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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="API documentation for the Rust `Nothing` struct in crate `syn`."><meta name="keywords" content="rust, rustlang, rust-lang, Nothing"><title>syn::parse::Nothing - Rust</title><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="../../light.css" id="themeStyle"><link rel="stylesheet" type="text/css" href="../../dark.css" disabled ><link rel="stylesheet" type="text/css" href="../../ayu.css" disabled ><script id="default-settings"></script><script src="../../storage.js"></script><noscript><link rel="stylesheet" href="../../noscript.css"></noscript><link rel="icon" type="image/svg+xml" href="../../favicon.svg">
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<link rel="alternate icon" type="image/png" href="../../favicon-16x16.png">
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<link rel="alternate icon" type="image/png" href="../../favicon-32x32.png"><style type="text/css">#crate-search{background-image:url("../../down-arrow.svg");}</style></head><body class="rustdoc struct"><!--[if lte IE 8]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><div class="sidebar-menu">☰</div><a href='../../syn/index.html'><div class='logo-container rust-logo'><img src='../../rust-logo.png' alt='logo'></div></a><p class="location">Struct Nothing</p><div class="sidebar-elems"><div class="block items"><a class="sidebar-title" href="#trait-implementations">Trait Implementations</a><div class="sidebar-links"><a href="#impl-Parse">Parse</a></div><a class="sidebar-title" href="#synthetic-implementations">Auto Trait Implementations</a><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><a class="sidebar-title" href="#blanket-implementations">Blanket Implementations</a><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><p class="location"><a href="../index.html">syn</a>::<wbr><a href="index.html">parse</a></p><script>window.sidebarCurrent = {name: "Nothing", ty: "struct", relpath: ""};</script><script defer src="sidebar-items.js"></script></div></nav><div class="theme-picker"><button id="theme-picker" aria-label="Pick another theme!" aria-haspopup="menu"><img src="../../brush.svg" width="18" alt="Pick another theme!"></button><div id="theme-choices" role="menu"></div></div><script src="../../theme.js"></script><nav class="sub"><form class="search-form"><div class="search-container"><div><select id="crate-search"><option value="All crates">All crates</option></select><input class="search-input" name="search" disabled autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"></div><span class="help-button">?</span>
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<a id="settings-menu" href="../../settings.html"><img src="../../wheel.svg" width="18" alt="Change settings"></a></div></form></nav><section id="main" class="content"><h1 class="fqn"><span class="out-of-band"><span id="render-detail"><a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">[<span class="inner">−</span>]</a></span><a class="srclink" href="../../src/syn/parse.rs.html#1281" title="goto source code">[src]</a></span><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></span></h1><div class="docblock type-decl hidden-by-usual-hider"><pre class="rust struct">pub struct Nothing;</pre></div><div class="docblock"><p>An empty syntax tree node that consumes no tokens when parsed.</p>
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<p>This is useful for attribute macros that want to ensure they are not
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provided any attribute args.</p>
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<div class="example-wrap"><pre class="rust rust-example-rendered">
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<span class="kw">use</span> <span class="ident">proc_macro</span>::<span class="ident">TokenStream</span>;
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<span class="kw">use</span> <span class="ident">syn</span>::<span class="ident">parse_macro_input</span>;
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<span class="kw">use</span> <span class="ident">syn</span>::<span class="ident">parse</span>::<span class="ident">Nothing</span>;
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<span class="attribute">#[<span class="ident">proc_macro_attribute</span>]</span>
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<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="op">-</span><span class="op">></span> <span class="ident">TokenStream</span> {
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<span class="macro">parse_macro_input</span><span class="macro">!</span>(<span class="ident">args</span> <span class="kw">as</span> <span class="ident">Nothing</span>);
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<span class="comment">/* ... */</span>
