From 3caf3c52021c994397f6305cfa3e99276deff4b0 Mon Sep 17 00:00:00 2001
From: Zzzen <callmetsing@gmail.com>
Date: Sat, 1 Jan 2022 13:44:05 +0800
Subject: [PATCH] fix: support `typeof this`

---
 .../tests/eslint-rules/no-undef.test.ts       |  9 +++++++
 .../src/referencer/TypeVisitor.ts             | 11 ++++++++-
 packages/typescript-estree/src/convert.ts     |  9 +++++++
 packages/typescript-estree/src/node-utils.ts  | 24 +++++++++++++++++++
 4 files changed, 52 insertions(+), 1 deletion(-)

diff --git a/packages/eslint-plugin/tests/eslint-rules/no-undef.test.ts b/packages/eslint-plugin/tests/eslint-rules/no-undef.test.ts
index 9cff63994d3..53dd3be8d0d 100644
--- a/packages/eslint-plugin/tests/eslint-rules/no-undef.test.ts
+++ b/packages/eslint-plugin/tests/eslint-rules/no-undef.test.ts
@@ -248,6 +248,15 @@ class Foo {}
     `
 export type AppState = typeof import('./src/store/reducers').default;
     `,
+    `
+const obj = {
+  foo: '',
+  bar() {
+    let self: typeof this;
+    let foo: typeof this.foo;
+  },
+};
+    `,
   ],
   invalid: [
     {
diff --git a/packages/scope-manager/src/referencer/TypeVisitor.ts b/packages/scope-manager/src/referencer/TypeVisitor.ts
index e9abb40f4f4..bbfbab23020 100644
--- a/packages/scope-manager/src/referencer/TypeVisitor.ts
+++ b/packages/scope-manager/src/referencer/TypeVisitor.ts
@@ -258,11 +258,20 @@ class TypeVisitor extends Visitor {
   protected TSTypeQuery(node: TSESTree.TSTypeQuery): void {
     if (node.exprName.type === AST_NODE_TYPES.Identifier) {
       this.#referencer.currentScope().referenceValue(node.exprName);
+    } else if (
+      (node.exprName.type as unknown) === AST_NODE_TYPES.ThisExpression
+    ) {
+      // technically exprName is either Identifier or QualifiedName, but eslint does not recognize `typeof this`,
+      // so we have translated it to ThisExpression.
+      return;
     } else {
       let expr = node.exprName.left;
-      while (expr.type !== AST_NODE_TYPES.Identifier) {
+      while (expr.type === TSESTree.AST_NODE_TYPES.TSQualifiedName) {
         expr = expr.left;
       }
+      if ((expr.type as unknown) === AST_NODE_TYPES.ThisExpression) {
+        return;
+      }
       this.#referencer.currentScope().referenceValue(expr);
     }
   }
diff --git a/packages/typescript-estree/src/convert.ts b/packages/typescript-estree/src/convert.ts
index f0fb7d3cf58..99453a9f409 100644
--- a/packages/typescript-estree/src/convert.ts
+++ b/packages/typescript-estree/src/convert.ts
@@ -20,6 +20,7 @@ import {
   isComputedProperty,
   isESTreeClassMember,
   isOptional,
+  isThisInTypeQuery,
   TSError,
   unescapeStringLiteralText,
 } from './node-utils';
@@ -787,6 +788,14 @@ export class Converter {
       }
 
       case SyntaxKind.Identifier: {
+        if (isThisInTypeQuery(node)) {
+          return this.createNode<TSESTree.ThisExpression>(
+            node as unknown as ts.ThisExpression,
+            {
+              type: AST_NODE_TYPES.ThisExpression,
+            },
+          );
+        }
         return this.createNode<TSESTree.Identifier>(node, {
           type: AST_NODE_TYPES.Identifier,
           name: node.text,
diff --git a/packages/typescript-estree/src/node-utils.ts b/packages/typescript-estree/src/node-utils.ts
index d8182aa5655..8bca0930cb7 100644
--- a/packages/typescript-estree/src/node-utils.ts
+++ b/packages/typescript-estree/src/node-utils.ts
@@ -663,3 +663,27 @@ export function firstDefined<T, U>(
   }
   return undefined;
 }
+
+export function identifierIsThisKeyword(id: ts.Identifier): boolean {
+  return id.originalKeywordKind === SyntaxKind.ThisKeyword;
+}
+
+export function isThisIdentifier(node: ts.Node | undefined): boolean {
+  return (
+    !!node &&
+    node.kind === SyntaxKind.Identifier &&
+    identifierIsThisKeyword(node as ts.Identifier)
+  );
+}
+
+export function isThisInTypeQuery(node: ts.Node): boolean {
+  if (!isThisIdentifier(node)) {
+    return false;
+  }
+
+  while (ts.isQualifiedName(node.parent) && node.parent.left === node) {
+    node = node.parent;
+  }
+
+  return node.parent.kind === SyntaxKind.TypeQuery;
+}