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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2026-08-23 13:28:57 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2026-08-23 13:28:57 -0700 |
| commit | 4352b8aee98005853aa63f57d6377282de17a33f (patch) | |
| tree | 27614d7a9ef05c32d089004e104364ce42324837 /rust/syn/meta.rs | |
| download | linux-stable-4352b8aee98005853aa63f57d6377282de17a33f.tar.gz linux-stable-4352b8aee98005853aa63f57d6377282de17a33f.zip | |
Merge tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linuxgrafted
Pull I3C updates from Alexandre Belloni:
"A new driver this cycle, for the AMD AXI I3C controller.
There are also new features such as IBI wakeup support, SETAASA device
discovery and ACPI support for the the DAA methods, meaning we can now
communicate with the SPD devices on DDR5 modules.
New driver:
- AMD AXI I3C master controller
Subsystem:
- I3C Common Command Code (CCC) handling improvements, especially
around GET CCCs
- SETAASA device discovery support
- ACPI support for all existing DAA methods like SETDASA, SETNEWDA as
well as I2C devices on I3C bus
- IBI-based wakeup support
Drivers:
- dw: SETAASA support
- mipi-i3c-hci: advertise IBI wakeup capability, AMD_PT I3C
controller support, PIO queue management support for HCI v1.2
- renesas: improve suspend to RAM support, add runtime PM support"
* tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linux: (70 commits)
i3c: dw: reduce do_daa time if there's no client
i3c: mipi-i3c-hci: Add support for AMD_PT I3C controller
i3c: mipi-i3c-hci: Add PIO queue management support for HCI v1.2
i3c: mipi-i3c-hci: Fix missing STAT_IBI_STATUS_THLD in PIO mode
i3c: dw: rename "pclk" to "apb" to match dt-binding
i3c: dw: make struct dw_i3c_cmd smaller
i3c: dw: use COMMAND_PORT_TRANSFER_ARG instead of hardcoding
i3c: renesas: Don't register devices when ENTDAA times out
i3c: master: dw-i3c-master: fix OD timing for first broadcast
i3c: mipi-i3c-hci: Advertise IBI wakeup capability
i3c: mipi-i3c-hci: Factor out i3c_hci_sysdev()
i3c: mipi-i3c-hci-pci: Propagate I3C wakeup requirements to PCI
i3c: master: Reject IBI requests from non-IBI-capable devices
i3c: master: Add helper to query bus wakeup requirements
i3c: master: Report wakeup events for IBIs
i3c: master: Support IBI-based wakeup capability
i3c: master: Fix potential UAF in i3c_device_match()
i3c: master: Fix potential UAF in i3c_device_uevent()
i3c: Make dev->desc locking assumptions explicit
i3c: master: Fix use-after-free of master->this
...
Diffstat (limited to 'rust/syn/meta.rs')
| -rw-r--r-- | rust/syn/meta.rs | 429 |
1 files changed, 429 insertions, 0 deletions
diff --git a/rust/syn/meta.rs b/rust/syn/meta.rs new file mode 100644 index 000000000..2dd138e6d --- /dev/null +++ b/rust/syn/meta.rs @@ -0,0 +1,429 @@ +// SPDX-License-Identifier: Apache-2.0 OR MIT + +//! Facility for interpreting structured content inside of an `Attribute`. + +use crate::error::{Error, Result}; +use crate::ext::IdentExt as _; +use crate::lit::Lit; +use crate::parse::{ParseStream, Parser}; +use crate::path::{Path, PathSegment}; +use crate::punctuated::Punctuated; +use proc_macro2::Ident; +use std::fmt::Display; + +/// Make a parser that is usable with `parse_macro_input!` in a +/// `#[proc_macro_attribute]` macro. +/// +/// *Warning:* When parsing attribute args **other than** the +/// `proc_macro::TokenStream` input of a `proc_macro_attribute`, you do **not** +/// need this function. In several cases your callers will get worse error +/// messages if you use this function, because the surrounding delimiter's span +/// is concealed from attribute macros by rustc. Use +/// [`Attribute::parse_nested_meta`] instead. +/// +/// [`Attribute::parse_nested_meta`]: crate::Attribute::parse_nested_meta +/// +/// # Example +/// +/// This example implements an attribute macro whose invocations look like this: +/// +/// ``` +/// # const IGNORE: &str = stringify! { +/// #[tea(kind = "EarlGrey", hot)] +/// struct Picard {...