fix: delete this in static class properties initialization

packages/babel-helper-create-class-features-plugin/package.json

@@ -24,6 +24,7 @@
     "@babel/helper-member-expression-to-functions": "workspace:^",
     "@babel/helper-optimise-call-expression": "workspace:^",
     "@babel/helper-replace-supers": "workspace:^",
+    "@babel/helper-skip-transparent-expression-wrappers": "workspace:^",
     "@babel/helper-split-export-declaration": "workspace:^"
   },
   "peerDependencies": {

packages/babel-helper-create-class-features-plugin/src/fields.ts

@@ -10,6 +10,7 @@ import type {
 } from "@babel/helper-member-expression-to-functions";
 import optimiseCall from "@babel/helper-optimise-call-expression";
 import annotateAsPure from "@babel/helper-annotate-as-pure";
+import { isTransparentExprWrapper } from "@babel/helper-skip-transparent-expression-wrappers";
 
 import * as ts from "./typescript";
 
@@ -890,6 +891,15 @@ type ReplaceThisState = {
 const thisContextVisitor = traverse.visitors.merge<ReplaceThisState>([
   {
     ThisExpression(path, state) {
+      // Replace `delete this` with `true`
+      const parent = path.findParent(
+        path => !isTransparentExprWrapper(path.node),
+      );
+      if (t.isUnaryExpression(parent.node, { operator: "delete" })) {
+        path.parentPath.replaceWith(t.booleanLiteral(true));
+        return;
+      }
+
       state.needsClassRef = true;
       path.replaceWith(t.cloneNode(state.classRef));
     },

packages/babel-plugin-proposal-class-properties/test/fixtures/public/delete-this/exec.js

@@ -0,0 +1,7 @@
+class Foo {
+  x = delete this;
+  static x = delete this;
+}
+
+expect(new Foo().x).toBe(true);
+expect(Foo.x).toBe(true);

packages/babel-plugin-proposal-class-properties/test/fixtures/public/delete-this/input.js

@@ -0,0 +1,4 @@
+class Foo {
+  x = delete this;
+  static x = delete this;
+}

packages/babel-plugin-proposal-class-properties/test/fixtures/public/delete-this/output.js

@@ -0,0 +1,7 @@
+var Foo = /*#__PURE__*/babelHelpers.createClass(function Foo() {
+  "use strict";
+
+  babelHelpers.classCallCheck(this, Foo);
+  babelHelpers.defineProperty(this, "x", delete this);
+});
+babelHelpers.defineProperty(Foo, "x", true);

yarn.lock

@@ -591,6 +591,7 @@ __metadata:
     "@babel/helper-optimise-call-expression": "workspace:^"
     "@babel/helper-plugin-test-runner": "workspace:^"
     "@babel/helper-replace-supers": "workspace:^"
+    "@babel/helper-skip-transparent-expression-wrappers": "workspace:^"
     "@babel/helper-split-export-declaration": "workspace:^"
     "@babel/plugin-syntax-class-static-block": ^7.14.5
     "@babel/preset-env": "workspace:^"