Class private properties (#7842)

* Update member-expression-to-functions

1. Babel using British spellings, so `memoise`
2. Provide a helper `AssignmentMemoiser` class, which will assign the memo'd value with the `n`th access.

* Private properties!

* Fixes

* Tests

* Update helper name

* Fix privates that reference other privates

* Don't extend a builtin

* Rebase

packages/babel-helper-member-expression-to-functions/README.md

@@ -26,7 +26,7 @@ const visitor = {
 
 // The helper requires three special methods on state: `get`, `set`, and
 // `call`.
-// Optionally, a special `memoize` method may be defined, which gets
+// Optionally, a special `memoise` method may be defined, which gets
 // called if the member is in a self-referential update expression.
 // Everything else will be passed through as normal.
 const state = {
@@ -55,10 +55,10 @@ const state = {
     );
   },
 
-  memoize(memberPath) {
+  memoise(memberPath) {
     const { node } = memberPath;
     if (node.computed) {
-      MEMOIZED.set(node, ...);
+      MEMOISED.set(node, ...);
     }
   },
 

packages/babel-helper-member-expression-to-functions/src/index.js

@@ -1,6 +1,39 @@
 import * as t from "@babel/types";
 
+class AssignmentMemoiser {
+  constructor() {
+    this._map = new WeakMap();
+  }
+
+  has(key) {
+    return this._map.has(key);
+  }
+
+  get(key) {
+    if (!this.has(key)) return;
+
+    const record = this._map.get(key);
+    const { value } = record;
+
+    record.count--;
+    if (record.count === 0) {
+      // The `count` access is the outermost function call (hopefully), so it
+      // does the assignment.
+      return t.assignmentExpression("=", value, key);
+    }
+    return value;
+  }
+
+  set(key, value, count) {
+    return this._map.set(key, { count, value });
+  }
+}
+
 const handle = {
+  memoise() {
+    // noop.
+  },
+
   handle(member) {
     const { node, parent, parentPath } = member;
 
@@ -9,11 +42,10 @@ const handle = {
     if (parentPath.isUpdateExpression({ argument: node })) {
       const { operator, prefix } = parent;
 
-      // Give the state handler a chance to memoize the member,
-      // since we'll reference it twice.
-      if (this.memoize) {
-        this.memoize(member);
-      }
+      // Give the state handler a chance to memoise the member, since we'll
+      // reference it twice. The second access (the set) should do the memo
+      // assignment.
+      this.memoise(member, 2);
 
       const value = t.binaryExpression(
         operator[0],
@@ -44,11 +76,10 @@ const handle = {
       let value = right;
 
       if (operator !== "=") {
-        // Give the state handler a chance to memoize the member,
-        // since we'll reference it twice.
-        if (this.memoize) {
-          this.memoize(member);
-        }
+        // Give the state handler a chance to memoise the member, since we'll
+        // reference it twice. The second access (the set) should do the memo
+        // assignment.
+        this.memoise(member, 2);
 
         value = t.binaryExpression(
           operator.slice(0, -1),
@@ -79,11 +110,12 @@ const handle = {
 // it wishes to be transformed.
 // Additionally, the caller must pass in a state object with at least
 // get, set, and call methods.
-// Optionally, a memoize method may be defined on the state, which will be
+// Optionally, a memoise method may be defined on the state, which will be
 // called when the member is a self-referential update.
 export default function memberExpressionToFunctions(path, visitor, state) {
   path.traverse(visitor, {
-    ...state,
     ...handle,
+    ...state,
+    memoiser: new AssignmentMemoiser(),
   });
 }

packages/babel-helper-replace-supers/src/index.js

@@ -70,9 +70,8 @@ const visitor = traverse.visitors.merge([
   },
 ]);
 
-const memoized = new WeakMap();
 const specHandlers = {
-  memoize(superMember) {
+  memoise(superMember, count) {
     const { scope, node } = superMember;
     const { computed, property } = node;
     if (!computed) {
@@ -84,44 +83,34 @@ const specHandlers = {
       return;
     }
 
-    memoized.set(property, memo);
+    this.memoiser.set(property, memo, count);
+  },
+
+  prop(superMember) {
+    const { computed, property } = superMember.node;
+    if (this.memoiser.has(property)) {
+      return t.cloneNode(this.memoiser.get(property));
+    }
+
+    if (computed) {
+      return t.cloneNode(property);
+    }
+
+    return t.stringLiteral(property.name);
   },
 
   get(superMember) {
-    const { computed, property } = superMember.node;
-    const thisExpr = t.thisExpression();
-
-    let prop;
-    if (computed && memoized.has(property)) {
-      prop = t.cloneNode(memoized.get(property));
-    } else {
-      prop = computed ? property : t.stringLiteral(property.name);
-    }
-
     return t.callExpression(this.file.addHelper("get"), [
       getPrototypeOfExpression(this.getObjectRef(), this.isStatic, this.file),
-      prop,
-      thisExpr,
+      this.prop(superMember),
+      t.thisExpression(),
     ]);
   },
 
   set(superMember, value) {
-    const { computed, property } = superMember.node;
-
-    let prop;
-    if (computed && memoized.has(property)) {
-      prop = t.assignmentExpression(
-        "=",
-        t.cloneNode(memoized.get(property)),
-        property,
-      );
-    } else {
-      prop = computed ? property : t.stringLiteral(property.name);
-    }
-
     return t.callExpression(this.file.addHelper("set"), [
       getPrototypeOfExpression(this.getObjectRef(), this.isStatic, this.file),
-      prop,
+      this.prop(superMember),
       value,
       t.thisExpression(),
       t.booleanLiteral(superMember.isInStrictMode()),
@@ -134,12 +123,21 @@ const specHandlers = {
 };
 
 const looseHandlers = {
-  memoize: specHandlers.memoize,
-  call: specHandlers.call,
+  ...specHandlers,
+
+  prop(superMember) {
+    const { property } = superMember.node;
+    if (this.memoiser.has(property)) {
+      return t.cloneNode(this.memoiser.get(property));
+    }
+
+    return t.cloneNode(property);
+  },
 
   get(superMember) {
     const { isStatic, superRef } = this;
-    const { property, computed } = superMember.node;
+    const { computed } = superMember.node;
+    const prop = this.prop(superMember);
 
     let object;
     if (isStatic) {
@@ -155,29 +153,12 @@ const looseHandlers = {
         : t.memberExpression(t.identifier("Object"), t.identifier("prototype"));
     }
 
-    let prop;
-    if (computed && memoized.has(property)) {
-      prop = t.cloneNode(memoized.get(property));
-    } else {
-      prop = property;
-    }
-
     return t.memberExpression(object, prop, computed);
   },
 
   set(superMember, value) {
-    const { property, computed } = superMember.node;
-
-    let prop;
-    if (computed && memoized.has(property)) {
-      prop = t.assignmentExpression(
-        "=",
-        t.cloneNode(memoized.get(property)),
-        property,
-      );
-    } else {
-      prop = property;
-    }
+    const { computed } = superMember.node;
+    const prop = this.prop(superMember);
 
     return t.assignmentExpression(
       "=",

packages/babel-helpers/src/helpers.js

@@ -967,3 +967,38 @@ helpers.applyDecoratedDescriptor = () => template.program.ast`
         return desc;
     }
 `;
+
+helpers.classPrivateFieldLooseKey = () => template.program.ast`
+  var id = 0;
+  export default function _classPrivateFieldKey(name) {
+    return "__private_" + (id++) + "_" + name;
+  }
+`;
+
+helpers.classPrivateFieldLooseBase = () => template.program.ast`
+  export default function _classPrivateFieldBase(receiver, privateKey) {
+    if (!Object.prototype.hasOwnProperty.call(receiver, privateKey)) {
+      throw new TypeError("attempted to use private field on non-instance");
+    }
+    return receiver;
+  }
+`;
+
+helpers.classPrivateFieldGet = () => template.program.ast`
+  export default function _classPrivateFieldGet(receiver, privateMap) {
+    if (!privateMap.has(receiver)) {
+      throw new TypeError("attempted to get private field on non-instance");
+    }
+    return privateMap.get(receiver);
+  }
+`;
+
+helpers.classPrivateFieldSet = () => template.program.ast`
+  export default function _classPrivateFieldSet(receiver, privateMap, value) {
+    if (!privateMap.has(receiver)) {
+      throw new TypeError("attempted to set private field on non-instance");
+    }
+    privateMap.set(receiver, value);
+    return value;
+  }
+`;

packages/babel-plugin-proposal-class-properties/package.json

@@ -10,6 +10,8 @@
   ],
   "dependencies": {
     "@babel/helper-function-name": "7.0.0-beta.47",
+    "@babel/helper-member-expression-to-functions": "7.0.0-beta.47",
+    "@babel/helper-optimise-call-expression": "7.0.0-beta.47",
     "@babel/helper-plugin-utils": "7.0.0-beta.47",
     "@babel/helper-replace-supers": "7.0.0-beta.47",
     "@babel/plugin-syntax-class-properties": "7.0.0-beta.47"

packages/babel-plugin-proposal-class-properties/src/index.js

@@ -3,6 +3,8 @@ import nameFunction from "@babel/helper-function-name";
 import syntaxClassProperties from "@babel/plugin-syntax-class-properties";
 import { template, traverse, types as t } from "@babel/core";
 import { environmentVisitor } from "@babel/helper-replace-supers";
+import memberExpressionToFunctions from "@babel/helper-member-expression-to-functions";
+import optimiseCall from "@babel/helper-optimise-call-expression";
 
 export default declare((api, options) => {
   api.assertVersion(7);
@@ -51,36 +53,206 @@ export default declare((api, options) => {
     environmentVisitor,
   ]);
 
