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 <!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="Source of the Rust file `/root/.cargo/registry/src/github.com-1ecc6299db9ec823/pin-project-internal-1.1.0/src/lib.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>lib.rs - source</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceCodePro-Semibold.ttf.woff2"><link rel="stylesheet" href="../../normalize.css"><link rel="stylesheet" href="../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" href="../../ayu.css" disabled><link rel="stylesheet" href="../../dark.css" disabled><link rel="stylesheet" href="../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../storage.js"></script><script defer src="../../source-script.js"></script><script defer src="../../source-files.js"></script><script defer src="../../main.js"></script><noscript><link rel="stylesheet" href="../../noscript.css"></noscript><link rel="alternate icon" type="image/png" href="../../favicon-16x16.png"><link rel="alternate icon" type="image/png" href="../../favicon-32x32.png"><link rel="icon" type="image/svg+xml" href="../../favicon.svg"></head><body class="rustdoc source"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><a class="sidebar-logo" href="../../pin_project_internal/index.html"><div class="logo-container"><img class="rust-logo" src="../../rust-logo.svg" alt="logo"></div></a></nav><main><div class="width-limiter"><nav class="sub"><a class="sub-logo-container" href="../../pin_project_internal/index.html"><img class="rust-logo" src="../../rust-logo.svg" alt="logo"></a><form class="search-form"><div class="search-container"><span></span><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../wheel.svg"></a></div></div></form></nav><section id="main-content" class="content"><div class="example-wrap"><pre class="src-line-numbers"><span id="1">1</span>
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 </pre><pre class="rust"><code><span class="doccomment">//! Implementation detail of the `pin-project` crate. - **do not use directly**

 </span><span class="attribute">#![doc(test(
     no_crate_inject,
     attr(
         deny(warnings, rust_2018_idioms, single_use_lifetimes),
         allow(dead_code, unused_variables)
     )
 ))]
 #![forbid(unsafe_code)]
 #![warn(rust_2018_idioms, single_use_lifetimes, unreachable_pub)]
 #![warn(clippy::pedantic)]
 #![allow(
     clippy::needless_doctest_main,
     clippy::similar_names,
     clippy::single_match_else,
     clippy::too_many_lines
 )]

 </span><span class="comment">// older compilers require explicit `extern crate`.
 </span><span class="attribute">#[allow(unused_extern_crates)]
 </span><span class="kw">extern crate </span>proc_macro;

 <span class="attribute">#[macro_use]
 </span><span class="kw">mod </span>utils;

 <span class="kw">mod </span>pin_project;
 <span class="kw">mod </span>pinned_drop;

 <span class="kw">use </span>proc_macro::TokenStream;

 <span class="doccomment">/// An attribute that creates projection types covering all the fields of
 /// struct or enum.
 ///
 /// This attribute creates projection types according to the following rules:
 ///
 /// - For the fields that use `#[pin]` attribute, create the pinned reference to
 ///   the field.
 /// - For the other fields, create a normal reference to the field.
 ///
 /// And the following methods are implemented on the original type:
 ///
 /// ```rust
 /// # use std::pin::Pin;
 /// # type Projection&lt;&#39;a&gt; = &amp;&#39;a ();
 /// # type ProjectionRef&lt;&#39;a&gt; = &amp;&#39;a ();
 /// # trait Dox {
 /// fn project(self: Pin&lt;&amp;mut Self&gt;) -&gt; Projection&lt;&#39;_&gt;;
 /// fn project_ref(self: Pin&lt;&amp;Self&gt;) -&gt; ProjectionRef&lt;&#39;_&gt;;
 /// # }
 /// ```
 ///
 /// By passing an argument with the same name as the method to the attribute,
 /// you can name the projection type returned from the method. This allows you
 /// to use pattern matching on the projected types.
 ///
 /// ```rust
 /// # use pin_project::pin_project;
 /// # use std::pin::Pin;
 /// #[pin_project(project = EnumProj)]
 /// enum Enum&lt;T&gt; {
 ///     Variant(#[pin] T),
 /// }
 ///
 /// impl&lt;T&gt; Enum&lt;T&gt; {
 ///     fn method(self: Pin&lt;&amp;mut Self&gt;) {
 ///         let this: EnumProj&lt;&#39;_, T&gt; = self.project();
 ///         match this {
 ///             EnumProj::Variant(x) =&gt; {
 ///                 let _: Pin&lt;&amp;mut T&gt; = x;
 ///             }
 ///         }
 ///     }
 /// }
 /// ```
 ///
 /// Note that the projection types returned by `project` and `project_ref` have
 /// an additional lifetime at the beginning of generics.
