FR: end // comment on EOF.
This example:
demonstrates two things related to // comments. (Actually one thing, which I propose to split in two.)
First is that such a comment breaks out from {$include} that does not end in a newline.
Second is that macro ending in a // comments out the rest of the line, allowing for some interesting debug constructs.
FR: end // when include ends, but preserve its behaviour in macros.