-  const buildClassPropertySpec = (
-    ref,
-    { key, value, computed },
-    scope,
-    state,
-  ) => {
+  // Traverses the class scope, handling private name references.  If an inner
+  // class redeclares the same private name, it will hand off traversal to the
+  // restricted visitor (which doesn't traverse the inner class's inner scope).
+  const privateNameVisitor = {
+    PrivateName(path) {
+      const { name } = this;
+      const { node, parentPath } = path;
+
+      if (!parentPath.isMemberExpression({ property: node })) return;
+      if (node.id.name !== name) return;
+      this.handle(parentPath);
+    },
+
+    Class(path) {
+      const { name } = this;
+      const body = path.get("body.body");
+
+      for (const prop of body) {
+        if (!prop.isClassPrivateProperty()) continue;
+        if (prop.node.key.id.name !== name) continue;
+
+        // This class redeclares the private name.
+        // So, we can only evaluate the things in the outer scope.
+        path.traverse(privateNameInnerVisitor, this);
+        path.skip();
+        break;
+      }
+    },
+  };
+
+  // Traverses the outer portion of a class, without touching the class's inner
+  // scope, for private names.
+  const privateNameInnerVisitor = traverse.visitors.merge([
+    {
+      PrivateName: privateNameVisitor.PrivateName,
+    },
+    environmentVisitor,
+  ]);
+
+  const privateNameHandlerSpec = {
+    memoise(member, count) {
+      const { scope } = member;
+      const { object } = member.node;
+
+      const memo = scope.maybeGenerateMemoised(object);
+      if (!memo) {
+        return;
+      }
+
+      this.memoiser.set(object, memo, count);
+    },
+
+    receiver(member) {
+      const { object } = member.node;
+
+      if (this.memoiser.has(object)) {
+        return t.cloneNode(this.memoiser.get(object));
+      }
+
+      return t.cloneNode(object);
+    },
+
+    get(member) {
+      const { map, file } = this;
+
+      return t.callExpression(file.addHelper("classPrivateFieldGet"), [
+        this.receiver(member),
+        t.cloneNode(map),
+      ]);
+    },
+
+    set(member, value) {
+      const { map, file } = this;
+
+      return t.callExpression(file.addHelper("classPrivateFieldSet"), [
+        this.receiver(member),
+        t.cloneNode(map),
+        value,
+      ]);
+    },
+
+    call(member, args) {
+      // The first access (the get) should do the memo assignment.
+      this.memoise(member, 1);
+
+      return optimiseCall(this.get(member), this.receiver(member), args);
+    },
+  };
+
+  const privateNameHandlerLoose = {
+    handle(member) {
+      const { prop, file } = this;
+      const { object } = member.node;
+
+      member.replaceWith(
+        template.expression`BASE(REF, PROP)[PROP]`({
+          BASE: file.addHelper("classPrivateFieldLooseBase"),
+          REF: object,
+          PROP: prop,
+        }),
+      );
+    },
+  };
+
+  function buildClassPropertySpec(ref, path, state) {
+    const { scope } = path;
+    const { key, value, computed } = path.node;
     return t.expressionStatement(
       t.callExpression(state.addHelper("defineProperty"), [
         ref,
-        t.isIdentifier(key) && !computed ? t.stringLiteral(key.name) : key,
+        computed || t.isLiteral(key) ? key : t.stringLiteral(key.name),
         value || scope.buildUndefinedNode(),
       ]),
     );
-  };
+  }
 
-  const buildClassPropertyLoose = (ref, { key, value, computed }, scope) => {
-    return template.statement`MEMBER = VALUE`({
-      MEMBER: t.memberExpression(
-        t.cloneNode(ref),
-        key,
-        computed || t.isLiteral(key),
+  function buildClassPropertyLoose(ref, path) {
+    const { scope } = path;
+    const { key, value, computed } = path.node;
+    return t.expressionStatement(
+      t.assignmentExpression(
+        "=",
+        t.memberExpression(ref, key, computed || t.isLiteral(key)),
+        value || scope.buildUndefinedNode(),
       ),
-      VALUE: value || scope.buildUndefinedNode(),
+    );
+  }
+
+  function buildClassPrivatePropertySpec(ref, path, initNodes, state) {
+    const { parentPath, scope } = path;
+    const { name } = path.node.key.id;
+
+    const map = scope.generateUidIdentifier(name);
+    memberExpressionToFunctions(parentPath, privateNameVisitor, {
+      name,
+      map,
+      file: state,
+      ...privateNameHandlerSpec,
     });
-  };
+
+    initNodes.push(
+      template.statement`var MAP = new WeakMap();`({
+        MAP: map,
+      }),
+    );
+
+    // Must be late evaluated in case it references another private field.
+    return () =>
+      template.statement`MAP.set(REF, VALUE);`({
+        MAP: map,
+        REF: ref,
+        VALUE: path.node.value || scope.buildUndefinedNode(),
+      });
+  }
+
+  function buildClassPrivatePropertyLoose(ref, path, initNodes, state) {
+    const { parentPath, scope } = path;
+    const { name } = path.node.key.id;
+
+    const prop = scope.generateUidIdentifier(name);
+
+    parentPath.traverse(privateNameVisitor, {
+      name,
+      prop,
+      file: state,
+      ...privateNameHandlerLoose,
+    });
+
+    initNodes.push(
+      template.statement`var PROP = HELPER(NAME);`({
+        PROP: prop,
+        HELPER: state.addHelper("classPrivateFieldLooseKey"),
+        NAME: t.stringLiteral(name),
+      }),
+    );
+
+    // Must be late evaluated in case it references another private field.
+    return () =>
+      template.statement`
+      Object.defineProperty(REF, PROP, {
+        // configurable is false by default
+        // enumerable is false by default
+        writable: true,
+        value: VALUE
+      });
+    `({
+        REF: ref,
+        PROP: prop,
+        VALUE: path.node.value || scope.buildUndefinedNode(),
+      });
+  }
 
   const buildClassProperty = loose
     ? buildClassPropertyLoose
     : buildClassPropertySpec;
 
+  const buildClassPrivateProperty = loose
+    ? buildClassPrivatePropertyLoose
+    : buildClassPrivatePropertySpec;
+
   return {
     inherits: syntaxClassProperties,
 
@@ -90,14 +262,35 @@ export default declare((api, options) => {
         let constructor;
         const props = [];
         const computedPaths = [];
+        const privateNames = new Set();
         const body = path.get("body");
 
         for (const path of body.get("body")) {
-          if (path.node.computed) {
+          const { computed, decorators } = path.node;
+          if (computed) {
             computedPaths.push(path);
           }
+          if (decorators && decorators.length > 0) {
+            throw path.buildCodeFrameError(
+              "Decorators transform is necessary.",
+            );
+          }
 
-          if (path.isClassProperty()) {
+          if (path.isClassPrivateProperty()) {
+            const { static: isStatic, key: { id: { name } } } = path.node;
+
+            if (isStatic) {
+              throw path.buildCodeFrameError(
+                "Static class fields are not spec'ed yet.",
+              );
+            }
+            if (privateNames.has(name)) {
+              throw path.buildCodeFrameError("Duplicate private field");
+            }
+            privateNames.add(name);
+          }
+
+          if (path.isProperty()) {
             props.push(path);
           } else if (path.isClassMethod({ kind: "constructor" })) {
             constructor = path;
@@ -141,22 +334,31 @@ export default declare((api, options) => {
           }
         }
 
+        // Transform private props before publics.
+        const privateMaps = [];
+        const privateMapInits = [];
         for (const prop of props) {
-          const propNode = prop.node;
-          if (propNode.decorators && propNode.decorators.length > 0) continue;
+          if (prop.isPrivate()) {
+            const inits = [];
+            privateMapInits.push(inits);
 
