Avoid transpiling class-properties as they are natively supported

[NullVoxPopuli]

This PR is incomplete -- current status: babel problem

goal: make babel do less:
tested at: https://github.com/NullVoxPopuli/babel-transpilation-tests
current problem: (all in babel, not ember-cli-babel) decorator plugin assumes class-properties plugin is needed (it's not)

This is not intended to be merged, but serves as something for folks to point their package.jsons at when they want to see if they can disable class-property transpilation across their whole app and addons.

hopefully: class property transformation is not required for decorators .

(it used to be required tho).
There is an assertion / error that's added by the decorators plugin tho.

Upon manual removal in the above demo everything still works fine.

Here is the the test:

input

function f(target, key, desc) {
  let oldGet = desc.get
  let oldInit = desc.initializer

  desc.get =() => {
    console.log('called f on ', key);
    return oldInit?.() || oldGet();
  }
}
class A {
  #a = 'hi';

  get #b() {
    return 'hello' + this.#a;
  }

  get c() { return this.#b; }

  @f g;

  @f h = 2;

  i = 3;
}

let a = new A();

console.log({ g: f.g, c: a.c, h: a.h, i: a.i });

output

remove lines which define g and h

"use strict";

var _class, _descriptor, _descriptor2;

function _applyDecoratedDescriptor(target, property, decorators, descriptor, context) { var desc = {}; Object.keys(descriptor).forEach(function (key) { desc[key] = descriptor[key]; }); desc.enumerable = !!desc.enumerable; desc.configurable = !!desc.configurable; if ('value' in desc || desc.initializer) { desc.writable = true; } desc = decorators.slice().reverse().reduce(function (desc, decorator) { return decorator(target, property, desc) || desc; }, desc); if (context && desc.initializer !== void 0) { desc.value = desc.initializer ? desc.initializer.call(context) : void 0; desc.initializer = undefined; } if (desc.initializer === void 0) { Object.defineProperty(target, property, desc); desc = null; } return desc; }

function _initializerWarningHelper(descriptor, context) { throw new Error('Decorating class property failed. Please ensure that ' + 'proposal-class-properties is enabled and runs after the decorators transform.'); }

function f(target, key, desc) {
  let oldGet = desc.get;
  let oldInit = desc.initializer;

  desc.get = () => {
    console.log('called f on ', key);
    return oldInit?.() || oldGet();
  };
}

let A = (_class = class A {
  #a = 'hi';

  get #b() {
    return 'hello' + this.#a;
  }

  get c() {
    return this.#b;
  }

  g = _initializerWarningHelper(_descriptor, this);
  h = _initializerWarningHelper(_descriptor2, this);
  i = 3;
}, (_descriptor = _applyDecoratedDescriptor(_class.prototype, "g", [f], {
  configurable: true,
  enumerable: true,
  writable: true,
  initializer: null
}), _descriptor2 = _applyDecoratedDescriptor(_class.prototype, "h", [f], {
  configurable: true,
  enumerable: true,
  writable: true,
  initializer: function () {
    return 2;
  }
})), _class);
let a = new A();
console.log({
  g: f.g,
  c: a.c,
  h: a.h,
  i: a.i
});

the goal of this effort is the following:

• to reduce the amount of work babel is doing
• to use one babel / ember-cli-babel instance for the whole app tree (the complexity brought by addons compliing themselves with their own ember-cli-babel has been problematic for app-land control).

To do this, a consuming app must have only one ember-cli-babel instance in the whole node_modules graph.

Related issues:

• Error: Decorating class property failed. Please ensure that proposal-class-properties is enabled and runs after the decorators transform. #447
• Is there a way to opt out of ember-cli-babel entirely? #446
• [Bug] browserslist and targets have no effect on the output of the build (potential performance problems as well) #417
• Error: Decorating class property failed. Please ensure that proposal-class-properties is enabled and runs after the decorators transform. #447

[NullVoxPopuli]

This won't be possible. best place we can spend effort is moving to platform-decorators