From 22098763a10d9c1340827fcf6edab66f153b27f0 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sun, 13 Sep 2026 12:27:00 -0700 Subject: Merge tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace Pull tracing fixes from Steven Rostedt: - Don't destroy user event fields when removal fails User event fields are destroyed before the event is removed from visibility. But that can fail leaving the still visible event with no fields. Move the destroying of the fields to after the event is successfully removed from visibility. - Initialize function graph state is fork before calling copy_exec_state() For non-CLONE_VM forks, copy_exec_state() allocates a new task_exec_state. If that allocation fails, ftrace_graph_exit_task() will free the tasks ret_stack pointer. Since that pointer is still using the parent's ret_stack, it mistakenly frees the parent's pointer too. Call ftrace_graph_init() on the task first which will NULL out the new tasks's ret_stack and if the copy fails, it will not free anything. - Remove FGRAPH_MAX_INDEX The macro FGRAPH_MAX_INDEX was added but never used. Remove it. - Save ent_size in function graph printing of nested functions The function graph tracer needs to look at the next event to see if the next event is the return of the current function entry. If it is, it prints a single line: ktime_get(); Otherwise it prints it like a nested function: tick_nohz_irq_exit() { ktime_get(); kcpustat_irq_exit(); } In order to look at the next event, it must save the current event so that it has the information to print from it. It saves the event in the iterator descriptor called "ent". What it doesn't save is the ent_size of the event which is now used to know if the function graph arguments are to be printed. The peek doesn't save the size so the size used happens to be that of the size of the last event that was seen. Save the entry event size in the iterator descriptor so that the correct size is used. - Fix several errors with freeing data in the histogram code The histogram code had a lot of leaked or or incorrect accounting when failures happen. Correct them. - Fix histogram regression of .percent and .graph modifiers Up until 6.3 histogram values could have "percent" or "graph" modifiers that changed how they were printed. But a change that added restricting histograms values from being strings, stack traces and other modifiers inadvertently prevented them from using the percent and graph modifiers, which were legal use cases for values. Put back the percent and graph modifiers. - Fix various typos in the comments - Set the trace_clock before initializing a histogram with clock argument The histogram API allows the user to specific which trace clock to use via a "clock=" string. The histogram is set up first before the clock is checked. If the passed in clock is not valid, it exits without fully fixing up the histogram leaving it on the list and a use-after-free can trigger. Update the clock argument first and if it fails then exit gracefully before the histogram trigger is placed on any lists. - Restore :mod: trailer after parsing in ftrace_set_clr_event The function ftrace_set_clr_event() modifies the parse string and needs to put it back to what was passed in. It searches for ":mod:" via a strsep() but fails to put back the first ':' in the string. Add back the ':' in the passed in string. - Take trace_array reference when opening a tracer options file The options files are dynamically created and some tracers add their own options. When a tracer adds their own list of options, the trace_array holding them has an array to hold the list of options for each tracer. This array increases in size via a krealloc(), and the new entry gets a newly allocated array to hold the options of the new tracer being added. The element in each entry of the tracer's option array holds a pointer back to the trace_array, a pointer to the tracer it is associated to, a pointer to the flags of the option. The issue is that these arrays are freed when the trace_array is freed when