-          if (propNode.static) {
-            staticNodes.push(
-              buildClassProperty(ref, propNode, path.scope, state),
+            privateMaps.push(
+              buildClassPrivateProperty(t.thisExpression(), prop, inits, state),
             );
+          }
+        }
+
+        let p = 0;
+        for (const prop of props) {
+          if (prop.node.static) {
+            staticNodes.push(buildClassProperty(t.cloneNode(ref), prop, state));
+          } else if (prop.isPrivate()) {
+            instanceBody.push(privateMaps[p]());
+            staticNodes.push(...privateMapInits[p]);
+            p++;
           } else {
             instanceBody.push(
-              buildClassProperty(
-                t.thisExpression(),
-                propNode,
-                path.scope,
-                state,
-              ),
+              buildClassProperty(t.thisExpression(), prop, state),
             );
           }
         }
@@ -220,6 +422,10 @@ export default declare((api, options) => {
         path.insertBefore(computedNodes);
         path.insertAfter(staticNodes);
       },
+
+      PrivateName(path) {
+        throw path.buildCodeFrameError(`Unknown PrivateName "${path}"`);
+      },
     },
   };
 });

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/assignment/input.js

@@ -0,0 +1,10 @@
+class Foo {
+  #foo = 0;
+
+  test(other) {
+    this.#foo += 1;
+    this.#foo = 2;
+    other.obj.#foo += 1;
+    other.obj.#foo = 2;
+  }
+}

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/assignment/output.js

@@ -0,0 +1,26 @@
+var Foo =
+/*#__PURE__*/
+function () {
+  "use strict";
+
+  function Foo() {
+    babelHelpers.classCallCheck(this, Foo);
+    Object.defineProperty(this, _foo, {
+      writable: true,
+      value: 0
+    });
+  }
+
+  babelHelpers.createClass(Foo, [{
+    key: "test",
+    value: function test(other) {
+      babelHelpers.classPrivateFieldLooseBase(this, _foo)[_foo] += 1;
+      babelHelpers.classPrivateFieldLooseBase(this, _foo)[_foo] = 2;
+      babelHelpers.classPrivateFieldLooseBase(other.obj, _foo)[_foo] += 1;
+      babelHelpers.classPrivateFieldLooseBase(other.obj, _foo)[_foo] = 2;
+    }
+  }]);
+  return Foo;
+}();
+
+var _foo = babelHelpers.classPrivateFieldLooseKey("foo");

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/call/exec.js

@@ -0,0 +1,15 @@
+class Foo {
+  #foo = function() {
+    return this;
+  }
+
+  test(other) {
+    return [this.#foo(), other.#foo()];
+  }
+}
+
+const f = new Foo;
+const o = new Foo;
+const test = f.test(o);
+expect(test[0]).toBe(f);
+expect(test[1]).toBe(o);

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/call/input.js

@@ -0,0 +1,10 @@
+class Foo {
+  #foo = function() {
+    return this;
+  }
+
+  test(other) {
+    this.#foo();
+    other.obj.#foo();
+  }
+}

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/call/output.js

@@ -0,0 +1,27 @@
+var Foo =
+/*#__PURE__*/
+function () {
+  "use strict";
+
+  function Foo() {
+    babelHelpers.classCallCheck(this, Foo);
+    Object.defineProperty(this, _foo, {
+      writable: true,
+      value: function () {
+        return this;
+      }
+    });
+  }
+
+  babelHelpers.createClass(Foo, [{
+    key: "test",
+    value: function test(other) {
+      babelHelpers.classPrivateFieldLooseBase(this, _foo)[_foo]();
+
+      babelHelpers.classPrivateFieldLooseBase(other.obj, _foo)[_foo]();
+    }
+  }]);
+  return Foo;
+}();
+
+var _foo = babelHelpers.classPrivateFieldLooseKey("foo");

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/canonical/exec.js

@@ -0,0 +1,73 @@
+class Point {
+    #x;
+    #y;
+
+    constructor(x = 0, y = 0) {
+        this.#x = +x;
+        this.#y = +y;
+    }
+
+    get x() { return this.#x }
+    set x(value) { this.#x = +value }
+
+    get y() { return this.#y }
+    set y(value) { this.#y = +value }
+
+    equals(p) { return this.#x === p.#x && this.#y === p.#y }
+
+    toString() { return `Point<${ this.#x },${ this.#y }>` }
+
+}
+
+const p1 = new Point(1, 2);
+const p2 = new Point(2, 3);
+const p3 = new Point(1, 2);
+
+expect(p1.x).toBe(1);
+expect(p1.y).toBe(2);
+expect(p2.x).toBe(2);
+expect(p2.y).toBe(3);
+expect(p3.x).toBe(1);
+expect(p3.y).toBe(2);
+
+expect(p1.equals(p1)).toBe(true)
+expect(p1.equals(p2)).toBe(false)
+expect(p1.equals(p3)).toBe(true)
+expect(p2.equals(p1)).toBe(false)
+expect(p2.equals(p2)).toBe(true)
+expect(p2.equals(p3)).toBe(false)
+expect(p3.equals(p1)).toBe(true)
+expect(p3.equals(p2)).toBe(false)
+expect(p3.equals(p3)).toBe(true)
+
+expect(p1.toString()).toBe("Point<1,2>")
+expect(p2.toString()).toBe("Point<2,3>")
+expect(p3.toString()).toBe("Point<1,2>")
+
+p1.x += 1;
+p1.y = 3;
+p2.x -= 1;
+p2.y = 3;
+p3.x = 0;
+p3.y = 0;
+
+expect(p1.x).toBe(2);
+expect(p1.y).toBe(3);
+expect(p2.x).toBe(1);
+expect(p2.y).toBe(3);
+expect(p3.x).toBe(0);
+expect(p3.y).toBe(0);
+
+expect(p1.equals(p1)).toBe(true)
+expect(p1.equals(p2)).toBe(false)
+expect(p1.equals(p3)).toBe(false)
+expect(p2.equals(p1)).toBe(false)
+expect(p2.equals(p2)).toBe(true)
+expect(p2.equals(p3)).toBe(false)
+expect(p3.equals(p1)).toBe(false)
+expect(p3.equals(p2)).toBe(false)
+expect(p3.equals(p3)).toBe(true)
+
+expect(p1.toString()).toBe("Point<2,3>")
+expect(p2.toString()).toBe("Point<1,3>")
+expect(p3.toString()).toBe("Point<0,0>")

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/canonical/input.js

@@ -0,0 +1,20 @@
+class Point {
+    #x;
+    #y;
+
+    constructor(x = 0, y = 0) {
+        this.#x = +x;
+        this.#y = +y;
+    }
+
+    get x() { return this.#x }
+    set x(value) { this.#x = +value }
+
+    get y() { return this.#y }
+    set y(value) { this.#y = +value }
+
+    equals(p) { return this.#x === p.#x && this.#y === p.#y }
+
+    toString() { return `Point<${ this.#x },${ this.#y }>` }
+
+}

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/canonical/options.json

@@ -0,0 +1,3 @@
+{
+  "minNodeVersion": "6.0.0"
+}

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/canonical/output.js

@@ -0,0 +1,52 @@
+var Point =
+/*#__PURE__*/
+function () {
+  "use strict";
+
+  function Point(_x2 = 0, _y2 = 0) {
+    babelHelpers.classCallCheck(this, Point);
+    Object.defineProperty(this, _x, {
+      writable: true,
+      value: void 0
+    });
+    Object.defineProperty(this, _y, {
+      writable: true,
+      value: void 0
+    });
+    babelHelpers.classPrivateFieldLooseBase(this, _x)[_x] = +_x2;
+    babelHelpers.classPrivateFieldLooseBase(this, _y)[_y] = +_y2;
+  }
+
+  babelHelpers.createClass(Point, [{
+    key: "equals",
+    value: function equals(p) {
+      return babelHelpers.classPrivateFieldLooseBase(this, _x)[_x] === babelHelpers.classPrivateFieldLooseBase(p, _x)[_x] && babelHelpers.classPrivateFieldLooseBase(this, _y)[_y] === babelHelpers.classPrivateFieldLooseBase(p, _y)[_y];
+    }
+  }, {
+    key: "toString",
+    value: function toString() {
+      return `Point<${babelHelpers.classPrivateFieldLooseBase(this, _x)[_x]},${babelHelpers.classPrivateFieldLooseBase(this, _y)[_y]}>`;
+    }
+  }, {
+    key: "x",
+    get: function () {
+      return babelHelpers.classPrivateFieldLooseBase(this, _x)[_x];
+    },
+    set: function (value) {
+      babelHelpers.classPrivateFieldLooseBase(this, _x)[_x] = +value;
+    }
+  }, {
+    key: "y",
+    get: function () {
+      return babelHelpers.classPrivateFieldLooseBase(this, _y)[_y];
+    },
+    set: function (value) {
+      babelHelpers.classPrivateFieldLooseBase(this, _y)[_y] = +value;
+    }
+  }]);
+  return Point;
+}();
+
+var _x = babelHelpers.classPrivateFieldLooseKey("x");
+
+var _y = babelHelpers.classPrivateFieldLooseKey("y");

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/constructor-collision/exec.js

@@ -0,0 +1,17 @@
+var foo = "bar";
+
+class Foo {
+  #bar = foo;
+
+  constructor() {
+    var foo = "foo";
+  }
+
+  test() {
+    return this.#bar;
+  }
+}
+
+const f = new Foo;
+expect(f.test()).toBe(foo);
+expect("bar" in f).toBe(false);

