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href="/language/concurrency"><div><span>Overview</span></div></a></li><li class="nav-item"><a class="nav-link" href="/language/async"><div><span>Asynchronous support</span></div></a></li><li class="nav-item"><a class="nav-link" href="/language/isolates"><div><span>Isolates</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#-sidenav-1-10" role="button" aria-expanded="false" aria-controls="-sidenav-1-10"><span>Null safety</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="-sidenav-1-10"><li class="nav-item"><a class="nav-link" href="/null-safety"><div><span>Sound null safety</span></div></a></li><li class="nav-item"><a class="nav-link" href="/null-safety/migration-guide"><div><span>Migrating to null safety</span></div></a></li><li class="nav-item"><a class="nav-link" 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href="/libraries/dart-async"><div><span>dart:async</span></div></a></li><li class="nav-item"><a class="nav-link" href="/libraries/dart-math"><div><span>dart:math</span></div></a></li><li class="nav-item"><a class="nav-link" href="/libraries/dart-convert"><div><span>dart:convert</span></div></a></li><li class="nav-item"><a class="nav-link" href="/libraries/dart-io"><div><span>dart:io</span></div></a></li><li class="nav-item"><a class="nav-link" href="/interop/js-interop"><div><span>dart:js_interop</span></div></a></li><div class="sidenav-divider"></div><li class="nav-item"><a class="nav-link" href="/libraries/collections/iterables"><div><span>Iterable collections</span></div></a></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#-sidenav-2-10" role="button" aria-expanded="false" aria-controls="-sidenav-2-10"><span>Asynchronous programming</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="-sidenav-2-10"><li class="nav-item"><a class="nav-link" href="/libraries/async/async-await"><div><span>Tutorial</span></div></a></li><li class="nav-item"><a class="nav-link" href="/libraries/async/futures-error-handling"><div><span>Futures and error handling</span></div></a></li><li class="nav-item"><a class="nav-link" href="/libraries/async/using-streams"><div><span>Using streams</span></div></a></li><li class="nav-item"><a class="nav-link" href="/libraries/async/creating-streams"><div><span>Creating streams</span></div></a></li></ul></li></ul></li><li class="nav-item"><button class="nav-link collapsed collapsible" data-toggle="collapse" data-target="#-sidenav-3" role="button" aria-expanded="false" aria-controls="-sidenav-3"><span>Effective Dart</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="-sidenav-3"><li class="nav-item"><a class="nav-link" href="/effective-dart"><div><span>Overview</span></div></a></li><li class="nav-item"><a class="nav-link" href="/effective-dart/style"><div><span>Style</span></div></a></li><li class="nav-item"><a class="nav-link" href="/effective-dart/documentation"><div><span>Documentation</span></div></a></li><li class="nav-item"><a class="nav-link" href="/effective-dart/usage"><div><span>Usage</span></div></a></li><li class="nav-item"><a class="nav-link" href="/effective-dart/design"><div><span>Design</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsed collapsible" data-toggle="collapse" data-target="#-sidenav-4" role="button" aria-expanded="false" aria-controls="-sidenav-4"><span>Packages</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="-sidenav-4"><li class="nav-item"><a class="nav-link" href="/tools/pub/packages"><div><span>How to use packages</span></div></a></li><li class="nav-item"><a class="nav-link" href="/resources/useful-packages"><div><span>Commonly used packages</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/pub/create-packages"><div><span>Creating packages</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/pub/publishing"><div><span>Publishing packages</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/pub/writing-package-pages"><div><span>Writing package pages</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/pub/workspaces"><div><span>Workspaces (monorepo support)</span></div></a></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#-sidenav-4-7" role="button" aria-expanded="false" aria-controls="-sidenav-4-7"><span>Package reference</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="-sidenav-4-7"><li class="nav-item"><a class="nav-link" href="/tools/pub/dependencies"><div><span>Dependencies</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/pub/glossary"><div><span>Glossary</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/pub/package-layout"><div><span>Package layout conventions</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/pub/environment-variables"><div><span>Pub environment variables</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/pub/pubspec"><div><span>Pubspec file</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/pub/troubleshoot"><div><span>Troubleshooting pub</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/pub/verified-publishers"><div><span>Verified publishers</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/pub/security-advisories"><div><span>Security