Update babel submodule for conformance tests to latest HEAD.
The test fixtures include a new one for a bug fix which @branchseer
intends to also apply to Oxc - https://github.com/babel/babel/pull/17050
(see #8342).
Some of Babel's exec tests contain a return statement at top level, in order to return a Promise.
e.g. ad572fd1a1/packages/babel-plugin-transform-private-methods/test/fixtures/private-method-loose/async/exec.js
These test files could not be parsed due to illegal position of `return`, and the tests were silently excluded.
This PR:
1. Includes those tests by passing `allow_return_outside_function: true` option to parser for exec tests.
2. Includes a "transform error" message in snapshot for any exec tests which produce errors in parser/transformer.
This PR supports transforming private `getter` or `setter` methods, and the output is a little different from Babel's output, For example:
Input:
```js
class Cls {
#prop = 0;
get #accessor() {
return this.#prop;
}
set #accessor(v) {
console.log(arguments);
this.#prop = v;
}
constructor() {
console.log(this.#accessor)
[this.#accessor] = [1];
}
}
```
[Babel's output](https://babeljs.io/repl#?browsers=defaults%2C%20not%20ie%2011%2C%20not%20ie_mob%2011&build=&builtIns=false&corejs=3.21&spec=false&loose=false&code_lz=MYGwhgzhAEDCIwN4ChrQMQAcBOB7T0AvNAAwDcyq0A5gKYAuGYwwtUu2AFAJTQpppsDAK7YAdtHoALAJYQAdFjyYKaAL5UIDJizYQOnAG69-A4LjH6QteSFzVOYbNWEBbWmPoRuqgdLmKOPhE0Ia-GlTmlvTYwsD0BiZUaFFWNnYO_grozKzs2NzJ0ADaWYq5ehwAuiHFAIxV4cgaQA&debug=false&forceAllTransforms=false&modules=false&shippedProposals=false&evaluate=false&fileSize=false&timeTravel=false&sourceType=script&lineWrap=true&presets=&prettier=false&targets=&version=7.26.4&externalPlugins=%40babel%2Fplugin-transform-class-properties%407.25.9%2C%40babel%2Fplugin-transform-private-methods%407.25.9%2C%40babel%2Fplugin-external-helpers%407.25.9&assumptions=%7B%7D):
```js
var _prop = new WeakMap();
var _Cls_brand = new WeakSet();
class Cls {
constructor() {
babelHelpers.classPrivateMethodInitSpec(this, _Cls_brand);
babelHelpers.classPrivateFieldInitSpec(this, _prop, 0);
console.log(babelHelpers.classPrivateGetter(_Cls_brand, this, _get_accessor));
[babelHelpers.classPrivateGetter(_Cls_brand, this, _get_accessor)] = [1];
}
}
function _get_accessor(_this) {
return babelHelpers.classPrivateFieldGet(_prop, _this);
}
function _set_accessor(_this2, v) {
var _arguments = [].slice.call(arguments, 1);
console.log(_arguments);
babelHelpers.classPrivateFieldSet(_prop, _this2, v);
}
```
Oxc's output:
```js
var _prop = new WeakMap();
var _Cls_brand = new WeakSet();
class Cls {
constructor() {
babelHelpers.classPrivateMethodInitSpec(this, _Cls_brand);
babelHelpers.classPrivateFieldInitSpec(this, _prop, 0);
console.log(_get_accessor.call(babelHelpers.assertClassBrand(_Cls_brand, this)));
[babelHelpers.toSetter(_set_accessor.bind(babelHelpers.assertClassBrand(_Cls_brand, this)), [])._] = [1];
}
}
function _get_accessor() {
return babelHelpers.classPrivateFieldGet2(_prop, this);
}
function _set_accessor(v) {
console.log(arguments);
babelHelpers.classPrivateFieldSet2(_prop, this, v);
}
```
### Main difference
```diff
// Babel
+ console.log(babelHelpers.classPrivateGetter(_Cls_brand, this, _get_accessor));
+ [babelHelpers.classPrivateGetter(_Cls_brand, this, _get_accessor)] = [1];
+ function _get_accessor(_this) {
+ return babelHelpers.classPrivateFieldGet(_prop, _this);
+ }
+ function _set_accessor(_this2, v) {
+ var _arguments = [].slice.call(arguments, 1);
+ console.log(_arguments);
+ babelHelpers.classPrivateFieldSet(_prop, _this2, v);
+ }
// Oxc
- console.log(_get_accessor.call(babelHelpers.assertClassBrand(_Cls_brand, this)));- -
- [babelHelpers.toSetter(_set_accessor.bind(babelHelpers.assertClassBrand(_Cls_brand, this)), [])._] = [1];
- function _get_accessor() {
- return babelHelpers.classPrivateFieldGet2(_prop, this);
- }
- function _set_accessor(v) {
- console.log(arguments);
- babelHelpers.classPrivateFieldSet2(_prop, this, v);
- }
```
From the main differences, we can see that Babel handles `getter` and `setter` methods using `classPrivateGetter` and `classPrivateSetter` helper functions, which causes all use `this` and `arguments` needs to rewrite to use a temp var instead in `getter` and `setter` methods. This is unnecessary and is not an efficient transformation for us.
Instead, I adapt binding a `this` instead of passing in `this`, this way we don't need to rewrite anything. We can't control the `helper` library for now, so I just transformed the AST to bind `this`, in the future, we can create a helper function to do the same thing.
All private methods will be moved out of class, so we need to transform all `super` expressions in private methods and transform identifiers that refer to class binding.