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/constructor-collision/input.js

@@ -0,0 +1,9 @@
+var foo = "bar";
+
+class Foo {
+  #bar = foo;
+
+  constructor() {
+    var foo = "foo";
+  }
+}

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/constructor-collision/output.js

@@ -0,0 +1,14 @@
+var foo = "bar";
+
+var Foo = function Foo() {
+  "use strict";
+
+  babelHelpers.classCallCheck(this, Foo);
+  Object.defineProperty(this, _bar, {
+    writable: true,
+    value: foo
+  });
+  var _foo = "foo";
+};
+
+var _bar = babelHelpers.classPrivateFieldLooseKey("bar");

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/declaration-order/LICENSE

@@ -0,0 +1,28 @@
+The << Software identified by reference to the Ecma Standard* ("Software)">>  is protected by copyright and is being
+made available under the  "BSD License", included below. This Software may be subject to third party rights (rights
+from parties other than Ecma International), including patent rights, and no licenses under such third party rights
+are granted under this license even if the third party concerned is a member of Ecma International.  SEE THE ECMA
+CODE OF CONDUCT IN PATENT MATTERS AVAILABLE AT http://www.ecma-international.org/memento/codeofconduct.htm FOR
+INFORMATION REGARDING THE LICENSING OF PATENT CLAIMS THAT ARE REQUIRED TO IMPLEMENT ECMA INTERNATIONAL STANDARDS*.
+
+Copyright (C) 2012-2013 Ecma International
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without modification, are permitted provided that the
+following conditions are met:
+1.   Redistributions of source code must retain the above copyright notice, this list of conditions and the following
+     disclaimer.
+2.   Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the
+     following disclaimer in the documentation and/or other materials provided with the distribution.
+3.   Neither the name of the authors nor Ecma International may be used to endorse or promote products derived from
+     this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE ECMA INTERNATIONAL "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
+SHALL ECMA INTERNATIONAL BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
+DAMAGE.
+
+* Ecma International Standards hereafter means Ecma International Standards as well as Ecma Technical Reports

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/declaration-order/exec.js

@@ -0,0 +1,8 @@
+class C {
+  y = this.#x;
+  #x;
+}
+
+expect(() => {
+  new C();
+}).toThrow();

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/declaration-order/input.js

@@ -0,0 +1,8 @@
+class C {
+  y = this.#x;
+  #x;
+}
+
+expect(() => {
+  new C();
+}).toThrow();

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/declaration-order/output.js

@@ -0,0 +1,16 @@
+var C = function C() {
+  "use strict";
+
+  babelHelpers.classCallCheck(this, C);
+  this.y = babelHelpers.classPrivateFieldLooseBase(this, _x)[_x];
+  Object.defineProperty(this, _x, {
+    writable: true,
+    value: void 0
+  });
+};
+
+var _x = babelHelpers.classPrivateFieldLooseKey("x");
+
+expect(() => {
+  new C();
+}).toThrow();

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/derived-multiple-supers/input.js

@@ -0,0 +1,11 @@
+class Foo extends Bar {
+  #bar = "foo";
+
+  constructor() {
+    if (condition) {
+      super();
+    } else {
+      super();
+    }
+  }
+}

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/derived-multiple-supers/output.js

@@ -0,0 +1,32 @@
+var Foo =
+/*#__PURE__*/
+function (_Bar) {
+  "use strict";
+
+  function Foo() {
+    var _this;
+
+    babelHelpers.classCallCheck(this, Foo);
+
+    if (condition) {
+      _this = babelHelpers.possibleConstructorReturn(this, babelHelpers.getPrototypeOf(Foo).call(this));
+      Object.defineProperty(babelHelpers.assertThisInitialized(babelHelpers.assertThisInitialized(babelHelpers.assertThisInitialized(_this))), _bar, {
+        writable: true,
+        value: "foo"
+      });
+    } else {
+      _this = babelHelpers.possibleConstructorReturn(this, babelHelpers.getPrototypeOf(Foo).call(this));
+      Object.defineProperty(babelHelpers.assertThisInitialized(babelHelpers.assertThisInitialized(babelHelpers.assertThisInitialized(_this))), _bar, {
+        writable: true,
+        value: "foo"
+      });
+    }
+
+    return babelHelpers.possibleConstructorReturn(_this);
+  }
+
+  babelHelpers.inherits(Foo, _Bar);
+  return Foo;
+}(Bar);
+
+var _bar = babelHelpers.classPrivateFieldLooseKey("bar");

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/derived/exec.js

@@ -0,0 +1,22 @@
+class Foo {
+  #prop = "foo";
+
+  foo() {
+    return this.#prop;
+  }
+}
+
+class Bar extends Foo {
+  #prop = "bar";
+
+  bar() {
+    return this.#prop;
+  }
+}
+
+const f = new Foo;
+expect(f.foo()).toBe("foo");
+
+const b = new Bar;
+expect(b.foo()).toBe("foo");
+expect(b.bar()).toBe("bar");

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/derived/input.js

@@ -0,0 +1,7 @@
+class Foo {
+  #prop = "foo";
+}
+
+class Bar extends Foo {
+  #prop = "bar";
+}

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/derived/output.js

@@ -0,0 +1,32 @@
+var Foo = function Foo() {
+  "use strict";
+
+  babelHelpers.classCallCheck(this, Foo);
+  Object.defineProperty(this, _prop, {
+    writable: true,
+    value: "foo"
+  });
+};
+
+var _prop = babelHelpers.classPrivateFieldLooseKey("prop");
+
+var Bar =
+/*#__PURE__*/
+function (_Foo) {
+  "use strict";
+
+  function Bar(...args) {
+    var _temp, _this;
+
+    babelHelpers.classCallCheck(this, Bar);
+    return babelHelpers.possibleConstructorReturn(_this, (_temp = _this = babelHelpers.possibleConstructorReturn(this, babelHelpers.getPrototypeOf(Bar).call(this, ...args)), Object.defineProperty(babelHelpers.assertThisInitialized(babelHelpers.assertThisInitialized(_this)), _prop2, {
+      writable: true,
+      value: "bar"
+    }), _temp));
+  }
+
+  babelHelpers.inherits(Bar, _Foo);
+  return Bar;
+}(Foo);
+
+var _prop2 = babelHelpers.classPrivateFieldLooseKey("prop");

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/extracted-this/input.js

@@ -0,0 +1,9 @@
+var foo = "bar";
+
+class Foo {
+  #bar = this;
+  #baz = foo;
+
+  constructor(foo) {
+  }
+}

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/extracted-this/output.js

@@ -0,0 +1,19 @@
+var foo = "bar";
+
+var Foo = function Foo(_foo) {
+  "use strict";
+
+  babelHelpers.classCallCheck(this, Foo);
+  Object.defineProperty(this, _bar, {
+    writable: true,
+    value: this
+  });
+  Object.defineProperty(this, _baz, {
+    writable: true,
+    value: foo
+  });
+};
+
+var _bar = babelHelpers.classPrivateFieldLooseKey("bar");
+
+var _baz = babelHelpers.classPrivateFieldLooseKey("baz");

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/foobar/input.js

@@ -0,0 +1,9 @@
+class Child extends Parent {
+  constructor() {
+    super();
+  }
+
+  #scopedFunctionWithThis = () => {
+    this.name = {};
+  }
+}

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/foobar/options.json

@@ -0,0 +1,3 @@
+{
+  "presets": [["stage-0", { "decoratorsLegacy": true }], "es2015"]
+}

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/foobar/output.js

@@ -0,0 +1,24 @@
+var Child =
+/*#__PURE__*/
+function (_Parent) {
+  "use strict";
+
+  function Child() {
+    var _this;
+
+    babelHelpers.classCallCheck(this, Child);
+    _this = babelHelpers.possibleConstructorReturn(this, babelHelpers.getPrototypeOf(Child).call(this));
+    Object.defineProperty(babelHelpers.assertThisInitialized(babelHelpers.assertThisInitialized(_this)), _scopedFunctionWithThis, {
+      writable: true,
+      value: function value() {
+        _this.name = {};
+      }
+    });
+    return _this;
+  }
+
+  babelHelpers.inherits(Child, _Parent);
+  return Child;
+}(Parent);
+
+var _scopedFunctionWithThis = babelHelpers.classPrivateFieldLooseKey("scopedFunctionWithThis");

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/instance-undefined/exec.js

@@ -0,0 +1,9 @@
+class Foo {
+  #bar;
+
+  test() {
+    return this.#bar;
+  }
+}
+
+expect(new Foo().test()).toBe(undefined);

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/instance-undefined/input.js

@@ -0,0 +1,3 @@
+class Foo {
+  #bar;
+}

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/instance-undefined/output.js

@@ -0,0 +1,11 @@
+var Foo = function Foo() {
+  "use strict";
+
+  babelHelpers.classCallCheck(this, Foo);
+  Object.defineProperty(this, _bar, {
+    writable: true,
+    value: void 0
+  });
+};
+
+var _bar = babelHelpers.classPrivateFieldLooseKey("bar");

