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macro to use syn Date: Fri, 4 Sep 2026 16:32:28 +0100 Message-ID: <20260904153226.40210-3-jackwh.whitehorn@gmail.com> X-Mailer: git-send-email 2.55.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Rewrites the fmt! macro to use `syn` for parsing, also adds support for trailing commas in fmt! and related macros. I've checked that a range of rust modules (android binder, nova core, samples) still compile and tested the behaviour is still correct using a modified rust_print module. Signed-off-by: Jack Whitehorn Suggested-by: Alice Ryhl Suggested-by: Miguel Ojeda Link: https://github.com/Rust-for-Linux/linux/issues/1227 Link: https://github.com/Rust-for-Linux/linux/issues/1172 --- rust/macros/fmt.rs | 161 ++++++++++++++++++++++++--------------------- rust/macros/lib.rs | 4 +- 2 files changed, 90 insertions(+), 75 deletions(-) diff --git a/rust/macros/fmt.rs b/rust/macros/fmt.rs index ce6c7249305a..994a2924e6fb 100644 --- a/rust/macros/fmt.rs +++ b/rust/macros/fmt.rs @@ -1,96 +1,109 @@ // SPDX-License-Identifier: GPL-2.0 =20 -use std::collections::BTreeSet; +use std::collections::HashMap; =20 -use proc_macro2::{Ident, TokenStream, TokenTree}; +use proc_macro2::{Ident, TokenStream}; use quote::quote_spanned; +use syn::{ + ext::IdentExt, + parse::{Parse, ParseStream}, + parse_quote, Expr, LitStr, Result, Token, +}; =20 -/// Please see [`crate::fmt`] for documentation. -pub(crate) fn fmt(input: TokenStream) -> TokenStream { - let mut input =3D input.into_iter(); - - let first_opt =3D input.next(); - let first_owned_str; - let mut names =3D BTreeSet::new(); - let first_span =3D { - let Some((mut first_str, first_span)) =3D (match first_opt.as_ref(= ) { - Some(TokenTree::Literal(first_lit)) =3D> { - first_owned_str =3D first_lit.to_string(); - Some(first_owned_str.as_str()).and_then(|first| { - let first =3D first.strip_prefix('"')?; - let first =3D first.strip_suffix('"')?; - Some((first, first_lit.span())) - }) - } - _ =3D> None, - }) else { - return first_opt.into_iter().chain(input).collect(); +pub(crate) struct FormatArgs { + format_string: LitStr, + positional_args: Vec, + named_args: HashMap, +} + +impl Parse for FormatArgs { + fn parse(input: ParseStream<'_>) -> Result { + let format_string: LitStr =3D input.parse()?; + + let mut args =3D FormatArgs { + format_string, + positional_args: Vec::new(), + named_args: HashMap::new(), }; =20 - // Parse `identifier`s from the format string. - // - // See https://doc.rust-lang.org/std/fmt/index.html#syntax. - while let Some((_, rest)) =3D first_str.split_once('{') { - first_str =3D rest; - if let Some(rest) =3D first_str.strip_prefix('{') { - first_str =3D rest; - continue; + if input.is_empty() { + return Ok(args); + } + input.parse::()?; + + while !input.is_empty() && !input.peek2(Token![=3D]) { + args.positional_args.push(input.parse()?); + if input.is_empty() { + return Ok(args); } - if let Some((name, rest)) =3D first_str.split_once('}') { - first_str =3D rest; - let name =3D name.split_once(':').map_or(name, |(name, _)|= name); - if !name.is_empty() && !name.chars().all(|c| c.is_ascii_di= git()) { - names.insert(name); - } + input.parse::()?; + } + + while !input.is_empty() { + let name: Ident =3D input.call(Ident::parse_any)?; + input.parse::()?; + let value: Expr =3D input.parse()?; + args.named_args.insert(name, value); + + if input.is_empty() { + return Ok(args); } + input.parse::()?; } - first_span - }; =20 - let adapter =3D quote_spanned!