rust_analyzer.html

<!DOCTYPE HTML>
<html lang="en" class="light sidebar-visible" dir="ltr">
    <head>
        <!-- Book generated using mdBook -->
        <meta charset="UTF-8">
        <title>rust_analyzer - rules_rust</title>


        <!-- Custom HTML head -->

        <meta name="description" content="">
        <meta name="viewport" content="width=device-width, initial-scale=1">
        <meta name="theme-color" content="#ffffff">

        <link rel="icon" href="favicon.svg">
        <link rel="shortcut icon" href="favicon.png">
        <link rel="stylesheet" href="css/variables.css">
        <link rel="stylesheet" href="css/general.css">
        <link rel="stylesheet" href="css/chrome.css">
        <link rel="stylesheet" href="css/print.css" media="print">

        <!-- Fonts -->
        <link rel="stylesheet" href="FontAwesome/css/font-awesome.css">
        <link rel="stylesheet" href="fonts/fonts.css">

        <!-- Highlight.js Stylesheets -->
        <link rel="stylesheet" href="highlight.css">
        <link rel="stylesheet" href="tomorrow-night.css">
        <link rel="stylesheet" href="ayu-highlight.css">

        <!-- Custom theme stylesheets -->


        <!-- Provide site root to javascript -->
        <script>
            var path_to_root = "";
            var default_theme = window.matchMedia("(prefers-color-scheme: dark)").matches ? "navy" : "light";
        </script>
        <!-- Start loading toc.js asap -->
        <script src="toc.js"></script>
    </head>
    <body>
    <div id="body-container">
        <!-- Work around some values being stored in localStorage wrapped in quotes -->
        <script>
            try {
                var theme = localStorage.getItem('mdbook-theme');
                var sidebar = localStorage.getItem('mdbook-sidebar');

                if (theme.startsWith('"') && theme.endsWith('"')) {
                    localStorage.setItem('mdbook-theme', theme.slice(1, theme.length - 1));
                }

                if (sidebar.startsWith('"') && sidebar.endsWith('"')) {
                    localStorage.setItem('mdbook-sidebar', sidebar.slice(1, sidebar.length - 1));
                }
            } catch (e) { }
        </script>

        <!-- Set the theme before any content is loaded, prevents flash -->
        <script>
            var theme;
            try { theme = localStorage.getItem('mdbook-theme'); } catch(e) { }
            if (theme === null || theme === undefined) { theme = default_theme; }
            const html = document.documentElement;
            html.classList.remove('light')
            html.classList.add(theme);
            html.classList.add("js");
        </script>

        <input type="checkbox" id="sidebar-toggle-anchor" class="hidden">

        <!-- Hide / unhide sidebar before it is displayed -->
        <script>
            var sidebar = null;
            var sidebar_toggle = document.getElementById("sidebar-toggle-anchor");
            if (document.body.clientWidth >= 1080) {
                try { sidebar = localStorage.getItem('mdbook-sidebar'); } catch(e) { }
                sidebar = sidebar || 'visible';
            } else {
                sidebar = 'hidden';
            }
            sidebar_toggle.checked = sidebar === 'visible';
            html.classList.remove('sidebar-visible');
            html.classList.add("sidebar-" + sidebar);
        </script>

        <nav id="sidebar" class="sidebar" aria-label="Table of contents">
            <!-- populated by js -->
            <mdbook-sidebar-scrollbox class="sidebar-scrollbox"></mdbook-sidebar-scrollbox>
            <noscript>
                <iframe class="sidebar-iframe-outer" src="toc.html"></iframe>
            </noscript>
            <div id="sidebar-resize-handle" class="sidebar-resize-handle">
                <div class="sidebar-resize-indicator"></div>
            </div>
        </nav>

