Add various private field and private method tests

This adds tests for implementation bugs in SpiderMonkey [1], plus
additional tests for implementation bugs in V8 and JSC.

[1] https://bugzilla.mozilla.org/show_bug.cgi?id=1723155

test/language/expressions/in/private-field-in-nested.js

@@ -0,0 +1,27 @@
+// Copyright (C) 2021 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: >
+  Can't nest `in` expressions when the left-hand side is PrivateIdentifier.
+info: |
+  Syntax
+    RelationalExpression[In, Yield, Await]:
+    [...]
+    [+In]PrivateIdentifier in ShiftExpression[?Yield, ?Await]
+esid: sec-relational-operators
+negative:
+  phase: parse
+  type: SyntaxError
+features: [class-fields-private, class-fields-private-in]
+---*/
+
+$DONOTEVALUATE();
+
+class C {
+  #field;
+
+  constructor() {
+    #field in #field in this;
+  }
+}

test/language/expressions/in/private-field-invalid-assignment-reference.js

@@ -0,0 +1,25 @@
+// Copyright (C) 2021 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: >
+  Private identifiers aren't valid simple assignment references.
+info: |
+  Syntax
+    for ( LeftHandSideExpression in Expression ) Statement 
+esid: sec-for-in-and-for-of-statements-static-semantics-early-errors
+negative:
+  phase: parse
+  type: SyntaxError
+features: [class-fields-private, class-fields-private-in]
+---*/
+
+$DONOTEVALUATE();
+
+class C {
+  #field;
+
+  m() {
+    for (#field in []) ;
+  }
+}

test/language/statements/class/elements/get-access-of-missing-private-static-getter.js

@@ -0,0 +1,38 @@
+// Copyright (C) 2021 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: Trying to get a private member without getter throws TypeError
+esid: sec-privatefieldget
+info: |
+  PrivateFieldGet ( P, O )
+    1. Assert: P is a Private Name.
+    2. If O is not an object, throw a TypeError exception.
+    3. If P.[[Kind]] is "field",
+      a. Let entry be PrivateFieldFind(P, O).
+      b. If entry is empty, throw a TypeError exception.
+      c. Return entry.[[PrivateFieldValue]].
+    4. Perform ? PrivateBrandCheck(O, P).
+    5. If P.[[Kind]] is "method",
+      a. Return P.[[Value]].
+    6. Else,
+      a. Assert: P.[[Kind]] is "accessor".
+      b. If P does not have a [[Get]] field, throw a TypeError exception.
+      c. Let getter be P.[[Get]].
+      d. Return ? Call(getter, O).
+features: [class-static-methods-private, class]
+---*/
+
+class C {
+  static set #f(v) {
+    throw new Test262Error();
+  }
+
+  static getAccess() {
+    return this.#f;
+  }
+}
+
+assert.throws(TypeError, function() {
+  C.getAccess();
+}, 'get operation on private accessor without getter should throw TypeError');

test/language/statements/class/elements/private-method-double-initialisation-get-and-set.js

@@ -0,0 +1,35 @@
+// Copyright (C) 2021 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: >
+  Throws TypeError when attempting to install private methods multiple times.
+esid: sec-privatemethodoraccessoradd
+info: |
+  7.3.28 PrivateMethodOrAccessorAdd ( method, O )
+    1. Assert: method.[[Kind]] is either method or accessor.
+    2. Let entry be ! PrivateElementFind(method.[[Key]], O).
+    3. If entry is not empty, throw a TypeError exception.
+    ...
+
+features: [class, class-methods-private]
+---*/
+
+class Base {
+  constructor(o) {
+    return o;
+  }
+}
+
+class C extends Base {
+  get #p() {}
+  set #p(x) {}
+}
+
+var obj = {};
+
+new C(obj);
+
+assert.throws(TypeError, function() {
+  new C(obj);
+});

test/language/statements/class/elements/private-method-double-initialisation-get.js

@@ -0,0 +1,34 @@
+// Copyright (C) 2021 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: >
+  Throws TypeError when attempting to install private methods multiple times.
+esid: sec-privatemethodoraccessoradd
+info: |
+  7.3.28 PrivateMethodOrAccessorAdd ( method, O )
+    1. Assert: method.[[Kind]] is either method or accessor.
+    2. Let entry be ! PrivateElementFind(method.[[Key]], O).
+    3. If entry is not empty, throw a TypeError exception.
+    ...
+
+features: [class, class-methods-private]
+---*/
+
+class Base {
+  constructor(o) {
+    return o;
+  }
+}
+
+class C extends Base {
+  get #p() {}
+}
+
+var obj = {};
+
+new C(obj);
+
+assert.throws(TypeError, function() {
+  new C(obj);
+});

test/language/statements/class/elements/private-method-double-initialisation-set.js

