Bug 1795880 - Add an ESLint rule to enforce using static imports where possible. r=arai,geckoview-reviewers,m_kato

Differential Revision: https://phabricator.services.mozilla.com/D160131

browser/components/firefoxview/firefox-view-notification-manager.sys.mjs

@@ -11,9 +11,7 @@ const RECENT_TABS_SYNC = "services.sync.lastTabFetch";
 const SHOULD_NOTIFY_FOR_TABS = "browser.tabs.firefox-view.notify-for-tabs";
 const lazy = {};
 
-const { XPCOMUtils } = ChromeUtils.importESModule(
-  "resource://gre/modules/XPCOMUtils.sys.mjs"
-);
+import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 XPCOMUtils.defineLazyModuleGetters(lazy, {
   BrowserWindowTracker: "resource:///modules/BrowserWindowTracker.jsm",

browser/components/firefoxview/firefox-view-tabs-setup-manager.sys.mjs

@@ -7,9 +7,7 @@
  * diverse inputs which drive the Firefox View synced tabs setup flow
  */
 
-const { XPCOMUtils } = ChromeUtils.importESModule(
-  "resource://gre/modules/XPCOMUtils.sys.mjs"
-);
+import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 const lazy = {};
 

browser/components/places/CommonNames.sys.mjs

@@ -2,9 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-const { XPCOMUtils } = ChromeUtils.importESModule(
-  "resource://gre/modules/XPCOMUtils.sys.mjs"
-);
+import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 const lazy = {};
 

browser/components/urlbar/UrlbarSearchOneOffs.sys.mjs

@@ -2,9 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-const { SearchOneOffs } = ChromeUtils.importESModule(
-  "resource:///modules/SearchOneOffs.sys.mjs"
-);
+import { SearchOneOffs } from "resource:///modules/SearchOneOffs.sys.mjs";
 
 const lazy = {};
 

browser/modules/BackgroundTask_uninstall.sys.mjs

@@ -3,9 +3,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-var { AppConstants } = ChromeUtils.importESModule(
-  "resource://gre/modules/AppConstants.sys.mjs"
-);
+import { AppConstants } from "resource://gre/modules/AppConstants.sys.mjs";
 
 export async function runBackgroundTask(commandLine) {
   if (AppConstants.platform !== "win") {

browser/themes/Windows8WindowFrameColor.sys.mjs

@@ -2,9 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-var { WindowsRegistry: Registry } = ChromeUtils.importESModule(
-  "resource://gre/modules/WindowsRegistry.sys.mjs"
-);
+import { WindowsRegistry as Registry } from "resource://gre/modules/WindowsRegistry.sys.mjs";
 
 export var Windows8WindowFrameColor = {
   _windowFrameColor: null,

devtools/client/storage/VariablesView.sys.mjs

@@ -14,9 +14,8 @@ const ITEM_FLASH_DURATION = 300; // ms
 
 import { require } from "resource://devtools/shared/loader/Loader.sys.mjs";
 
-const { XPCOMUtils } = ChromeUtils.importESModule(
-  "resource://gre/modules/XPCOMUtils.sys.mjs"
-);
+import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
+
 const EventEmitter = require("resource://devtools/shared/event-emitter.js");
 const DevToolsUtils = require("resource://devtools/shared/DevToolsUtils.js");
 const {

docs/code-quality/lint/linters/eslint-plugin-mozilla.rst

@@ -72,6 +72,7 @@ The plugin implements the following rules:
    eslint-plugin-mozilla/use-ownerGlobal
    eslint-plugin-mozilla/use-returnValue
    eslint-plugin-mozilla/use-services
+   eslint-plugin-mozilla/use-static-import
    eslint-plugin-mozilla/valid-ci-uses
    eslint-plugin-mozilla/valid-lazy
    eslint-plugin-mozilla/valid-services