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}</pre></div>
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<pre><code class="language-text">error: unexpected token
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--> src/main.rs:3:19
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3 | #[my_attr(asdf)]
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| ^^^^
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</code></pre>
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</div><h2 id="trait-implementations" class="small-section-header">Trait Implementations<a href="#trait-implementations" class="anchor"></a></h2><div id="trait-implementations-list"><h3 id="impl-Parse" class="impl"><code class="in-band">impl <a class="trait" href="../../syn/parse/trait.Parse.html" title="trait syn::parse::Parse">Parse</a> for <a class="struct" href="../../syn/parse/struct.Nothing.html" title="struct syn::parse::Nothing">Nothing</a></code><a href="#impl-Parse" class="anchor"></a><a class="srclink" href="../../src/syn/parse.rs.html#1283-1287" title="goto source code">[src]</a></h3><div class="impl-items"><h4 id="method.parse" class="method hidden"><code>fn <a href="../../syn/parse/trait.Parse.html#tymethod.parse" class="fnname">parse</a>(_input: <a class="type" href="../../syn/parse/type.ParseStream.html" title="type syn::parse::ParseStream">ParseStream</a><'_>) -> <a class="type" href="../../syn/parse/type.Result.html" title="type syn::parse::Result">Result</a><Self></code><a class="srclink" href="../../src/syn/parse.rs.html#1284-1286" title="goto source code">[src]</a></h4></div></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"><h3 id="impl-RefUnwindSafe" class="impl"><code class="in-band">impl <a class="trait" href="https://doc.rust-lang.org/nightly/std/panic/trait.RefUnwindSafe.html" title="trait std::panic::RefUnwindSafe">RefUnwindSafe</a> for <a class="struct" href="../../syn/parse/struct.Nothing.html" title="struct syn::parse::Nothing">Nothing</a></code><a href="#impl-RefUnwindSafe" class="anchor"></a></h3><div class="impl-items"></div><h3 id="impl-Send" class="impl"><code class="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="../../syn/parse/struct.Nothing.html" title="struct syn::parse::Nothing">Nothing</a></code><a href="#impl-Send" class="anchor"></a></h3><div class="impl-items"></div><h3 id="impl-Sync" class="impl"><code class="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="../../syn/parse/struct.Nothing.html" title="struct syn::parse::Nothing">Nothing</a></code><a href="#impl-Sync" class="anchor"></a></h3><div class="impl-items"></div><h3 id="impl-Unpin" class="impl"><code class="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="../../syn/parse/struct.Nothing.html" title="struct syn::parse::Nothing">Nothing</a></code><a href="#impl-Unpin" class="anchor"></a></h3><div class="impl-items"></div><h3 id="impl-UnwindSafe" class="impl"><code class="in-band">impl <a class="trait" href="https://doc.rust-lang.org/nightly/std/panic/trait.UnwindSafe.html" title="trait std::panic::UnwindSafe">UnwindSafe</a> for <a class="struct" href="../../syn/parse/struct.Nothing.html" title="struct syn::parse::Nothing">Nothing</a></code><a href="#impl-UnwindSafe" class="anchor"></a></h3><div class="impl-items"></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"><h3 id="impl-Any" class="impl"><code class="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></code><a href="#impl-Any" class="anchor"></a><a class="srclink" href="https://doc.rust-lang.org/nightly/src/core/any.rs.html#108-112" title="goto source code">[src]</a></h3><div class="impl-ite
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</div></div><h3 id="impl-Borrow%3CT%3E" class="impl"><code class="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></code><a href="#impl-Borrow%3CT%3E" class="anchor"></a><a class="srclink" href="https://doc.rust-lang.org/nightly/src/core/borrow.rs.html#210-214" title="goto source code">[src]</a></h3><div class="impl-items"><h4 id="method.borrow" class="method hidden"><code>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</code><a class="srclink" href="https://doc.rust-lang.org/nightly/src/core/borrow.rs.html#211-213" title="goto source code">[src]</a></h4><div class='docblock hidden'><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>
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</div></div><h3 id="impl-BorrowMut%3CT%3E" class="impl"><code class="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></code><a href="#impl-BorrowMut%3CT%3E" class="anchor"></a><a class="srclink" href="https://doc.rust-lang.org/nightly/src/core/borrow.rs.html#217-221" title="goto source code">[src]</a></h3><div class="impl-items"><h4 id="method.borrow_mut" class="method hidden"><code>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</code><a class="srclink" href="https://doc.rust-lang.org/nightly/src/core/borrow.rs.html#218-220" title="goto source code">[src]</a></h4><div class='docblock hidden'><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>
