Editorial: more obvious syntax for macros

[bakkot]

Macros like ReturnIfAbrupt and IfAbruptRejectPromise are called like AOs, but they can have effects on the control flow and aliases in caller, which is confusing.

We should make it more obvious at the callsites that these are not normal AOs.

(I don't think this extends to the ? and ! macros, since uses of those symbols do not look like a normal AO invocation.)

[ljharb]

Perhaps we could find all non-symbolic uses of ReturnIfAbrupt, and find a way to replace it with ?/!?

Then, perhaps we could come up with a symbolic form of IfAbruptRejectPromise?

[bakkot]

Then, perhaps we could come up with a symbolic form of IfAbruptRejectPromise?

And IfAbruptCloseIterator, presumably? I think it's probably better to have some way of marking macros in general, rather than trying to invent unique syntax for each one.

[jmdyck]

Shorthands that are invoked like abstract ops:

• ReturnIfAbrupt
• Await
• IfAbruptRejectPromise
• NormalCompletion
• ThrowCompletion

However, I think NormalCompletion and ThrowCompletion could be defined as regular abstract ops.

[ljharb]

Both already are, no? If not, they should be.

[jmdyck]

Well, they say they're abstract operations, but they're defined as shorthands, so they're weird.

[ExE-Boss]

We could probably prefix their names with a % sign, which is what assembly languages generally do, and it’s probably more visible than suffixing them with an ! without any other syntax highlighting, e.g.:

• %ReturnIfAbrupt(argument)
• %IfAbruptRejectPromise(value, promiseCapability)
• %IfAbruptCloseIterator(value, iteratorRecord)

This would also solve #2498.

[michaelficarra]

Closing as duplicate of #2498.