 ///
 /// ```text
 /// let this: EnumProj&lt;&#39;_, T&gt; = self.project();
 ///                    ^^
 /// ```
 ///
 /// The visibility of the projected types and projection methods is based on the
 /// original type. However, if the visibility of the original type is `pub`, the
 /// visibility of the projected types and the projection methods is downgraded
 /// to `pub(crate)`.
 ///
 /// # Safety
 ///
 /// This attribute is completely safe. In the absence of other `unsafe` code
 /// *that you write*, it is impossible to cause [undefined
 /// behavior][undefined-behavior] with this attribute.
 ///
 /// This is accomplished by enforcing the four requirements for pin projection
 /// stated in [the Rust documentation][pin-projection]:
 ///
 /// 1. The struct must only be [`Unpin`] if all the structural fields are
 ///    [`Unpin`].
 ///
 ///    To enforce this, this attribute will automatically generate an [`Unpin`]
 ///    implementation for you, which will require that all structurally pinned
 ///    fields be [`Unpin`].
 ///
 ///    If you attempt to provide an [`Unpin`] impl, the blanket impl will then
 ///    apply to your type, causing a compile-time error due to the conflict with
 ///    the second impl.
 ///
 ///    If you wish to provide a manual [`Unpin`] impl, you can do so via the
 ///    [`UnsafeUnpin`][unsafe-unpin] argument.
 ///
 /// 2. The destructor of the struct must not move structural fields out of its
 ///    argument.
 ///
 ///    To enforce this, this attribute will generate code like this:
 ///
 ///    ```rust
 ///    struct MyStruct {}
 ///    trait MyStructMustNotImplDrop {}
 ///    # #[allow(unknown_lints, drop_bounds)]
 ///    impl&lt;T: Drop&gt; MyStructMustNotImplDrop for T {}
 ///    impl MyStructMustNotImplDrop for MyStruct {}
 ///    ```
 ///
 ///    If you attempt to provide an [`Drop`] impl, the blanket impl will then
 ///    apply to your type, causing a compile-time error due to the conflict with
 ///    the second impl.
 ///
 ///    If you wish to provide a custom [`Drop`] impl, you can annotate an impl
 ///    with [`#[pinned_drop]`][pinned-drop]. This impl takes a pinned version of
 ///    your struct - that is, [`Pin`]`&lt;&amp;mut MyStruct&gt;` where `MyStruct` is the
 ///    type of your struct.
 ///
 ///    You can call `.project()` on this type as usual, along with any other
 ///    methods you have defined. Because your code is never provided with
 ///    a `&amp;mut MyStruct`, it is impossible to move out of pin-projectable
 ///    fields in safe code in your destructor.
 ///
 /// 3. You must make sure that you uphold the [`Drop`
 ///    guarantee][drop-guarantee]: once your struct is pinned, the memory that
 ///    contains the content is not overwritten or deallocated without calling
 ///    the content&#39;s destructors.
 ///
 ///    Safe code doesn&#39;t need to worry about this - the only way to violate
 ///    this requirement is to manually deallocate memory (which is `unsafe`),
 ///    or to overwrite a field with something else.
 ///    Because your custom destructor takes [`Pin`]`&lt;&amp;mut MyStruct&gt;`, it&#39;s
 ///    impossible to obtain a mutable reference to a pin-projected field in safe
 ///    code.
 ///
 /// 4. You must not offer any other operations that could lead to data being
 ///    moved out of the structural fields when your type is pinned.
 ///
 ///    As with requirement 3, it is impossible for safe code to violate this.
 ///    This crate ensures that safe code can never obtain a mutable reference to
 ///    `#[pin]` fields, which prevents you from ever moving out of them in safe
 ///    code.
 ///
 /// Pin projections are also incompatible with [`#[repr(packed)]`][repr-packed]
 /// types. Attempting to use this attribute on a `#[repr(packed)]` type results
 /// in a compile-time error.
 ///
 /// # Examples
 ///
 /// `#[pin_project]` can be used on structs and enums.