its instance it represents is removed from the instances directory. There's a race that an open of one of these options files can happen when the instance is being removed. Add a new helper function to be called by the open function of the options file to iterate all existing trace_arrays under a lock and find the one that has the given option element in one of it's tracer arrays. If found, then update the associated trace_array's reference counter to keep it from being freed. If not found, have the open call return -ENODEV. - Disable interrupts when acquiring the lock in rb_wake_up_waiters() The function rb_wake_up_waiters() assumes it will be called in interrupt context and does not disable irqs when taking cpu_buffer->reader_lock, which can be called in hard interrupt context. The issue is in PREEMPT_RT, this function is called in thread context leaving this lock open to a deadlock. Take the lock with interrupts disabled. - Use rcu_assign_pointer() for tmp_ops filter hash The tmp_ops used in update_ftrace_direct_mod() assigns its filter_hash field directly, but that field is annotated as __rcu and sparse complains. Assign it with rcu_assign_pointer() - Fix use-after-free in enable_trigger_private_data_free() The trace_event_call is accessed through the event_trigger_data's trace_event_file pointer to put the trace_event_call on freeing. The issue is that the trace_event_file data may have been freed already causing a use-after-free. Add a field to the event_trigger_data that points directly to the trace_event_call so that it can decrement its reference directly without needing to go through the trace_event_file. - Fix accounting of buffer data remote headers trace_buffer_desc_size() and trace_remote_alloc_buffer() undercount the number of pages is needed for the asked for size as it doesn't take into account the meta data on each page. Add a helper function to do the calculation properly and use that in these functions. - Catch nr_page_va overflow in ring_buffer_desc sizing The number of pages per remote ring buffer is capped by ring_buffer_desc::nr_page_va (32 bits). A buffer_size large enough to overflow that field would silently allocate a descriptor smaller than what was asked for. - Do not resize the subbuf order if any per_cpu buffer is disabled The mmapping of ring buffers disables resizing the subbuffers, but it is done per-cpu whereas the subbuf size change is done for all the per_cpu buffers under the buffer->mutex. It could change the size of some while the mapping is happening on others. Have the resize of the subbuf order check all the per_cpu buffers under the lock to see if any of them is disabled before starting and causing an inconsistency between buffers that are being mapped. * tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (25 commits) ring-buffer: Check resize_disabled before publishing the new subbuf order tracing/remotes: Catch nr_page_va overflow in ring_buffer_desc sizing tracing/remotes: Account for ring buffer page header in size calculation tracing: Don't dereference trace_event_file in deferred trigger free ftrace: Use rcu_assign_pointer() for tmp_ops filter hash ring-buffer: Acquire the lock with irqsave in rb_wake_up_waiters() tracing: Take trace_array reference when opening a tracer options file tracing: Fix ring_buffer_read_page_size() kernel-doc tracing: Restore :mod: trailer after parsing in ftrace_set_clr_event() tracing: Fix memory corruption from a "STACKTRACE" histogram key tracing: Fix memory corruption from the histogram stacktrace modifier tracing: Undo the registration when enabling the histogram trigger fails tracing: Take the reference before publishing the named histogram trigger tracing: Set the trace clock before registering the histogram trigger tracing: Fix typo "preceeded" in comment tracing: Fix typo "availabe" in comment tracing: Let histogram values keep the percent and graph modifiers tracing: Keep the entry count when the histogram stats allocation fails tracing: Free histogram the field rejected for a bad modifier