<!DOCTYPE HTML> <html lang="en" class="sidebar-visible no-js"> <head> <!-- Book generated using mdBook --> <meta charset="UTF-8"> <title>What is rustc? - The rustc book</title> <meta content="text/html; charset=utf-8" http-equiv="Content-Type"> <meta name="description" content=""> <meta name="viewport" content="width=device-width, initial-scale=1"> <meta name="theme-color" content="#ffffff" /> <link rel="stylesheet" href="book.css"> <link href="https://fonts.googleapis.com/css?family=Open+Sans:300italic,400italic,600italic,700italic,800italic,400,300,600,700,800" rel="stylesheet" type="text/css"> <link href="https://fonts.googleapis.com/css?family=Source+Code+Pro:500" rel="stylesheet" type="text/css"> <link rel="shortcut icon" href="favicon.png"> <!-- Font Awesome --> <link rel="stylesheet" href="_FontAwesome/css/font-awesome.css"> <link rel="stylesheet" href="highlight.css"> <link rel="stylesheet" href="tomorrow-night.css"> <link rel="stylesheet" href="ayu-highlight.css"> <!-- Custom theme stylesheets --> </head> <body class="light"> <!-- Work around some values being stored in localStorage wrapped in quotes --> <script type="text/javascript"> try { var theme = localStorage.getItem('mdbook-theme'); 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html.classList.add("sidebar-" + sidebar); </script> <nav id="sidebar" class="sidebar" aria-label="Table of contents"> <ol class="chapter"><li><a href="what-is-rustc.html" class="active"><strong aria-hidden="true">1.</strong> What is rustc?</a></li><li><a href="command-line-arguments.html"><strong aria-hidden="true">2.</strong> Command-line arguments</a></li><li><a href="lints/index.html"><strong aria-hidden="true">3.</strong> Lints</a></li><li><ol class="section"><li><a href="lints/levels.html"><strong aria-hidden="true">3.1.</strong> Lint levels</a></li><li><a href="lints/groups.html"><strong aria-hidden="true">3.2.</strong> Lint Groups</a></li><li><a href="lints/listing/index.html"><strong aria-hidden="true">3.3.</strong> Lint listing</a></li><li><ol class="section"><li><a href="lints/listing/allowed-by-default.html"><strong aria-hidden="true">3.3.1.</strong> Allowed-by-default lints</a></li><li><a href="lints/listing/warn-by-default.html"><strong aria-hidden="true">3.3.2.</strong> Warn-by-default lints</a></li><li><a href="lints/listing/deny-by-default.html"><strong aria-hidden="true">3.3.3.</strong> Deny-by-default lints</a></li></ol></li></ol></li><li><a href="codegen-options/index.html"><strong aria-hidden="true">4.</strong> Codegen options</a></li><li><a href="targets/index.html"><strong aria-hidden="true">5.</strong> Targets</a></li><li><ol class="section"><li><a href="targets/built-in.html"><strong aria-hidden="true">5.1.</strong> Built-in Targets</a></li><li><a href="targets/custom.html"><strong aria-hidden="true">5.2.</strong> Custom Targets</a></li></ol></li><li><a href="contributing.html"><strong aria-hidden="true">6.</strong> Contributing to rustc</a></li></ol> </nav> <div id="page-wrapper" class="page-wrapper"> <div class="page"> <div id="menu-bar" class="menu-bar"> <div id="menu-bar-sticky-container"> <div class="left-buttons"> <button id="sidebar-toggle" class="icon-button" type="button" title="Toggle Table of Contents" aria-label="Toggle Table of Contents" aria-controls="sidebar"> <i class="fa fa-bars"></i> </button> <button id="theme-toggle" class="icon-button" type="button" title="Change theme" aria-label="Change theme" aria-haspopup="true" aria-expanded="false" aria-controls="theme-list"> <i class="fa fa-paint-brush"></i> </button> <ul id="theme-list" class="theme-popup" aria-label="Themes" role="menu"> <li role="none"><button role="menuitem" class="theme" id="light">Light <span class="default">(default)</span></button></li> <li role="none"><button role="menuitem" class="theme" id="rust">Rust</button></li> <li role="none"><button role="menuitem" class="theme" id="coal">Coal</button></li> <li role="none"><button role="menuitem" class="theme" id="navy">Navy</button></li> <li role="none"><button role="menuitem" class="theme" id="ayu">Ayu</button></li> </ul> <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar"> <i class="fa fa-search"></i> </button> </div> <h1 class="menu-title">The rustc book</h1> <div class="right-buttons"> <a href="print.html" title="Print this book" aria-label="Print this book"> <i id="print-button" class="fa fa-print"></i> </a> </div> </div> </div> <div id="search-wrapper" class="hidden"> <form id="searchbar-outer" class="searchbar-outer"> <input type="search" name="search" id="searchbar" name="searchbar" placeholder="Search this book ..." aria-controls="searchresults-outer" aria-describedby="searchresults-header"> </form> <div id="searchresults-outer" class="searchresults-outer hidden"> <div id="searchresults-header" class="searchresults-header"></div> <ul id="searchresults"> </ul> </div> </div> <!