 ///
 /// ```rust
 /// use std::pin::Pin;
 ///
 /// use pin_project::pin_project;
 ///
 /// #[pin_project]
 /// struct Struct&lt;T, U&gt; {
 ///     #[pin]
 ///     pinned: T,
 ///     unpinned: U,
 /// }
 ///
 /// impl&lt;T, U&gt; Struct&lt;T, U&gt; {
 ///     fn method(self: Pin&lt;&amp;mut Self&gt;) {
 ///         let this = self.project();
 ///         let _: Pin&lt;&amp;mut T&gt; = this.pinned;
 ///         let _: &amp;mut U = this.unpinned;
 ///     }
 /// }
 /// ```
 ///
 /// ```rust
 /// use std::pin::Pin;
 ///
 /// use pin_project::pin_project;
 ///
 /// #[pin_project]
 /// struct TupleStruct&lt;T, U&gt;(#[pin] T, U);
 ///
 /// impl&lt;T, U&gt; TupleStruct&lt;T, U&gt; {
 ///     fn method(self: Pin&lt;&amp;mut Self&gt;) {
 ///         let this = self.project();
 ///         let _: Pin&lt;&amp;mut T&gt; = this.0;
 ///         let _: &amp;mut U = this.1;
 ///     }
 /// }
 /// ```
 ///
 /// To use `#[pin_project]` on enums, you need to name the projection type
 /// returned from the method.
 ///
 /// ```rust
 /// use std::pin::Pin;
 ///
 /// use pin_project::pin_project;
 ///
 /// #[pin_project(project = EnumProj)]
 /// enum Enum&lt;T, U&gt; {
 ///     Tuple(#[pin] T),
 ///     Struct { field: U },
 ///     Unit,
 /// }
 ///
 /// impl&lt;T, U&gt; Enum&lt;T, U&gt; {
 ///     fn method(self: Pin&lt;&amp;mut Self&gt;) {
 ///         match self.project() {
 ///             EnumProj::Tuple(x) =&gt; {
 ///                 let _: Pin&lt;&amp;mut T&gt; = x;
 ///             }
 ///             EnumProj::Struct { field } =&gt; {
 ///                 let _: &amp;mut U = field;
 ///             }
 ///             EnumProj::Unit =&gt; {}
 ///         }
 ///     }
 /// }
 /// ```
 ///
 /// When `#[pin_project]` is used on enums, only named projection types and
 /// methods are generated because there is no way to access variants of
 /// projected types without naming it.
 /// For example, in the above example, only the `project` method is generated,
 /// and the `project_ref` method is not generated.
 /// (When `#[pin_project]` is used on structs, both methods are always generated.)
 ///
 /// ```rust,compile_fail,E0599
 /// # use pin_project::pin_project;
 /// # use std::pin::Pin;
 /// #
 /// # #[pin_project(project = EnumProj)]
 /// # enum Enum&lt;T, U&gt; {
 /// #     Tuple(#[pin] T),
 /// #     Struct { field: U },
 /// #     Unit,
 /// # }
 /// #
 /// impl&lt;T, U&gt; Enum&lt;T, U&gt; {
 ///     fn call_project_ref(self: Pin&lt;&amp;Self&gt;) {
 ///         let _this = self.project_ref();
 ///         //~^ ERROR no method named `project_ref` found for struct `Pin&lt;&amp;Enum&lt;T, U&gt;&gt;` in the current scope
 ///     }
 /// }
 /// ```
 ///
 /// If you want to call `.project()` multiple times or later use the
 /// original [`Pin`] type, it needs to use [`.as_mut()`][`Pin::as_mut`] to avoid
 /// consuming the [`Pin`].
 ///
 /// ```rust
 /// use std::pin::Pin;
 ///
 /// use pin_project::pin_project;
 ///
 /// #[pin_project]
 /// struct Struct&lt;T&gt; {
 ///     #[pin]
 ///     field: T,
 /// }
 ///
 /// impl&lt;T&gt; Struct&lt;T&gt; {
 ///     fn call_project_twice(mut self: Pin&lt;&amp;mut Self&gt;) {
 ///         // `project` consumes `self`, so reborrow the `Pin&lt;&amp;mut Self&gt;` via `as_mut`.
