awkward structure in mjs build

[tzvetelin-vassilev]

mjs module looks like:

var Module = (() => {
	var _scriptDir = import.meta.url;

	return (
		async function(Module = {})  {
			var Module = typeof Module != "undefined" ? Module : {};

			// module stuff
		}
	);
})();

export default Module;

There are a few problems with this:

• Safari doesn't understands this and I truly believe the cause is a Safari bug (tested under Safari 16.4 MacOS / iOS)
• Default argument value assumes that argument is defined
• Hoisting doesn't work here, es module provides module scope

You could really name things better. The first Module actually is a factory that generates a Module, the second one is Module closure and the third one is the Module, which is the factory result.

[tzvetelin-vassilev]

I have posted the problem to webkit. You can find it here:

https://bugs.webkit.org/show_bug.cgi?id=255396

but Safari developers are refusing to solve the problem and they have their arguments.

[kleisauke]

The Safari issue is a duplicate of #18357, which was erroneously reintroduced with PR #18551.

The underlying Webkit issue is tracked at https://bugs.webkit.org/show_bug.cgi?id=223533.

[tzvetelin-vassilev]

Thanks for the bug reference. For last 25 months the issue status is still NEW. Probably Safari developers will never fix this. I suggest to remove the following line:

var Module = typeof Module != "undefined" ? Module : {};

in mjs build and everything will work fine.

[sbc100]

Yes, that line looks completely redundant at best.

And yes I agree the way do do modularization probably needs to work for be more readable/intuitive. I've been trying to find ways to refactor it and clean its still ongoing.

[sbc100]

BTW I think #19656 will go a small way towards improving this.

[sbc100]

A few other recent changes that have made things better here: #20962 #20961