advisories</span></div></a></li><li 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representation</span></div></a></li><li class="nav-item"><a class="nav-link" href="/resources/google-apis"><div><span>Google APIs</span></div></a></li><li class="nav-item"><a class="nav-link" href="/multiplatform-apps"><div><span>Multi-platform apps</span></div></a></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#-sidenav-5-5" role="button" aria-expanded="false" aria-controls="-sidenav-5-5"><span>Command-line & server apps</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="-sidenav-5-5"><li class="nav-item"><a class="nav-link" href="/server"><div><span>Overview</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tutorials/server/get-started"><div><span>Get started</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tutorials/server/cmdline"><div><span>Write command-line apps</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tutorials/server/fetch-data"><div><span>Fetch data from the internet</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tutorials/server/httpserver"><div><span>Write HTTP servers</span></div></a></li><li class="nav-item"><a class="nav-link" href="/server/libraries"><div><span>Libraries & packages</span></div></a></li><li class="nav-item"><a class="nav-link" href="/server/google-cloud"><div><span>Google Cloud</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#-sidenav-5-6" role="button" aria-expanded="false" aria-controls="-sidenav-5-6"><span>Web apps</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="-sidenav-5-6"><li class="nav-item"><a class="nav-link" href="/web"><div><span>Overview</span></div></a></li><li class="nav-item"><a class="nav-link" href="/web/get-started"><div><span>Get 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data-toggle="collapse" data-target="#-sidenav-10" role="button" aria-expanded="true" aria-controls="-sidenav-10"><span>Related sites</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse show" id="-sidenav-10"><li class="nav-item"><a class="nav-link" href="https://api.dart.dev" target="_blank" rel="noopener"><div><span>API reference</span><span class="material-symbols" aria-hidden="true">open_in_new</span></div></a></li><li class="nav-item"><a class="nav-link" href="https://medium.com/dartlang" target="_blank" rel="noopener"><div><span>Blog</span><span class="material-symbols" aria-hidden="true">open_in_new</span></div></a></li><li class="nav-item"><a class="nav-link" href="https://dartpad.dev" target="_blank" rel="noopener"><div><span>DartPad (online editor)</span><span class="material-symbols" aria-hidden="true">open_in_new</span></div></a></li><li class="nav-item"><a class="nav-link" href="https://flutter.dev" target="_blank" rel="noopener"><div><span>Flutter</span><span class="material-symbols" aria-hidden="true">open_in_new</span></div></a></li><li class="nav-item"><a class="nav-link" href="https://pub.dev" target="_blank" rel="noopener"><div><span>Package site</span><span class="material-symbols" aria-hidden="true">open_in_new</span></div></a></li></ul></li></ul></div><main id="page-content"><div id="site-toc--side" class="site-toc"><header class="site-toc__title">Contents</header><ul class="section-nav"><li class="toc-entry nav-item"><a class="nav-link" href="#apply-fixes">Apply fixes</a></li><li class="toc-entry nav-item"><a class="nav-link" href="#customize">Customize behavior</a><ul class="nav"><li class="toc-entry nav-item"><a class="nav-link" href="#example">Example</a></li></ul></li><li class="toc-entry nav-item"><a class="nav-link" href="#vs-code-support">VS Code support</a></li></ul></div><article><div class="content"><div id="site-content-title"><h1>dart fix</h1></div><div id="site-toc--inline" class="site-toc"><header class="site-toc__title">Contents</header><ul class="section-nav"><li class="toc-entry"><a href="#apply-fixes">Apply fixes</a></li><li class="toc-entry"><a href="#customize">Customize behavior</a><ul><li class="toc-entry"><a href="#example">Example</a></li></ul></li><li class="toc-entry"><a href="#vs-code-support">VS Code support</a></li></ul></div><p>The <code>dart fix</code> command finds and fixes two types of issues:</p><ul><li><p>Analysis issues identified by <a href="/tools/dart-analyze"><code>dart analyze</code></a> that have associated automated fixes (sometimes called <em>quick-fixes</em> or <em>code actions</em>).</p></li><li><p>Outdated API usages when updating to newer releases of the Dart and Flutter SDKs.