(Imported from Trac #891, reported by zzo38 on 2011-09-29)
I have suggestion allowing unknown fields in a .cabal file, and if they are named with X- at front, they will not have warning message, and will be ignored if they are not understand.
It should also do similar thing with sections named with X- at front, where, it if it doesn't understand that section, it ignore entire section with no warning/error (regardless of field names), but if it can use that section, it is still warnings for unknown fields in that section without X- at front.
(Imported comment by zzo38 on 2011-09-29)
Thing described in first paragraph already works.
Since this doesn't have any activity since 2011, I propose closing. Please re-open or file a new ticket if this is something that is still desired.