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/instance/exec.js

@@ -0,0 +1,16 @@
+class Foo {
+  #bar = "foo";
+
+  test() {
+    return this.#bar;
+  }
+
+  static test(foo) {
+    return foo.#bar;
+  }
+}
+
+const f = new Foo();
+expect(f.test()).toBe("foo");
+expect(Foo.test(f)).toBe("foo");
+expect("bar" in f).toBe(false);

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/instance/input.js

@@ -0,0 +1,3 @@
+class Foo {
+  #bar = "foo";
+}

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/instance/output.js

@@ -0,0 +1,11 @@
+var Foo = function Foo() {
+  "use strict";
+
+  babelHelpers.classCallCheck(this, Foo);
+  Object.defineProperty(this, _bar, {
+    writable: true,
+    value: "foo"
+  });
+};
+
+var _bar = babelHelpers.classPrivateFieldLooseKey("bar");

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/multiple/exec.js

@@ -0,0 +1,11 @@
+class Foo {
+  #x = 0;
+  #y = this.#x + 1;
+
+  test() {
+    return this.#y;
+  }
+}
+
+const f = new Foo();
+expect(f.test()).toBe(1);

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/multiple/input.js

@@ -0,0 +1,4 @@
+class Foo {
+  #x = 0;
+  #y = this.#x;
+}

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/multiple/output.js

@@ -0,0 +1,17 @@
+var Foo = function Foo() {
+  "use strict";
+
+  babelHelpers.classCallCheck(this, Foo);
+  Object.defineProperty(this, _x, {
+    writable: true,
+    value: 0
+  });
+  Object.defineProperty(this, _y, {
+    writable: true,
+    value: babelHelpers.classPrivateFieldLooseBase(this, _x)[_x]
+  });
+};
+
+var _x = babelHelpers.classPrivateFieldLooseKey("x");
+
+var _y = babelHelpers.classPrivateFieldLooseKey("y");

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/native-classes/input.js

@@ -0,0 +1,18 @@
+class Foo {
+  static #foo = "foo";
+  #bar = "bar";
+
+  static test() {
+    return Foo.#foo;
+  }
+
+  test() {
+    return this.#bar;
+  }
+}
+
+const f = new Foo();
+expect("foo" in Foo).toBe(false)
+expect("bar" in f).toBe(false)
+expect(Foo.test()).toBe("foo")
+expect(f.test()).toBe("bar")

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/native-classes/options.json

@@ -0,0 +1,3 @@
+{
+  "throws": "Static class fields are not spec'ed yet."
+}

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/native-classes/output.js

@@ -0,0 +1,18 @@
+var _foo, _bar;
+
+class Foo {
+  constructor() {
+    Object.defineProperty(this, _bar, {
+      writable: true,
+      value: "bar"
+    });
+  }
+
+}
+
+_foo = babelHelpers.classPrivateFieldKey("foo");
+Object.defineProperty(Foo, _foo, {
+  writable: true,
+  value: "foo"
+});
+_bar = babelHelpers.classPrivateFieldKey("bar");

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/non-block-arrow-func/input.mjs

@@ -0,0 +1,11 @@
+export default param =>
+  class App {
+    static #props = {
+      prop1: 'prop1',
+      prop2: 'prop2'
+    }
+
+    getParam() {
+      return param;
+    }
+  }

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/non-block-arrow-func/options.json

@@ -0,0 +1,3 @@
+{
+  "throws": "Static class fields are not spec'ed yet."
+}

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/non-block-arrow-func/output.mjs

@@ -0,0 +1,25 @@
+export default (param => {
+  var _props, _class, _temp;
+
+  return _temp = _class =
+  /*#__PURE__*/
+  function () {
+    function App() {
+      babelHelpers.classCallCheck(this, App);
+    }
+
+    babelHelpers.createClass(App, [{
+      key: "getParam",
+      value: function getParam() {
+        return param;
+      }
+    }]);
+    return App;
+  }(), _props = babelHelpers.classPrivateFieldKey("props"), Object.defineProperty(_class, _props, {
+    writable: true,
+    value: {
+      prop1: 'prop1',
+      prop2: 'prop2'
+    }
+  }), _temp;
+});

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/options.json

@@ -0,0 +1,3 @@
+{
+  "plugins": ["external-helpers",["proposal-class-properties", { "loose": true }], "transform-classes", "transform-block-scoping", "syntax-class-properties"]
+}

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/private-in-derived/input.js

@@ -0,0 +1,8 @@
+class Outer {
+  #outer;
+
+  constructor() {
+    class Test extends this.#outer {
+    }
+  }
+}

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/private-in-derived/output.js

@@ -0,0 +1,23 @@
+var Outer = function Outer() {
+  "use strict";
+
+  babelHelpers.classCallCheck(this, Outer);
+  Object.defineProperty(this, _outer, {
+    writable: true,
+    value: void 0
+  });
+
+  var Test =
+  /*#__PURE__*/
+  function (_babelHelpers$classPr) {
+    function Test() {
+      babelHelpers.classCallCheck(this, Test);
+      return babelHelpers.possibleConstructorReturn(this, babelHelpers.getPrototypeOf(Test).apply(this, arguments));
+    }
+
+    babelHelpers.inherits(Test, _babelHelpers$classPr);
+    return Test;
+  }(babelHelpers.classPrivateFieldLooseBase(this, _outer)[_outer]);
+};
+
+var _outer = babelHelpers.classPrivateFieldLooseKey("outer");

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/reevaluated/input.js

@@ -0,0 +1,43 @@
+function classFactory() {
+  return class Foo {
+    #foo = "foo";
+    static #bar = "bar";
+
+    instance() {
+      return this.#foo;
+    }
+
+    static() {
+      return Foo.#bar;
+    }
+
+    static instance(inst) {
+      return inst.#foo;
+    }
+
+    static static() {
+      return Foo.#bar;
+    }
+  }
+}
+
+const Foo1 = classFactory();
+const Foo2 = classFactory();
+
+const f1 = new Foo1;
+const f2 = new Foo2;
+
+expect(f1.instance()).toBe("foo");
+expect(f1.static()).toBe("bar");
+expect(f2.instance()).toBe("foo");
+expect(f2.static()).toBe("bar");
+
+expect(Foo1.instance(f1)).toBe("foo");
+expect(Foo1.static()).toBe("bar");
+expect(Foo2.instance(f2)).toBe("foo");
+expect(Foo2.static()).toBe("bar");
+
+assert.throws(() => f1.instance.call(f2));
+assert.throws(() => f2.instance.call(f1));
+assert.throws(() => Foo1.instance(f2));
+assert.throws(() => Foo2.instance(f1));

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/reevaluated/options.json

@@ -0,0 +1,3 @@
+{
+  "throws": "Static class fields are not spec'ed yet."
+}

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/reevaluated/output.js

@@ -0,0 +1,18 @@
+function classFactory() {
+  var _bar, _foo;
+
+  var Foo = function Foo() {
+    babelHelpers.classCallCheck(this, Foo);
+    Object.defineProperty(this, _foo, {
+      writable: true,
+      value: "foo"
+    });
+  };
+
+  _bar = babelHelpers.classPrivateFieldKey("bar");
+  Object.defineProperty(Foo, _bar, {
+    writable: true,
+    value: "bar"
+  });
+  _foo = babelHelpers.classPrivateFieldKey("foo");
+}

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/reference-in-other-property/input.js

@@ -0,0 +1,7 @@
+class Foo {
+  one = this.#private;
+  #two = this.#private;
+  #private = 0;
+  three = this.#private;
+  #four = this.#private;
+}

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/reference-in-other-property/output.js

@@ -0,0 +1,25 @@
+var Foo = function Foo() {
+  "use strict";
+
+  babelHelpers.classCallCheck(this, Foo);
+  this.one = babelHelpers.classPrivateFieldLooseBase(this, _private)[_private];
+  Object.defineProperty(this, _two, {
+    writable: true,
+    value: babelHelpers.classPrivateFieldLooseBase(this, _private)[_private]
+  });
+  Object.defineProperty(this, _private, {
+    writable: true,
+    value: 0
+  });
+  this.three = babelHelpers.classPrivateFieldLooseBase(this, _private)[_private];
+  Object.defineProperty(this, _four, {
+    writable: true,
+    value: babelHelpers.classPrivateFieldLooseBase(this, _private)[_private]
+  });
+};
+
+var _two = babelHelpers.classPrivateFieldLooseKey("two");
+
+var _private = babelHelpers.classPrivateFieldLooseKey("private");
+
+var _four = babelHelpers.classPrivateFieldLooseKey("four");

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/static-export/input.mjs

@@ -0,0 +1,7 @@
+export class MyClass {
+  static #property = value;
+}
+
+export default class MyClass2 {
+  static #property = value;
+}