</p></li></ul><aside class="alert alert-success"><div class="alert-header"><span class="material-symbols" aria-hidden="true">lightbulb</span> <span>Tip</span></div><div class="alert-content"><p>To learn about <code>dart fix</code> in a video format, check out this <a href="https://www.youtube.com/watch/OBIuSrg_Quo">deep dive</a> on <strong>Decoding Flutter</strong>:</p><iframe width="560" height="315" src="https://www.youtube.com/embed/OBIuSrg_Quo" title="Using Dart analyze & Dart fix" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" allowfullscreen loading="lazy"></iframe><br><p><a href="https://www.youtube.com/watch/OBIuSrg_Quo" target="_blank" rel="noopener" title="Open 'Using Dart analyze & Dart fix' video in new tab">Using Dart analyze & Dart fix</a></p></div></aside><p><a id="usage"></a></p><div class="header-wrapper"><h2 id="apply-fixes">Apply fixes</h2><a class="heading-link" href="#apply-fixes" aria-label="Link to 'Apply fixes' section">#</a></div><p>To preview proposed changes, use the <code>--dry-run</code> flag:</p><div class="code-block-wrapper language-console"><div class="code-block-body"><pre class="shiki dash-light" tabindex="0"><code><span class="line"><span style="color:#222222">$ dart fix --dry-run</span></span></code></pre></div></div><p>To apply the proposed changes, use the <code>--apply</code> flag:</p><div class="code-block-wrapper language-console"><div class="code-block-body"><pre class="shiki dash-light" tabindex="0"><code><span class="line"><span style="color:#222222">$ dart fix --apply</span></span></code></pre></div></div><p><a id="customization"></a></p><div class="header-wrapper"><h2 id="customize">Customize behavior</h2><a class="heading-link" href="#customize" aria-label="Link to 'Customize behavior' section">#</a></div><p>The <code>dart fix</code> command only applies fixes when there is a "problem" identified by a diagnostic. Some diagnostics, such as compilation errors, are implicitly enabled, while others, such as lints, must be explicitly enabled in the <a href="/tools/analysis">analysis options file</a>, as individual preferences for these vary.</p><p>You can sometimes increase the number of fixes that can be applied by enabling additional lints. Note that not all diagnostics have associated fixes.</p><div class="header-wrapper"><h3 id="example">Example</h3><a class="heading-link" href="#example" aria-label="Link to 'Example' section">#</a></div><p>Imagine you have code like this:</p><div class="code-block-wrapper language-dart"><div class="code-block-body"><span class="code-block-language" title="Language dart">dart</span><pre class="shiki dash-light" tabindex="0"><code><span class="line"><span style="color:#D43324">class</span><span style="color:#0468D7"> Vector2d</span><span style="color:#222222"> {</span></span> <span class="line"><span style="color:#D43324"> final</span><span style="color:#0468D7"> double</span><span style="color:#222222"> x, y;</span></span> <span class="line"><span style="color:#0468D7"> Vector2d</span><span style="color:#222222">(</span><span style="color:#D43324">this</span><span style="color:#222222">.x, </span><span style="color:#D43324">this</span><span style="color:#222222">.y);</span></span> <span class="line"><span style="color:#222222">}</span></span> <span class="line"></span> <span class="line"><span style="color:#D43324">class</span><span style="color:#0468D7"> Vector3d</span><span style="color:#D43324"> extends</span><span style="color:#0468D7"> Vector2d</span><span style="color:#222222"> {</span></span> <span class="line"><span style="color:#D43324"> final</span><span style="color:#0468D7"> double</span><span style="color:#222222"> z;</span></span> <span class="line"><span style="color:#0468D7"> Vector3d</span><span style="color:#222222">(</span><span style="color:#D43324">final</span><span style="color:#0468D7"> double</span><span style="color:#222222"> x, </span><span style="color:#D43324">final</span><span style="color:#0468D7"> double</span><span style="color:#222222"> y, </span><span style="color:#D43324">this</span><span style="color:#222222">.z) : </span><span style="color:#D43324">super</span><span style="color:#222222">(x, y);</span></span> <span class="line"><span style="color:#222222">}</span></span></code></pre></div></div><p>Dart 2.17 introduced a new language feature called super initializers, which allows you to write the constructor of <code>Vector3d</code> with a more compact style:</p><div class="code-block-wrapper language-dart"><div class="code-block-body"><span class="code-block-language" title="Language dart">dart</span><pre class="shiki dash-light" tabindex="0"><code><span class="line"><span style="color:#D43324">class</span><span style="color:#0468D7"> Vector3d</span><span style="color:#D43324"> extends</span><span style="color:#0468D7"> Vector2d</span><span style="color:#222222"> {</span></span> <span class="line"><span style="color:#D43324"> final</span><span style="color:#0468D7"> double</span><span style="color:#222222"> z;</span></span> <span class="line"><span style="color:#0468D7"> Vector3d</span><span style="color:#222222">(</span><span style="color:#D43324">super</span><span style="color:#222222">.x, </span><span style="color:#D43324">super</span><span style="color:#222222">.y, </span><span style="color:#D43324">this</span><span style="color:#222222">.z);</span></span> <span class="line"><span style="color:#222222">}</span></span></code></pre></div></div><p>To enable <code>dart fix</code> to upgrade existing code to use this feature, and to ensure that the analyzer warns you when you later forget to use it, configure your <code>analysis_options.yaml</code> file as follows:</p><div class="code-block-wrapper language-yaml"><div class="code-block-body"><span