 ///         self.as_mut().project();
 ///         self.as_mut().project();
 ///     }
 /// }
 /// ```
 ///
 /// # `!Unpin`
 ///
 /// If you want to ensure that [`Unpin`] is not implemented, use the `!Unpin`
 /// argument to `#[pin_project]`.
 ///
 /// ```rust
 /// use pin_project::pin_project;
 ///
 /// #[pin_project(!Unpin)]
 /// struct Struct&lt;T&gt; {
 ///     field: T,
 /// }
 /// ```
 ///
 /// This is equivalent to using `#[pin]` attribute for the [`PhantomPinned`]
 /// field.
 ///
 /// ```rust
 /// use std::marker::PhantomPinned;
 ///
 /// use pin_project::pin_project;
 ///
 /// #[pin_project]
 /// struct Struct&lt;T&gt; {
 ///     field: T,
 ///     #[pin] // &lt;------ This `#[pin]` is required to make `Struct` to `!Unpin`.
 ///     _pin: PhantomPinned,
 /// }
 /// ```
 ///
 /// Note that using [`PhantomPinned`] without `#[pin]` attribute has no effect.
 ///
 /// # `UnsafeUnpin`
 ///
 /// If you want to implement [`Unpin`] manually, you must use the `UnsafeUnpin`
 /// argument to `#[pin_project]`.
 ///
 /// ```rust
 /// use pin_project::{pin_project, UnsafeUnpin};
 ///
 /// #[pin_project(UnsafeUnpin)]
 /// struct Struct&lt;T, U&gt; {
 ///     #[pin]
 ///     pinned: T,
 ///     unpinned: U,
 /// }
 ///
 /// unsafe impl&lt;T: Unpin, U&gt; UnsafeUnpin for Struct&lt;T, U&gt; {}
 /// ```
 ///
 /// Note the usage of the unsafe [`UnsafeUnpin`] trait, instead of the usual
 /// [`Unpin`] trait. [`UnsafeUnpin`] behaves exactly like [`Unpin`], except that
 /// is unsafe to implement. This unsafety comes from the fact that pin
 /// projections are being used. If you implement [`UnsafeUnpin`], you must
 /// ensure that it is only implemented when all pin-projected fields implement
 /// [`Unpin`].
 ///
 /// See [`UnsafeUnpin`] trait for more details.
 ///
 /// # `#[pinned_drop]`
 ///
 /// In order to correctly implement pin projections, a type&#39;s [`Drop`] impl must
 /// not move out of any structurally pinned fields. Unfortunately,
 /// [`Drop::drop`] takes `&amp;mut Self`, not [`Pin`]`&lt;&amp;mut Self&gt;`.
 ///
 /// To ensure that this requirement is upheld, the `#[pin_project]` attribute
 /// will provide a [`Drop`] impl for you. This [`Drop`] impl will delegate to
 /// an impl block annotated with `#[pinned_drop]` if you use the `PinnedDrop`
 /// argument to `#[pin_project]`.
 ///
 /// This impl block acts just like a normal [`Drop`] impl,
 /// except for the following two:
 ///
 /// - `drop` method takes [`Pin`]`&lt;&amp;mut Self&gt;`
 /// - Name of the trait is `PinnedDrop`.
 ///
 /// ```rust
 /// # use std::pin::Pin;
 /// pub trait PinnedDrop {
 ///     fn drop(self: Pin&lt;&amp;mut Self&gt;);
 /// }
 /// ```
 ///
 /// `#[pin_project]` implements the actual [`Drop`] trait via `PinnedDrop` you
 /// implemented. To drop a type that implements `PinnedDrop`, use the [`drop`]
 /// function just like dropping a type that directly implements [`Drop`].
 ///
 /// In particular, it will never be called more than once, just like
 /// [`Drop::drop`].
 ///
 /// For example:
 ///
 /// ```rust
 /// use std::{fmt::Debug, pin::Pin};
 ///
 /// use pin_project::{pin_project, pinned_drop};
 ///
 /// #[pin_project(PinnedDrop)]
 /// struct PrintOnDrop&lt;T: Debug, U: Debug&gt; {
 ///     #[pin]
 ///     pinned_field: T,
 ///     unpin_field: U,
 /// }
 ///
 /// #[pinned_drop]
 /// impl&lt;T: Debug, U: Debug&gt; PinnedDrop for PrintOnDrop&lt;T, U&gt; {
 ///     fn drop(self: Pin&lt;&amp;mut Self&gt;) {
 ///         println!(&quot;Dropping pinned field: {:?}&quot;, self.pinned_field);
 ///         println!(&quot;Dropping unpin field: {:?}&quot;, self.unpin_field);
 ///     }
 /// }
 ///
 /// fn main() {
 ///     let _x = PrintOnDrop { pinned_field: true, unpin_field: 40 };
 /// }
 /// ```
 ///
 /// See also [`#[pinned_drop]`][macro@pinned_drop] attribute.
