feat: add auto-accessor fields support to class-methods-use-this (#19789)

sethamus · web-flow · commit 677a2837a173 · 2025-06-10T10:18:14.000-04:00
* feat: add auto-accessor fields support to class-methods-use-this

* add more tests

* docs: clarify auto-accessor fields
diff --git a/docs/src/rules/class-methods-use-this.md b/docs/src/rules/class-methods-use-this.md
@@ -109,7 +109,7 @@ class C {
 This rule has four options:
 
 * `"exceptMethods"` allows specified method names to be ignored with this rule.
-* `"enforceForClassFields"` enforces that functions used as instance field initializers utilize `this`. (default: `true`)
+* `"enforceForClassFields"` enforces that arrow functions and function expressions used as instance field initializers utilize `this`. This also applies to auto-accessor fields (fields declared with the `accessor` keyword) which are part of the [stage 3 decorators proposal](https://github.com/tc39/proposal-decorators). (default: `true`)
 * `"ignoreOverrideMethods"` ignores members that are marked with the `override` modifier. (TypeScript only, default: `false`)
 * `"ignoreClassesWithImplements"` ignores class members that are defined within a class that `implements` an interface. (TypeScript only)
 
@@ -159,7 +159,7 @@ class A {
 "class-methods-use-this": [<enabled>, { "enforceForClassFields": true | false }]
 ```
 
-The `enforceForClassFields` option enforces that arrow functions and function expressions used as instance field initializers utilize `this`. (default: `true`)
+The `enforceForClassFields` option enforces that arrow functions and function expressions used as instance field initializers utilize `this`. This also applies to auto-accessor fields (fields declared with the `accessor` keyword) which are part of the [stage 3 decorators proposal](https://github.com/tc39/proposal-decorators). (default: `true`)
 
 Examples of **incorrect** code for this rule with the `{ "enforceForClassFields": true }` option (default):
 
@@ -203,6 +203,51 @@ class A {
 
 :::
 
+Examples of **incorrect** TypeScript code for this rule with the `{ "enforceForClassFields": true }` option (default):
+
+::: incorrect
+
+```ts
+/*eslint class-methods-use-this: ["error", { "enforceForClassFields": true }] */
+
+class A {
+    foo = () => {}
+    accessor bar = () => {}
+}
+```
+
+:::
+
+Examples of **correct** TypeScript code for this rule with the `{ "enforceForClassFields": true }` option (default):
+
+::: correct
+
+```ts
+/*eslint class-methods-use-this: ["error", { "enforceForClassFields": true }] */
+
+class A {
+    foo = () => {this;}
+    accessor bar = () => {this;}
+}
+```
+
+:::
+
+Examples of **correct** TypeScript code for this rule with the `{ "enforceForClassFields": false }` option:
+
+::: correct
+
+```ts
+/*eslint class-methods-use-this: ["error", { "enforceForClassFields": false }] */
+
+class A {
+    foo = () => {}
+    accessor bar = () => {}
+}
+```
+
+:::
+
 ### ignoreOverrideMethods
 
 ```ts
diff --git a/lib/rules/class-methods-use-this.js b/lib/rules/class-methods-use-this.js
@@ -111,6 +111,7 @@ module.exports = {
 			switch (node.type) {
 				case "MethodDefinition":
 					return !node.static && node.kind !== "constructor";
+				case "AccessorProperty":
 				case "PropertyDefinition":
 					return !node.static && enforceForClassFields;
 				default:
@@ -218,6 +219,8 @@ module.exports = {
 			/*
 			 * Class field value are implicit functions.
 			 */
+			"AccessorProperty > *.key:exit": pushContext,
+			"AccessorProperty:exit": popContext,
 			"PropertyDefinition > *.key:exit": pushContext,
 			"PropertyDefinition:exit": popContext,
 
@@ -233,6 +236,10 @@ module.exports = {
 			ThisExpression: markThisUsed,
 			Super: markThisUsed,
 			...(enforceForClassFields && {
+				"AccessorProperty > ArrowFunctionExpression.value":
+					enterFunction,
+				"AccessorProperty > ArrowFunctionExpression.value:exit":
+					exitFunction,
 				"PropertyDefinition > ArrowFunctionExpression.value":
 					enterFunction,
 				"PropertyDefinition > ArrowFunctionExpression.value:exit":
diff --git a/tests/lib/rules/class-methods-use-this.js b/tests/lib/rules/class-methods-use-this.js
@@ -483,9 +483,14 @@ ruleTesterTypeScript.run("class-methods-use-this", rule, {
 		{ code: "class A { 42() { } }", options: [{ exceptMethods: ["42"] }] },
 		"class A { foo = function() {this} }",
 		"class A { foo = () => {this} }",
+		"class A { accessor foo = function() {this} }",
+		"class A { accessor foo = () => {this} }",
+		"class A { accessor foo = 1; }",
 		"class A { foo = () => {super.toString} }",
 		"class A { static foo = function() {} }",
 		"class A { static foo = () => {} }",
+		"class A { static accessor foo = function() {} }",
+		"class A { static accessor foo = () => {} }",
 		{
 			code: "class A { #bar() {} }",
 			options: [{ exceptMethods: ["#bar"] }],
@@ -498,6 +503,14 @@ ruleTesterTypeScript.run("class-methods-use-this", rule, {
 			code: "class A { foo = () => {} }",
 			options: [{ enforceForClassFields: false }],
 		},
+		{
+			code: "class A { accessor foo = function () {} }",
+			options: [{ enforceForClassFields: false }],
+		},
+		{
+			code: "class A { accessor foo = () => {} }",
+			options: [{ enforceForClassFields: false }],
+		},
 		{
 			code: "class A { override foo = () => {} }",
 			options: [{ enforceForClassFields: false }],
@@ -728,6 +741,70 @@ ruleTesterTypeScript.run("class-methods-use-this", rule, {
 		},
 		{
 			code: `
+  class Foo {
+	accessor method = function () {}
+  }
+        `,
+			errors: [
+				{
+					messageId: "missingThis",
+				},
+			],
+		},
+		{
+			code: `
+  class Foo {
+    accessor method = () => {}
+  }
+        `,
+			errors: [
+				{
+					messageId: "missingThis",
+				},
+			],
+		},
+		{
+			code: `
+  class Foo {
+    private accessor method = () => {}
+  }
+        `,
+			errors: [
+				{
+					messageId: "missingThis",
+				},
+			],
+		},
+		{
+			code: `
+  class Foo {
+    protected accessor method = () => {}
+  }
+        `,
+			errors: [
+				{
+					messageId: "missingThis",
+				},
+			],
+		},
+		{
+			code: `
+	class A {
+		foo() {
+			return class {
+				accessor bar = this;
+			};
+		}
+	}
+			`,
+			errors: [
+				{
+					messageId: "missingThis",
+				},
+			],
+		},
+		{
+			code: `
   class Derived extends Base {
     override method() {}
   }