Large re-architecting of class properties transform. Split transform into 3 phases:
1. Transform instance properties when entering class.
2. Transform private fields during traversal of class body.
3. Transform static properties and static blocks when exiting class.
This ensures that code which has to be moved outside of the class (static property initializers, static blocks, computed keys) can get transformed by other transforms before they're moved out.
Also fixes a problem where we previously registered private properties too early - on entering the class, rather than the class *body*, so private fields in `extends` clause of a nested class were misinterpretted.
Instance property initializers are moved into constructor. If symbols they reference are shadowed within constructor, rename those symbols.
Input:
```js
class C {
prop = foo();
constructor(foo) {
console.log(foo);
}
}
```
Output:
```js
class C {
constructor(_foo) { // <-- renamed
this.prop = foo(); // <-- moved into constructor
console.log(_foo); // <-- renamed
}
}
```
This PR support for transforming `super.prop` to `babelHelpers.superPropGet(_B, "prop", _B)`
Input:
```js
class A {
static prop = 1;
}
class B extends A {
static prop = 2;
static propA = super.prop;
static getPropA = () => super.prop;
}
```
Output:
```js
var _B;
class A {}
babelHelpers.defineProperty(A, "prop", 1);
class B extends A {}
_B = B;
babelHelpers.defineProperty(B, "prop", 2);
babelHelpers.defineProperty(B, "propA", babelHelpers.superPropGet(_B, "prop", _B));
babelHelpers.defineProperty(B, "getPropA", () => babelHelpers.superPropGet(_B, "prop", _B));
```
Support `private_fields_as_properties` assumption in class properties transform. This assumption is also enabled by the transform's `loose` option.
Optional chain (e.g. `this?.#prop`) is not yet implemented, but all other usages of private fields are supported. We'll handle optional chain in a follow-on PR.
Override some transform conformance test fixtures for class properties transform, where:
* Our output differs from Babel in cosmetic manner only.
* Our transform intentionally works differently from Babel.
* Babel's fixtures enable arrow functions transform, which malfunctions in our implementation. But we're not trying to test arrow functions transform here, so disable it.
`JsonReporter` which the custom test reporter introduced in #7715 uses does not provide error message in `message` prop, where cause of failure is failing assertions. So tests failing due to failing assertions were omitted from snapshot. Include them.
Also add count of passing tests at top of the snapshot.
Fully support transforming ChainExpression in class properties. Our implementation has some differences in execution order compared to Babel, but we have passed all execution-related tests.
Similar to #7516. Fix class properties transform to replace references to class name in static prop initializers with temp var.
Input:
```js
class C {
static getSelf = () => C;
}
const C2 = C;
C = 123;
assert(C2.getSelf() === C);
```
Output:
```js
var _C;
class C {}
_C = C;
_defineProperty(C, "getSelf", () => _C);
const C2 = C;
C = 123;
assert(C2.getSelf() === C);
```
Previously, temp var wasn't used so code was `_defineProperty(C, "getSelf", () => C);`. `C` is altered later by `C = 123`, so `C2.getSelf()` returned `123`, instead of reference to the class.
Fix class properties transform to create a temp var for class when it's required.
Input:
```js
class C {
static getSelf = () => this;
}
const C2 = C;
C = 123;
assert(C2.getSelf() === C);
```
Output:
```js
var _C;
class C {}
_C = C;
_defineProperty(C, "getSelf", () => _C);
const C2 = C;
C = 123;
assert(C2.getSelf() === C);
```
Previously, temp var wasn't used so code was `_defineProperty(C, "getSelf", () => C);`. `C` is altered later by `C = 123`, so `C2.getSelf()` returned `123`, instead of reference to the class.
The logic around when a temp var is required and when it's not, and when/where it's referenced is ridiculously complicated. So add some debug assert mechanisms to double-check the logic.
Transform private property accesses in static prop initializers. e.g.:
Input:
```js
class C {
static #x = 123;
static y = this.#x;
}
```
Transformed:
```js
class C {}
var _x = { _: 123 };
babelHelpers.defineProperty(C, "y", babelHelpers.assertClassBrand(C, C, _x)._);
```
`this.#x` has been transformed to `babelHelpers.assertClassBrand(C, C, _x)._`.
Add class properties transform.
Implementation is incomplete. Notable missing parts:
* Scopes are not updated where property initializers move from class body into class constructor / `_super` function.
* Does not handle binding shadowing problems when property initializers move from class body into class constructor.
* `this` and references to class name in static property initializers need to be transformed to point to a temp var.
* Not all usages of private properties are supported (see below).
* Code which is moved to outside of class body is not transformed by other transforms for class declarations (works OK for class expressions). This includes static property initializers, static blocks, and computed property/method keys.
* Only basic checks for whether computed property/method keys may have side effects.
* Numerous other small issues noted in TODO comments through the code.
### Private properties
Currently does not handle the following usages of private properties:
```js
class Class {
#prop;
static #static;
method() {
object?.#prop;
object?.#prop();
[object.#prop] = [1];
({x: object.#prop} = {x: 1});
object.#prop`xyz`;
object?.#static;
object?.#static();
[object.#static] = [1];
({x: object.#static} = {x: 1});
object.#static`xyz`;
}
}
```
Part of https://github.com/oxc-project/oxc/pull/7074
In async-to-generator and async-generator-functions plugins, we may need to transform the async arrow function to a regular generator function, now we can reuse the ability of the ArrowFunction plugin by enabling `ArrowFunctionConverter`.
I will fix semantic errors in the follow-up PR
Passed 15/19 tests. The remaining 4 failed tests related to `this` expression, the problem same as I mentioned in #6658. I will fix them in follow-up PRs.