(first_span =3D> ::kernel::fmt::Adapter); + return Ok(args); + } +} =20 - let mut args =3D TokenStream::from_iter(first_opt); +/// Please see [`crate::fmt`] for documentation. +pub(crate) fn fmt(args: FormatArgs) -> Result { + let FormatArgs { + format_string, + positional_args, + mut named_args, + } =3D args; + + let span =3D format_string.span(); + + // Add inline parameters as named arguments, so they are adapted appro= priately + // Input: fmt!("{name}") + // Output: fmt!("{name}", name =3D ::kernel::fmt::Adapter(&(name))) { - let mut flush =3D |args: &mut TokenStream, current: &mut TokenStre= am| { - let current =3D std::mem::take(current); - if !current.is_empty() { - let (lhs, rhs) =3D (|| { - let mut current =3D current.into_iter(); - let mut acc =3D TokenStream::new(); - while let Some(tt) =3D current.next() { - // Split on `=3D` only once to handle cases like `= a =3D b =3D c`. - if matches!(&tt, TokenTree::Punct(p) if p.as_char(= ) =3D=3D '=3D') { - names.remove(acc.to_string().as_str()); - // Include the `=3D` itself to keep the handli= ng below uniform. - acc.extend([tt]); - return (Some(acc), current.collect::()); - } - acc.extend([tt]); - } - (None, acc) - })(); - args.extend(quote_spanned!(first_span =3D> #lhs #adapter(&= (#rhs)))); + let format_string =3D format_string.value(); + let mut format_string =3D format_string.as_str(); + while let Some((_, rest)) =3D format_string.split_once('{') { + format_string =3D rest; + + if let Some(rest) =3D format_string.strip_prefix('{') { + format_string =3D rest; + continue; } - }; =20 - let mut current =3D TokenStream::new(); - for tt in input { - match &tt { - TokenTree::Punct(p) if p.as_char() =3D=3D ',' =3D> { - flush(&mut args, &mut current); - &mut args + if let Some((name, rest)) =3D format_string.split_once('}') { + format_string =3D rest; + let name =3D name.split_once(':').map_or(name, |(name, _)|= name); + if !name.is_empty() && !name.chars().all(|c| c.is_ascii_di= git()) { + let ident =3D Ident::new(name, span); + let expr =3D parse_quote!(#ident); + named_args.entry(ident).or_insert(expr); } - _ =3D> &mut current, } - .extend([tt]); } - flush(&mut args, &mut current); } =20 - for name in names { - let name =3D Ident::new(name, first_span); - args.extend(quote_spanned!(first_span =3D> , #name =3D #adapter(&#= name))); - } + // Wrap positional and named arguments with `kernel::fmt::Adapter` + let adapter =3D quote_spanned!(span =3D> ::kernel::fmt::Adapter); + let positional_args =3D positional_args + .into_iter() + .map(|value| quote_spanned!(span =3D> #adapter(&(#value)))); + let named_args =3D named_args + .into_iter() + .map(|(name, value)| quote_spanned!(span =3D> #name =3D #adapter(&= (#value)))); + + let args =3D [quote_spanned!(span =3D> #format_string)] + .into_iter() + .chain(positional_args) + .chain(named_args); =20 - quote_spanned!(first_span =3D> ::core::format_args!(#args)) + Ok(quote_spanned!(span =3D> ::core::format_args!(#(#args),*))) } diff --git a/rust/macros/lib.rs b/rust/macros/lib.rs index 24f96feaeb34..730607775a70 100644 --- a/rust/macros/lib.rs +++ b/rust/macros/lib.rs @@ -277,7 +277,9 @@ pub fn export(attr: TokenStream, input: TokenStream) ->= TokenStream { /// [`pr_info!`]: ../kernel/macro.pr_info.html #[proc_macro] pub fn fmt(input: TokenStream) -> TokenStream { - fmt::fmt(input.into()).into() + fmt::fmt(parse_macro_input!(input)) + .unwrap_or_else(|e| e.into_compile_error()) + .into() } =20 /// Concatenate two identifiers. --=20 2.55.0