tracing: Free histogram the var ref when its initialization fails ... --- rust/syn/attr.rs | 838 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 838 insertions(+) create mode 100644 rust/syn/attr.rs (limited to 'rust/syn/attr.rs') diff --git a/rust/syn/attr.rs b/rust/syn/attr.rs new file mode 100644 index 000000000..020b31f9d --- /dev/null +++ b/rust/syn/attr.rs @@ -0,0 +1,838 @@ +// SPDX-License-Identifier: Apache-2.0 OR MIT + +#[cfg(feature = "parsing")] +use crate::error::Error; +#[cfg(feature = "parsing")] +use crate::error::Result; +use crate::expr::Expr; +use crate::mac::MacroDelimiter; +#[cfg(feature = "parsing")] +use crate::meta::{self, ParseNestedMeta}; +#[cfg(feature = "parsing")] +use crate::parse::{Parse, ParseStream, Parser}; +use crate::path::Path; +use crate::token; +use proc_macro2::TokenStream; +#[cfg(feature = "printing")] +use std::iter; +#[cfg(feature = "printing")] +use std::slice; + +ast_struct! { + /// An attribute, like `#[repr(transparent)]`. + /// + ///
+ /// + /// # Syntax + /// + /// Rust has six types of attributes. + /// + /// - Outer attributes like `#[repr(transparent)]`. These appear outside or + /// in front of the item they describe. + /// + /// - Inner attributes like `#![feature(proc_macro)]`. These appear inside + /// of the item they describe, usually a module. + /// + /// - Outer one-line doc comments like `/// Example`. + /// + /// - Inner one-line doc comments like `//! Please file an issue`. + /// + /// - Outer documentation blocks `/** Example */`. + /// + /// - Inner documentation blocks `/*! Please file an issue */`. + /// + /// The `style` field of type `AttrStyle` distinguishes whether an attribute + /// is outer or inner. + /// + /// Every attribute has a `path` that indicates the intended interpretation + /// of the rest of the attribute's contents. The path and the optional + /// additional contents are represented together in the `meta` field of the + /// attribute in three possible varieties: + /// + /// - Meta::Path — attributes whose information content conveys just a + /// path, for example the `#[test]` attribute. + /// + /// - Meta::List — attributes that carry arbitrary tokens after the + /// path, surrounded by a delimiter (parenthesis, bracket, or brace). For + /// example `#[derive(Copy)]` or `#[precondition(x < 5)]`. + /// + /// - Meta::NameValue — attributes with an `=` sign after the path, + /// followed by a Rust expression. For example `#[path = + /// "sys/windows.rs"]`. + /// + /// All doc comments are represented in the NameValue style with a path of + /// "doc", as this is how they are processed by the compiler and by + /// `macro_rules!` macros. + /// + /// ```text + /// #[derive(Copy, Clone)] + /// ~~~~~~Path + /// ^^^^^^^^^^^^^^^^^^^Meta::List + /// + /// #[path = "sys/windows.rs"] + /// ~~~~Path + /// ^^^^^^^^^^^^^^^^^^^^^^^Meta::NameValue + /// + /// #[test] + /// ^^^^Meta::Path + /// ``` + /// + ///
+ /// + /// # Parsing from tokens to Attribute + /// + /// This type does not implement the [`Parse`] trait and thus cannot be + /// parsed directly by [`ParseStream::parse`]. Instead use + /// [`ParseStream::call`] with one of the two parser functions + /// [`Attribute::parse_outer`] or [`Attribute::parse_inner`] depending on + /// which you intend to parse. + /// + /// [`Parse`]: crate::parse::Parse + /// [`ParseStream::parse`]: crate::parse::ParseBuffer::parse + /// [`ParseStream::call`]: crate::parse::ParseBuffer::call + /// + /// ``` + /// use syn::{Attribute, Ident, Result, Token}; + /// use syn::parse::{Parse, ParseStream}; + /// + /// // Parses a unit struct with attributes. + /// // + /// // #[path = "s.tmpl"] + /// // struct S; + /// struct UnitStruct { + /// attrs: Vec, + /// struct_token: Token![struct], + /// name: Ident, + /// semi_token: Token![;], + /// } + /// + /// impl Parse for UnitStruct { + /// fn parse(input: ParseStream) -> Result { + /// Ok(UnitStruct { + /// attrs: input.call(Attribute::parse_outer)?, + /// struct_token: input.parse()?, + /// name: input.parse()?, + /// semi_token: input.parse()?, + /// }) + /// } + /// } + /// ``` + /// + ///


