1 files changed, 99 insertions, 0 deletions
diff --git a/tools/lint/eslint/eslint-plugin-mozilla/lib/rules/reject-eager-module-in-lazy-getter.js b/tools/lint/eslint/eslint-plugin-mozilla/lib/rules/reject-eager-module-in-lazy-getter.js
new file mode 100644
index 0000000000..133dd6d71f
--- /dev/null
+++ b/tools/lint/eslint/eslint-plugin-mozilla/lib/rules/reject-eager-module-in-lazy-getter.js
@@ -0,0 +1,99 @@
+/**
+ * @fileoverview Reject use of lazy getters for modules that's loaded early in
+ *               the startup process and not necessarily be lazy.
+ *
+ * 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 isString(node) {
+  return node.type === "Literal" && typeof node.value === "string";
+}
+
+function isEagerModule(resourceURI) {
+  return [
+    "resource://gre/modules/XPCOMUtils",
+    "resource://gre/modules/AppConstants",
+  ].includes(resourceURI.replace(/(\.jsm|\.jsm\.js|\.js|\.sys\.mjs)$/, ""));
+}
+
+function checkEagerModule(context, node, resourceURI) {
+  if (!isEagerModule(resourceURI)) {
+    return;
+  }
+  context.report({
+    node,
+    messageId: "eagerModule",
+    data: { uri: resourceURI },
+  });
+}
+
+module.exports = {
+  meta: {
+    docs: {
+      url: "https://firefox-source-docs.mozilla.org/code-quality/lint/linters/eslint-plugin-mozilla/rules/tools/lint/eslint/eslint-plugin-mozilla/lib/rules/reject-eager-module-in-lazy-getter.html",
+    },
+    messages: {
+      eagerModule:
+        'Module "{{uri}}" is known to be loaded early in the startup process, and should be loaded eagerly, instead of defining a lazy getter.',
+    },
+    schema: [],
+    type: "problem",
+  },
+
+  create(context) {
+    return {
+      CallExpression(node) {
+        if (node.callee.type !== "MemberExpression") {
+          return;
+        }
+
+        let callerSource;
+        try {
+          callerSource = helpers.getASTSource(node.callee);
+        } catch (e) {
+          return;
+        }
+
+        if (callerSource === "ChromeUtils.defineModuleGetter") {
+          if (node.arguments.length < 3) {
+            return;
+          }
+          const resourceURINode = node.arguments[2];
+          if (!isString(resourceURINode)) {
+            return;
+          }
+          checkEagerModule(context, node, resourceURINode.value);
+        } else if (
+          callerSource === "XPCOMUtils.defineLazyModuleGetters" ||
+          callerSource === "ChromeUtils.defineESModuleGetters"
+        ) {
+          if (node.arguments.length < 2) {
+            return;
+          }
+          const obj = node.arguments[1];
+          if (obj.type !== "ObjectExpression") {
+            return;
+          }
+          for (let prop of obj.properties) {
+            if (prop.type !== "Property") {
+              continue;
+            }
+            if (prop.kind !== "init") {
+              continue;
+            }
+            const resourceURINode = prop.value;
+            if (!isString(resourceURINode)) {
+              continue;
+            }
+            checkEagerModule(context, node, resourceURINode.value);
+          }
+        }
+      },
+    };
+  },
+};