[dcl.init.ref] Add missing comma, turn into sub-bullets

[Tsche]

No description provided.

[eisenwave]

The comma seems grammatically necessary and improves readability.

[tkoeppe]

Hm, but the new comma makes it more ambiguous how the top-level ", or" chain relates to the individual list item. I don't find the status quo particularly unclear. Which misreading are you worried about?

[Tsche]

The confusion was whether this is to be read as

( is an rvalue (but not a bit-field) or an lvalue of function type ) and “cv1 T1” is reference-compatible with “cv2 T2”

or

is an rvalue (but not a bit-field) or ( an lvalue of function type and “cv1 T1” is reference-compatible with “cv2 T2” )

@t3nsor suggested the extra comma to disambiguate. I think it's slightly clearer, but I see your concern with the ", or". Unfortunately I see no easy way to turn this into a proper bulleted list rather than a run-on sentence either.

[Tsche]

We could turn this into two separate bullets

• is an rvalue (but not a bit-field) and “cv1 T1” is reference-compatible with “cv2 T2”, or
• is an lvalue of function type and “cv1 T1” is reference-compatible with “cv2 T2”, or

but that seems strictly worse to me. I wouldn't want to repeat "and “cv1 T1” is reference-compatible with “cv2 T2”" twice.

[tkoeppe]

Yes, that was what I suspected. Is this really a point of confusion, or just an academic exercise in grammar parsing? I thought it was quite clear, and if we had wanted the "and reference-compatible" part to only apply to the second option, we would have said it more elaborately.

If we must, we could entertain sub-bullets like this:

• is either
  • an rvalue (but not a bitfield) or
  • an lvalue of function type, and
• [CONTINUING SAME BULLET] cv1 etc etc reference compatible with cv2 T2", or
• [...]

(I can't present this in markdown; there are only meant to be two top-level bullets here, not three.)

But I think I'd like to hear from at least one other person who is genuinely uncertain of the reading.

[jensmaurer]

I like the additional level of bullets, which is both structurally clearer and allows the comma.

[Tsche]

I've updated it to the sub-bullets variant.