 ///
 /// # `project_replace` method
 ///
 /// In addition to the `project` and `project_ref` methods which are always
 /// provided when you use the `#[pin_project]` attribute, there is a third
 /// method, `project_replace` which can be useful in some situations. It is
 /// equivalent to [`Pin::set`], except that the unpinned fields are moved and
 /// returned, instead of being dropped in-place.
 ///
 /// ```rust
 /// # use std::pin::Pin;
 /// # type ProjectionOwned = ();
 /// # trait Dox {
 /// fn project_replace(self: Pin&lt;&amp;mut Self&gt;, other: Self) -&gt; ProjectionOwned;
 /// # }
 /// ```
 ///
 /// The `ProjectionOwned` type is identical to the `Self` type, except that
 /// all pinned fields have been replaced by equivalent [`PhantomData`] types.
 ///
 /// This method is opt-in, because it is only supported for [`Sized`] types, and
 /// because it is incompatible with the [`#[pinned_drop]`][pinned-drop]
 /// attribute described above. It can be enabled by using
 /// `#[pin_project(project_replace)]`.
 ///
 /// For example:
 ///
 /// ```rust
 /// use std::{marker::PhantomData, pin::Pin};
 ///
 /// use pin_project::pin_project;
 ///
 /// #[pin_project(project_replace)]
 /// struct Struct&lt;T, U&gt; {
 ///     #[pin]
 ///     pinned_field: T,
 ///     unpinned_field: U,
 /// }
 ///
 /// impl&lt;T, U&gt; Struct&lt;T, U&gt; {
 ///     fn method(self: Pin&lt;&amp;mut Self&gt;, other: Self) {
 ///         let this = self.project_replace(other);
 ///         let _: U = this.unpinned_field;
 ///         let _: PhantomData&lt;T&gt; = this.pinned_field;
 ///     }
 /// }
 /// ```
 ///
 /// By passing the value to the `project_replace` argument, you can name the
 /// returned type of the `project_replace` method. This is necessary whenever
 /// destructuring the return type of the `project_replace` method, and work in exactly
 /// the same way as the `project` and `project_ref` arguments.
 ///
 /// ```rust
 /// use pin_project::pin_project;
 ///
 /// #[pin_project(project_replace = EnumProjOwn)]
 /// enum Enum&lt;T, U&gt; {
 ///     A {
 ///         #[pin]
 ///         pinned_field: T,
 ///         unpinned_field: U,
 ///     },
 ///     B,
 /// }
 ///
 /// let mut x = Box::pin(Enum::A { pinned_field: 42, unpinned_field: &quot;hello&quot; });
 ///
 /// match x.as_mut().project_replace(Enum::B) {
 ///     EnumProjOwn::A { unpinned_field, .. } =&gt; assert_eq!(unpinned_field, &quot;hello&quot;),
 ///     EnumProjOwn::B =&gt; unreachable!(),
 /// }
 /// ```
 ///
 /// [`PhantomData`]: core::marker::PhantomData
 /// [`PhantomPinned`]: core::marker::PhantomPinned
 /// [`Pin::as_mut`]: core::pin::Pin::as_mut
 /// [`Pin::set`]: core::pin::Pin::set
 /// [`Pin`]: core::pin::Pin
 /// [`UnsafeUnpin`]: https://docs.rs/pin-project/1/pin_project/trait.UnsafeUnpin.html
 /// [drop-guarantee]: core::pin#drop-guarantee
 /// [pin-projection]: core::pin#projections-and-structural-pinning
 /// [pinned-drop]: macro@pin_project#pinned_drop
 /// [repr-packed]: https://doc.rust-lang.org/nomicon/other-reprs.html#reprpacked
 /// [undefined-behavior]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
 /// [unsafe-unpin]: macro@pin_project#unsafeunpin
 </span><span class="attribute">#[proc_macro_attribute]
 </span><span class="kw">pub fn </span>pin_project(args: TokenStream, input: TokenStream) -&gt; TokenStream {
     pin_project::attribute(<span class="kw-2">&amp;</span>args.into(), input.into()).into()
 }

 <span class="doccomment">/// An attribute used for custom implementations of [`Drop`].
