pub const fn adjoins(a: &RegionSide, b: &RegionSide) -> boolExpand description
Whether one run picks up exactly where the other stops, in the same block of the same unit.
Two runs that tile one stretch of code are that stretch’s period, not two copies of it. A hand-unrolled loop repeats one operation by construction, and the second half is not a site anyone can be sent to: the duplication is the whole block, and the whole block is already where the reader is looking.
The question is asked in statements rather than bytes so that a blank line or a comment between the two halves cannot change the answer, and it is asked inside one block because adjacency across units means nothing — two functions are two sites however the file happens to lay them out.