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/static-export/options.json

@@ -0,0 +1,3 @@
+{
+  "throws": "Static class fields are not spec'ed yet."
+}

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/static-export/output.mjs

@@ -0,0 +1,21 @@
+var _property, _property2;
+
+export var MyClass = function MyClass() {
+  babelHelpers.classCallCheck(this, MyClass);
+};
+_property = babelHelpers.classPrivateFieldKey("property");
+Object.defineProperty(MyClass, _property, {
+  writable: true,
+  value: value
+});
+
+var MyClass2 = function MyClass2() {
+  babelHelpers.classCallCheck(this, MyClass2);
+};
+
+_property2 = babelHelpers.classPrivateFieldKey("property");
+Object.defineProperty(MyClass2, _property2, {
+  writable: true,
+  value: value
+});
+export { MyClass2 as default };

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/static-infer-name/input.js

@@ -0,0 +1,3 @@
+var Foo = class {
+  static #num = 0;
+}

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/static-infer-name/options.json

@@ -0,0 +1,3 @@
+{
+  "throws": "Static class fields are not spec'ed yet."
+}

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/static-infer-name/output.js

@@ -0,0 +1,8 @@
+var _num, _class, _temp;
+
+var Foo = (_temp = _class = function Foo() {
+  babelHelpers.classCallCheck(this, Foo);
+}, _num = babelHelpers.classPrivateFieldKey("num"), Object.defineProperty(_class, _num, {
+  writable: true,
+  value: 0
+}), _temp);

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/static-inherited/input.js

@@ -0,0 +1,70 @@
+class Base {
+  static #foo = 1;
+
+  static getThis() {
+    return this.#foo;
+  }
+
+  static updateThis(val) {
+    return this.#foo = val;
+  }
+
+  static getClass() {
+    return Base.#foo;
+  }
+
+  static updateClass(val) {
+    return Base.#foo = val;
+  }
+}
+
+class Sub1 extends Base {
+  static #foo = 2;
+
+  static update(val) {
+    return this.#foo = val;
+  }
+}
+
+class Sub2 extends Base {
+}
+
+expect(Base.getThis()).toBe(1);
+expect(Base.getClass()).toBe(1);
+assert.throws(() => Sub1.getThis());
+expect(Sub1.getClass()).toBe(1);
+assert.throws(() => Sub2.getThis());
+expect(Sub2.getClass()).toBe(1);
+
+expect(Sub1.update(3)).toBe(3);
+expect(Base.getThis()).toBe(1);
+expect(Base.getClass()).toBe(1);
+assert.throws(() => Sub1.getThis());
+expect(Sub1.getClass()).toBe(1);
+assert.throws(() => Sub2.getThis());
+expect(Sub2.getClass()).toBe(1);
+
+expect(Base.updateThis(4)).toBe(4);
+expect(Base.getThis()).toBe(4);
+expect(Base.getClass()).toBe(4);
+assert.throws(() => Sub1.getThis());
+expect(Sub1.getClass()).toBe(4);
+assert.throws(() => Sub2.getThis());
+expect(Sub2.getClass()).toBe(4);
+
+expect(Base.updateClass(5)).toBe(5);
+expect(Base.getThis()).toBe(5);
+expect(Base.getClass()).toBe(5);
+assert.throws(() => Sub1.getThis());
+expect(Sub1.getClass()).toBe(5);
+assert.throws(() => Sub2.getThis());
+expect(Sub2.getClass()).toBe(5);
+
+assert.throws(() => Sub2.updateThis(6));
+expect(Sub2.updateClass(7)).toBe(7);
+expect(Base.getThis()).toBe(7);
+expect(Base.getClass()).toBe(7);
+assert.throws(() => Sub1.getThis());
+expect(Sub1.getClass()).toBe(7);
+assert.throws(() => Sub2.getThis());
+expect(Sub2.getClass()).toBe(7);

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/static-inherited/options.json

@@ -0,0 +1,3 @@
+{
+  "throws": "Static class fields are not spec'ed yet."
+}

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/static-inherited/output.js

@@ -0,0 +1,55 @@
+var _foo, _foo2;
+
+var Base =
+/*#__PURE__*/
+function () {
+  function Base() {
+    babelHelpers.classCallCheck(this, Base);
+  }
+
+  babelHelpers.createClass(Base, null, [{
+    key: "m",
+    value: function m() {
+      return babelHelpers.classPrivateFieldBase(this, _foo)[_foo];
+    }
+  }]);
+  return Base;
+}();
+
+_foo = babelHelpers.classPrivateFieldKey("foo");
+Object.defineProperty(Base, _foo, {
+  writable: true,
+  value: 1
+});
+
+var Sub1 =
+/*#__PURE__*/
+function (_Base) {
+  babelHelpers.inherits(Sub1, _Base);
+
+  function Sub1() {
+    babelHelpers.classCallCheck(this, Sub1);
+    return babelHelpers.possibleConstructorReturn(this, (Sub1.__proto__ || Object.getPrototypeOf(Sub1)).apply(this, arguments));
+  }
+
+  return Sub1;
+}(Base);
+
+_foo2 = babelHelpers.classPrivateFieldKey("foo");
+Object.defineProperty(Sub1, _foo2, {
+  writable: true,
+  value: 2
+});
+
+var Sub2 =
+/*#__PURE__*/
+function (_Base2) {
+  babelHelpers.inherits(Sub2, _Base2);
+
+  function Sub2() {
+    babelHelpers.classCallCheck(this, Sub2);
+    return babelHelpers.possibleConstructorReturn(this, (Sub2.__proto__ || Object.getPrototypeOf(Sub2)).apply(this, arguments));
+  }
+
+  return Sub2;
+}(Base);

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/static-undefined/input.js

@@ -0,0 +1,15 @@
+class Foo {
+  static #bar;
+
+  static test() {
+    return Foo.#bar;
+  }
+
+  test() {
+    return Foo.#bar;
+  }
+}
+
+expect("bar" in Foo).toBe(false)
+expect(Foo.test()).toBe(undefined)
+expect(Foo.test()).toBe(undefined)

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/static-undefined/options.json

@@ -0,0 +1,3 @@
+{
+  "throws": "Static class fields are not spec'ed yet."
+}

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/static-undefined/output.js

@@ -0,0 +1,11 @@
+var _bar;
+
+var Foo = function Foo() {
+  babelHelpers.classCallCheck(this, Foo);
+};
+
+_bar = babelHelpers.classPrivateFieldKey("bar");
+Object.defineProperty(Foo, _bar, {
+  writable: true,
+  value: void 0
+});

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/static/input.js

@@ -0,0 +1,15 @@
+class Foo {
+  static #bar = "foo";
+
+  static test() {
+    return Foo.#bar;
+  }
+
+  test() {
+    return Foo.#bar;
+  }
+}
+
+expect("bar" in Foo).toBe(false)
+expect(Foo.test()).toBe("foo")
+expect(Foo.test()).toBe("foo")

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/static/options.json

@@ -0,0 +1,3 @@
+{
+  "throws": "Static class fields are not spec'ed yet."
+}

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/static/output.js

@@ -0,0 +1,28 @@
+var _bar;
+
+var Foo =
+/*#__PURE__*/
+function () {
+  function Foo() {
+    babelHelpers.classCallCheck(this, Foo);
+  }
+
+  babelHelpers.createClass(Foo, [{
+    key: "test",
+    value: function test() {
+      return babelHelpers.classPrivateFieldBase(Foo, _bar)[_bar];
+    }
+  }], [{
+    key: "test",
+    value: function test() {
+      return babelHelpers.classPrivateFieldBase(Foo, _bar)[_bar];
+    }
+  }]);
+  return Foo;
+}();
+
+_bar = babelHelpers.classPrivateFieldKey("bar");
+Object.defineProperty(Foo, _bar, {
+  writable: true,
+  value: "foo"
+});

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/super-expression/input.js

@@ -0,0 +1,7 @@
+class Foo extends Bar {
+  #bar = "foo";
+
+  constructor() {
+    foo(super());
+  }
+}

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/super-expression/output.js

@@ -0,0 +1,21 @@
+var Foo =
+/*#__PURE__*/
+function (_Bar) {
+  "use strict";
+
+  function Foo() {
+    var _temp, _this;
+
+    babelHelpers.classCallCheck(this, Foo);
+    foo((_temp = _this = babelHelpers.possibleConstructorReturn(this, babelHelpers.getPrototypeOf(Foo).call(this)), Object.defineProperty(babelHelpers.assertThisInitialized(babelHelpers.assertThisInitialized(_this)), _bar, {
+      writable: true,
+      value: "foo"
+    }), _temp));
+    return _this;
+  }
+
+  babelHelpers.inherits(Foo, _Bar);
+  return Foo;
+}(Bar);
+
+var _bar = babelHelpers.classPrivateFieldLooseKey("bar");

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/super-statement/input.js

@@ -0,0 +1,7 @@
+class Foo extends Bar {
+  #bar = "foo";
+
+  constructor() {
+    super();
+  }
+}

