Propose new rule: no-unsafe-this-access

Author: NullVoxPopuli

lib/rules/no-unsafe-this-access-in-async-function.js

@@ -0,0 +1,160 @@
+'use strict';
+
+const ERROR_MESSAGE =
+  // eslint-disable-next-line eslint-plugin/prefer-placeholders
+  'Unsafe `this` access after `await`. ' +
+  'Guard against accessing data on destroyed objects with `@ember/destroyable` `isDestroyed` and `isDestroying`';
+
+const types = require('../utils/types');
+const { getImportIdentifier } = require('../utils/import');
+
+// Test here:
+// https://astexplorer.net/#/gist/e364803b7c576e08f232839bf3c17287/15913876e050a1ca02af71932e14b14242e36ead
+
+/**
+ * These objects have their own destroyable APIs on `this`
+ */
+const FRAMEWORK_EXTENDABLES = [
+  {
+    importPath: '@glimmer/component',
+  },
+  {
+    importPath: '@ember/component',
+  },
+  {
+    importPath: '@ember/component/helper',
+  },
+  {
+    importPath: '@ember/routing/route',
+  },
+  {
+    importPath: '@ember/controller',
+  },
+];
+
+// if already has protection, also early return
+// two forms:
+//   - isDestroying(this) || isDestroyed(this) // on any destroyable object
+//   - this.isDestroying || this.isDestroyed  // available on most framework objects
+function isProtection(node) {
+  const fns = new Set(['isDestroying', 'isDestroyed']);
+
+  switch (node.type) {
+    case 'CallExpression': {
+      return (
+        fns.has(node.callee.name) &&
+        node.arguments.length === 1 &&
+        node.arguments[0].type === 'ThisExpression'
+      );
+    }
+    case 'MemberExpression':
+      return node.object.type === 'ThisExpression' && fns.has(node.property.name);
+    default:
+      console.log('unhandled protection check', node);
+  }
+
+  return false;
+}
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+/** @type {import('eslint').Rule.RuleModule} */
+module.exports = {
+  meta: {
+    type: 'suggestion',
+    docs: {
+      description: 'disallow `this` access after await unless destruction protection is present',
+      category: 'Miscellaneous',
+      recommended: true,
+      url: 'https://github.com/ember-cli/eslint-plugin-ember/tree/master/docs/rules/no-unsafe-this-access-in-async-function.md',
+    },
+    fixable: 'code',
+    schema: [],
+  },
+
+  create(context) {
+    const inFunction = [];
+    const inClass = [];
+    let encounteredAwait;
+    let lastProtection;
+
+    // https://eslint.org/docs/developer-guide/working-with-rules#contextgetsourcecode
+    const source = context.getSourceCode();
+
+    return {
+      ClassDeclaration(node) {
+        inClass.push(node);
+      },
+      'ClassDeclaration:exit'(node) {
+        inClass.pop();
+      },
+      FunctionExpression(node) {
+        inFunction.push(node);
+        encounteredAwait = null;
+      },
+      'FunctionExpression:exit'(node) {
+        inFunction.pop();
+      },
+      IfStatement(node) {
+        const { test } = node;
+
+        switch (test.type) {
+          case 'LogicalExpression': {
+            const { left, right } = test;
+
+            if (isProtection(left) || isProtection(right)) {
+              lastProtection = node;
+              encounteredAwait = null;
+            }
+            break;
+          }
+          default:
+            console.log('unhandled if statestatement', node);
+        }
+      },
+      AwaitExpression(node) {
+        if (inClass.length === 0) {
+          return;
+        }
+        if (inFunction.length === 0) {
+          return;
+        }
+
+        encounteredAwait = node.parent;
+      },
+      MemberExpression(node) {
+        if (node.object.type !== 'ThisExpression') {
+          return;
+        }
+        if (!encounteredAwait) {
+          return;
+        }
+
+        context.report({
+          node: node.object,
+          message: ERROR_MESSAGE,
+
+          // https://eslint.org/docs/developer-guide/working-with-rules#applying-fixes
+          *fix(fixer) {
+            if (!encounteredAwait) {
+              return;
+            }
+
+            const toFix = encounteredAwait;
+            encounteredAwait = null;
+
+            const protection = '\nif (isDestroying(this) || isDestroyed(this)) return;';
+            const original = source.getText(toFix);
+
+            yield fixer.replaceText(toFix, original + protection);
+
+            // extend range of the fix to the range
+            yield fixer.insertTextBefore(toFix, '');
+            yield fixer.insertTextAfter(toFix, '');
+          },
+        });
+      },
+    };
+  },
+};