| <!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="An empty syntax tree node that consumes no tokens when parsed."><meta name="keywords" content="rust, rustlang, rust-lang, Nothing"><title>Nothing in syn::parse - Rust</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" type="text/css" href="../../normalize.css"><link rel="stylesheet" type="text/css" href="../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" type="text/css" href="../../ayu.css" disabled><link rel="stylesheet" type="text/css" href="../../dark.css" disabled><link rel="stylesheet" type="text/css" href="../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../storage.js"></script><script src="../../crates.js"></script><script defer src="../../main.js"></script> |
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| </a><h2 class="location">Struct Nothing</h2><div class="sidebar-elems"><div class="block items"><h3 class="sidebar-title"><a href="#trait-implementations">Trait Implementations</a></h3><div class="sidebar-links"><a href="#impl-Parse">Parse</a></div><h3 class="sidebar-title"><a href="#synthetic-implementations">Auto Trait Implementations</a></h3><div class="sidebar-links"><a href="#impl-RefUnwindSafe">RefUnwindSafe</a><a href="#impl-Send">Send</a><a href="#impl-Sync">Sync</a><a href="#impl-Unpin">Unpin</a><a href="#impl-UnwindSafe">UnwindSafe</a></div><h3 class="sidebar-title"><a href="#blanket-implementations">Blanket Implementations</a></h3><div class="sidebar-links"><a href="#impl-Any">Any</a><a href="#impl-Borrow%3CT%3E">Borrow<T></a><a href="#impl-BorrowMut%3CT%3E">BorrowMut<T></a><a href="#impl-From%3CT%3E">From<T></a><a href="#impl-Into%3CU%3E">Into<U></a><a href="#impl-TryFrom%3CU%3E">TryFrom<U></a><a href="#impl-TryInto%3CU%3E">TryInto<U></a></div></div><h2 class="location">Other items in<br><a href="../index.html">syn</a>::<wbr><a href="index.html">parse</a></h2><div id="sidebar-vars" data-name="Nothing" data-ty="struct" data-relpath=""></div><script defer src="sidebar-items.js"></script></div></nav><main><div class="width-limiter"><div class="sub-container"><a class="sub-logo-container" href="../../syn/index.html"><img class="rust-logo" src="../../rust-logo.png" alt="logo"></a><nav class="sub"><div class="theme-picker"><button id="theme-picker" aria-label="Pick another theme!" aria-haspopup="menu" title="themes"><img width="18" height="18" alt="Pick another theme!" src="../../brush.svg"></button><div id="theme-choices" role="menu"></div></div><form class="search-form"><div class="search-container"><div> |
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| <h1 class="fqn"><span class="in-band">Struct <a href="../index.html">syn</a>::<wbr><a href="index.html">parse</a>::<wbr><a class="struct" href="#">Nothing</a><button id="copy-path" onclick="copy_path(this)" title="Copy item path to clipboard"><img src="../../clipboard.svg" width="19" height="18" alt="Copy item path"></button></span></h1><span class="out-of-band"> |
| <a class="srclink" href="../../src/syn/parse.rs.html#1281" title="goto source code">source</a> · |
| <a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">[<span class="inner">−</span>]</a></span></div> |
| <div class="docblock item-decl"><pre class="rust struct"><code>pub struct Nothing;</code></pre></div><div class="item-info"><div class="stab portability">This is supported on <strong>crate feature <code>parsing</code></strong> only.</div></div><details class="rustdoc-toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>An empty syntax tree node that consumes no tokens when parsed.</p> |
| <p>This is useful for attribute macros that want to ensure they are not |
| provided any attribute args.</p> |
| |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use</span> <span class="ident">proc_macro::TokenStream</span>; |
| <span class="kw">use</span> <span class="ident">syn::parse_macro_input</span>; |
| <span class="kw">use</span> <span class="ident">syn::parse::Nothing</span>; |
| |