} +/// # }; +/// ``` +/// +/// The "parameters" supported by the attribute are: +/// +/// - `kind = "..."` +/// - `hot` +/// - `with(sugar, milk, ...)`, a comma-separated list of ingredients +/// +/// ``` +/// # extern crate proc_macro; +/// # +/// use proc_macro::TokenStream; +/// use syn::{parse_macro_input, LitStr, Path}; +/// +/// # const IGNORE: &str = stringify! { +/// #[proc_macro_attribute] +/// # }; +/// pub fn tea(args: TokenStream, input: TokenStream) -> TokenStream { +/// let mut kind: Option<LitStr> = None; +/// let mut hot: bool = false; +/// let mut with: Vec<Path> = Vec::new(); +/// let tea_parser = syn::meta::parser(|meta| { +/// if meta.path.is_ident("kind") { +/// kind = Some(meta.value()?.parse()?); +/// Ok(()) +/// } else if meta.path.is_ident("hot") { +/// hot = true; +/// Ok(()) +/// } else if meta.path.is_ident("with") { +/// meta.parse_nested_meta(|meta| { +/// with.push(meta.path); +/// Ok(()) +/// }) +/// } else { +/// Err(meta.error("unsupported tea property")) +/// } +/// }); +/// +/// parse_macro_input!(args with tea_parser); +/// eprintln!("kind={kind:?} hot={hot} with={with:?}"); +/// +/// /* ... */ +/// # TokenStream::new() +/// } +/// ``` +/// +/// The `syn::meta` library will take care of dealing with the commas including +/// trailing commas, and producing sensible error messages on unexpected input. +/// +/// ```console +/// error: expected `,` +/// --> src/main.rs:3:37 +/// | +/// 3 | #[tea(kind = "EarlGrey", with(sugar = "lol", milk))] +/// | ^ +/// ``` +/// +/// # Example +/// +/// Same as above but we factor out most of the logic into a separate function. +/// +/// ``` +/// # extern crate proc_macro; +/// # +/// use proc_macro::TokenStream; +/// use syn::meta::ParseNestedMeta; +/// use syn::parse::{Parser, Result}; +/// use syn::{parse_macro_input, LitStr, Path}; +/// +/// # const IGNORE: &str = stringify! { +/// #[proc_macro_attribute] +/// # }; +/// pub fn tea(args: TokenStream, input: TokenStream) -> TokenStream { +/// let mut attrs = TeaAttributes::default(); +/// let tea_parser = syn::meta::parser(|meta| attrs.parse(meta)); +/// parse_macro_input!(args with tea_parser); +/// +/// /* ... */ +/// # TokenStream::new() +/// } +/// +/// #[derive(Default)] +/// struct TeaAttributes { +/// kind: Option<LitStr>, +/// hot: bool, +/// with: Vec<Path>, +/// } +/// +/// impl TeaAttributes { +/// fn parse(&mut self, meta: ParseNestedMeta) -> Result<()> { +/// if meta.path.is_ident("kind") { +/// self.kind = Some(meta.value()?.parse()?); +/// Ok(()) +/// } else /* just like in last example */ +/// # { unimplemented!() } +/// +/// } +/// } +/// ``` +pub fn parser(logic: impl FnMut(ParseNestedMeta) -> Result<()>) -> impl Parser<Output = ()> { + |input: ParseStream| { + if input.is_empty() { + Ok(()) + } else { + parse_nested_meta(input, logic) + } + } +} + +/// Context for parsing a single property in the conventional syntax for +/// structured attributes. +/// +/// # Examples +/// +/// Refer to usage examples on the following two entry-points: +/// +/// - [`Attribute::parse_nested_meta`] if you have an entire `Attribute` to +/// parse. Always use this if possible. Generally this is able to produce +/// better error messages because `Attribute` holds span information for all +/// of the delimiters therein. +/// +/// - [`syn::meta::parser`] if you are implementing a `proc_macro_attribute` +/// macro and parsing the arguments to the attribute macro, i.e. the ones +/// written in the same attribute that dispatched the macro invocation. Rustc +/// does not pass span information for the surrounding delimiters into the +/// attribute macro invocation in this situation, so error messages might be +/// less precise. +/// +/// [`Attribute::parse_nested_meta`]: crate::Attribute::parse_nested_meta +/// [`syn::meta::parser`]: crate::meta::parser +#[non_exhaustive] +pub struct ParseNestedMeta<'a> { + pub path: Path, + pub input: ParseStream<'a>, +} + +impl<'a> ParseNestedMeta<'a> { + /// Used when parsing `key = "value"` syntax. + /// + /// All it does is advance `meta.input` past the `=` sign in the input. You + /// could accomplish the same effect by writing + /// `meta.parse::<Token![=]>()?