Scopes: Should we require scopes/ranges to be properly nested (i.e. disallow straddling)

[szuend]

While the start/end item encoding enforces a tree structure, negative column deltas could still result in scopes that are not properly nested, e.g.:

 A |
   |
   |   B |
   |     |
   |     |
         |
         |

Could be encoded as start item A, start item B, 'end item B, end item Awhereend item A` has a negative column delta.

Should consumers reject scopes encoding like these?

[nicolo-ribaudo]

Could we maybe enforce that the delta is positive in the format itself, by storing it as an uint rather than as a signed integer?

[hbenl]

I agree that we should require proper nesting. It is somewhat implicit because the scopes that we are encoding need to be properly nested themselves but we could state this explicitly and also require that consumers reject a sourcemap with scopes that aren't properly nested.

Could we maybe enforce that the delta is positive in the format itself, by storing it as an uint rather than as a signed integer?

I don't see how since we're using VLQ, which (AFAIK) doesn't have a way to encode uints.