| <span class="attribute">#[<span class="ident">proc_macro_attribute</span>]</span> |
| <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">my_attr</span>(<span class="ident">args</span>: <span class="ident">TokenStream</span>, <span class="ident">input</span>: <span class="ident">TokenStream</span>) -> <span class="ident">TokenStream</span> { |
| <span class="macro">parse_macro_input!</span>(<span class="ident">args</span> <span class="kw">as</span> <span class="ident">Nothing</span>); |
| |
| <span class="comment">/* ... */</span> |
| }</code></pre></div> |
| <div class="example-wrap"><pre class="language-text"><code>error: unexpected token |
| --> src/main.rs:3:19 |
| | |
| 3 | #[my_attr(asdf)] |
| | ^^^^</code></pre></div></div></details><h2 id="trait-implementations" class="small-section-header">Trait Implementations<a href="#trait-implementations" class="anchor"></a></h2><div id="trait-implementations-list"><details class="rustdoc-toggle implementors-toggle" open><summary><div id="impl-Parse" class="impl has-srclink"><div class="rightside"><a class="srclink" href="../../src/syn/parse.rs.html#1283-1287" title="goto source code">source</a></div><a href="#impl-Parse" class="anchor"></a><h3 class="code-header in-band">impl <a class="trait" href="trait.Parse.html" title="trait syn::parse::Parse">Parse</a> for <a class="struct" href="struct.Nothing.html" title="struct syn::parse::Nothing">Nothing</a></h3></div></summary><div class="impl-items"><div id="method.parse" class="method trait-impl has-srclink"><div class="rightside"><a class="srclink" href="../../src/syn/parse.rs.html#1284-1286" title="goto source code">source</a></div><a href="#method.parse" class="anchor"></a><h4 class="code-header">fn <a href="trait.Parse.html#tymethod.parse" class="fnname">parse</a>(_input: <a class="type" href="type.ParseStream.html" title="type syn::parse::ParseStream">ParseStream</a><'_>) -> <a class="type" href="type.Result.html" title="type syn::parse::Result">Result</a><Self></h4></div></div></details></div><h2 id="synthetic-implementations" class="small-section-header">Auto Trait Implementations<a href="#synthetic-implementations" class="anchor"></a></h2><div id="synthetic-implementations-list"><div id="impl-RefUnwindSafe" class="impl has-srclink"><div class="rightside"></div><a href="#impl-RefUnwindSafe" class="anchor"></a><h3 class="code-header in-band">impl <a class="trait" href="https://doc.rust-lang.org/nightly/core/panic/unwind_safe/trait.RefUnwindSafe.html" title="trait core::panic::unwind_safe::RefUnwindSafe">RefUnwindSafe</a> for <a class="struct" href="struct.Nothing.html" title="struct syn::parse::Nothing">Nothing</a></h3></div><div id="impl-Send" class="impl has-srclink"><div class="rightside"></div><a href="#impl-Send" class="anchor"></a><h3 class="code-header in-band">impl <a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Send.html" title="trait core::marker::Send">Send</a> for <a class="struct" href="struct.Nothing.html" title="struct syn::parse::Nothing">Nothing</a></h3></div><div id="impl-Sync" class="impl has-srclink"><div class="rightside"></div><a href="#impl-Sync" class="anchor"></a><h3 class="code-header in-band">impl <a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sync.html" title="trait core::marker::Sync">Sync</a> for <a class="struct" href="struct.Nothing.html" title="struct syn::parse::Nothing">Nothing</a></h3></div><div id="impl-Unpin" class="impl has-srclink"><div class="rightside"></div><a href="#impl-Unpin" class="anchor"></a><h3 class="code-header in-band">impl <a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Unpin.html" title="trait core::marker::Unpin">Unpin</a> for <a class="struct" href="struct.Nothing.html" title="struct syn::parse::Nothing">Nothing</a></h3></div><div id="impl-UnwindSafe" class="impl has-srclink"><div class="rightside"></div><a href="#impl-UnwindSafe" class="anchor"></a><h3 class="code-header in-band">impl <a class="trait" href="https://doc.rust-lang.org/nightly/core/panic/unwind_safe/trait.UnwindSafe.html" title="trait