docs/code-quality/lint/linters/eslint-plugin-mozilla/use-static-import.rst

@@ -0,0 +1,21 @@
+use-static-import
+=================
+
+Requires the use of static imports in system ES module files (``.sys.mjs``)
+where possible.
+
+Examples of incorrect code for this rule:
+-----------------------------------------
+
+.. code-block:: js
+
+    const { XPCOMUtils } = ChromeUtils.importESModule("resource://gre/modules/XPCOMUtils.sys.mjs");
+    const { XPCOMUtils: foo } = ChromeUtils.importESModule("resource://gre/modules/XPCOMUtils.sys.mjs");
+
+Examples of correct code for this rule:
+---------------------------------------
+
+.. code-block:: js
+
+    import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
+    import { XPCOMUtils as foo } from "resource://gre/modules/XPCOMUtils.sys.mjs";

docshell/base/URIFixup.sys.mjs

@@ -18,9 +18,7 @@
 
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
-const { AppConstants } = ChromeUtils.importESModule(
-  "resource://gre/modules/AppConstants.sys.mjs"
-);
+import { AppConstants } from "resource://gre/modules/AppConstants.sys.mjs";
 
 const lazy = {};
 

dom/push/PushService.sys.mjs

@@ -4,9 +4,7 @@
 
 import { AppConstants } from "resource://gre/modules/AppConstants.sys.mjs";
 
-const { clearTimeout, setTimeout } = ChromeUtils.importESModule(
-  "resource://gre/modules/Timer.sys.mjs"
-);
+import { clearTimeout, setTimeout } from "resource://gre/modules/Timer.sys.mjs";
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 export var PushServiceWebSocket;

dom/push/PushServiceHttp2.sys.mjs

@@ -7,9 +7,7 @@ import { PushRecord } from "resource://gre/modules/PushRecord.sys.mjs";
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
-const { clearTimeout, setTimeout } = ChromeUtils.importESModule(
-  "resource://gre/modules/Timer.sys.mjs"
-);
+import { clearTimeout, setTimeout } from "resource://gre/modules/Timer.sys.mjs";
 
 import { PushCrypto } from "resource://gre/modules/PushCrypto.sys.mjs";
 

intl/locale/LangPackMatcher.sys.mjs

@@ -2,9 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-const { XPCOMUtils } = ChromeUtils.importESModule(
-  "resource://gre/modules/XPCOMUtils.sys.mjs"
-);
+import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 const lazy = {};
 

js/xpconnect/loader/XPCOMUtils.sys.mjs

@@ -4,9 +4,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-const { AppConstants } = ChromeUtils.importESModule(
-  "resource://gre/modules/AppConstants.sys.mjs"
-);
+import { AppConstants } from "resource://gre/modules/AppConstants.sys.mjs";
 
 let global = Cu.getGlobalForObject({});
 

mobile/android/modules/geckoview/GeckoViewUtils.sys.mjs

@@ -5,9 +5,7 @@
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 import { Log } from "resource://gre/modules/Log.sys.mjs";
 
-const { clearTimeout, setTimeout } = ChromeUtils.importESModule(
-  "resource://gre/modules/Timer.sys.mjs"
-);
+import { clearTimeout, setTimeout } from "resource://gre/modules/Timer.sys.mjs";
 
 const lazy = {};
 

toolkit/components/backgroundtasks/tests/BackgroundTask_wait.sys.mjs

@@ -3,9 +3,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-const { setTimeout } = ChromeUtils.importESModule(
-  "resource://gre/modules/Timer.sys.mjs"
-);
+import { setTimeout } from "resource://gre/modules/Timer.sys.mjs";
 
 export function runBackgroundTask(commandLine) {
   let delay = 10;

toolkit/components/credentialmanagement/IdentityCredentialPromptService.sys.mjs

@@ -4,9 +4,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
  */
 
-const { XPCOMUtils } = ChromeUtils.importESModule(
-  "resource://gre/modules/XPCOMUtils.sys.mjs"
-);
+import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 const lazy = {};
 

toolkit/components/telemetry/dap/DAPTelemetrySender.sys.mjs

@@ -2,9 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-const { XPCOMUtils } = ChromeUtils.importESModule(
-  "resource://gre/modules/XPCOMUtils.sys.mjs"
-);
+import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 let lazy = {};
 