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/super-statement/output.js

@@ -0,0 +1,22 @@
+var Foo =
+/*#__PURE__*/
+function (_Bar) {
+  "use strict";
+
+  function Foo() {
+    var _this;
+
+    babelHelpers.classCallCheck(this, Foo);
+    _this = babelHelpers.possibleConstructorReturn(this, babelHelpers.getPrototypeOf(Foo).call(this));
+    Object.defineProperty(babelHelpers.assertThisInitialized(babelHelpers.assertThisInitialized(_this)), _bar, {
+      writable: true,
+      value: "foo"
+    });
+    return _this;
+  }
+
+  babelHelpers.inherits(Foo, _Bar);
+  return Foo;
+}(Bar);
+
+var _bar = babelHelpers.classPrivateFieldLooseKey("bar");

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/update/exec.js

@@ -0,0 +1,27 @@
+class Foo {
+  #foo = 0;
+
+  test(other) {
+    return [
+      this.#foo++,
+      this.#foo,
+      ++this.#foo,
+      this.#foo,
+      other.obj.#foo++,
+      other.obj.#foo,
+      ++other.obj.#foo,
+      other.obj.#foo,
+    ];
+  }
+}
+
+const f = new Foo;
+const results = f.test({ obj: f });
+expect(results[0]).toBe(0);
+expect(results[1]).toBe(1);
+expect(results[2]).toBe(2);
+expect(results[3]).toBe(2);
+expect(results[4]).toBe(2);
+expect(results[5]).toBe(3);
+expect(results[6]).toBe(4);
+expect(results[7]).toBe(4);

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/update/input.js

@@ -0,0 +1,10 @@
+class Foo {
+  #foo = 0;
+
+  test(other) {
+    this.#foo++;
+    ++this.#foo;
+    other.obj.#foo++;
+    ++other.obj.#foo;
+  }
+}

packages/babel-plugin-proposal-class-properties/test/fixtures/private-loose/update/output.js

@@ -0,0 +1,26 @@
+var Foo =
+/*#__PURE__*/
+function () {
+  "use strict";
+
+  function Foo() {
+    babelHelpers.classCallCheck(this, Foo);
+    Object.defineProperty(this, _foo, {
+      writable: true,
+      value: 0
+    });
+  }
+
+  babelHelpers.createClass(Foo, [{
+    key: "test",
+    value: function test(other) {
+      babelHelpers.classPrivateFieldLooseBase(this, _foo)[_foo]++;
+      ++babelHelpers.classPrivateFieldLooseBase(this, _foo)[_foo];
+      babelHelpers.classPrivateFieldLooseBase(other.obj, _foo)[_foo]++;
+      ++babelHelpers.classPrivateFieldLooseBase(other.obj, _foo)[_foo];
+    }
+  }]);
+  return Foo;
+}();
+
+var _foo = babelHelpers.classPrivateFieldLooseKey("foo");

packages/babel-plugin-proposal-class-properties/test/fixtures/private/assignment/input.js

@@ -0,0 +1,10 @@
+class Foo {
+  #foo = 0;
+
+  test(other) {
+    this.#foo += 1;
+    this.#foo = 2;
+    other.obj.#foo += 1;
+    other.obj.#foo = 2;
+  }
+}

packages/babel-plugin-proposal-class-properties/test/fixtures/private/assignment/output.js

@@ -0,0 +1,26 @@
+var Foo =
+/*#__PURE__*/
+function () {
+  "use strict";
+
+  function Foo() {
+    babelHelpers.classCallCheck(this, Foo);
+
+    _foo.set(this, 0);
+  }
+
+  babelHelpers.createClass(Foo, [{
+    key: "test",
+    value: function test(other) {
+      var _other$obj;
+
+      babelHelpers.classPrivateFieldSet(this, _foo, babelHelpers.classPrivateFieldGet(this, _foo) + 1);
+      babelHelpers.classPrivateFieldSet(this, _foo, 2);
+      babelHelpers.classPrivateFieldSet(_other$obj = other.obj, _foo, babelHelpers.classPrivateFieldGet(_other$obj, _foo) + 1);
+      babelHelpers.classPrivateFieldSet(other.obj, _foo, 2);
+    }
+  }]);
+  return Foo;
+}();
+
+var _foo = new WeakMap();

packages/babel-plugin-proposal-class-properties/test/fixtures/private/call/exec.js

@@ -0,0 +1,15 @@
+class Foo {
+  #foo = function() {
+    return this;
+  }
+
+  test(other) {
+    return [this.#foo(), other.#foo()];
+  }
+}
+
+const f = new Foo;
+const o = new Foo;
+const test = f.test(o);
+expect(test[0]).toBe(f);
+expect(test[1]).toBe(o);

packages/babel-plugin-proposal-class-properties/test/fixtures/private/call/input.js

@@ -0,0 +1,10 @@
+class Foo {
+  #foo = function() {
+    return this;
+  }
+
+  test(other) {
+    this.#foo();
+    other.obj.#foo();
+  }
+}

packages/babel-plugin-proposal-class-properties/test/fixtures/private/call/output.js

@@ -0,0 +1,26 @@
+var Foo =
+/*#__PURE__*/
+function () {
+  "use strict";
+
+  function Foo() {
+    babelHelpers.classCallCheck(this, Foo);
+
+    _foo.set(this, function () {
+      return this;
+    });
+  }
+
+  babelHelpers.createClass(Foo, [{
+    key: "test",
+    value: function test(other) {
+      var _other$obj;
+
+      babelHelpers.classPrivateFieldGet(this, _foo).call(this);
+      babelHelpers.classPrivateFieldGet(_other$obj = other.obj, _foo).call(_other$obj);
+    }
+  }]);
+  return Foo;
+}();
+
+var _foo = new WeakMap();

packages/babel-plugin-proposal-class-properties/test/fixtures/private/canonical/exec.js

@@ -0,0 +1,73 @@
+class Point {
+    #x;
+    #y;
+
+    constructor(x = 0, y = 0) {
+        this.#x = +x;
+        this.#y = +y;
+    }
+
+    get x() { return this.#x }
+    set x(value) { this.#x = +value }
+
+    get y() { return this.#y }
+    set y(value) { this.#y = +value }
+
+    equals(p) { return this.#x === p.#x && this.#y === p.#y }
+
+    toString() { return `Point<${ this.#x },${ this.#y }>` }
+
+}
+
+const p1 = new Point(1, 2);
+const p2 = new Point(2, 3);
+const p3 = new Point(1, 2);
+
+expect(p1.x).toBe(1);
+expect(p1.y).toBe(2);
+expect(p2.x).toBe(2);
+expect(p2.y).toBe(3);
+expect(p3.x).toBe(1);
+expect(p3.y).toBe(2);
+
+expect(p1.equals(p1)).toBe(true)
+expect(p1.equals(p2)).toBe(false)
+expect(p1.equals(p3)).toBe(true)
+expect(p2.equals(p1)).toBe(false)
+expect(p2.equals(p2)).toBe(true)
+expect(p2.equals(p3)).toBe(false)
+expect(p3.equals(p1)).toBe(true)
+expect(p3.equals(p2)).toBe(false)
+expect(p3.equals(p3)).toBe(true)
+
+expect(p1.toString()).toBe("Point<1,2>")
+expect(p2.toString()).toBe("Point<2,3>")
+expect(p3.toString()).toBe("Point<1,2>")
+
+p1.x += 1;
+p1.y = 3;
+p2.x -= 1;
+p2.y = 3;
+p3.x = 0;
+p3.y = 0;
+
+expect(p1.x).toBe(2);
+expect(p1.y).toBe(3);
+expect(p2.x).toBe(1);
+expect(p2.y).toBe(3);
+expect(p3.x).toBe(0);
+expect(p3.y).toBe(0);
+
+expect(p1.equals(p1)).toBe(true)
+expect(p1.equals(p2)).toBe(false)
+expect(p1.equals(p3)).toBe(false)
+expect(p2.equals(p1)).toBe(false)
+expect(p2.equals(p2)).toBe(true)
+expect(p2.equals(p3)).toBe(false)
+expect(p3.equals(p1)).toBe(false)
+expect(p3.equals(p2)).toBe(false)
+expect(p3.equals(p3)).toBe(true)
+
+expect(p1.toString()).toBe("Point<2,3>")
+expect(p2.toString()).toBe("Point<1,3>")
+expect(p3.toString()).toBe("Point<0,0>")

packages/babel-plugin-proposal-class-properties/test/fixtures/private/canonical/input.js

@@ -0,0 +1,20 @@
+class Point {
+    #x;
+    #y;
+
+    constructor(x = 0, y = 0) {
+        this.#x = +x;
+        this.#y = +y;
+    }
+
+    get x() { return this.#x }
+    set x(value) { this.#x = +value }
+
+    get y() { return this.#y }
+    set y(value) { this.#y = +value }
+
+    equals(p) { return this.#x === p.#x && this.#y === p.#y }
+
+    toString() { return `Point<${ this.#x },${ this.#y }>` }
+
+}

packages/babel-plugin-proposal-class-properties/test/fixtures/private/canonical/options.json