core::panic::unwind_safe::UnwindSafe">UnwindSafe</a> for <a class="struct" href="struct.Nothing.html" title="struct syn::parse::Nothing">Nothing</a></h3></div></div><h2 id="blanket-implementations" class="small-section-header">Blanket Implementations<a href="#blanket-implementations" class="anchor"></a></h2><div id="blanket-implementations-list"><details class="rustdoc-toggle implementors-toggle" open><summary><div id="impl-Any" class="impl has-srclink"><div class="rightside"><a class="srclink" href="https://doc.rust-lang.org/nightly/src/core/any.rs.html#132-136" title="goto source code">source</a></div><a href="#impl-Any" class="anchor"></a><h3 class="code-header in-band">impl<T> <a class="trait" href="https://doc.rust-lang.org/nightly/core/any/trait.Any.html" title="trait core::any::Any">Any</a> for T <span class="where fmt-newline">where<br> T: 'static + ?<a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>, </span></h3></div></summary><div class="impl-items"><details class="rustdoc-toggle method-toggle" open><summary><div id="method.type_id" class="method trait-impl has-srclink"><div class="rightside"><a class="srclink" href="https://doc.rust-lang.org/nightly/src/core/any.rs.html#133" title="goto source code">source</a></div><a href="#method.type_id" class="anchor"></a><h4 class="code-header">pub fn <a href="https://doc.rust-lang.org/nightly/core/any/trait.Any.html#tymethod.type_id" class="fnname">type_id</a>(&self) -> <a class="struct" href="https://doc.rust-lang.org/nightly/core/any/struct.TypeId.html" title="struct core::any::TypeId">TypeId</a></h4></div></summary><div class='docblock'><p>Gets the <code>TypeId</code> of <code>self</code>. <a href="https://doc.rust-lang.org/nightly/core/any/trait.Any.html#tymethod.type_id">Read more</a></p> |
| </div></details></div></details><details class="rustdoc-toggle implementors-toggle" open><summary><div id="impl-Borrow%3CT%3E" class="impl has-srclink"><div class="rightside"><a class="srclink" href="https://doc.rust-lang.org/nightly/src/core/borrow.rs.html#209-214" title="goto source code">source</a></div><a href="#impl-Borrow%3CT%3E" class="anchor"></a><h3 class="code-header in-band">impl<T> <a class="trait" href="https://doc.rust-lang.org/nightly/core/borrow/trait.Borrow.html" title="trait core::borrow::Borrow">Borrow</a><T> for T <span class="where fmt-newline">where<br> T: ?<a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>, </span></h3></div></summary><div class="impl-items"><details class="rustdoc-toggle method-toggle" open><summary><div id="method.borrow" class="method trait-impl has-srclink"><div class="rightside"><a class="srclink" href="https://doc.rust-lang.org/nightly/src/core/borrow.rs.html#211" title="goto source code">source</a></div><a href="#method.borrow" class="anchor"></a><h4 class="code-header">pub fn <a href="https://doc.rust-lang.org/nightly/core/borrow/trait.Borrow.html#tymethod.borrow" class="fnname">borrow</a>(&self) -> <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&</a>T</h4></div></summary><div class='docblock'><p>Immutably borrows from an owned value. <a href="https://doc.rust-lang.org/nightly/core/borrow/trait.Borrow.html#tymethod.borrow">Read more</a></p> |
| </div></details></div></details><details class="rustdoc-toggle implementors-toggle" open><summary><div id="impl-BorrowMut%3CT%3E" class="impl has-srclink"><div class="rightside"><a class="srclink" href="https://doc.rust-lang.org/nightly/src/core/borrow.rs.html#218-222" title="goto source code">source</a></div><a href="#impl-BorrowMut%3CT%3E" class="anchor"></a><h3 class="code-header in-band">impl<T> <a class="trait" href="https://doc.rust-lang.org/nightly/core/borrow/trait.BorrowMut.html" title="trait core::borrow::BorrowMut">BorrowMut</a><T> for T <span class="where fmt-newline">where<br> T: ?