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26 lines
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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 a given configuration is set."><title>assert_cfg 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>cfg</a></h2><h3><a href="#">Sections</a></h3><ul class="block top-toc"><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_cfg</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_cfg.rs.html#39-49">Source</a> </span></div><pre class="rust item-decl"><code>macro_rules! assert_cfg {
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() => { ... };
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($($cfg:meta)+, $msg:expr $(,)?) => { ... };
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($($cfg:tt)*) => { ... };
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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 a given configuration is set.</p>
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<h2 id="examples"><a class="doc-anchor" href="#examples">§</a>Examples</h2>
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<p>A project will simply fail to compile if the given configuration is not set.</p>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="comment">// We're not masochists
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</span><span class="macro">assert_cfg!</span>(not(target_pointer_width = <span class="string">"16"</span>));</code></pre></div>
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<p>If a project does not support a set of configurations, you may want to
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report why. There is the option of providing a compile error message string:</p>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="macro">assert_cfg!</span>(any(unix, windows), <span class="string">"There is only support for Unix or Windows"</span>);
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<span class="comment">// User needs to specify a database back-end
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</span><span class="macro">assert_cfg!</span>(all(not(all(feature = <span class="string">"mysql"</span>, feature = <span class="string">"mongodb"</span>)),
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any( feature = <span class="string">"mysql"</span>, feature = <span class="string">"mongodb"</span>)),
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<span class="string">"Must exclusively use MySQL or MongoDB as database back-end"</span>);</code></pre></div>
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<p>Some configurations are impossible. For example, we can’t be compiling for
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both macOS <em>and</em> Windows simultaneously:</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_cfg!</span>(all(target_os = <span class="string">"macos"</span>,
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target_os = <span class="string">"windows"</span>),
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<span class="string">"No, that's not how it works! ಠ_ಠ"</span>);</code></pre></div>
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</div></details></section></div></main></body></html> |