fix: push newClass only when class is decorated

[JLHwung]

Q	A
Fixed Issues?	Fixes #14242 (comment)
Patch: Bug Fix?	Y
Major: Breaking Change?
Minor: New Feature?
Tests Added + Pass?	Yes
Documentation PR Link
Any Dependency Changes?
License	MIT

Before this PR we always push newClass to the return of applyDecs but did not provide such bindings at the transformer when the class is not decorated. This PR resolves this issue.

[JLHwung]

The original test case is renamed to *-with-initializers/exec.js. They are replaced by a simpler test without initializers, which exactly catches this bug.

[babel-bot]

Build successful! You can test your changes in the REPL here: https://babeljs.io/repl/build/51410/

[JLHwung]

The guard is removed because the transformer always provides an array literal for memberDecs.

[JLHwung]

A dub initializer should be pushed when the member decorators do not introduce initializers, which can only be known at runtime.

[JLHwung]

Same for classDecs.

[nicolo-ribaudo]

cc @pzuraq if you have time to review!

[wvq]

I'm sorry, after some test, It's still have problem, Maybe this plugin need more testcase.

This merge fixed my comment on #14242 , But class decorator and method decorator Cannot exist at the same time.

function logged(value, { kind, name }) {
  if (kind === 'method') {
    return function () {}
  }
  return value
}

```javascript

@logged
class C {
  @logged m(arg) {}
}

TypeError: _initClass is not a function

[JLHwung]

@wvq Turns out the helpers-generated is out-of-dated, I am surprised that the test is still passing. I will open a new PR soon.

[nicolo-ribaudo]

We should also make CI fail when that happens. The tests aren't failing because make bootstrap regenerates the helpers.

[wvq]

:( still have problem with the generated source.
And I found a new bug with this merge.

Function applyMemberDecs always push two function to ret at least,
https://github.com/babel/babel/blame/4f80f5c4171bcdcf1c6a41d0234bb167bd27e0e7/packages/babel-helpers/src/helpers/applyDecs.js#L494-L515

but staticInitLocal is optional push https://github.com/babel/babel/blame/4f80f5c4171bcdcf1c6a41d0234bb167bd27e0e7/packages/babel-plugin-proposal-decorators/src/transformer-2021-12.ts#L824-L827

so, with a method decorator, It may compile to:

[_initProto, _Todo, _initClass] = _applyDecs(this, [[log, 2, 'hello']], [log])

But there always have two function, It need to be:

[_initProto, _initStatic, _Todo, _initClass] = _applyDecs(this, [[log, 2, "hello"]], [log]);

Why not use an object with clear keys (or a fixed size array) instead of dynamic arrays，
it's much more reliable.

[JLHwung]

@wvq I believe it has been fixed in #14335, could you try that merge instead?

Why not use an object with clear keys (or a fixed size array) instead of dynamic arrays

Array destructuring is indeed harder to maintain than object keys, however, it yields to smaller code after minification, since object keys is harder to mangle properly and thus not enabled by default in uglifyJS/terser.