Struct syn::Attribute[][src]

pub struct Attribute {
    pub pound_token: Pound,
    pub style: AttrStyle,
    pub bracket_token: Bracket,
    pub path: Path,
    pub tts: TokenStream,
    pub is_sugared_doc: bool,

An attribute like #[repr(transparent)].

This type is available if Syn is built with the "derive" or "full" feature.


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 doc comments like /// # Example.
  • Inner doc comments like //! Please file an issue.
  • Outer block comments /** # Example */.
  • Inner block comments /*! Please file an issue */.

The style field of type AttrStyle distinguishes whether an attribute is outer or inner. Doc comments and block comments are promoted to attributes that have is_sugared_doc set to true, as this is how they are processed by the compiler and by macro_rules! macros.

The path field gives the possibly colon-delimited path against which the attribute is resolved. It is equal to "doc" for desugared doc comments. The tts field contains the rest of the attribute body as tokens.

#[derive(Copy)]      #[crate::precondition x < 5]
  ^^^^^^~~~~~~         ^^^^^^^^^^^^^^^^^^^ ~~~~~
   path  tts                   path         tts

Use the interpret_meta method to try parsing the tokens of an attribute into the structured representation that is used by convention across most Rust libraries.



impl Attribute

impl Attribute

Parses the tokens after the path as a Meta if possible.

Trait Implementations

impl ToTokens for Attribute

Write self to the given TokenStream. Read more

Convert self directly into a TokenStream object. Read more

impl Debug for Attribute

Formats the value using the given formatter. Read more

impl Clone for Attribute

Returns a copy of the value. Read more

Performs copy-assignment from source. Read more

impl Eq for Attribute

impl PartialEq for Attribute

This method tests for self and other values to be equal, and is used by ==. Read more

This method tests for !=.

impl Hash for Attribute

Feeds this value into the given [Hasher]. Read more

Feeds a slice of this type into the given [Hasher]. Read more

Auto Trait Implementations

impl !Send for Attribute

impl !Sync for Attribute