1 files changed, 160 insertions, 0 deletions
diff --git a/tools/lint/eslint/eslint-plugin-mozilla/lib/rules/no-redeclare-with-import-autofix.js b/tools/lint/eslint/eslint-plugin-mozilla/lib/rules/no-redeclare-with-import-autofix.js
new file mode 100644
index 0000000000..d914e003d3
--- /dev/null
+++ b/tools/lint/eslint/eslint-plugin-mozilla/lib/rules/no-redeclare-with-import-autofix.js
@@ -0,0 +1,160 @@
+/**
+ * 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 { dirname, join } = require("path");
+
+const eslintBasePath = dirname(require.resolve("eslint"));
+
+const noredeclarePath = join(eslintBasePath, "rules/no-redeclare.js");
+const baseRule = require(noredeclarePath);
+const astUtils = require(join(eslintBasePath, "rules/utils/ast-utils.js"));
+
+// Hack alert: our eslint env is pretty confused about `require` and
+// `loader` for devtools modules - so ignore it for now.
+// See bug 1812547
+const gIgnoredImports = new Set(["loader", "require"]);
+
+/**
+ * Create a trap for a call to `report` that the original rule is
+ * trying to make on `context`.
+ *
+ * Returns a function that forwards to `report` but provides a fixer
+ * for redeclared imports that just removes those imports.
+ *
+ * @return {function}
+ */
+function trapReport(context) {
+  return function (obj) {
+    let declarator = obj.node.parent;
+    while (
+      declarator &&
+      declarator.parent &&
+      declarator.type != "VariableDeclarator"
+    ) {
+      declarator = declarator.parent;
+    }
+    if (
+      declarator &&
+      declarator.type == "VariableDeclarator" &&
+      declarator.id.type == "ObjectPattern" &&
+      declarator.init.type == "CallExpression"
+    ) {
+      let initialization = declarator.init;
+      if (
+        astUtils.isSpecificMemberAccess(
+          initialization.callee,
+          "ChromeUtils",
+          /^import(ESModule|)$/
+        )
+      ) {
+        // Hack alert: our eslint env is pretty confused about `require` and
+        // `loader` for devtools modules - so ignore it for now.
+        // See bug 1812547
+        if (gIgnoredImports.has(obj.node.name)) {
+          return;
+        }
+        // OK, we've got something we can fix. But we should be careful in case
+        // there are multiple imports being destructured.
+        // Do the easy (and common) case first - just one property:
+        if (declarator.id.properties.length == 1) {
+          context.report({
+            node: declarator.parent,
+            messageId: "duplicateImport",
+            data: {
+              name: declarator.id.properties[0].key.name,
+            },
+            fix(fixer) {
+              return fixer.remove(declarator.parent);
+            },
+          });
+          return;
+        }
+
+        // OK, figure out which import is duplicated here:
+        let node = obj.node.parent;
+        // Then remove a comma after it, or a comma before
+        // if there's no comma after it.
+        let sourceCode = context.getSourceCode();
+        let rangeToRemove = node.range;
+        let tokenAfter = sourceCode.getTokenAfter(node);
+        let tokenBefore = sourceCode.getTokenBefore(node);
+        if (astUtils.isCommaToken(tokenAfter)) {
+          rangeToRemove[1] = tokenAfter.range[1];
+        } else if (astUtils.isCommaToken(tokenBefore)) {
+          rangeToRemove[0] = tokenBefore.range[0];
+        }
+        context.report({
+          node,
+          messageId: "duplicateImport",
+          data: {
+            name: node.key.name,
+          },
+          fix(fixer) {
+            return fixer.removeRange(rangeToRemove);
+          },
+        });
+        return;
+      }
+    }
+    if (context.options[0]?.errorForNonImports) {
+      // Report the result from no-redeclare - we can't autofix it.
+      // This can happen for other redeclaration issues, e.g. naming
+      // variables in a way that conflicts with builtins like "URL" or
+      // "escape".
+      context.report(obj);
+    }
+  };
+}
+
+module.exports = {
+  meta: {
+    docs: {
+      url: "https://firefox-source-docs.mozilla.org/code-quality/lint/linters/eslint-plugin-mozilla/rules/no-redeclare-with-import-autofix.html",
+    },
+    messages: {
+      ...baseRule.meta.messages,
+      duplicateImport:
+        "The import of '{{ name }}' is redundant with one set up earlier (e.g. head.js or the browser window environment). It should be removed.",
+    },
+    schema: [
+      {
+        type: "object",
+        properties: {
+          errorForNonImports: {
+            type: "boolean",
+            default: true,
+          },
+        },
+        additionalProperties: false,
+      },
+    ],
+    type: "suggestion",
+    fixable: "code",
+  },
+
+  create(context) {
+    // Test modules get the browser env applied wrongly in some cases,
+    // don't try and remove imports there. This works out of the box
+    // for sys.mjs modules because eslint won't check builtinGlobals
+    // for the no-redeclare rule.
+    if (context.getFilename().endsWith(".jsm")) {
+      return {};
+    }
+    let newOptions = [{ builtinGlobals: true }];
+    const contextForBaseRule = Object.create(context, {
+      report: {
+        value: trapReport(context),
+        writable: false,
+      },
+      options: {
+        value: newOptions,
+      },
+    });
+    return baseRule.create(contextForBaseRule);
+  },
+};