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    /// Quasi-quotation macro that accepts input like the [`quote!`] macro but uses
    /// type inference to figure out a return type for those tokens.
    ///
    /// [`quote!`]: https://docs.rs/quote/0.6/quote/index.html
    ///
    /// The return type can be any syntax tree node that implements the [`Parse`]
    /// trait.
    ///
    /// [`Parse`]: parse/trait.Parse.html
    ///
    /// ```edition2018
    /// use quote::quote;
    /// use syn::{parse_quote, Stmt};
    ///
    /// fn main() {
    ///     let name = quote!(v);
    ///     let ty = quote!(u8);
    ///
    ///     let stmt: Stmt = parse_quote! {
    ///         let #name: #ty = Default::default();
    ///     };
    ///
    ///     println!("{:#?}", stmt);
    /// }
    /// ```
    ///
    /// *This macro is available if Syn is built with the `"parsing"` feature,
    /// although interpolation of syntax tree nodes into the quoted tokens is only
    /// supported if Syn is built with the `"printing"` feature as well.*
    ///
    /// # Example
    ///
    /// The following helper function adds a bound `T: HeapSize` to every type
    /// parameter `T` in the input generics.
    ///
    /// ```edition2018
    /// use syn::{parse_quote, Generics, GenericParam};
    ///
    /// // Add a bound `T: HeapSize` to every type parameter T.
    /// fn add_trait_bounds(mut generics: Generics) -> Generics {
    ///     for param in &mut generics.params {
    ///         if let GenericParam::Type(type_param) = param {
    ///             type_param.bounds.push(parse_quote!(HeapSize));
    ///         }
    ///     }
    ///     generics
    /// }
    /// ```
    ///
    /// # Special cases
    ///
    /// This macro can parse the following additional types as a special case even
    /// though they do not implement the `Parse` trait.
    ///
    /// - [`Attribute`] — parses one attribute, allowing either outer like `#[...]`
    ///   or inner like `#![...]`
    /// - [`Punctuated<T, P>`] — parses zero or more `T` separated by punctuation
    ///   `P` with optional trailing punctuation
    ///
    /// [`Attribute`]: struct.Attribute.html
    /// [`Punctuated<T, P>`]: punctuated/struct.Punctuated.html
    ///
    /// # Panics
    ///
    /// Panics if the tokens fail to parse as the expected syntax tree type. The
    /// caller is responsible for ensuring that the input tokens are syntactically
    /// valid.
    #[macro_export(local_inner_macros)]
    macro_rules! parse_quote {
        ($($tt:tt)*) => {
            $crate::parse_quote::parse($crate::export::From::from(quote_impl!($($tt)*)))
        };
    }

    #[cfg(not(syn_can_call_macro_by_path))]
    #[doc(hidden)]
    #[macro_export]
    macro_rules! quote_impl {
        ($($tt:tt)*) => {
            // Require caller to have their own `#[macro_use] extern crate quote`.
            quote!($($tt)*)
        };
    }

    #[cfg(syn_can_call_macro_by_path)]
    #[doc(hidden)]
    #[macro_export]
    macro_rules! quote_impl {
        ($($tt:tt)*) => {
            $crate::export::quote::quote!($($tt)*)
        };
    }

    ////////////////////////////////////////////////////////////////////////////////
    // Can parse any type that implements Parse.

    use parse::{Parse, ParseStream, Parser, Result};
    use proc_macro2::TokenStream;

    // Not public API.
    #[doc(hidden)]
    pub fn parse<T: ParseQuote>(token_stream: TokenStream) -> T {
        let parser = T::parse;
        match parser.parse2(token_stream) {
            Ok(t) => t,
            Err(err) => panic!("{}", err),
        }
    }

    // Not public API.
    #[doc(hidden)]
    pub trait ParseQuote: Sized {
        fn parse(input: ParseStream) -> Result<Self>;
    }

    impl<T: Parse> ParseQuote for T {
        fn parse(input: ParseStream) -> Result<Self> {
            <T as Parse>::parse(input)
        }
    }

    ////////////////////////////////////////////////////////////////////////////////
    // Any other types that we want `parse_quote!` to be able to parse.

    use punctuated::Punctuated;
    #[cfg(any(feature = "full", feature = "derive"))]
    use {attr, Attribute};

    #[cfg(any(feature = "full", feature = "derive"))]
    impl ParseQuote for Attribute {
        fn parse(input: ParseStream) -> Result<Self> {
            if input.peek(Token![#]) && input.peek2(Token![!]) {
                attr::parsing::single_parse_inner(input)
            } else {
                attr::parsing::single_parse_outer(input)
            }
        }
    }

    impl<T: Parse, P: Parse> ParseQuote for Punctuated<T, P> {
        fn parse(input: ParseStream) -> Result<Self> {
            Self::parse_terminated(input)
        }
    }

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