@@ -0,0 +1,3 @@
+{
+  "minNodeVersion": "6.0.0"
+}

packages/babel-plugin-proposal-class-properties/test/fixtures/private/canonical/output.js

@@ -0,0 +1,49 @@
+var Point =
+/*#__PURE__*/
+function () {
+  "use strict";
+
+  function Point(_x2 = 0, _y2 = 0) {
+    babelHelpers.classCallCheck(this, Point);
+
+    _x.set(this, void 0);
+
+    _y.set(this, void 0);
+
+    babelHelpers.classPrivateFieldSet(this, _x, +_x2);
+    babelHelpers.classPrivateFieldSet(this, _y, +_y2);
+  }
+
+  babelHelpers.createClass(Point, [{
+    key: "equals",
+    value: function equals(p) {
+      return babelHelpers.classPrivateFieldGet(this, _x) === babelHelpers.classPrivateFieldGet(p, _x) && babelHelpers.classPrivateFieldGet(this, _y) === babelHelpers.classPrivateFieldGet(p, _y);
+    }
+  }, {
+    key: "toString",
+    value: function toString() {
+      return `Point<${babelHelpers.classPrivateFieldGet(this, _x)},${babelHelpers.classPrivateFieldGet(this, _y)}>`;
+    }
+  }, {
+    key: "x",
+    get: function () {
+      return babelHelpers.classPrivateFieldGet(this, _x);
+    },
+    set: function (value) {
+      babelHelpers.classPrivateFieldSet(this, _x, +value);
+    }
+  }, {
+    key: "y",
+    get: function () {
+      return babelHelpers.classPrivateFieldGet(this, _y);
+    },
+    set: function (value) {
+      babelHelpers.classPrivateFieldSet(this, _y, +value);
+    }
+  }]);
+  return Point;
+}();
+
+var _x = new WeakMap();
+
+var _y = new WeakMap();

packages/babel-plugin-proposal-class-properties/test/fixtures/private/constructor-collision/exec.js

@@ -0,0 +1,17 @@
+var foo = "bar";
+
+class Foo {
+  #bar = foo;
+
+  constructor() {
+    var foo = "foo";
+  }
+
+  test() {
+    return this.#bar;
+  }
+}
+
+const f = new Foo;
+expect(f.test()).toBe(foo);
+expect("bar" in f).toBe(false);

packages/babel-plugin-proposal-class-properties/test/fixtures/private/constructor-collision/input.js

@@ -0,0 +1,9 @@
+var foo = "bar";
+
+class Foo {
+  #bar = foo;
+
+  constructor() {
+    var foo = "foo";
+  }
+}

packages/babel-plugin-proposal-class-properties/test/fixtures/private/constructor-collision/output.js

@@ -0,0 +1,13 @@
+var foo = "bar";
+
+var Foo = function Foo() {
+  "use strict";
+
+  babelHelpers.classCallCheck(this, Foo);
+
+  _bar.set(this, foo);
+
+  var _foo = "foo";
+};
+
+var _bar = new WeakMap();

packages/babel-plugin-proposal-class-properties/test/fixtures/private/declaration-order/LICENSE

@@ -0,0 +1,28 @@
+The << Software identified by reference to the Ecma Standard* ("Software)">>  is protected by copyright and is being
+made available under the  "BSD License", included below. This Software may be subject to third party rights (rights
+from parties other than Ecma International), including patent rights, and no licenses under such third party rights
+are granted under this license even if the third party concerned is a member of Ecma International.  SEE THE ECMA
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+Copyright (C) 2012-2013 Ecma International
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without modification, are permitted provided that the
+following conditions are met:
+1.   Redistributions of source code must retain the above copyright notice, this list of conditions and the following
+     disclaimer.
+2.   Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the
+     following disclaimer in the documentation and/or other materials provided with the distribution.
+3.   Neither the name of the authors nor Ecma International may be used to endorse or promote products derived from
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packages/babel-plugin-proposal-class-properties/test/fixtures/private/declaration-order/exec.js

@@ -0,0 +1,8 @@
+class C {
+  y = this.#x;
+  #x;
+}
+
+expect(() => {
+  new C();
+}).toThrow();

packages/babel-plugin-proposal-class-properties/test/fixtures/private/declaration-order/input.js

@@ -0,0 +1,8 @@
+class C {
+  y = this.#x;
+  #x;
+}
+
+expect(() => {
+  new C();
+}).toThrow();

packages/babel-plugin-proposal-class-properties/test/fixtures/private/declaration-order/output.js

@@ -0,0 +1,14 @@
+var C = function C() {
+  "use strict";
+
+  babelHelpers.classCallCheck(this, C);
+  babelHelpers.defineProperty(this, "y", babelHelpers.classPrivateFieldGet(this, _x));
+
+  _x.set(this, void 0);
+};
+
+var _x = new WeakMap();
+
+expect(() => {
+  new C();
+}).toThrow();

packages/babel-plugin-proposal-class-properties/test/fixtures/private/derived-multiple-supers/input.js

@@ -0,0 +1,11 @@
+class Foo extends Bar {
+  #bar = "foo";
+
+  constructor() {
+    if (condition) {
+      super();
+    } else {
+      super();
+    }
+  }
+}

packages/babel-plugin-proposal-class-properties/test/fixtures/private/derived-multiple-supers/output.js

@@ -0,0 +1,28 @@
+var Foo =
+/*#__PURE__*/
+function (_Bar) {
+  "use strict";
+
+  function Foo() {
+    var _this;
+
+    babelHelpers.classCallCheck(this, Foo);
+
+    if (condition) {
+      _this = babelHelpers.possibleConstructorReturn(this, babelHelpers.getPrototypeOf(Foo).call(this));
+
+      _bar.set(babelHelpers.assertThisInitialized(babelHelpers.assertThisInitialized(babelHelpers.assertThisInitialized(_this))), "foo");
+    } else {
+      _this = babelHelpers.possibleConstructorReturn(this, babelHelpers.getPrototypeOf(Foo).call(this));
+
+      _bar.set(babelHelpers.assertThisInitialized(babelHelpers.assertThisInitialized(babelHelpers.assertThisInitialized(_this))), "foo");
+    }
+
+    return babelHelpers.possibleConstructorReturn(_this);
+  }
+
+  babelHelpers.inherits(Foo, _Bar);
+  return Foo;
+}(Bar);
+
+var _bar = new WeakMap();

packages/babel-plugin-proposal-class-properties/test/fixtures/private/derived/exec.js

@@ -0,0 +1,22 @@
+class Foo {
+  #prop = "foo";
+
+  foo() {
+    return this.#prop;
+  }
+}
+
+class Bar extends Foo {
+  #prop = "bar";
+
+  bar() {
+    return this.#prop;
+  }
+}
+
+const f = new Foo;
+expect(f.foo()).toBe("foo");
+
+const b = new Bar;
+expect(b.foo()).toBe("foo");
+expect(b.bar()).toBe("bar");

packages/babel-plugin-proposal-class-properties/test/fixtures/private/derived/input.js

@@ -0,0 +1,7 @@
+class Foo {
+  #prop = "foo";
+}
+
+class Bar extends Foo {
+  #prop = "bar";
+}

packages/babel-plugin-proposal-class-properties/test/fixtures/private/derived/output.js

@@ -0,0 +1,27 @@
+var Foo = function Foo() {
+  "use strict";
+
+  babelHelpers.classCallCheck(this, Foo);
+
+  _prop.set(this, "foo");
+};
+
+var _prop = new WeakMap();
+
+var Bar =
+/*#__PURE__*/
+function (_Foo) {
+  "use strict";
+
+  function Bar(...args) {
+    var _temp, _this;
+
+    babelHelpers.classCallCheck(this, Bar);
+    return babelHelpers.possibleConstructorReturn(_this, (_temp = _this = babelHelpers.possibleConstructorReturn(this, babelHelpers.getPrototypeOf(Bar).call(this, ...args)), _prop2.set(babelHelpers.assertThisInitialized(babelHelpers.assertThisInitialized(_this)), "bar"), _temp));
+  }
+
+  babelHelpers.inherits(Bar, _Foo);
+  return Bar;
+}(Foo);
+
+var _prop2 = new WeakMap();

packages/babel-plugin-proposal-class-properties/test/fixtures/private/extracted-this/input.js

@@ -0,0 +1,9 @@
+var foo = "bar";
+
+class Foo {
+  #bar = this;
+  #baz = foo;
+
+  constructor(foo) {
+  }
+}

packages/babel-plugin-proposal-class-properties/test/fixtures/private/extracted-this/output.js

@@ -0,0 +1,15 @@
+var foo = "bar";
+
+var Foo = function Foo(_foo) {
+  "use strict";
+
+  babelHelpers.classCallCheck(this, Foo);
+
+  _bar.set(this, this);
+
+  _baz.set(this, foo);
+};
+
+var _bar = new WeakMap();
+
+var _baz = new WeakMap();