Synced to Apple’s issue tracker as rdar://128016621

Could this code action extend to cover bitwise operators as well?

Yes, that would make sense.

@ahoppen as you mentioned in #1539, being overly restrictive is more of a problem than being too permissive. However for DeMorgan's law, the situation is a bit different. We may identify multiple candidate expressions as we walk up the syntax tree, e.g. !(a != b || !(c && d)), which I believe isn't a terribly uncommon form of expression.

I can think of two possible ways to deal with the ambiguity,

1. pick the nearest or the farthermost candidate expression;
2. provide a code action for each candidate expression encountered as we ascend to the root expression.

It’s probably one of these situations where we need some reference implementation and then use it to decide what feels best. But I think starting with the outermost expression makes sense as a start.

Shall we support generalised DeMorgan's in addition to dual DeMorgan's?
e.g. !a && !b && !c -> !(a || b || c)

I would start with one direction. The dual would be a nice follow-up after that.