@@ -0,0 +1,34 @@
+// Copyright (C) 2021 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: >
+  Throws TypeError when attempting to install private methods multiple times.
+esid: sec-privatemethodoraccessoradd
+info: |
+  7.3.28 PrivateMethodOrAccessorAdd ( method, O )
+    1. Assert: method.[[Kind]] is either method or accessor.
+    2. Let entry be ! PrivateElementFind(method.[[Key]], O).
+    3. If entry is not empty, throw a TypeError exception.
+    ...
+
+features: [class, class-methods-private]
+---*/
+
+class Base {
+  constructor(o) {
+    return o;
+  }
+}
+
+class C extends Base {
+  set #p(x) {}
+}
+
+var obj = {};
+
+new C(obj);
+
+assert.throws(TypeError, function() {
+  new C(obj);
+});

test/language/statements/class/elements/private-method-double-initialisation.js

@@ -0,0 +1,34 @@
+// Copyright (C) 2021 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: >
+  Throws TypeError when attempting to install private methods multiple times.
+esid: sec-privatemethodoraccessoradd
+info: |
+  7.3.28 PrivateMethodOrAccessorAdd ( method, O )
+    1. Assert: method.[[Kind]] is either method or accessor.
+    2. Let entry be ! PrivateElementFind(method.[[Key]], O).
+    3. If entry is not empty, throw a TypeError exception.
+    ...
+
+features: [class, class-methods-private]
+---*/
+
+class Base {
+  constructor(o) {
+    return o;
+  }
+}
+
+class C extends Base {
+  #m() {}
+}
+
+var obj = {};
+
+new C(obj);
+
+assert.throws(TypeError, function() {
+  new C(obj);
+});

test/language/statements/class/elements/private-method-not-writable.js

@@ -0,0 +1,33 @@
+// Copyright (C) 2021 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: >
+  Throws TypeError when attempting to overwrite a private method.
+esid: sec-privateset
+info: |
+  7.3.30 PrivateSet ( P, O, value )
+  1. Let entry be ! PrivateElementFind(P, O).
+  2. If entry is empty, throw a TypeError exception.
+  3. If entry.[[Kind]] is field, then
+    ...
+  4. Else if entry.[[Kind]] is method, then
+    a. Throw a TypeError exception.
+  5. ...
+
+features: [class, class-methods-private]
+---*/
+
+class C {
+  #m() {}
+
+  assign() {
+    this.#m = 0;
+  }
+}
+
+var obj = new C();
+
+assert.throws(TypeError, function() {
+  obj.assign();
+});

test/language/statements/class/elements/private-static-method-not-writable.js

@@ -0,0 +1,31 @@
+// Copyright (C) 2021 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: >
+  Throws TypeError when attempting to overwrite a private static method.
+esid: sec-privateset
+info: |
+  7.3.30 PrivateSet ( P, O, value )
+  1. Let entry be ! PrivateElementFind(P, O).
+  2. If entry is empty, throw a TypeError exception.
+  3. If entry.[[Kind]] is field, then
+    ...
+  4. Else if entry.[[Kind]] is method, then
+    a. Throw a TypeError exception.
+  5. ...
+
+features: [class, class-static-methods-private]
+---*/
+
+class C {
+  static #m() {}
+
+  static assign() {
+    this.#m = 0;
+  }
+}
+
+assert.throws(TypeError, function() {
+  C.assign();
+});

test/language/statements/class/elements/privatefieldset-evaluation-order-1.js

@@ -0,0 +1,43 @@
+// Copyright (C) 2021 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: >
+  Evaluation order when resolving private fields.
+esid: sec-runtime-semantics-keyeddestructuringassignmentevaluation
+info: |
+  13.15.5.6 Runtime Semantics: KeyedDestructuringAssignmentEvaluation
+    1. If DestructuringAssignmentTarget is neither an ObjectLiteral nor an ArrayLiteral, then
+      a. Let lref be the result of evaluating DestructuringAssignmentTarget.
+      b. ReturnIfAbrupt(lref).
+  2. ...
+
+  9.1.1.3.4 GetThisBinding ( )
+    1. Assert: envRec.[[ThisBindingStatus]] is not lexical.
+    2. If envRec.[[ThisBindingStatus]] is uninitialized, throw a ReferenceError exception.
+    3. ...
+
+features: [class, class-fields-private]
+---*/
+
+class C extends class {} {
+  #field;
+
+  constructor() {
+    var init = () => super();
+
+    var object = {
+      get a() {
+        init();
+      }
+    };
+
+    // Accessing |this| should throw a ReferenceError before there's an attempt
+    // to invoke the getter.
+    ({a: this.#field} = object);
+  }
+}
+
+assert.throws(ReferenceError, function() {
+  new C();
+});