        <div id="page-wrapper" class="page-wrapper">

            <div class="page">
                <div id="menu-bar-hover-placeholder"></div>
                <div id="menu-bar" class="menu-bar sticky">
                    <div class="left-buttons">
                        <label id="sidebar-toggle" class="icon-button" for="sidebar-toggle-anchor" title="Toggle Table of Contents" aria-label="Toggle Table of Contents" aria-controls="sidebar">
                            <i class="fa fa-bars"></i>
                        </label>
                        <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</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">rules_rust</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>
                        <a href="https://github.com/bazelbuild/rules_rust" title="Git repository" aria-label="Git repository">
                            <i id="git-repository-button" class="fa fa-github"></i>
                        </a>

                    </div>
                </div>

                <div id="search-wrapper" class="hidden">
                    <form id="searchbar-outer" class="searchbar-outer">
                        <input type="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>
                    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>
                        <h1 id="rust-analyzer"><a class="header" href="#rust-analyzer">Rust Analyzer</a></h1>
<p><code>rules_rust</code> ships a one-shot installer that configures
<a href="https://rust-analyzer.github.io/">rust-analyzer</a> to use the project's Bazel
toolchain. After setup, rust-analyzer, the proc-macro server, and rustfmt
all come from Bazel — no host Rust install required.</p>
<h2 id="quick-start"><a class="header" href="#quick-start">Quick start</a></h2>
<p>Pick your editor below. Each runs the same <code>setup</code> tool with a different
subcommand — <code>setup</code> is re-runnable any time.</p>
<h3 id="vscode"><a class="header" href="#vscode">VSCode</a></h3>
<ol>
<li>Install the
<a href="https://marketplace.visualstudio.com/items?itemName=rust-lang.rust-analyzer">rust-analyzer extension</a>.</li>
<li>
<pre><code>bazel run @rules_rust//tools/rust_analyzer:setup -- vscode
</code></pre>
</li>
<li>Reload the VSCode window.</li>
</ol>
<p><code>.vscode/settings.json</code> is always written; a <code>*.code-workspace</code> at
the workspace root is picked up too. Existing user keys and comments
survive re-runs, so <code>.vscode/settings.json</code> and <code>.code-workspace</code> are
safe to commit.</p>
<p>Add the launcher dir to <code>.gitignore</code>:</p>
<pre><code>.vscode/.rules_rust_analyzer/
</code></pre>
<p>Re-run <code>setup</code> after a toolchain change (rustup update, <code>MODULE.bazel</code>
edit, <code>bazel clean --expunge</code>).</p>
<h3 id="neovim"><a class="header" href="#neovim">Neovim</a></h3>
<pre><code>bazel run @rules_rust//tools/rust_analyzer:setup -- neovim
</code></pre>
<p>Prints an <code>nvim-lspconfig</code> Lua snippet to stdout. Paste it into your
<code>init.lua</code> (or pipe to a file you <code>require</code>). Restart Neovim.</p>
<p>For <a href="https://github.com/mrcjkb/rustaceanvim"><code>rustaceanvim</code></a> users:
pass the printed <code>cmd</code> and <code>settings</code> table through its <code>server</code>
option (<code>vim.g.rustaceanvim = { server = { cmd = ..., settings = ... } }</code>).</p>
<h3 id="helix"><a class="header" href="#helix">Helix</a></h3>
<pre><code>bazel run @rules_rust//tools/rust_analyzer:setup -- helix
</code></pre>
<p>Prints a <code>languages.toml</code> snippet. Paste it into
<code>&lt;workspace&gt;/.helix/languages.toml</code>. Restart Helix.</p>
<h3 id="other-editors-cocnvim-vim-lsp-ale-etc"><a class="header" href="#other-editors-cocnvim-vim-lsp-ale-etc">Other editors (<code>coc.nvim</code>, <code>vim-lsp</code>, ALE, etc.)</a></h3>
<pre><code>bazel run @rules_rust//tools/rust_analyzer:setup -- print