`, so at most it is a minor convenience to + /// use `meta.value()?`. + /// + /// # Example + /// + /// ``` + /// use syn::{parse_quote, Attribute, LitStr}; + /// + /// let attr: Attribute = parse_quote! { + /// #[tea(kind = "EarlGrey")] + /// }; + /// // conceptually: + /// if attr.path().is_ident("tea") { // this parses the `tea` + /// attr.parse_nested_meta(|meta| { // this parses the `(` + /// if meta.path.is_ident("kind") { // this parses the `kind` + /// let value = meta.value()?; // this parses the `=` + /// let s: LitStr = value.parse()?; // this parses `"EarlGrey"` + /// if s.value() == "EarlGrey" { + /// // ... + /// } + /// Ok(()) + /// } else { + /// Err(meta.error("unsupported attribute")) + /// } + /// })?; + /// } + /// # anyhow::Ok(()) + /// ``` + pub fn value(&self) -> Result<ParseStream<'a>> { + self.input.parse::<Token![=]>()?; + Ok(self.input) + } + + /// Used when parsing `list(...)` syntax **if** the content inside the + /// nested parentheses is also expected to conform to Rust's structured + /// attribute convention. + /// + /// # Example + /// + /// ``` + /// use syn::{parse_quote, Attribute}; + /// + /// let attr: Attribute = parse_quote! { + /// #[tea(with(sugar, milk))] + /// }; + /// + /// if attr.path().is_ident("tea") { + /// attr.parse_nested_meta(|meta| { + /// if meta.path.is_ident("with") { + /// meta.parse_nested_meta(|meta| { // <--- + /// if meta.path.is_ident("sugar") { + /// // Here we can go even deeper if needed. + /// Ok(()) + /// } else if meta.path.is_ident("milk") { + /// Ok(()) + /// } else { + /// Err(meta.error("unsupported ingredient")) + /// } + /// }) + /// } else { + /// Err(meta.error("unsupported tea property")) + /// } + /// })?; + /// } + /// # anyhow::Ok(()) + /// ``` + /// + /// # Counterexample + /// + /// If you don't need `parse_nested_meta`'s help in parsing the content + /// written within the nested parentheses, keep in mind that you can always + /// just parse it yourself from the exposed ParseStream. Rust syntax permits + /// arbitrary tokens within those parentheses so for the crazier stuff, + /// `parse_nested_meta` is not what you want. + /// + /// ``` + /// use syn::{parenthesized, parse_quote, Attribute, LitInt}; + /// + /// let attr: Attribute = parse_quote! { + /// #[repr(align(32))] + /// }; + /// + /// let mut align: Option<LitInt> = None; + /// if attr.path().is_ident("repr") { + /// attr.parse_nested_meta(|meta| { + /// if meta.path.is_ident("align") { + /// let content; + /// parenthesized!(content in meta.input); + /// align = Some(content.parse()?); + /// Ok(()) + /// } else { + /// Err(meta.error("unsupported repr")) + /// } + /// })?; + /// } + /// # anyhow::Ok(()) + /// ``` + pub fn parse_nested_meta( + &self, + logic: impl FnMut(ParseNestedMeta) -> Result<()>, + ) -> Result<()> { + let content; + parenthesized!