test/language/statements/class/elements/privatefieldset-evaluation-order-2.js

@@ -0,0 +1,36 @@
+// Copyright (C) 2021 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: >
+  Evaluation order when resolving private fields.
+esid: sec-runtime-semantics-keyeddestructuringassignmentevaluation
+info: |
+  13.15.5.6 Runtime Semantics: KeyedDestructuringAssignmentEvaluation
+    1. If DestructuringAssignmentTarget is neither an ObjectLiteral nor an ArrayLiteral, then
+      a. Let lref be the result of evaluating DestructuringAssignmentTarget.
+      b. ReturnIfAbrupt(lref).
+  2. Let v be ? GetV(value, propertyName).
+  3. ...
+
+features: [class, class-fields-private]
+---*/
+
+class C {
+  #field;
+
+  m() {
+    var object = {
+      get a() {
+        throw new Test262Error();
+      }
+    };
+
+    // The getter is executed before the check if the private field is present.
+    ({a: this.#field} = object);
+  }
+}
+
+assert.throws(Test262Error, function() {
+  C.prototype.m.call({});
+});

test/language/statements/class/elements/privatefieldset-evaluation-order-3.js

@@ -0,0 +1,45 @@
+// Copyright (C) 2021 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: >
+  Evaluation order when resolving private fields.
+esid: sec-runtime-semantics-keyeddestructuringassignmentevaluation
+info: |
+  13.15.5.6 Runtime Semantics: KeyedDestructuringAssignmentEvaluation
+    1. If DestructuringAssignmentTarget is neither an ObjectLiteral nor an ArrayLiteral, then
+      a. Let lref be the result of evaluating DestructuringAssignmentTarget.
+      b. ReturnIfAbrupt(lref).
+  2. Let v be ? GetV(value, propertyName).
+  3. ...
+
+features: [class, class-fields-private]
+---*/
+
+class Base {
+  constructor(o) {
+    return o;
+  }
+}
+
+class C extends Base {
+  #field;
+
+  m() {
+    var init = () => new C(this);
+
+    var object = {
+      get a() {
+        init();
+
+        return "pass";
+      }
+    };
+
+    ({a: this.#field} = object);
+
+    assert.sameValue(this.#field, "pass");
+  }
+}
+
+C.prototype.m.call({});

test/language/statements/class/elements/privatefieldset-typeerror-10.js

@@ -0,0 +1,45 @@
+// Copyright (C) 2021 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: >
+  TypeError when setting private field not in `this`'s [[PrivateFieldValues]]
+esid: sec-putvalue
+info: |
+  PutValue ( V, W )
+    ...
+    6. Else if IsPropertyReference(V), then
+      ...
+      b. If IsPrivateReference(V), then
+        i. Let env be the running execution context's PrivateNameEnvironment.
+        ii. Let field be ? ResolveBinding(GetReferencedName(V), env).
+        iii. Assert: field is a Private Name.
+        iv. Perform ? PrivateFieldSet(field, base, W).
+
+  PrivateFieldSet (P, O, value )
+    1. Assert: P is a Private Name value.
+    2. If O is not an object, throw a TypeError exception.
+    3. Let entry be PrivateFieldFind(P, O).
+    4. If entry is empty, throw a TypeError exception.
+
+  PrivateFieldFind (P, O)
+    1. Assert: P is a Private Name value.
+    2. Assert: O is an object with a [[PrivateFieldValues]] internal slot.
+    3. For each element entry in O.[[PrivateFieldValues]],
+      a. If entry.[[PrivateName]] is P, return entry.
+    4. Return empty.
+
+features: [class, class-fields-private]
+---*/
+
+class C {
+  #field;
+
+  m() {
+    [...this.#field] = [];
+  }
+}
+
+assert.throws(TypeError, function() {
+  C.prototype.m.call({});
+});

