19 lines
5.1 KiB
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19 lines
5.1 KiB
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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="Asserts that types are equal in size."><title>assert_eq_size in static_assertions - Rust</title><script>if(window.location.protocol!=="file:")document.head.insertAdjacentHTML("beforeend","SourceSerif4-Regular-6b053e98.ttf.woff2,FiraSans-Regular-0fe48ade.woff2,FiraSans-Medium-e1aa3f0a.woff2,SourceCodePro-Regular-8badfe75.ttf.woff2,SourceCodePro-Semibold-aa29a496.ttf.woff2".split(",").map(f=>`<link rel="preload" as="font" type="font/woff2" crossorigin href="../static.files/${f}">`).join(""))</script><link rel="stylesheet" href="../static.files/normalize-9960930a.css"><link rel="stylesheet" href="../static.files/rustdoc-42caa33d.css"><meta name="rustdoc-vars" data-root-path="../" data-static-root-path="../static.files/" data-current-crate="static_assertions" data-themes="" data-resource-suffix="" data-rustdoc-version="1.84.0 (9fc6b4312 2025-01-07)" data-channel="1.84.0" data-search-js="search-92e6798f.js" data-settings-js="settings-0f613d39.js" ><script src="../static.files/storage-59e33391.js"></script><script defer src="sidebar-items.js"></script><script defer src="../static.files/main-5f194d8c.js"></script><noscript><link rel="stylesheet" href="../static.files/noscript-893ab5e7.css"></noscript><link rel="alternate icon" type="image/png" href="../static.files/favicon-32x32-6580c154.png"><link rel="icon" type="image/svg+xml" href="../static.files/favicon-044be391.svg"></head><body class="rustdoc macro"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="mobile-topbar"><button class="sidebar-menu-toggle" title="show sidebar"></button><a class="logo-container" href="../static_assertions/index.html"><img src="https://raw.githubusercontent.com/nvzqz/static-assertions-rs/assets/Icon.png" alt=""></a></nav><nav class="sidebar"><div class="sidebar-crate"><a class="logo-container" href="../static_assertions/index.html"><img src="https://raw.githubusercontent.com/nvzqz/static-assertions-rs/assets/Icon.png" alt="logo"></a><h2><a href="../static_assertions/index.html">static_<wbr>assertions</a><span class="version">1.1.0</span></h2></div><div class="sidebar-elems"><section id="rustdoc-toc"><h2 class="location"><a href="#">assert_<wbr>eq_<wbr>size</a></h2><h3><a href="#">Sections</a></h3><ul class="block top-toc"><li><a href="#alternatives" title="Alternatives">Alternatives</a></li><li><a href="#examples" title="Examples">Examples</a></li></ul></section><div id="rustdoc-modnav"><h2 class="in-crate"><a href="index.html">In crate static_<wbr>assertions</a></h2></div></div></nav><div class="sidebar-resizer"></div><main><div class="width-limiter"><rustdoc-search></rustdoc-search><section id="main-content" class="content"><div class="main-heading"><span class="rustdoc-breadcrumbs"><a href="index.html">static_assertions</a></span><h1>Macro <span class="macro">assert_eq_size</span><button id="copy-path" title="Copy item path to clipboard">Copy item path</button></h1><rustdoc-toolbar></rustdoc-toolbar><span class="sub-heading"><a class="src" href="../src/static_assertions/assert_eq_size.rs.html#34-40">Source</a> </span></div><pre class="rust item-decl"><code>macro_rules! assert_eq_size {
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($x:ty, $($xs:ty),+ $(,)?) => { ... };
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}</code></pre><details class="toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>Asserts that types are equal in size.</p>
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<p>When performing operations such as pointer casts or dealing with <a href="https://doc.rust-lang.org/std/primitive.usize.html"><code>usize</code></a>
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versus <a href="https://doc.rust-lang.org/std/primitive.u64.html"><code>u64</code></a> versus <a href="https://doc.rust-lang.org/std/primitive.u32.html"><code>u32</code></a>, the size of your types matter. That is where
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this macro comes into play.</p>
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<h2 id="alternatives"><a class="doc-anchor" href="#alternatives">§</a>Alternatives</h2>
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<p>There also exists <a href="macro.assert_eq_size_val.html"><code>assert_eq_size_val</code></a> and
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<a href="macro.assert_eq_size_ptr.html"><code>assert_eq_size_ptr</code></a>. Instead of specifying
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types to compare, values’ sizes can be directly compared against each other.</p>
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<h2 id="examples"><a class="doc-anchor" href="#examples">§</a>Examples</h2>
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<p>These three types, despite being very different, all have the same size:</p>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="macro">assert_eq_size!</span>([u8; <span class="number">4</span>], (u16, u16), u32);</code></pre></div>
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<p>The following example fails to compile because <code>u32</code> has 4 times the size of
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<code>u8</code>:</p>
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<div class="example-wrap compile_fail"><a href="#" class="tooltip" title="This example deliberately fails to compile">ⓘ</a><pre class="rust rust-example-rendered"><code><span class="macro">assert_eq_size!</span>(u32, u8);</code></pre></div>
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</div></details></section></div></main></body></html> |