</code></pre>
<p>Prints a generic JSON snippet using the <code>rust-analyzer.*</code> keys VSCode
uses. <code>coc.nvim</code> reads them via <code>coc-settings.json</code> (open with
<code>:CocConfig</code>); <code>vim-lsp</code> / ALE / <code>LanguageClient-neovim</code> accept the
same keys via plugin-specific config files.</p>
<h2 id="flags"><a class="header" href="#flags">Flags</a></h2>
<p>Re-runnable at any time. Global flags work on any subcommand.</p>
<div class="table-wrapper"><table><thead><tr><th>Flag</th><th>Effect</th></tr></thead><tbody>
<tr><td><code>--skip-proc-macro-server</code></td><td>Don't manage the proc-macro key.</td></tr>
<tr><td><code>--skip-rustfmt</code></td><td>Don't manage the formatter key (use host rustfmt).</td></tr>
<tr><td><code>--per-package-workspaces</code> / <code>--no-per-package-workspaces</code></td><td>Opt this developer in/out of per-package workspace splitting (see below).</td></tr>
<tr><td><code>--clippy</code> / <code>--no-clippy</code></td><td>Opt this developer in/out of running clippy on save and streaming its diagnostics alongside rustc's.</td></tr>
<tr><td><code>--clean</code></td><td>Delete <code>&lt;launcher-dir&gt;/cache/</code> before running the rest of setup. See Troubleshooting.</td></tr>
</tbody></table>
</div>
<p>The <code>--clippy</code> and <code>--per-package-workspaces</code> toggles are <strong>per-user</strong>: they mutate <code>&lt;launcher-dir&gt;/user_config.json</code> (gitignored) instead of the shared committed settings file. Two developers on the same workspace can hold different preferences without touching the checked-in configuration. Editing <code>user_config.json</code> by hand works too.</p>
<p>The <code>vscode</code> subcommand adds:</p>
<div class="table-wrapper"><table><thead><tr><th>Flag</th><th>Effect</th></tr></thead><tbody>
<tr><td><code>--settings-json &lt;path&gt;</code></td><td>Override the settings.json output. Defaults to <code>&lt;workspace&gt;/.vscode/settings.json</code>.</td></tr>
<tr><td><code>--code-workspace &lt;path&gt;</code></td><td><code>.code-workspace</code> file to also update. Required when the workspace root has more than one.</td></tr>
<tr><td><code>--no-code-workspace</code></td><td>Skip the <code>.code-workspace</code> write.</td></tr>
<tr><td><code>--settings-key &lt;key&gt;</code></td><td>Nest managed keys under this key inside the <code>.code-workspace</code> (default: <code>settings</code>).</td></tr>
<tr><td><code>--dry-run</code></td><td>Print each would-be-written file to stdout.</td></tr>
<tr><td><code>--replace</code></td><td>Overwrite managed keys instead of merging. Sibling <code>folders</code> / <code>tasks</code> / <code>extensions</code> in a <code>.code-workspace</code> survive.</td></tr>
</tbody></table>
</div>
<h2 id="what-you-get"><a class="header" href="#what-you-get">What you get</a></h2>
<ul>
<li><strong><code>▶ Run Tests</code> / <code>▶ Run Test</code></strong> codelens on every <code>#[cfg(test)] mod</code> and
individual <code>#[test]</code>.</li>
<li><strong>On-save squiggles</strong> from rustc diagnostics. Matches <code>cargo check</code> —
errors anywhere in the dep graph surface at their actual file paths.</li>
<li><strong>Format-on-save</strong> via the Bazel-toolchain rustfmt.</li>
<li><strong>Workspace reload</strong> on watched <code>BUILD</code> / <code>MODULE.bazel</code> changes.</li>
</ul>
<h2 id="troubleshooting"><a class="header" href="#troubleshooting">Troubleshooting</a></h2>
<h3 id="symbols--deps-look-wrong"><a class="header" href="#symbols--deps-look-wrong">Symbols / deps look wrong</a></h3>
<p>Restart rust-analyzer (or save a <code>BUILD</code> file). If that doesn't fix
it, re-run setup with <code>--clean</code> to nuke the discovery cache:</p>
<pre><code>bazel run @rules_rust//tools/rust_analyzer:setup -- --clean vscode
</code></pre>
<p>Works with any subcommand (<code>vscode</code> / <code>neovim</code> / <code>helix</code> / <code>print</code>).</p>