toolkit/modules/Troubleshoot.sys.mjs

@@ -11,9 +11,7 @@ import { E10SUtils } from "resource://gre/modules/E10SUtils.sys.mjs";
 const { FeatureGate } = ChromeUtils.import(
   "resource://featuregates/FeatureGate.jsm"
 );
-const { PlacesDBUtils } = ChromeUtils.importESModule(
-  "resource://gre/modules/PlacesDBUtils.sys.mjs"
-);
+import { PlacesDBUtils } from "resource://gre/modules/PlacesDBUtils.sys.mjs";
 
 // We use a list of prefs for display to make sure we only show prefs that
 // are useful for support and won't compromise the user's privacy.  Note that

tools/lint/eslint/eslint-plugin-mozilla/lib/configs/recommended.js

@@ -60,6 +60,12 @@ module.exports = {
         ],
       },
     },
+    {
+      files: ["**/*.sys.mjs"],
+      rules: {
+        "mozilla/use-static-import": "error",
+      },
+    },
     {
       excludedFiles: ["**/*.sys.mjs"],
       files: ["**/*.mjs"],
@@ -71,6 +77,7 @@ module.exports = {
     {
       files: ["**/*.mjs"],
       rules: {
+        "mozilla/use-static-import": "error",
         // This rule defaults to not allowing "use strict" in module files since
         // they are always loaded in strict mode.
         strict: "error",

tools/lint/eslint/eslint-plugin-mozilla/lib/helpers.js

@@ -554,6 +554,21 @@ module.exports = {
     return true;
   },
 
+  isTopLevel(ancestors) {
+    for (let parent of ancestors) {
+      switch (parent.type) {
+        case "ArrowFunctionExpression":
+        case "FunctionDeclaration":
+        case "FunctionExpression":
+        case "PropertyDefinition":
+        case "StaticBlock":
+        case "BlockStatement":
+          return false;
+      }
+    }
+    return true;
+  },
+
   /**
    * Check whether `this` expression points the global this.
    *

tools/lint/eslint/eslint-plugin-mozilla/lib/index.js

@@ -85,6 +85,7 @@ module.exports = {
     "use-isInstance": require("./rules/use-isInstance"),
     "use-returnValue": require("../lib/rules/use-returnValue"),
     "use-services": require("../lib/rules/use-services"),
+    "use-static-import": require("../lib/rules/use-static-import"),
     "valid-ci-uses": require("../lib/rules/valid-ci-uses"),
     "valid-lazy": require("../lib/rules/valid-lazy"),
     "valid-services": require("../lib/rules/valid-services"),

tools/lint/eslint/eslint-plugin-mozilla/lib/rules/use-static-import.js

@@ -0,0 +1,87 @@
+/**
+ * @fileoverview Require use of static imports where possible.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+"use strict";
+
+const helpers = require("../helpers");
+
+function isIdentifier(node, id) {
+  return node && node.type === "Identifier" && node.name === id;
+}
+
+module.exports = {
+  meta: {
+    docs: {
+      url:
+        "https://firefox-source-docs.mozilla.org/code-quality/lint/linters/eslint-plugin-mozilla/use-static-import.html",
+    },
+    fixable: "code",
+    messages: {
+      useStaticImport:
+        "Please use static import instead of ChromeUtils.importESModule",
+    },
+    type: "suggestion",
+  },
+
+  create(context) {
+    return {
+      VariableDeclarator(node) {
+        if (
+          node.init?.type != "CallExpression" ||
+          node.init?.callee?.type != "MemberExpression" ||
+          !context.getFilename().endsWith(".sys.mjs") ||
+          !helpers.isTopLevel(context.getAncestors())
+        ) {
+          return;
+        }
+
+        let callee = node.init.callee;
+
+        if (
+          isIdentifier(callee.object, "ChromeUtils") &&
+          isIdentifier(callee.property, "importESModule") &&
+          callee.parent.arguments.length == 1
+        ) {
+          let sourceCode = context.getSourceCode();
+          let importItemSource;
+          if (node.id.type != "ObjectPattern") {
+            importItemSource = sourceCode.getText(node.id);
+          } else {
+            importItemSource = "{ ";
+            let initial = true;
+            for (let property of node.id.properties) {
+              if (!initial) {
+                importItemSource += ", ";
+              }
+              initial = false;
+              if (property.key.name == property.value.name) {
+                importItemSource += property.key.name;
+              } else {
+                importItemSource += `${property.key.name} as ${property.value.name}`;
+              }
+            }
+            importItemSource += " }";
+          }
+
+          context.report({
+            node: node.parent,
+            messageId: "useStaticImport",
+            fix(fixer) {
+              return fixer.replaceText(
+                node.parent,
+                `import ${importItemSource} from ${sourceCode.getText(
+                  callee.parent.arguments[0]
+                )}`
+              );
+            },
+          });
+        }
+      },
+    };
+  },
+};