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</div></div><h3 id="impl-From%3CT%3E" class="impl"><code class="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</code><a href="#impl-From%3CT%3E" class="anchor"></a><a class="srclink" href="https://doc.rust-lang.org/nightly/src/core/convert/mod.rs.html#552-556" title="goto source code">[src]</a></h3><div class="impl-items"><h4 id="method.from" class="method hidden"><code>pub fn <a href="https://doc.rust-lang.org/nightly/core/convert/trait.From.html#tymethod.from" class="fnname">from</a>(t: T) -> T</code><a class="srclink" href="https://doc.rust-lang.org/nightly/src/core/convert/mod.rs.html#553-555" title="goto source code">[src]</a></h4><div class='docblock hidden'><p>Performs the conversion.</p>
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</div></div><h3 id="impl-Into%3CU%3E" class="impl"><code class="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></code><a href="#impl-Into%3CU%3E" class="anchor"></a><a class="srclink" href="https://doc.rust-lang.org/nightly/src/core/convert/mod.rs.html#541-548" title="goto source code">[src]</a></h3><div class="impl-items"><h4 id="method.into" class="method hidden"><code>pub fn <a href="https://doc.rust-lang.org/nightly/core/convert/trait.Into.html#tymethod.into" class="fnname">into</a>(self) -> U</code><a class="srclink" href="https://doc.rust-lang.org/nightly/src/core/convert/mod.rs.html#545-547" title="goto source code">[src]</a></h4><div class='docblock hidden'><p>Performs the conversion.</p>
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</div></div><h3 id="impl-TryFrom%3CU%3E" class="impl"><code class="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></code><a href="#impl-TryFrom%3CU%3E" class="anchor"></a><a class="srclink" href="https://doc.rust-lang.org/nightly/src/core/convert/mod.rs.html#589-598" title="goto source code">[src]</a></h3><div class="impl-items"><h4 id="associatedtype.Error" class="type"><code>type <a href="https://doc.rust-lang.org/nightly/core/convert/trait.TryFrom.html#associatedtype.Error" class="type">Error</a> = <a class="enum" href="https://doc.rust-lang.org/nightly/core/convert/enum.Infallible.html" title="enum core::convert::Infallible">Infallible</a></code></h4><div class='docblock'><p>The type returned in the event of a conversion error.</p>
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</div><h4 id="method.try_from" class="method hidden"><code>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="type" href="https://doc.rust-lang.org/nightly/core/convert/trait.TryFrom.html#associatedtype.Error" title="type core::convert::TryFrom::Error">Error</a>></code><a class="srclink" href="https://doc.rust-lang.org/nightly/src/core/convert/mod.rs.html#595-597" title="goto source code">[src]</a></h4><div class='docblock hidden'><p>Performs the conversion.</p>
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</div></div><h3 id="impl-TryInto%3CU%3E" class="impl"><code class="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></code><a href="#impl-TryInto%3CU%3E" class="anchor"></a><a class="srclink" href="https://doc.rust-lang.org/nightly/src/core/convert/mod.rs.html#575-584" title="goto source code">[src]</a></h3><div class="impl-items"><h4 id="associatedtype.Error-1" class="type"><code>type <a href="https://doc.rust-lang.org/nightly/core/convert/trait.TryInto.html#associatedtype.Error" class="type">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="type" href="https://doc.rust-lang.org/nightly/core/convert/trait.TryFrom.html#associatedtype.Error" title="type core::convert::TryFrom::Error">Error</a></code></h4><div class='docblock'><p>The type returned in the event of a conversion error.</p>
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</div><h4 id="method.try_into" class="method hidden"><code>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="type" href="https://doc.rust-lang.org/nightly/core/convert/trait.TryFrom.html#associatedtype.Error" title="type core::convert::TryFrom::Error">Error</a>></code><a class="srclink" href="https://doc.rust-lang.org/nightly/src/core/convert/mod.rs.html#581-583" title="goto source code">[src]</a></h4><div class='docblock hidden'><p>Performs the conversion.</p>
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</div></div></div></section><section id="search" class="content hidden"></section><section class="footer"></section><script>window.rootPath = "../../";window.currentCrate = "syn";</script><script src="../../main.js"></script><script defer src="../../search-index.js"></script></body></html>
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