Evaluate object and initializer when setting a private method

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

@@ -299,8 +299,12 @@ const privateNameHandlerSpec = {
           value,
         ]);
       }
-      return t.callExpression(file.addHelper("readOnlyError"), [
-        t.stringLiteral(`#${name}`),
+      return t.sequenceExpression([
+        this.receiver(member),
+        value,
+        t.callExpression(file.addHelper("readOnlyError"), [
+          t.stringLiteral(`#${name}`),
+        ]),
       ]);
     }
     return t.callExpression(file.addHelper("classPrivateFieldSet"), [

packages/babel-plugin-proposal-private-methods/test/fixtures/accessors-loose/reassignment/exec.js

@@ -0,0 +1,13 @@
+let counter = 0;
+class Foo {
+  constructor() {
+    this.#privateFieldValue = ++counter;
+  }
+
+  get #privateFieldValue() {
+    return 42;
+  }
+}
+
+expect(() => new Foo).toThrow();
+expect(counter).toBe(1);

packages/babel-plugin-proposal-private-methods/test/fixtures/accessors-loose/reassignment/input.js

@@ -0,0 +1,10 @@
+let counter = 0;
+class Foo {
+  constructor() {
+    this.#privateFieldValue = ++counter;
+  }
+
+  get #privateFieldValue() {
+    return 42;
+  }
+}

packages/babel-plugin-proposal-private-methods/test/fixtures/accessors-loose/reassignment/output.js

@@ -0,0 +1,18 @@
+var counter = 0;
+
+var _privateFieldValue = babelHelpers.classPrivateFieldLooseKey("privateFieldValue");
+
+class Foo {
+  constructor() {
+    Object.defineProperty(this, _privateFieldValue, {
+      get: _get_privateFieldValue,
+      set: void 0
+    });
+    babelHelpers.classPrivateFieldLooseBase(this, _privateFieldValue)[_privateFieldValue] = ++counter;
+  }
+
+}
+
+var _get_privateFieldValue = function () {
+  return 42;
+};

packages/babel-plugin-proposal-private-methods/test/fixtures/accessors/reassignment/exec.js

@@ -0,0 +1,18 @@
+let results = [];
+class Foo {
+  constructor() {
+    this.self.#privateFieldValue = results.push(2);
+  }
+
+  get self() {
+    results.push(1);
+    return this;
+  }
+
+  get #privateFieldValue() {
+    return 42;
+  }
+}
+
+expect(() => new Foo).toThrow(TypeError);
+expect(results).toStrictEqual([1, 2]);

packages/babel-plugin-proposal-private-methods/test/fixtures/accessors/reassignment/input.js

@@ -0,0 +1,15 @@
+let results = [];
+class Foo {
+  constructor() {
+    this.self.#privateFieldValue = results.push(2);
+  }
+
+  get self() {
+    results.push(1);
+    return this;
+  }
+
+  get #privateFieldValue() {
+    return 42;
+  }
+}

packages/babel-plugin-proposal-private-methods/test/fixtures/accessors/reassignment/output.js

@@ -0,0 +1,24 @@
+var results = [];
+
+var _privateFieldValue = new WeakMap();
+
+class Foo {
+  constructor() {
+    _privateFieldValue.set(this, {
+      get: _get_privateFieldValue,
+      set: void 0
+    });
+
+    this.self, results.push(2), babelHelpers.readOnlyError("#privateFieldValue");
+  }
+
+  get self() {
+    results.push(1);
+    return this;
+  }
+
+}
+
+var _get_privateFieldValue = function () {
+  return 42;
+};

packages/babel-plugin-proposal-private-methods/test/fixtures/accessors/set-only-getter/output.js

@@ -14,7 +14,7 @@ class Cl {
       value: 0
     });
 
-    babelHelpers.readOnlyError("#privateFieldValue");
+    this, 1, babelHelpers.readOnlyError("#privateFieldValue");
   }
 
 }

packages/babel-plugin-proposal-private-methods/test/fixtures/private-method-loose/reassignment/exec.js

@@ -0,0 +1,13 @@
+let counter = 0;
+class Foo {
+  constructor() {
+    this.#privateMethod = ++counter;
+  }
+
+  #privateMethod() {
+    return 42;
+  }
+}
+
+expect(() => new Foo).toThrow();
+expect(counter).toBe(1);

packages/babel-plugin-proposal-private-methods/test/fixtures/private-method-loose/reassignment/input.js

@@ -0,0 +1,10 @@
+let counter = 0;
+class Foo {
+  constructor() {
+    this.#privateMethod = ++counter;
+  }
+
+  #privateMethod() {
+    return 42;
+  }
+}

packages/babel-plugin-proposal-private-methods/test/fixtures/private-method-loose/reassignment/output.js

@@ -0,0 +1,17 @@
+var counter = 0;
+
+var _privateMethod = babelHelpers.classPrivateFieldLooseKey("privateMethod");
+
+class Foo {
+  constructor() {
+    Object.defineProperty(this, _privateMethod, {
+      value: _privateMethod2
+    });
+    babelHelpers.classPrivateFieldLooseBase(this, _privateMethod)[_privateMethod] = ++counter;
+  }
+
+}
+
+var _privateMethod2 = function _privateMethod2() {
+  return 42;
+};

packages/babel-plugin-proposal-private-methods/test/fixtures/private-method/read-only/output.js

@@ -6,7 +6,7 @@ class A {
   }
 
   run() {
-    babelHelpers.readOnlyError("#method");
+    this, 2, babelHelpers.readOnlyError("#method");
   }
 
 }

packages/babel-plugin-proposal-private-methods/test/fixtures/private-method/reassignment/exec.js

@@ -0,0 +1,18 @@
+let results = [];
+class Foo {
+  constructor() {
+    this.self.#privateFieldValue = results.push(2);
+  }
+
+  get self() {
+    results.push(1);
+    return this;
+  }
+
+  #privateFieldValue() {
+    return 42;
+  }
+}
+
+expect(() => new Foo).toThrow(TypeError);
+expect(results).toStrictEqual([1, 2]);

packages/babel-plugin-proposal-private-methods/test/fixtures/private-method/reassignment/input.js

@@ -0,0 +1,15 @@
+let results = [];
+class Foo {
+  constructor() {
+    this.self.#privateFieldValue = results.push(2);
+  }
+
+  get self() {
+    results.push(1);
+    return this;
+  }
+
+  #privateFieldValue() {
+    return 42;
+  }
+}

packages/babel-plugin-proposal-private-methods/test/fixtures/private-method/reassignment/output.js

@@ -0,0 +1,21 @@
+var results = [];
+
+var _privateFieldValue = new WeakSet();
+
+class Foo {
+  constructor() {
+    _privateFieldValue.add(this);
+
+    this.self, results.push(2), babelHelpers.readOnlyError("#privateFieldValue");
+  }
+
+  get self() {
+    results.push(1);
+    return this;
+  }
+
+}
+
+var _privateFieldValue2 = function _privateFieldValue2() {
+  return 42;
+};