Bug 1880535 - Enable ESLint rule no-unused-private-class-members. r=Gijs,webdriver-reviewers,webcompat-reviewers,extension-reviewers,application-update-reviewers,devtools-reviewers,translations-reviewers,bytesized,twisniewski,jhirsch,robwu,whimboo

Differential Revision: https://phabricator.services.mozilla.com/D202002

browser/components/shopping/content/shopping-sidebar.js

@@ -10,7 +10,6 @@
   const SHOPPING_SIDEBAR_WIDTH_PREF =
     "browser.shopping.experience2023.sidebarWidth";
   class ShoppingSidebar extends MozXULElement {
-    #browser;
     #initialized;
 
     static get markup() {
@@ -46,7 +45,6 @@
       }
       this.resizeObserverFn = this.resizeObserverFn.bind(this);
       this.appendChild(this.constructor.fragment);
-      this.#browser = this.querySelector(".shopping-sidebar");
 
       let previousWidth = Services.prefs.getIntPref(
         SHOPPING_SIDEBAR_WIDTH_PREF,

browser/components/urlbar/private/SuggestBackendJs.sys.mjs

@@ -278,7 +278,6 @@ export class SuggestBackendJs extends BaseFeature {
   #config = {};
 
   #emitter = null;
-  #logger = null;
   #onSettingsSync = null;
 }
 

browser/extensions/report-site-issue/test/browser/head.js

@@ -38,8 +38,6 @@ async function promiseAddonEnabled() {
 }
 
 class HelpMenuHelper {
-  #popup = null;
-
   async open() {
     this.popup = document.getElementById("menu_HelpPopup");
     ok(this.popup, "Help menu should exist");

devtools/client/webconsole/components/Output/LazyMessageList.js

@@ -158,10 +158,6 @@ class LazyMessageList extends Component {
   #cachedHeights;
   #scrollHandlerBinding;
 
-  get #maxIndex() {
-    return this.props.items.length - 1;
-  }
-
   get #overdrawHeight() {
     return this.props.scrollOverdrawCount * this.props.itemDefaultHeight;
   }

devtools/client/webconsole/test/browser/browser_webconsole_object_inspector_private_properties.js

@@ -30,9 +30,11 @@ add_task(async function () {
       }
 
       #privateProperty;
+      // eslint-disable-next-line no-unused-private-class-members
       #privateMethod() {
         return Math.random();
       }
+      // eslint-disable-next-line no-unused-private-class-members
       get #privateGetter() {
         return 42;
       }

devtools/shared/commands/tracer/tracer-command.js

@@ -6,13 +6,11 @@
 
 class TracerCommand {
   constructor({ commands }) {
-    this.#targetCommand = commands.targetCommand;
     this.#targetConfigurationCommand = commands.targetConfigurationCommand;
     this.#resourceCommand = commands.resourceCommand;
   }
 
   #resourceCommand;
-  #targetCommand;
   #targetConfigurationCommand;
   #isTracing = false;
 

devtools/shared/network-observer/NetworkResponseListener.sys.mjs

@@ -77,13 +77,8 @@ export class NetworkResponseListener {
    *
    * @type {nsIInputStream}
    */
+  // eslint-disable-next-line no-unused-private-class-members
   #inputStream = null;
-  /**
-   * Explicit flag to check if this listener was already destroyed.
-   *
-   * @type {boolean}
-   */
-  #isDestroyed = false;
   /**
    * Internal promise used to hold the completion of #getSecurityInfo.
    *
@@ -553,8 +548,6 @@ export class NetworkResponseListener {
     this.#inputStream = null;
     this.#converter = null;
     this.#request = null;
-
-    this.#isDestroyed = true;
   }
 
   /**

remote/components/RemoteAgent.sys.mjs

@@ -484,12 +484,6 @@ class RemoteAgentParentProcess {
 }
 
 class RemoteAgentContentProcess {
-  #classID;
-
-  constructor() {
-    this.#classID = Components.ID("{8f685a9d-8181-46d6-a71d-869289099c6d}");
-  }
-
   get running() {
     let reply = Services.cpmm.sendSyncMessage("RemoteAgent:IsRunning");
     if (!reply.length) {

toolkit/components/translations/actors/AboutTranslationsChild.sys.mjs

@@ -83,17 +83,6 @@ export class AboutTranslationsChild extends JSWindowActorChild {
     );
   }
 
-  /**
-   * @returns {TranslationsChild}
-   */
-  #getTranslationsChild() {
-    const child = this.contentWindow.windowGlobalChild.getActor("Translations");
-    if (!child) {
-      throw new Error("Unable to find the TranslationsChild");
-    }
-    return child;
-  }
-
   /**
    * A privileged promise can't be used in the content page, so convert a privileged
    * promise into a content one.

toolkit/mozapps/extensions/internal/SitePermsAddonProvider.sys.mjs

@@ -273,8 +273,6 @@ class SitePermsAddonWrapper {
 }
 
 class SitePermsAddonInstalling extends SitePermsAddonWrapper {
-  #install = null;
-
   /**
    * @param {string} siteOriginNoSuffix: The origin this addon is installed
    *                                     for, WITHOUT the suffix generated from
@@ -293,7 +291,6 @@ class SitePermsAddonInstalling extends SitePermsAddonWrapper {
     };
 
     super(siteOriginNoSuffix, [permission]);
-    this.#install = install;
   }
 
   get existingAddon() {

toolkit/mozapps/update/AppUpdater.sys.mjs

@@ -411,20 +411,6 @@ export class AppUpdater {
     return Services.sysinfo.getProperty("isPackagedApp");
   }
 
-  // true when updating in background is enabled.
-  get #updateStagingEnabled() {
-    LOG(
-      "AppUpdater:#updateStagingEnabled" +
-        "canStageUpdates: " +
-        this.aus.canStageUpdates
-    );
-    return (
-      !this.aus.disabled &&
-      !this.#updateDisabledByPackage &&
-      this.aus.canStageUpdates
-    );
-  }
-
   /**
    * Downloads an update mar or connects to an in-progress download.
    * Doesn't resolve until the update is ready to install, or a failure state

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

@@ -320,6 +320,11 @@ module.exports = {
     "no-unsanitized/method": "error",
     "no-unsanitized/property": "error",
 
+    // Disallow unused private class members.
+    // This rule will be a recommended rule in ESLint v9 so may be removed
+    // when we upgrade to that.
+    "no-unused-private-class-members": "error",
+
     // No declaring variables that are never used
     "no-unused-vars": [
       "error",