+ /// + /// # Parsing from Attribute to structured arguments + /// + /// The grammar of attributes in Rust is very flexible, which makes the + /// syntax tree not that useful on its own. In particular, arguments of the + /// `Meta::List` variety of attribute are held in an arbitrary `tokens: + /// TokenStream`. Macros are expected to check the `path` of the attribute, + /// decide whether they recognize it, and then parse the remaining tokens + /// according to whatever grammar they wish to require for that kind of + /// attribute. Use [`parse_args()`] to parse those tokens into the expected + /// data structure. + /// + /// [`parse_args()`]: Attribute::parse_args + /// + ///


+ /// + /// # Doc comments + /// + /// The compiler transforms doc comments, such as `/// comment` and `/*! + /// comment */`, into attributes before macros are expanded. Each comment is + /// expanded into an attribute of the form `#[doc = r"comment"]`. + /// + /// As an example, the following `mod` items are expanded identically: + /// + /// ``` + /// # use syn::{ItemMod, parse_quote}; + /// let doc: ItemMod = parse_quote! { + /// /// Single line doc comments + /// /// We write so many! + /// /** + /// * Multi-line comments... + /// * May span many lines + /// */ + /// mod example { + /// //! Of course, they can be inner too + /// /*! And fit in a single line */ + /// } + /// }; + /// let attr: ItemMod = parse_quote! { + /// #[doc = r" Single line doc comments"] + /// #[doc = r" We write so many!"] + /// #[doc = r" + /// * Multi-line comments... + /// * May span many lines + /// "] + /// mod example { + /// #![doc = r" Of course, they can be inner too"] + /// #![doc = r" And fit in a single line "] + /// } + /// }; + /// assert_eq!(doc, attr); + /// ``` + #[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))] + pub struct Attribute { + pub pound_token: Token![#], + pub style: AttrStyle, + pub bracket_token: token::Bracket, + pub meta: Meta, + } +} + +impl Attribute { + /// Returns the path that identifies the interpretation of this attribute. + /// + /// For example this would return the `test` in `#[test]`, the `derive` in + /// `#[derive(Copy)]`, and the `path` in `#[path = "sys/windows.rs"]`. + pub fn path(&self) -> &Path { + self.meta.path() + } + + /// Parse the arguments to the attribute as a syntax tree. + /// + /// This is similar to pulling out the `TokenStream` from `Meta::List` and + /// doing `syn::parse2::(meta_list.tokens)`, except that using + /// `parse_args` the error message has a more useful span when `tokens` is + /// empty. + /// + /// The surrounding delimiters are *not* included in the input to the + /// parser. + /// + /// ```text + /// #[my_attr(value < 5)] + /// ^^^^^^^^^ what gets parsed + /// ``` + /// + /// # Example + /// + /// ``` + /// use syn::{parse_quote, Attribute, Expr}; + /// + /// let attr: Attribute = parse_quote! { + /// #[precondition(value < 5)] + /// }; + /// + /// if attr.path().is_ident("precondition") { + /// let precondition: Expr = attr.parse_args()?; + /// // ... + /// } + /// # anyhow::Ok(()) + /// ``` + #[cfg(feature = "parsing")] + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + pub fn parse_args(&self) -> Result { + self.parse_args_with(T::parse) + } + + /// Parse the arguments to the attribute using the given parser. + /// + /// # Example + /// + /// ``` + /// use syn::{parse_quote, Attribute}; + /// + /// let attr: Attribute = parse_quote! { + /// #[inception { #[brrrrrrraaaaawwwwrwrrrmrmrmmrmrmmmmm] }] + /// }; + /// + /// let bwom = attr.parse_args_with(Attribute::parse_outer)?; + /// + /// // Attribute does not have a Parse impl, so we couldn't directly do: + /// // let bwom: Attribute = attr.parse_args()?; + /// # anyhow::Ok(()) + /// ``` + #[cfg(feature = "parsing")] + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + pub fn parse_args_with(&self, parser: F) -> Result { + match &self.meta { + Meta::Path(path) => Err(crate::error::new2( + path.segments.first().unwrap().ident.span(), + path.segments.last().unwrap().ident.span(), + format!