test/language/statements/class/elements/privatefieldset-typeerror-11.js

@@ -0,0 +1,45 @@
+// Copyright (C) 2021 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: >
+  TypeError when setting private field not in `this`'s [[PrivateFieldValues]]
+esid: sec-putvalue
+info: |
+  PutValue ( V, W )
+    ...
+    6. Else if IsPropertyReference(V), then
+      ...
+      b. If IsPrivateReference(V), then
+        i. Let env be the running execution context's PrivateNameEnvironment.
+        ii. Let field be ? ResolveBinding(GetReferencedName(V), env).
+        iii. Assert: field is a Private Name.
+        iv. Perform ? PrivateFieldSet(field, base, W).
+
+  PrivateFieldSet (P, O, value )
+    1. Assert: P is a Private Name value.
+    2. If O is not an object, throw a TypeError exception.
+    3. Let entry be PrivateFieldFind(P, O).
+    4. If entry is empty, throw a TypeError exception.
+
+  PrivateFieldFind (P, O)
+    1. Assert: P is a Private Name value.
+    2. Assert: O is an object with a [[PrivateFieldValues]] internal slot.
+    3. For each element entry in O.[[PrivateFieldValues]],
+      a. If entry.[[PrivateName]] is P, return entry.
+    4. Return empty.
+
+features: [class, class-fields-private]
+---*/
+
+class C {
+  #field;
+
+  m() {
+    ({...this.#field} = {});
+  }
+}
+
+assert.throws(TypeError, function() {
+  C.prototype.m.call({});
+});

test/language/statements/class/elements/privatefieldset-typeerror-6.js

@@ -0,0 +1,45 @@
+// Copyright (C) 2021 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: >
+  TypeError when setting private field not in `this`'s [[PrivateFieldValues]]
+esid: sec-putvalue
+info: |
+  PutValue ( V, W )
+    ...
+    6. Else if IsPropertyReference(V), then
+      ...
+      b. If IsPrivateReference(V), then
+        i. Let env be the running execution context's PrivateNameEnvironment.
+        ii. Let field be ? ResolveBinding(GetReferencedName(V), env).
+        iii. Assert: field is a Private Name.
+        iv. Perform ? PrivateFieldSet(field, base, W).
+
+  PrivateFieldSet (P, O, value )
+    1. Assert: P is a Private Name value.
+    2. If O is not an object, throw a TypeError exception.
+    3. Let entry be PrivateFieldFind(P, O).
+    4. If entry is empty, throw a TypeError exception.
+
+  PrivateFieldFind (P, O)
+    1. Assert: P is a Private Name value.
+    2. Assert: O is an object with a [[PrivateFieldValues]] internal slot.
+    3. For each element entry in O.[[PrivateFieldValues]],
+      a. If entry.[[PrivateName]] is P, return entry.
+    4. Return empty.
+
+features: [class, class-fields-private]
+---*/
+
+class C {
+  #field;
+
+  m() {
+    for (this.#field of [1]) ;
+  }
+}
+
+assert.throws(TypeError, function() {
+  C.prototype.m.call({});
+});

test/language/statements/class/elements/privatefieldset-typeerror-7.js

@@ -0,0 +1,45 @@
+// Copyright (C) 2021 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: >
+  TypeError when setting private field not in `this`'s [[PrivateFieldValues]]
+esid: sec-putvalue
+info: |
+  PutValue ( V, W )
+    ...
+    6. Else if IsPropertyReference(V), then
+      ...
+      b. If IsPrivateReference(V), then
+        i. Let env be the running execution context's PrivateNameEnvironment.
+        ii. Let field be ? ResolveBinding(GetReferencedName(V), env).
+        iii. Assert: field is a Private Name.
+        iv. Perform ? PrivateFieldSet(field, base, W).
+
+  PrivateFieldSet (P, O, value )
+    1. Assert: P is a Private Name value.
+    2. If O is not an object, throw a TypeError exception.
+    3. Let entry be PrivateFieldFind(P, O).
+    4. If entry is empty, throw a TypeError exception.
+
+  PrivateFieldFind (P, O)
+    1. Assert: P is a Private Name value.
+    2. Assert: O is an object with a [[PrivateFieldValues]] internal slot.
+    3. For each element entry in O.[[PrivateFieldValues]],
+      a. If entry.[[PrivateName]] is P, return entry.
+    4. Return empty.
+
+features: [class, class-fields-private]
+---*/
+
+class C {
+  #field;
+
+  m() {
+    for (this.#field in {a: 0}) ;
+  }
+}
+
+assert.throws(TypeError, function() {
+  C.prototype.m.call({});
+});

