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    #![doc(html_root_url = "https://docs.rs/tokio-macros/1.0.0")]
    #![allow(clippy::needless_doctest_main)]
    #![warn(
        missing_debug_implementations,
        missing_docs,
        rust_2018_idioms,
        unreachable_pub
    )]
    #![cfg_attr(docsrs, deny(broken_intra_doc_links))]
    #![doc(test(
        no_crate_inject,
        attr(deny(warnings, rust_2018_idioms), allow(dead_code, unused_variables))
    ))]

    //! Macros for use with Tokio

    // This `extern` is required for older `rustc` versions but newer `rustc`
    // versions warn about the unused `extern crate`.
    #[allow(unused_extern_crates)]
    extern crate proc_macro;

    mod entry;
    mod select;

    use proc_macro::TokenStream;

    /// Marks async function to be executed by the selected runtime. This macro
    /// helps set up a `Runtime` without requiring the user to use
    /// [Runtime](../tokio/runtime/struct.Runtime.html) or
    /// [Builder](../tokio/runtime/struct.Builder.html) directly.
    ///
    /// Note: This macro is designed to be simplistic and targets applications that
    /// do not require a complex setup. If the provided functionality is not
    /// sufficient, you may be interested in using
    /// [Builder](../tokio/runtime/struct.Builder.html), which provides a more
    /// powerful interface.
    ///
    /// Note: This macro can be used on any function and not just the `main`
    /// function. Using it on a non-main function makes the function behave as if it
    /// was synchronous by starting a new runtime each time it is called. If the
    /// function is called often, it is preferable to create the runtime using the
    /// runtime builder so the runtime can be reused across calls.
    ///
    /// # Multi-threaded runtime
    ///
    /// To use the multi-threaded runtime, the macro can be configured using
    ///
    /// ```
    /// #[tokio::main(flavor = "multi_thread", worker_threads = 10)]
    /// # async fn main() {}
    /// ```
    ///
    /// The `worker_threads` option configures the number of worker threads, and
    /// defaults to the number of cpus on the system. This is the default flavor.
    ///
    /// Note: The multi-threaded runtime requires the `rt-multi-thread` feature
    /// flag.
    ///
    /// # Current thread runtime
    ///
    /// To use the single-threaded runtime known as the `current_thread` runtime,
    /// the macro can be configured using
    ///
    /// ```
    /// #[tokio::main(flavor = "current_thread")]
    /// # async fn main() {}
    /// ```
    ///
    /// ## Function arguments:
    ///
    /// Arguments are allowed for any functions aside from `main` which is special
    ///
    /// ## Usage
    ///
    /// ### Using the multi-thread runtime
    ///
    /// ```rust
    /// #[tokio::main]
    /// async fn main() {
    ///     println!("Hello world");
    /// }
    /// ```
    ///
    /// Equivalent code not using `#[tokio::main]`
    ///
    /// ```rust
    /// fn main() {
    ///     tokio::runtime::Builder::new_multi_thread()
    ///         .enable_all()
    ///         .build()
    ///         .unwrap()
    ///         .block_on(async {
    ///             println!("Hello world");
    ///         })
    /// }
    /// ```
    ///
    /// ### Using current thread runtime
    ///
    /// The basic scheduler is single-threaded.
    ///
    /// ```rust
    /// #[tokio::main(flavor = "current_thread")]
    /// async fn main() {
    ///     println!("Hello world");
    /// }
    /// ```
    ///
    /// Equivalent code not using `#[tokio::main]`
    ///
    /// ```rust
    /// fn main() {
    ///     tokio::runtime::Builder::new_current_thread()
    ///         .enable_all()
    ///         .build()
    ///         .unwrap()
    ///         .block_on(async {
    ///             println!("Hello world");
    ///         })
    /// }
    /// ```
    ///
    /// ### Set number of worker threads
    ///
    /// ```rust
    /// #[tokio::main(worker_threads = 2)]
    /// async fn main() {
    ///     println!("Hello world");
    /// }
    /// ```
    ///
    /// Equivalent code not using `#[tokio::main]`
    ///
    /// ```rust
    /// fn main() {
    ///     tokio::runtime::Builder::new_multi_thread()
    ///         .worker_threads(2)
    ///         .enable_all()
    ///         .build()
    ///         .unwrap()
    ///         .block_on(async {
    ///             println!("Hello world");
    ///         })
    /// }
    /// ```
    ///
    /// ### NOTE:
    ///
    /// If you rename the Tokio crate in your dependencies this macro will not work.
    /// If you must rename the current version of Tokio because you're also using an
    /// older version of Tokio, you _must_ make the current version of Tokio
    /// available as `tokio` in the module where this macro is expanded.
    #[proc_macro_attribute]
    #[cfg(not(test))] // Work around for rust-lang/rust#62127
    pub fn main(args: TokenStream, item: TokenStream) -> TokenStream {
        entry::main(args, item, true)
    }