( + "expected attribute arguments in parentheses: {}[{}(...)]", + parsing::DisplayAttrStyle(&self.style), + parsing::DisplayPath(path), + ), + )), + Meta::NameValue(meta) => Err(Error::new( + meta.eq_token.span, + format_args!( + "expected parentheses: {}[{}(...)]", + parsing::DisplayAttrStyle(&self.style), + parsing::DisplayPath(&meta.path), + ), + )), + Meta::List(meta) => meta.parse_args_with(parser), + } + } + + /// Parse the arguments to the attribute, expecting it to follow the + /// conventional structure used by most of Rust's built-in attributes. + /// + /// The [*Meta Item Attribute Syntax*][syntax] section in the Rust reference + /// explains the convention in more detail. Not all attributes follow this + /// convention, so [`parse_args()`][Self::parse_args] is available if you + /// need to parse arbitrarily goofy attribute syntax. + /// + /// [syntax]: https://doc.rust-lang.org/reference/attributes.html#meta-item-attribute-syntax + /// + /// # Example + /// + /// We'll parse a struct, and then parse some of Rust's `#[repr]` attribute + /// syntax. + /// + /// ``` + /// use syn::{parenthesized, parse_quote, token, ItemStruct, LitInt}; + /// + /// let input: ItemStruct = parse_quote! { + /// #[repr(C, align(4))] + /// pub struct MyStruct(u16, u32); + /// }; + /// + /// let mut repr_c = false; + /// let mut repr_transparent = false; + /// let mut repr_align = None::; + /// let mut repr_packed = None::; + /// for attr in &input.attrs { + /// if attr.path().is_ident("repr") { + /// attr.parse_nested_meta(|meta| { + /// // #[repr(C)] + /// if meta.path.is_ident("C") { + /// repr_c = true; + /// return Ok(()); + /// } + /// + /// // #[repr(transparent)] + /// if meta.path.is_ident("transparent") { + /// repr_transparent = true; + /// return Ok(()); + /// } + /// + /// // #[repr(align(N))] + /// if meta.path.is_ident("align") { + /// let content; + /// parenthesized!(content in meta.input); + /// let lit: LitInt = content.parse()?; + /// let n: usize = lit.base10_parse()?; + /// repr_align = Some(n); + /// return Ok(()); + /// } + /// + /// // #[repr(packed)] or #[repr(packed(N))], omitted N means 1 + /// if meta.path.is_ident("packed") { + /// if meta.input.peek(token::Paren) { + /// let content; + /// parenthesized!(content in meta.input); + /// let lit: LitInt = content.parse()?; + /// let n: usize = lit.base10_parse()?; + /// repr_packed = Some(n); + /// } else { + /// repr_packed = Some(1); + /// } + /// return Ok(()); + /// } + /// + /// Err(meta.error("unrecognized repr")) + /// })?; + /// } + /// } + /// # anyhow::Ok(()) + /// ``` + /// + /// # Alternatives + /// + /// In some cases, for attributes which have nested layers of structured + /// content, the following less flexible approach might be more convenient: + /// + /// ``` + /// # use syn::{parse_quote, ItemStruct}; + /// # + /// # let input: ItemStruct = parse_quote! { + /// # #[repr(C, align(4))] + /// # pub struct MyStruct(u16, u32); + /// # }; + /// # + /// use syn::punctuated::Punctuated; + /// use syn::{parenthesized, token, Error, LitInt, Meta, Token}; + /// + /// let mut repr_c = false; + /// let mut repr_transparent = false; + /// let mut repr_align = None::; + /// let mut repr_packed = None::; + /// for attr in &input.attrs { + /// if attr.path().is_ident("repr") { + /// let nested = attr.parse_args_with(Punctuated::::parse_terminated)?; + /// for meta in nested { + /// match meta { + /// // #[repr(C)] + /// Meta::Path(path) if path.is_ident("C") => { + /// repr_c = true; + /// } + /// + /// // #[repr(align(N))] + /// Meta::List(meta) if meta.path.is_ident("align") => { + /// let lit: LitInt = meta.parse_args()?; + /// let n: usize = lit.base10_parse()?; + /// repr_align = Some(n); + /// } + /// + /// /* ... */ + /// + /// _ => { + /// return Err(Error::new_spanned(meta, "unrecognized repr")); + /// } + /// } + /// } + /// } + /// } + /// # Ok(()) + /// ``` + #[cfg(feature = "parsing")] + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + pub fn parse_nested_meta( + &self, + logic: impl FnMut(ParseNestedMeta) -> Result<()>, + ) -> Result<()> { + self.parse_args_with(meta::parser(logic)) + } + + /// Parses zero or more outer attributes from the stream. + /// + /// # Example + /// + /// See + /// [*Parsing from tokens to Attribute*](#parsing-from-tokens-to-attribute). + #[cfg(feature = "parsing")] + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + pub fn parse_outer(input: ParseStream) -> Result> { + let mut attrs = Vec::new(); + while input.peek(Token![#]) { + attrs.push(input.call(parsing::single_parse_outer)?); + } + Ok(attrs) + } + + /// Parses zero or more inner attributes from the stream. + /// + /// # Example + /// + /// See + /// [*Parsing from tokens to Attribute*](#parsing-from-tokens-to-attribute). + #[cfg(feature = "parsing")] + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + pub fn parse_inner(input: ParseStream) -> Result> { + let mut attrs = Vec::new(); + parsing::parse_inner(input, &mut attrs)?; + Ok(attrs) + } +} + +ast_enum! { + /// Distinguishes between attributes that decorate an item and attributes + /// that are contained within an item. + /// + /// # Outer attributes + /// + /// - `#[repr(transparent)]` + /// - `/// # Example` + /// - `/** Please file an issue */` + /// + /// # Inner attributes + /// + /// - `#![feature(proc_macro)]` + /// - `//! # Example` + /// - `/*! Please file an issue */` + #[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))] + pub enum AttrStyle { + Outer, + Inner(Token![!]), + } +} + +ast_enum! { + /// Content of a compile-time structured attribute. + /// + /// ## Path + /// + /// A meta path is like the `test` in `#[test]`. + /// + /// ## List + /// + /// A meta list is like the `derive(Copy)` in `#[derive(Copy)]`. + /// + /// ## NameValue + /// + /// A name-value meta is like the `path = "..."` in `#[path = + /// "sys/windows.rs"]`. + /// + /// # Syntax tree enum + /// + /// This type is a [syntax tree enum]. + /// + /// [syntax tree enum]: crate::expr::Expr#syntax-tree-enums + #[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))] + pub enum Meta { + Path(Path), + + /// A structured list within an attribute, like `derive(Copy, Clone)`. + List(MetaList), + + /// A name-value pair within an attribute, like `feature = "nightly"`. + NameValue(MetaNameValue), + } +} + +ast_struct! { + /// A structured list within an attribute, like `derive(Copy, Clone)`. + #[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))] + pub struct MetaList { + pub path: Path, + pub delimiter: MacroDelimiter, + pub tokens: TokenStream, + } +} + +ast_struct! { + /// A name-value pair within an attribute, like `feature = "nightly"`. + #[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))] + pub struct MetaNameValue { + pub path: Path, + pub eq_token: Token![=], + pub value: Expr, + } +} + +impl Meta { + /// Returns the path that begins this structured meta item. + /// + /// For example this would return the `test` in `#[test]`, the `derive` in + /// `#[derive(Copy)]`, and the `path` in `#[path = "sys/windows.rs"]`. + pub fn path(&self) -> &Path { + match self { + Meta::Path(path) => path, + Meta::List(meta) => &meta.path, + Meta::NameValue(meta) => &meta.path, + } + } + + /// Error if this is a `Meta::List` or `Meta::NameValue`. + #[cfg(feature = "parsing")] + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + pub fn require_path_only(&self) -> Result<&Path> { + let error_span = match self { + Meta::Path(path) => return Ok(path), + Meta::List(meta) => meta.delimiter.span().open(), + Meta::NameValue(meta) => meta.eq_token.span, + }; + Err(Error::new(error_span, "unexpected token in attribute")) + } + + /// Error if this is a `Meta::Path` or `Meta::NameValue`. + #[cfg(feature = "parsing")] + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + pub fn require_list(&self) -> Result<&MetaList> { + match self { + Meta::List(meta) => Ok(meta), + Meta::Path(path) => Err(crate::error::new2( + path.segments.first().unwrap().ident.span(), + path.segments.last().unwrap().ident.span(), + format!