<a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>, </span></h3></div></summary><div class="impl-items"><details class="rustdoc-toggle method-toggle" open><summary><div id="method.borrow_mut" class="method trait-impl has-srclink"><div class="rightside"><a class="srclink" href="https://doc.rust-lang.org/nightly/src/core/borrow.rs.html#219" title="goto source code">source</a></div><a href="#method.borrow_mut" class="anchor"></a><h4 class="code-header">pub fn <a href="https://doc.rust-lang.org/nightly/core/borrow/trait.BorrowMut.html#tymethod.borrow_mut" class="fnname">borrow_mut</a>(&mut self) -> <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&mut </a>T</h4></div></summary><div class='docblock'><p>Mutably borrows from an owned value. <a href="https://doc.rust-lang.org/nightly/core/borrow/trait.BorrowMut.html#tymethod.borrow_mut">Read more</a></p> |
| </div></details></div></details><details class="rustdoc-toggle implementors-toggle" open><summary><div id="impl-From%3CT%3E" class="impl has-srclink"><div class="rightside"><a class="srclink" href="https://doc.rust-lang.org/nightly/src/core/convert/mod.rs.html#546-550" title="goto source code">source</a></div><a href="#impl-From%3CT%3E" class="anchor"></a><h3 class="code-header in-band">impl<T> <a class="trait" href="https://doc.rust-lang.org/nightly/core/convert/trait.From.html" title="trait core::convert::From">From</a><T> for T</h3></div></summary><div class="impl-items"><details class="rustdoc-toggle method-toggle" open><summary><div id="method.from" class="method trait-impl has-srclink"><div class="rightside"><a class="srclink" href="https://doc.rust-lang.org/nightly/src/core/convert/mod.rs.html#547" title="goto source code">source</a></div><a href="#method.from" class="anchor"></a><h4 class="code-header">pub fn <a href="https://doc.rust-lang.org/nightly/core/convert/trait.From.html#tymethod.from" class="fnname">from</a>(t: T) -> T</h4></div></summary><div class='docblock'><p>Performs the conversion.</p> |
| </div></details></div></details><details class="rustdoc-toggle implementors-toggle" open><summary><div id="impl-Into%3CU%3E" class="impl has-srclink"><div class="rightside"><a class="srclink" href="https://doc.rust-lang.org/nightly/src/core/convert/mod.rs.html#534-541" title="goto source code">source</a></div><a href="#impl-Into%3CU%3E" class="anchor"></a><h3 class="code-header in-band">impl<T, U> <a class="trait" href="https://doc.rust-lang.org/nightly/core/convert/trait.Into.html" title="trait core::convert::Into">Into</a><U> for T <span class="where fmt-newline">where<br> U: <a class="trait" href="https://doc.rust-lang.org/nightly/core/convert/trait.From.html" title="trait core::convert::From">From</a><T>, </span></h3></div></summary><div class="impl-items"><details class="rustdoc-toggle method-toggle" open><summary><div id="method.into" class="method trait-impl has-srclink"><div class="rightside"><a class="srclink" href="https://doc.rust-lang.org/nightly/src/core/convert/mod.rs.html#538" title="goto source code">source</a></div><a href="#method.into" class="anchor"></a><h4 class="code-header">pub fn <a href="https://doc.rust-lang.org/nightly/core/convert/trait.Into.html#tymethod.into" class="fnname">into</a>(self) -> U</h4></div></summary><div class='docblock'><p>Performs the conversion.</p> |
| </div></details></div></details><details class="rustdoc-toggle implementors-toggle" open><summary><div id="impl-TryFrom%3CU%3E" class="impl has-srclink"><div class="rightside"><a class="srclink" href="https://doc.rust-lang.org/nightly/src/core/convert/mod.rs.html#584-593" title="goto source code">source</a></div><a href="#impl-TryFrom%3CU%3E" class="anchor"></a><h3 class="code-header in-band">impl<T, U> <a class="trait" href="https://doc.rust-lang.org/nightly/core/convert/trait.TryFrom.html" title="trait core::convert::TryFrom">TryFrom</a><U> for T <span class="where fmt-newline">where<br> U: <a class="trait" href="https://doc.rust-lang.org/nightly/core/convert/trait.Into.html" title="trait core::convert::Into">Into</a><T>, </span></h3></div></summary><div class="impl-items"><details class="rustdoc-toggle" open><summary><div id="associatedtype.Error-1" class="type trait-impl has-srclink"><a href="#associatedtype.Error-1" class="anchor"></a><h4 class="code-header">type <a href="https://doc.rust-lang.org/nightly/core/convert/trait.TryFrom.html#associatedtype.Error" class="associatedtype">Error</a> = <a class="enum" href="https://doc.rust-lang.org/nightly/core/convert/enum.Infallible.html" title="enum core::convert::Infallible">Infallible</a></h4></div></summary><div class='docblock'><p>The type returned in the event of a conversion error.</p> |
