InitExprKind { struct InitTupleField { attrs: Vec, - /// `<-` is not valid in constructor syntax; it is parsed anyway so that it can be rejected - /// with a proper diagnostic instead of a parse error. - left_arrow_token: Option, value: Expr, } @@ -84,20 +81,6 @@ fn normalize(self) -> InitExprStruct { rest: None, } } - - fn validate(&self, dcx: &mut DiagCtxt) -> Result<(), ErrorGuaranteed> { - let mut result = Ok(()); - for field in &self.fields { - if let Some(left_arrow_token) = &field.left_arrow_token { - result = Err(dcx.error( - left_arrow_token, - "`<-` is not supported in tuple constructor syntax; name the fields by index \ - instead, e.g. `Type { 0 <- initializer, 1: value }`", - )); - } - } - result - } } struct This { @@ -153,8 +136,6 @@ pub(crate) fn expand_with_cfg( ) -> Result { let initializer = match initializer.kind { InitExprKind::Tuple(expr) => { - expr.validate(dcx)?; - let mut initializer = Initializer { attrs: initializer.attrs, this: initializer.this, @@ -578,9 +559,20 @@ fn parse_with_path(path: Path, input: syn::parse::ParseStream<'_>) -> syn::Resul let paren_token = parenthesized!(content in input); let mut fields = Punctuated::new(); while !content.is_empty() { + let attrs = content.call(Attribute::parse_outer)?; + + if let Some(left_arrow_token) = content.parse::>()? { + DiagCtxt::current(|dcx| { + dcx.error( + left_arrow_token, + "`<-` is not supported in tuple constructor syntax; name the fields by index \ + instead, e.g. `Type { 0 <- initializer, 1: value }`", + ) + }); + } + fields.push_value(InitTupleField { - attrs: content.call(Attribute::parse_outer)?, - left_arrow_token: content.parse()?, + attrs, value: content.parse()?, }); if content.is_empty() { @@ -757,13 +749,8 @@ fn to_tokens(&self, tokens: &mut TokenStream) { impl ToTokens for InitTupleField { fn to_tokens(&self, tokens: &mut TokenStream) { - let Self { - attrs, - left_arrow_token, - value, - } = self; + let Self { attrs, value } = self; tokens.append_all(attrs); - left_arrow_token.to_tokens(tokens); value.to_tokens(tokens); } } diff --git a/rust/pin-init/internal/src/lib.rs b/rust/pin-init/internal/src/lib.rs index 0410024ba1e6..07b3d33d2282 100644 --- a/rust/pin-init/internal/src/lib.rs +++ b/rust/pin-init/internal/src/lib.rs @@ -10,7 +10,6 @@ #![allow(missing_docs)] use proc_macro::TokenStream; -use syn::parse_macro_input; use crate::diagnostics::DiagCtxt; @@ -23,43 +22,46 @@ #[proc_macro_attribute] pub fn pin_data(args: TokenStream, input: TokenStream) -> TokenStream { - let args = parse_macro_input!(args); - let input = parse_macro_input!(input); - DiagCtxt::for_item(|dcx| pin_data::pin_data(args, input, dcx)).into() + DiagCtxt::for_item(|dcx| pin_data::pin_data(syn::parse(args)?, syn::parse(input)?, dcx)).into() } #[proc_macro_attribute] pub fn pinned_drop(args: TokenStream, input: TokenStream) -> TokenStream { - let args = parse_macro_input!(args); - let input = parse_macro_input!(input); - DiagCtxt::for_item(|dcx| pinned_drop::pinned_drop(args, input, dcx)).into() + DiagCtxt::for_item(|dcx| pinned_drop::pinned_drop(syn::parse(args)?, syn::parse(input)?, dcx)) + .into() } #[proc_macro_derive(Zeroable)] pub fn derive_zeroable(input: TokenStream) -> TokenStream { - let input = parse_macro_input!(input); - DiagCtxt::for_item(|dcx| zeroable::derive(input, dcx)).into() + DiagCtxt::for_item(|dcx| zeroable::derive(syn::parse(input)?, dcx)).into() } #[proc_macro_derive(MaybeZeroable)] pub fn maybe_derive_zeroable(input: TokenStream) -> TokenStream { - let input = parse_macro_input!(input); - DiagCtxt::for_item(|dcx| zeroable::maybe_derive(input, dcx)).into() + DiagCtxt::for_item(|dcx| zeroable::maybe_derive(syn::parse(input)?, dcx)).into() } #[proc_macro] pub fn init(input: TokenStream) -> TokenStream { - let input = parse_macro_input!(input); DiagCtxt::for_expr(|dcx| { - init::expand_with_cfg(input, Some("::core::convert::Infallible"), false, dcx) + init::expand_with_cfg( + syn::parse(input)?, + Some("::core::convert::Infallible"), + false, + dcx, + ) }) .into() } #[proc_macro] pub fn pin_init(input: TokenStream) -> TokenStream { - let input = parse_macro_input!(input); DiagCtxt::for_expr(|dcx| { - init::expand_with_cfg(input, Some("::core::convert::Infallible"), true, dcx) + init::expand_with_cfg( + syn::parse(input)?, + Some("::core::convert::Infallible"), + true, + dcx, + ) }) .into() } -- 2.54.0