( + "expected attribute arguments in parentheses: `{}(...)`", + parsing::DisplayPath(path), + ), + )), + Meta::NameValue(meta) => Err(Error::new(meta.eq_token.span, "expected `(`")), + } + } + + /// Error if this is a `Meta::Path` or `Meta::List`. + #[cfg(feature = "parsing")] + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + pub fn require_name_value(&self) -> Result<&MetaNameValue> { + match self { + Meta::NameValue(meta) => Ok(meta), + Meta::Path(path) => Err(crate::error::new2( + path.segments.first().unwrap().ident.span(), + path.segments.last().unwrap().ident.span(), + format!( + "expected a value for this attribute: `{} = ...`", + parsing::DisplayPath(path), + ), + )), + Meta::List(meta) => Err(Error::new(meta.delimiter.span().open(), "expected `=`")), + } + } +} + +impl MetaList { + /// See [`Attribute::parse_args`]. + #[cfg(feature = "parsing")] + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + pub fn parse_args(&self) -> Result { + self.parse_args_with(T::parse) + } + + /// See [`Attribute::parse_args_with`]. + #[cfg(feature = "parsing")] + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + pub fn parse_args_with(&self, parser: F) -> Result { + let scope = self.delimiter.span().close(); + crate::parse::parse_scoped(parser, scope, self.tokens.clone()) + } + + /// See [`Attribute::parse_nested_meta`]. + #[cfg(feature = "parsing")] + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + pub fn parse_nested_meta( + &self, + logic: impl FnMut(ParseNestedMeta) -> Result<()>, + ) -> Result<()> { + self.parse_args_with(meta::parser(logic)) + } +} + +#[cfg(feature = "printing")] +pub(crate) trait FilterAttrs<'a> { + type Ret: Iterator; + + fn outer(self) -> Self::Ret; + #[cfg(feature = "full")] + fn inner(self) -> Self::Ret; +} + +#[cfg(feature = "printing")] +impl<'a> FilterAttrs<'a> for &'a [Attribute] { + type Ret = iter::Filter, fn(&&Attribute) -> bool>; + + fn outer(self) -> Self::Ret { + fn is_outer(attr: &&Attribute) -> bool { + match attr.style { + AttrStyle::Outer => true, + AttrStyle::Inner(_) => false, + } + } + self.iter().filter(is_outer) + } + + #[cfg(feature = "full")] + fn inner(self) -> Self::Ret { + fn is_inner(attr: &&Attribute) -> bool { + match attr.style { + AttrStyle::Inner(_) => true, + AttrStyle::Outer => false, + } + } + self.iter().filter(is_inner) + } +} + +impl From for Meta { + fn from(meta: Path) -> Meta { + Meta::Path(meta) + } +} + +impl From for Meta { + fn from(meta: MetaList) -> Meta { + Meta::List(meta) + } +} + +impl From for Meta { + fn from(meta: MetaNameValue) -> Meta { + Meta::NameValue(meta) + } +} + +#[cfg(feature = "parsing")] +pub(crate) mod parsing { + use crate::attr::{AttrStyle, Attribute, Meta, MetaList, MetaNameValue}; + use crate::error::Result; + use crate::expr::{Expr, ExprLit}; + use crate::lit::Lit; + use crate::parse::discouraged::Speculative as _; + use crate::parse::{Parse, ParseStream}; + use crate::path::Path; + use crate::{mac, token}; + use proc_macro2::Ident; + use std::fmt::{self, Display}; + + pub(crate) fn parse_inner(input: ParseStream, attrs: &mut Vec) -> Result<()> { + while input.peek(Token![#]) && input.peek2(Token![!]) { + attrs.push(input.call(single_parse_inner)?); + } + Ok(()) + } + + pub(crate) fn single_parse_inner(input: ParseStream) -> Result { + let content; + Ok(Attribute { + pound_token: input.parse()?, + style: AttrStyle::Inner(input.parse()?), + bracket_token: bracketed!(content in input), + meta: content.parse()?, + }) + } + + pub(crate) fn single_parse_outer(input: ParseStream) -> Result { + let content; + Ok(Attribute { + pound_token: input.parse()?, + style: AttrStyle::Outer, + bracket_token: bracketed!