logical-assignment: Do not assign names to anonymous functions

[arku]

Q	A
Fixed Issues?	Fixes #11362
Patch: Bug Fix?	Yes
Major: Breaking Change?	No
Minor: New Feature?	No
Tests Added + Pass?	Yes
Documentation PR Link
Any Dependency Changes?
License	MIT

[Andarist]

A bunch of stuff can be introduced to make the function anonymous, the easiest ones would be:

1. unwrap from array

var _f;

var f;
((_f = f) !== null && _f !== void 0 ? _f : f = [function () {}][0]).name;

2. introduce a helper

function ensureAnonymous(fn) { return fn }
var _f;

var f;
((_f = f) !== null && _f !== void 0 ? _f : f = ensureAnonymous(function () {})).name;

Both of those are valid es5 so I would consider them being better alternatives. I don't think that all current transforms (but I might be wrong) are that much concerned about .name, it's more of a "best effort" from what I remember. So maybe it's not worth doing crazy stuff to cover this? Or maybe a crazy hack could be hidden behind spec: true option?

[jridgewell]

We actually could update the spec to give anonymous closures a name. We don't have it for any of the math assignment operators, because the function just gets coerced into a number. I'll open an issue.

introduce a helper

Using a IIFE sounds good to me. I don't think we need a helper, though, it's not that much code.

[jridgewell]

tc39/proposal-logical-assignment#23 (comment) mentions that we can also use a SequenceExpression to do this:

// input
foo ??= function() {};

// output
foo ?? (foo = (0, function() {}));

[arku]

@jridgewell I have updated my PR with the suggested changes. Do you mind taking another look?

[nicolo-ribaudo]

Thanks!

[nicolo-ribaudo]

Note for reviewers: the "exec" and "transform" tests are in different folders because they have different configs.

[jridgewell]

@babel/babel Any idea what's going on with the tests?

[nicolo-ribaudo]

@JLHwung It is related to exports, maybe you know 🤔

[JLHwung]

Rebased on upstream. The exports error should be fixed in recent releases.

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