fix: do not filter report from functions within class elements (#13106)

eslint/babel-eslint-plugin/src/rules/no-invalid-this.js

@@ -17,7 +17,13 @@ export default ruleComposer.filterReports(noInvalidThisRule, problem => {
         node.key.type === "PrivateIdentifier")
     ) {
       inClassMember = true;
-      return;
+      break;
+    } else if (
+      node.type === "FunctionDeclaration" ||
+      node.type === "FunctionExpression"
+    ) {
+      inClassMember = false;
+      break;
     }
 
     node = node.parent;

eslint/babel-eslint-plugin/test/rules/no-invalid-this.js

@@ -93,6 +93,30 @@ const patterns = [
     invalid: [],
   },
 
+  {
+    code: "class A {a = () => { function b() { return this.b;} };};",
+    parserOptions: { ecmaVersion: 6 },
+    valid: [],
+    invalid: [NORMAL, USE_STRICT, IMPLIED_STRICT, MODULES],
+    errors: [
+      {
+        message: "Unexpected 'this'.",
+      },
+    ],
+  },
+
+  {
+    code: "class A {a = () => { (function b() { return this.b;}); };};",
+    parserOptions: { ecmaVersion: 6 },
+    valid: [],
+    invalid: [NORMAL, USE_STRICT, IMPLIED_STRICT, MODULES],
+    errors: [
+      {
+        message: "Unexpected 'this'.",
+      },
+    ],
+  },
+
   // Class Private methods
   {
     code: "class A {#a = this.b;};",
@@ -108,6 +132,30 @@ const patterns = [
     invalid: [],
   },
 
+  {
+    code: "class A {#a = () => { function b() { return this.b;} };};",
+    parserOptions: { ecmaVersion: 6 },
+    valid: [],
+    invalid: [NORMAL, USE_STRICT, IMPLIED_STRICT, MODULES],
+    errors: [
+      {
+        message: "Unexpected 'this'.",
+      },
+    ],
+  },
+
+  {
+    code: "class A {#a = () => { (function b() { return this.b;}); };};",
+    parserOptions: { ecmaVersion: 6 },
+    valid: [],
+    invalid: [NORMAL, USE_STRICT, IMPLIED_STRICT, MODULES],
+    errors: [
+      {
+        message: "Unexpected 'this'.",
+      },
+    ],
+  },
+
   {
     code: "class A {#a() {return this.b;};};",
     parserOptions: { ecmaVersion: 6 },