 ///
 /// This attribute is used in conjunction with the `PinnedDrop` argument to
 /// the [`#[pin_project]`][macro@pin_project] attribute.
 ///
 /// The impl block annotated with this attribute acts just like a normal
 /// [`Drop`] impl, except for the following two:
 ///
 /// - `drop` method takes [`Pin`]`&lt;&amp;mut Self&gt;`
 /// - Name of the trait is `PinnedDrop`.
 ///
 /// ```rust
 /// # use std::pin::Pin;
 /// pub trait PinnedDrop {
 ///     fn drop(self: Pin&lt;&amp;mut Self&gt;);
 /// }
 /// ```
 ///
 /// `#[pin_project]` implements the actual [`Drop`] trait via `PinnedDrop` you
 /// implemented. To drop a type that implements `PinnedDrop`, use the [`drop`]
 /// function just like dropping a type that directly implements [`Drop`].
 ///
 /// In particular, it will never be called more than once, just like
 /// [`Drop::drop`].
 ///
 /// # Examples
 ///
 /// ```rust
 /// use std::pin::Pin;
 ///
 /// use pin_project::{pin_project, pinned_drop};
 ///
 /// #[pin_project(PinnedDrop)]
 /// struct PrintOnDrop {
 ///     #[pin]
 ///     field: u8,
 /// }
 ///
 /// #[pinned_drop]
 /// impl PinnedDrop for PrintOnDrop {
 ///     fn drop(self: Pin&lt;&amp;mut Self&gt;) {
 ///         println!(&quot;Dropping: {}&quot;, self.field);
 ///     }
 /// }
 ///
 /// fn main() {
 ///     let _x = PrintOnDrop { field: 50 };
 /// }
 /// ```
 ///
 /// See also [&quot;pinned-drop&quot; section of `#[pin_project]` attribute][pinned-drop].
 ///
 /// # Why `#[pinned_drop]` attribute is needed?
 ///
 /// Implementing `PinnedDrop::drop` is safe, but calling it is not safe.
 /// This is because destructors can be called multiple times in safe code and
 /// [double dropping is unsound][rust-lang/rust#62360].
 ///
 /// Ideally, it would be desirable to be able to forbid manual calls in
 /// the same way as [`Drop::drop`], but the library cannot do it. So, by using
 /// macros and replacing them with private traits like the following,
 /// this crate prevent users from calling `PinnedDrop::drop` in safe code.
 ///
 /// ```rust
 /// # use std::pin::Pin;
 /// pub trait PinnedDrop {
 ///     unsafe fn drop(self: Pin&lt;&amp;mut Self&gt;);
 /// }
 /// ```
 ///
 /// This allows implementing [`Drop`] safely using `#[pinned_drop]`.
 /// Also by using the [`drop`] function just like dropping a type that directly
 /// implements [`Drop`], can drop safely a type that implements `PinnedDrop`.
 ///
 /// [rust-lang/rust#62360]: https://github.com/rust-lang/rust/pull/62360
 /// [`Pin`]: core::pin::Pin
 /// [pinned-drop]: macro@pin_project#pinned_drop
 </span><span class="attribute">#[proc_macro_attribute]
 </span><span class="kw">pub fn </span>pinned_drop(args: TokenStream, input: TokenStream) -&gt; TokenStream {
     <span class="kw">let </span>input = <span class="macro">syn::parse_macro_input!</span>(input);
     pinned_drop::attribute(<span class="kw-2">&amp;</span>args.into(), input).into()
 }

 <span class="comment">// Not public API.
 </span><span class="attribute">#[doc(hidden)]
 #[proc_macro_derive(__PinProjectInternalDerive, attributes(pin))]
 </span><span class="kw">pub fn </span>__pin_project_internal_derive(input: TokenStream) -&gt; TokenStream {
     pin_project::derive(input.into()).into()
 }
 </code></pre></div>
 </section></div></main><div id="rustdoc-vars" data-root-path="../../" data-current-crate="pin_project_internal" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html>