<h3 id="diagnostics-stopped-appearing"><a class="header" href="#diagnostics-stopped-appearing">Diagnostics stopped appearing</a></h3>
<p>Check <code>&lt;workspace&gt;/.rules_rust_analyzer/flycheck.log</code>.</p>
<h3 id="after-bazel-clean---expunge-or-toolchain-changes"><a class="header" href="#after-bazel-clean---expunge-or-toolchain-changes">After <code>bazel clean --expunge</code> or toolchain changes</a></h3>
<p>Re-run <code>setup</code>.</p>
<h3 id="noisy-cargo-metadata-errors-on-startup"><a class="header" href="#noisy-cargo-metadata-errors-on-startup">Noisy <code>cargo metadata</code> errors on startup</a></h3>
<p><code>setup</code> does not manage <code>rust-analyzer.files.excludeDirs</code>. If your
workspace has stub <code>Cargo.toml</code> files that aren't meant to be
auto-loaded (common in <code>rules_rust</code> itself under <code>examples/</code>,
<code>crate_universe/</code>, etc.), rust-analyzer still finds them and logs
errors. Silence them by adding the directory names to <code>settings.json</code>
yourself — your entries survive future <code>setup</code> runs:</p>
<pre><code>"rust-analyzer.files.excludeDirs": ["examples", "some_other_dir"]
</code></pre>
<p>Trade-off: <code>files.excludeDirs</code> also hides those sources from
rust-analyzer's virtual filesystem, so files under those directories
won't get IDE features even if they're part of a Bazel-discovered
crate. Only exclude directories whose sources you're willing to lose
IDE support on.</p>
<h2 id="workspace-splitting"><a class="header" href="#workspace-splitting">Workspace splitting</a></h2>
<p>By default the whole project is treated as a single workspace.</p>
<p>For monorepos where indexing the whole graph is too slow, pass
<code>--per-package-workspaces</code>. Discover then scopes to the saved file's
package + deps; rust-analyzer reloads when you jump to a different
package. Caveat: <em>dependents</em> of the package you're working on aren't
indexed, so "find usages" can miss callers in other packages.</p>
<p>Switch any time by re-running <code>setup</code> with or without the flag.</p>
<h2 id="debugging"><a class="header" href="#debugging">Debugging</a></h2>
<p>The <code>▶ Debug</code> codelens VSCode renders next to <code>#[test]</code> functions
<strong>does not work</strong> for Bazel projects. Use <code>.vscode/launch.json</code> + F5
instead:</p>
<pre><code>bazel run @rules_rust//tools/vscode:gen_launch_json
</code></pre>
<p>Install
<a href="https://marketplace.visualstudio.com/items?itemName=vadimcn.vscode-lldb">CodeLLDB</a>
first. Set a breakpoint inside the test and run the target — one
launch config covers every test in that binary.</p>

                    </main>

                    <nav class="nav-wrapper" aria-label="Page navigation">
                        <!-- Mobile navigation buttons -->
                            <a rel="prev" href="extract_cargo_lints.html" class="mobile-nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
                                <i class="fa fa-angle-left"></i>
                            </a>

                            <a rel="next prefetch" href="unpretty.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 rel="prev" href="extract_cargo_lints.html" class="nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
                        <i class="fa fa-angle-left"></i>
                    </a>

                    <a rel="next prefetch" href="unpretty.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>
            window.playground_copyable = true;
        </script>


        <script src="elasticlunr.min.js"></script>
        <script src="mark.min.js"></script>
        <script src="searcher.js"></script>

        <script src="clipboard.min.js"></script>
        <script src="highlight.js"></script>
        <script src="book.js"></script>

        <!-- Custom JS scripts -->


    </div>
    </body>
</html>