(content in input), + meta: content.parse()?, + }) + } + + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + impl Parse for Meta { + fn parse(input: ParseStream) -> Result { + let path = parse_outermost_meta_path(input)?; + parse_meta_after_path(path, input) + } + } + + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + impl Parse for MetaList { + fn parse(input: ParseStream) -> Result { + let path = parse_outermost_meta_path(input)?; + parse_meta_list_after_path(path, input) + } + } + + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + impl Parse for MetaNameValue { + fn parse(input: ParseStream) -> Result { + let path = parse_outermost_meta_path(input)?; + parse_meta_name_value_after_path(path, input) + } + } + + // Unlike meta::parse_meta_path which accepts arbitrary keywords in the path, + // only the `unsafe` keyword is accepted as an attribute's outermost path. + fn parse_outermost_meta_path(input: ParseStream) -> Result { + if input.peek(Token![unsafe]) { + let unsafe_token: Token![unsafe] = input.parse()?; + Ok(Path::from(Ident::new("unsafe", unsafe_token.span))) + } else { + Path::parse_mod_style(input) + } + } + + pub(crate) fn parse_meta_after_path(path: Path, input: ParseStream) -> Result { + if input.peek(token::Paren) || input.peek(token::Bracket) || input.peek(token::Brace) { + parse_meta_list_after_path(path, input).map(Meta::List) + } else if input.peek(Token![=]) { + parse_meta_name_value_after_path(path, input).map(Meta::NameValue) + } else { + Ok(Meta::Path(path)) + } + } + + fn parse_meta_list_after_path(path: Path, input: ParseStream) -> Result { + let (delimiter, tokens) = mac::parse_delimiter(input)?; + Ok(MetaList { + path, + delimiter, + tokens, + }) + } + + fn parse_meta_name_value_after_path(path: Path, input: ParseStream) -> Result { + let eq_token: Token![=] = input.parse()?; + let ahead = input.fork(); + let lit: Option = ahead.parse()?; + let value = if let (Some(lit), true) = (lit, ahead.is_empty()) { + input.advance_to(&ahead); + Expr::Lit(ExprLit { + attrs: Vec::new(), + lit, + }) + } else if input.peek(Token![#]) && input.peek2(token::Bracket) { + return Err(input.error("unexpected attribute inside of attribute")); + } else { + input.parse()? + }; + Ok(MetaNameValue { + path, + eq_token, + value, + }) + } + + pub(super) struct DisplayAttrStyle<'a>(pub &'a AttrStyle); + + impl<'a> Display for DisplayAttrStyle<'a> { + fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result { + formatter.write_str(match self.0 { + AttrStyle::Outer => "#", + AttrStyle::Inner(_) => "#!", + }) + } + } + + pub(super) struct DisplayPath<'a>(pub &'a Path); + + impl<'a> Display for DisplayPath<'a> { + fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result { + for (i, segment) in self.0.segments.iter().enumerate() { + if i > 0 || self.0.leading_colon.is_some() { + formatter.write_str("::")?; + } + write!(formatter, "{}", segment.ident)?; + } + Ok(()) + } + } +} + +#[cfg(feature = "printing")] +mod printing { + use crate::attr::{AttrStyle, Attribute, Meta, MetaList, MetaNameValue}; + use crate::path; + use crate::path::printing::PathStyle; + use proc_macro2::TokenStream; + use quote::ToTokens; + + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for Attribute { + fn to_tokens(&self, tokens: &mut TokenStream) { + self.pound_token.to_tokens(tokens); + if let AttrStyle::Inner(b) = &self.style { + b.to_tokens(tokens); + } + self.bracket_token.surround(tokens, |tokens| { + self.meta.to_tokens(tokens); + }); + } + } + + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for Meta { + fn to_tokens(&self, tokens: &mut TokenStream) { + match self { + Meta::Path(path) => path::printing::print_path(tokens, path, PathStyle::Mod), + Meta::List(meta_list) => meta_list.to_tokens(tokens), + Meta::NameValue(meta_name_value) => meta_name_value.to_tokens(tokens), + } + } + } + + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for MetaList { + fn to_tokens(&self, tokens: &mut TokenStream) { + path::printing::print_path(tokens, &self.path, PathStyle::Mod); + self.delimiter.surround(tokens, self.tokens.clone()); + } + } + + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for MetaNameValue { + fn to_tokens(&self, tokens: &mut TokenStream) { + path::printing::print_path(tokens, &self.path, PathStyle::Mod); + self.eq_token.to_tokens(tokens); + self.value.to_tokens(tokens); + } + } +} -- cgit v1.3.1