test/language/statements/class/elements/privatefieldset-typeerror-8.js

@@ -0,0 +1,45 @@
+// Copyright (C) 2021 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: >
+  TypeError when setting private field not in `this`'s [[PrivateFieldValues]]
+esid: sec-putvalue
+info: |
+  PutValue ( V, W )
+    ...
+    6. Else if IsPropertyReference(V), then
+      ...
+      b. If IsPrivateReference(V), then
+        i. Let env be the running execution context's PrivateNameEnvironment.
+        ii. Let field be ? ResolveBinding(GetReferencedName(V), env).
+        iii. Assert: field is a Private Name.
+        iv. Perform ? PrivateFieldSet(field, base, W).
+
+  PrivateFieldSet (P, O, value )
+    1. Assert: P is a Private Name value.
+    2. If O is not an object, throw a TypeError exception.
+    3. Let entry be PrivateFieldFind(P, O).
+    4. If entry is empty, throw a TypeError exception.
+
+  PrivateFieldFind (P, O)
+    1. Assert: P is a Private Name value.
+    2. Assert: O is an object with a [[PrivateFieldValues]] internal slot.
+    3. For each element entry in O.[[PrivateFieldValues]],
+      a. If entry.[[PrivateName]] is P, return entry.
+    4. Return empty.
+
+features: [class, class-fields-private]
+---*/
+
+class C {
+  #field;
+
+  m() {
+    [this.#field] = [1];
+  }
+}
+
+assert.throws(TypeError, function() {
+  C.prototype.m.call({});
+});

test/language/statements/class/elements/privatefieldset-typeerror-9.js

@@ -0,0 +1,45 @@
+// Copyright (C) 2021 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: >
+  TypeError when setting private field not in `this`'s [[PrivateFieldValues]]
+esid: sec-putvalue
+info: |
+  PutValue ( V, W )
+    ...
+    6. Else if IsPropertyReference(V), then
+      ...
+      b. If IsPrivateReference(V), then
+        i. Let env be the running execution context's PrivateNameEnvironment.
+        ii. Let field be ? ResolveBinding(GetReferencedName(V), env).
+        iii. Assert: field is a Private Name.
+        iv. Perform ? PrivateFieldSet(field, base, W).
+
+  PrivateFieldSet (P, O, value )
+    1. Assert: P is a Private Name value.
+    2. If O is not an object, throw a TypeError exception.
+    3. Let entry be PrivateFieldFind(P, O).
+    4. If entry is empty, throw a TypeError exception.
+
+  PrivateFieldFind (P, O)
+    1. Assert: P is a Private Name value.
+    2. Assert: O is an object with a [[PrivateFieldValues]] internal slot.
+    3. For each element entry in O.[[PrivateFieldValues]],
+      a. If entry.[[PrivateName]] is P, return entry.
+    4. Return empty.
+
+features: [class, class-fields-private]
+---*/
+
+class C {
+  #field;
+
+  m() {
+    ({a: this.#field} = {a: 0});
+  }
+}
+
+assert.throws(TypeError, function() {
+  C.prototype.m.call({});
+});

test/language/statements/class/elements/set-access-of-missing-private-static-setter.js

@@ -0,0 +1,39 @@
+// Copyright (C) 2021 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: Trying to set a private member without setter throws TypeError
+esid: sec-privatefieldset
+info: |
+  PrivateFieldSet ( P, O, value )
+    1. Assert: P is a Private Name.
+    2. If O is not an object, throw a TypeError exception.
+    3. If P.[[Kind]] is "field",
+      a. Let entry be PrivateFieldFind(P, O).
+      b. If entry is empty, throw a TypeError exception.
+      c. Set entry.[[PrivateFieldValue]] to value.
+      d. Return.
+    4. If P.[[Kind]] is "method", throw a TypeError exception.
+    5. Else,
+      a. Assert: P.[[Kind]] is "accessor".
+      b. If O.[[PrivateFieldBrands]] does not contain P.[[Brand]], throw a TypeError exception.
+      c. If P does not have a [[Set]] field, throw a TypeError exception.
+      d. Let setter be P.[[Set]].
+      e. Perform ? Call(setter, O, value).
+      f. Return.
+features: [class-static-methods-private, class]
+---*/
+
+class C {
+  static get #f() {
+    throw new Test262Error();
+  }
+
+  static setAccess() {
+    this.#f = 'Test262';
+  }
+}
+
+assert.throws(TypeError, function() {
+  C.setAccess();
+}, 'set operation on private accessor without setter should throw TypeError');