    /// Marks async function to be executed by selected runtime. This macro helps set up a `Runtime`
    /// without requiring the user to use [Runtime](../tokio/runtime/struct.Runtime.html) or
    /// [Builder](../tokio/runtime/struct.builder.html) directly.
    ///
    /// ## Function arguments:
    ///
    /// Arguments are allowed for any functions aside from `main` which is special
    ///
    /// ## Usage
    ///
    /// ### Using default
    ///
    /// ```rust
    /// #[tokio::main(flavor = "current_thread")]
    /// async fn main() {
    ///     println!("Hello world");
    /// }
    /// ```
    ///
    /// Equivalent code not using `#[tokio::main]`
    ///
    /// ```rust
    /// fn main() {
    ///     tokio::runtime::Builder::new_current_thread()
    ///         .enable_all()
    ///         .build()
    ///         .unwrap()
    ///         .block_on(async {
    ///             println!("Hello world");
    ///         })
    /// }
    /// ```
    ///
    /// ### NOTE:
    ///
    /// If you rename the Tokio crate in your dependencies this macro will not work.
    /// If you must rename the current version of Tokio because you're also using an
    /// older version of Tokio, you _must_ make the current version of Tokio
    /// available as `tokio` in the module where this macro is expanded.
    #[proc_macro_attribute]
    #[cfg(not(test))] // Work around for rust-lang/rust#62127
    pub fn main_rt(args: TokenStream, item: TokenStream) -> TokenStream {
        entry::main(args, item, false)
    }

    /// Marks async function to be executed by runtime, suitable to test environment
    ///
    /// ## Usage
    ///
    /// ### Multi-thread runtime
    ///
    /// ```no_run
    /// #[tokio::test(flavor = "multi_thread", worker_threads = 1)]
    /// async fn my_test() {
    ///     assert!(true);
    /// }
    /// ```
    ///
    /// ### Using default
    ///
    /// The default test runtime is single-threaded.
    ///
    /// ```no_run
    /// #[tokio::test]
    /// async fn my_test() {
    ///     assert!(true);
    /// }
    /// ```
    ///
    /// ### NOTE:
    ///
    /// If you rename the Tokio crate in your dependencies this macro will not work.
    /// If you must rename the current version of Tokio because you're also using an
    /// older version of Tokio, you _must_ make the current version of Tokio
    /// available as `tokio` in the module where this macro is expanded.
    #[proc_macro_attribute]
    pub fn test(args: TokenStream, item: TokenStream) -> TokenStream {
        entry::test(args, item, true)
    }

    /// Marks async function to be executed by runtime, suitable to test environment
    ///
    /// ## Usage
    ///
    /// ```no_run
    /// #[tokio::test]
    /// async fn my_test() {
    ///     assert!(true);
    /// }
    /// ```
    ///
    /// ### NOTE:
    ///
    /// If you rename the Tokio crate in your dependencies this macro will not work.
    /// If you must rename the current version of Tokio because you're also using an
    /// older version of Tokio, you _must_ make the current version of Tokio
    /// available as `tokio` in the module where this macro is expanded.
    #[proc_macro_attribute]
    pub fn test_rt(args: TokenStream, item: TokenStream) -> TokenStream {
        entry::test(args, item, false)
    }

    /// Always fails with the error message below.
    /// ```text
    /// The #[tokio::main] macro requires rt or rt-multi-thread.
    /// ```
    #[proc_macro_attribute]
    pub fn main_fail(_args: TokenStream, _item: TokenStream) -> TokenStream {
        syn::Error::new(
            proc_macro2::Span::call_site(),
            "The #[tokio::main] macro requires rt or rt-multi-thread.",
        )
        .to_compile_error()
        .into()
    }

    /// Always fails with the error message below.
    /// ```text
    /// The #[tokio::test] macro requires rt or rt-multi-thread.
    /// ```
    #[proc_macro_attribute]
    pub fn test_fail(_args: TokenStream, _item: TokenStream) -> TokenStream {
        syn::Error::new(
            proc_macro2::Span::call_site(),
            "The #[tokio::test] macro requires rt or rt-multi-thread.",
        )
        .to_compile_error()
        .into()
    }

    /// Implementation detail of the `select!` macro. This macro is **not** intended
    /// to be used as part of the public API and is permitted to change.
    #[proc_macro]
    #[doc(hidden)]
    pub fn select_priv_declare_output_enum(input: TokenStream) -> TokenStream {
        select::declare_output_enum(input)
    }