(content in self.input); + parse_nested_meta(&content, logic) + } + + /// Report that the attribute's content did not conform to expectations. + /// + /// The span of the resulting error will cover `meta.path` *and* everything + /// that has been parsed so far since it. + /// + /// There are 2 ways you might call this. First, if `meta.path` is not + /// something you recognize: + /// + /// ``` + /// # use syn::Attribute; + /// # + /// # fn example(attr: &Attribute) -> syn::Result<()> { + /// attr.parse_nested_meta(|meta| { + /// if meta.path.is_ident("kind") { + /// // ... + /// Ok(()) + /// } else { + /// Err(meta.error("unsupported tea property")) + /// } + /// })?; + /// # Ok(()) + /// # } + /// ``` + /// + /// In this case, it behaves exactly like + /// `syn::Error::new_spanned(&meta.path, "message...")`. + /// + /// ```console + /// error: unsupported tea property + /// --> src/main.rs:3:26 + /// | + /// 3 | #[tea(kind = "EarlGrey", wat = "foo")] + /// | ^^^ + /// ``` + /// + /// More usefully, the second place is if you've already parsed a value but + /// have decided not to accept the value: + /// + /// ``` + /// # use syn::Attribute; + /// # + /// # fn example(attr: &Attribute) -> syn::Result<()> { + /// use syn::Expr; + /// + /// attr.parse_nested_meta(|meta| { + /// if meta.path.is_ident("kind") { + /// let expr: Expr = meta.value()?.parse()?; + /// match expr { + /// Expr::Lit(expr) => /* ... */ + /// # unimplemented!(), + /// Expr::Path(expr) => /* ... */ + /// # unimplemented!(), + /// Expr::Macro(expr) => /* ... */ + /// # unimplemented!(), + /// _ => Err(meta.error("tea kind must be a string literal, path, or macro")), + /// } + /// } else /* as above */ + /// # { unimplemented!() } + /// + /// })?; + /// # Ok(()) + /// # } + /// ``` + /// + /// ```console + /// error: tea kind must be a string literal, path, or macro + /// --> src/main.rs:3:7 + /// | + /// 3 | #[tea(kind = async { replicator.await })] + /// | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + /// ``` + /// + /// Often you may want to use `syn::Error::new_spanned` even in this + /// situation. In the above code, that would be: + /// + /// ``` + /// # use syn::{Error, Expr}; + /// # + /// # fn example(expr: Expr) -> syn::Result<()> { + /// match expr { + /// Expr::Lit(expr) => /* ... */ + /// # unimplemented!(), + /// Expr::Path(expr) => /* ... */ + /// # unimplemented!(), + /// Expr::Macro(expr) => /* ... */ + /// # unimplemented!(), + /// _ => Err(Error::new_spanned(expr, "unsupported expression type for `kind`")), + /// } + /// # } + /// ``` + /// + /// ```console + /// error: unsupported expression type for `kind` + /// --> src/main.rs:3:14 + /// | + /// 3 | #[tea(kind = async { replicator.await })] + /// | ^^^^^^^^^^^^^^^^^^^^^^^^^^ + /// ``` + pub fn error(&self, msg: impl Display) -> Error { + let start_span = self.path.segments[0].ident.span(); + let end_span = self.input.cursor().prev_span(); + crate::error::new2(start_span, end_span, msg) + } +} + +pub(crate) fn parse_nested_meta( + input: ParseStream, + mut logic: impl FnMut(ParseNestedMeta) -> Result<()>, +) -> Result<()> { + loop { + let path = input.call(parse_meta_path)?; + logic(ParseNestedMeta { path, input })?; + if input.is_empty() { + return Ok(()); + } + input.parse::<Token![,]>()?; + if input.is_empty() { + return Ok(()); + } + } +} + +// Like Path::parse_mod_style, but accepts keywords in the path. +fn parse_meta_path(input: ParseStream) -> Result<Path> { + Ok(Path { + leading_colon: input.parse()?, + segments: { + let mut segments = Punctuated::new(); + if input.peek(Ident::peek_any) { + let ident = Ident::parse_any(input)?; + segments.push_value(PathSegment::from(ident)); + } else if input.is_empty() { + return Err(input.error("expected nested attribute")); + } else if input.peek(Lit) { + return Err(input.error("unexpected literal in nested attribute, expected ident")); + } else { + return Err(input.error("unexpected token in nested attribute, expected ident")); + } + while input.peek(Token![::]) { + let punct = input.parse()?; + segments.push_punct(punct); + let ident = Ident::parse_any(input)?; + segments.push_value(PathSegment::from(ident)); + } + segments + }, + }) +} |