| </div></details><details class="rustdoc-toggle method-toggle" open><summary><div id="method.try_from" class="method trait-impl has-srclink"><div class="rightside"><a class="srclink" href="https://doc.rust-lang.org/nightly/src/core/convert/mod.rs.html#590" title="goto source code">source</a></div><a href="#method.try_from" class="anchor"></a><h4 class="code-header">pub fn <a href="https://doc.rust-lang.org/nightly/core/convert/trait.TryFrom.html#tymethod.try_from" class="fnname">try_from</a>(value: U) -> <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a><T, <T as <a class="trait" href="https://doc.rust-lang.org/nightly/core/convert/trait.TryFrom.html" title="trait core::convert::TryFrom">TryFrom</a><U>>::<a class="associatedtype" href="https://doc.rust-lang.org/nightly/core/convert/trait.TryFrom.html#associatedtype.Error" title="type core::convert::TryFrom::Error">Error</a>></h4></div></summary><div class='docblock'><p>Performs the conversion.</p> |
| </div></details></div></details><details class="rustdoc-toggle implementors-toggle" open><summary><div id="impl-TryInto%3CU%3E" class="impl has-srclink"><div class="rightside"><a class="srclink" href="https://doc.rust-lang.org/nightly/src/core/convert/mod.rs.html#570-579" title="goto source code">source</a></div><a href="#impl-TryInto%3CU%3E" class="anchor"></a><h3 class="code-header in-band">impl<T, U> <a class="trait" href="https://doc.rust-lang.org/nightly/core/convert/trait.TryInto.html" title="trait core::convert::TryInto">TryInto</a><U> for T <span class="where fmt-newline">where<br> U: <a class="trait" href="https://doc.rust-lang.org/nightly/core/convert/trait.TryFrom.html" title="trait core::convert::TryFrom">TryFrom</a><T>, </span></h3></div></summary><div class="impl-items"><details class="rustdoc-toggle" open><summary><div id="associatedtype.Error" class="type trait-impl has-srclink"><a href="#associatedtype.Error" class="anchor"></a><h4 class="code-header">type <a href="https://doc.rust-lang.org/nightly/core/convert/trait.TryInto.html#associatedtype.Error" class="associatedtype">Error</a> = <U as <a class="trait" href="https://doc.rust-lang.org/nightly/core/convert/trait.TryFrom.html" title="trait core::convert::TryFrom">TryFrom</a><T>>::<a class="associatedtype" href="https://doc.rust-lang.org/nightly/core/convert/trait.TryFrom.html#associatedtype.Error" title="type core::convert::TryFrom::Error">Error</a></h4></div></summary><div class='docblock'><p>The type returned in the event of a conversion error.</p> |
| </div></details><details class="rustdoc-toggle method-toggle" open><summary><div id="method.try_into" class="method trait-impl has-srclink"><div class="rightside"><a class="srclink" href="https://doc.rust-lang.org/nightly/src/core/convert/mod.rs.html#576" title="goto source code">source</a></div><a href="#method.try_into" class="anchor"></a><h4 class="code-header">pub fn <a href="https://doc.rust-lang.org/nightly/core/convert/trait.TryInto.html#tymethod.try_into" class="fnname">try_into</a>(self) -> <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a><U, <U as <a class="trait" href="https://doc.rust-lang.org/nightly/core/convert/trait.TryFrom.html" title="trait core::convert::TryFrom">TryFrom</a><T>>::<a class="associatedtype" href="https://doc.rust-lang.org/nightly/core/convert/trait.TryFrom.html#associatedtype.Error" title="type core::convert::TryFrom::Error">Error</a>></h4></div></summary><div class='docblock'><p>Performs the conversion.</p> |
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