class="code-block-language" title="Language yaml">yaml</span><pre class="shiki dash-light" tabindex="0"><code><span class="line"><span style="color:#0468D7">linter</span><span style="color:#222222">:</span></span> <span class="line"><span style="color:#0468D7"> rules</span><span style="color:#222222">:</span></span> <span class="line"><span style="color:#222222"> - </span><span style="color:#11796D">use_super_parameters</span></span></code></pre></div></div><p>We also need to make sure the code enables the required <a href="/resources/language/evolution#language-versioning">language version</a>. Super initializers were introduced in Dart 2.17, so update <code>pubspec.yaml</code> to have at least that in the lower SDK constraint:</p><div class="code-block-wrapper language-yaml"><div class="code-block-body"><span class="code-block-language" title="Language yaml">yaml</span><pre class="shiki dash-light" tabindex="0"><code><span class="line"><span style="color:#0468D7">environment</span><span style="color:#222222">:</span></span> <span class="line"><span style="color:#0468D7"> sdk</span><span style="color:#222222">: </span><span style="color:#11796D">">=2.17.0 <4.0.0"</span></span></code></pre></div></div><p>You should then see the following when viewing the proposed changes:</p><div class="code-block-wrapper language-console"><div class="code-block-body"><pre class="shiki dash-light" tabindex="0"><code><span class="line"><span style="color:#222222">$ dart fix --dry-run</span></span> <span class="line"><span style="color:#222222">Computing fixes in myapp (dry run)... 9.0s</span></span> <span class="line"></span> <span class="line"><span style="color:#222222">1 proposed fixes in 1 files.</span></span> <span class="line"></span> <span class="line"><span style="color:#222222">lib/myapp.dart</span></span> <span class="line"><span style="color:#222222"> use_super_parameters • 1 fix</span></span></code></pre></div></div><p>To learn more about customizing analysis results and behavior, see <a href="/tools/analysis">Customizing static analysis</a>.</p><div class="header-wrapper"><h2 id="vs-code-support">VS Code support</h2><a class="heading-link" href="#vs-code-support" aria-label="Link to 'VS Code support' section">#</a></div><p>When you open a project in VS Code, the Dart plugin scans the project for issues that <code>dart fix</code> can repair. If it finds issues for repair, VS Code displays a prompt to remind you.</p><img src="/assets/img/tools/vscode/dart_fix_notification.png" width="550" height="175" alt="VS Code notification about 'dart fix'"><p>After running <code>dart pub get</code> or <code>dart pub upgrade</code>, VS Code might also display this prompt if package changes add issues that <code>dart fix</code> can repair.</p><p>Save all of your files before running <code>dart fix</code>. This ensures that Dart uses the latest versions of your files.</p><p id="page-github-links"><span>Unless stated otherwise, the documentation on this site reflects Dart 3.7.0. Page last updated on 2024-12-10.</span> <a href="https://github.com/dart-lang/site-www/tree/main/src/content/tools/dart-fix.md" target="_blank" rel="noopener">View source</a> <span>or </span><a href="https://github.com/dart-lang/site-www/issues/new?template=1_page_issue.yml&page-url=https://dart.dev/tools/dart-fix/&page-source=https://github.com/dart-lang/site-www/tree/main/src/content/tools/dart-fix.md" title="Report an issue with this page" target="_blank" rel="noopener">report an issue</a>.</p></div></article></main></div><footer id="page-footer"><div class="footer-section footer-main"><a href="/" class="brand" title="Dart"><img src="/assets/img/logo/logo-white-text.svg" alt="Dart" width="164"></a><div class="footer-social-links"><a href="https://medium.com/dartlang" target="_blank" rel="noopener" title="Dart's Medium publication"><svg><use href="/assets/img/social/medium.svg#medium"></use></svg> </a><a href="https://github.com/dart-lang" target="_blank" rel="noopener" title="Dart's GitHub organization"><svg><use href="/assets/img/social/github.svg#github"></use></svg> </a><a href="https://bsky.app/profile/dart.dev" target="_blank" rel="noopener" title="Dart's Bluesky profile"><svg><use href="/assets/img/social/bluesky.svg#bluesky"></use></svg> </a><a href="https://twitter.com/dart_lang" target="_blank" rel="noopener" title="Dart's X (Twitter) profile"><svg><use href="/assets/img/social/x.svg#x"></use></svg></a></div></div><div class="footer-section footer-tray"><div class="footer-licenses">Except as otherwise noted, this site is licensed under a <a href="https://creativecommons.org/licenses/by/4.0/">Creative Commons Attribution 4.0 International License</a>, and code samples are licensed under the <a href="https://opensource.org/licenses/BSD-3-Clause">3-Clause BSD License</a>.</div><div class="footer-utility-links"><ul><li><a href="/terms" title="Terms of use">Terms</a></li><li><a href="https://policies.google.com/privacy" target="_blank" rel="noopener" title="Privacy policy">Privacy</a></li><li><a href="/security" title="Security philosophy and practices">Security</a></li></ul></div></div></footer></div></body></html>