tools/lint/eslint/eslint-plugin-mozilla/tests/use-static-import.js

@@ -0,0 +1,88 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// ------------------------------------------------------------------------------
+// Requirements
+// ------------------------------------------------------------------------------
+
+var rule = require("../lib/rules/use-static-import");
+var RuleTester = require("eslint").RuleTester;
+
+const ruleTester = new RuleTester({
+  parserOptions: { ecmaVersion: 13, sourceType: "module" },
+});
+
+// ------------------------------------------------------------------------------
+// Tests
+// ------------------------------------------------------------------------------
+
+function callError() {
+  return [{ messageId: "useStaticImport", type: "VariableDeclaration" }];
+}
+
+ruleTester.run("use-static-import", rule, {
+  valid: [
+    {
+      // Already converted, no issues.
+      code:
+        'import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";',
+      filename: "test.sys.mjs",
+    },
+    {
+      // Inside an if statement.
+      code:
+        'if (foo) { const { XPCOMUtils } = ChromeUtils.importESModule("resource://gre/modules/XPCOMUtils.sys.mjs") }',
+      filename: "test.sys.mjs",
+    },
+    {
+      // Inside a function.
+      code:
+        'function foo() { const { XPCOMUtils } = ChromeUtils.importESModule("resource://gre/modules/XPCOMUtils.sys.mjs") }',
+      filename: "test.sys.mjs",
+    },
+    {
+      // importESModule with two args cannot be converted.
+      code:
+        'const { f } = ChromeUtils.importESModule("some/module.sys.mjs", { loadInDevToolsLoader : true });',
+      filename: "test.sys.mjs",
+    },
+    {
+      // A non-system file attempting to import a system file should not be
+      // converted.
+      code:
+        'const { XPCOMUtils } = ChromeUtils.importESModule("resource://gre/modules/XPCOMUtils.sys.mjs")',
+      filename: "test.mjs",
+    },
+  ],
+  invalid: [
+    {
+      // Simple import in system module should be converted.
+      code:
+        'const { XPCOMUtils } = ChromeUtils.importESModule("resource://gre/modules/XPCOMUtils.sys.mjs")',
+      errors: callError(),
+      filename: "test.sys.mjs",
+      output:
+        'import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs"',
+    },
+    {
+      // Should handle rewritten variables as well.
+      code:
+        'const { XPCOMUtils: foo } = ChromeUtils.importESModule("resource://gre/modules/XPCOMUtils.sys.mjs")',
+      errors: callError(),
+      filename: "test.sys.mjs",
+      output:
+        'import { XPCOMUtils as foo } from "resource://gre/modules/XPCOMUtils.sys.mjs"',
+    },
+    {
+      // Should handle multiple variables.
+      code:
+        'const { foo, XPCOMUtils } = ChromeUtils.importESModule("resource://gre/modules/XPCOMUtils.sys.mjs")',
+      errors: callError(),
+      filename: "test.sys.mjs",
+      output:
+        'import { foo, XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs"',
+    },
+  ],
+});