-- Apply ARIA attributes after the sidebar and the sidebar toggle button are added to the DOM --> <script type="text/javascript"> document.getElementById('sidebar-toggle').setAttribute('aria-expanded', sidebar === 'visible'); document.getElementById('sidebar').setAttribute('aria-hidden', sidebar !== 'visible'); Array.from(document.querySelectorAll('#sidebar a')).forEach(function(link) { link.setAttribute('tabIndex', sidebar === 'visible' ? 0 : -1); }); </script> <div id="content" class="content"> <main> <a class="header" href="what-is-rustc.html#what-is-rustc" id="what-is-rustc"><h1>What is rustc?</h1></a> <p>Welcome to "The rustc book"! <code>rustc</code> is the compiler for the Rust programming language, provided by the project itself. Compilers take your source code and produce binary code, either as a library or executable.</p> <p>Most Rust programmers don't invoke <code>rustc</code> directly, but instead do it through <a href="../cargo/index.html">Cargo</a>. It's all in service of <code>rustc</code> though! If you want to see how Cargo calls <code>rustc</code>, you can</p> <pre><code class="language-bash">$ cargo build --verbose </code></pre> <p>And it will print out each <code>rustc</code> invocation. This book can help you understand what each of these options does. Additionally, while most Rustaceans use Cargo, not all do: sometimes they integrate <code>rustc</code> into other build systems. This book should provide a guide to all of the options you'd need to do so.</p> <a class="header" href="what-is-rustc.html#basic-usage" id="basic-usage"><h2>Basic usage</h2></a> <p>Let's say you've got a little hello world program in a file <code>hello.rs</code>:</p> <pre><pre class="playpen"><code class="language-rust">fn main() { println!("Hello, world!"); } </code></pre></pre> <p>To turn this source code into an executable, you can use <code>rustc</code>:</p> <pre><code class="language-bash">$ rustc hello.rs $ ./hello # on a *NIX $ .\hello.exe # on Windows </code></pre> <p>Note that we only ever pass <code>rustc</code> the <em>crate root</em>, not every file we wish to compile. For example, if we had a <code>main.rs</code> that looked like this:</p> <pre><code class="language-rust ignore">mod foo; fn main() { foo::hello(); } </code></pre> <p>And a <code>foo.rs</code> that had this:</p> <pre><code class="language-rust ignore">fn hello() { println!("Hello, world!"); } </code></pre> <p>To compile this, we'd run this command:</p> <pre><code class="language-bash">$ rustc main.rs </code></pre> <p>No need to tell <code>rustc</code> about <code>foo.rs</code>; the <code>mod</code> statements give it everything that it needs. This is different than how you would use a C compiler, where you invoke the compiler on each file, and then link everything together. In other words, the <em>crate</em> is a translation unit, not a particular module.</p> </main> <nav class="nav-wrapper" aria-label="Page navigation"> <!-- Mobile navigation buttons --> <a rel="next" href="command-line-arguments.html" class="mobile-nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right"> <i class="fa fa-angle-right"></i> </a> <div style="clear: both"></div> </nav> </div> </div> <nav class="nav-wide-wrapper" aria-label="Page navigation"> <a href="command-line-arguments.html" class="nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right"> <i class="fa fa-angle-right"></i> </a> </nav> </div> <script src="searchindex.js" type="text/javascript" charset="utf-8"></script> <script src="elasticlunr.min.js" type="text/javascript" charset="utf-8"></script> <script src="mark.min.js" type="text/javascript" charset="utf-8"></script> <script src="searcher.js" type="text/javascript" charset="utf-8"></script> <script src="clipboard.min.js" type="text/javascript" charset="utf-8"></script> <script src="highlight.js" type="text/javascript" charset="utf-8"></script> <script src="book.js" type="text/javascript" charset="utf-8"></script> <!-- Custom JS scripts --> </body> </html>