I don't think the front end knows what sizeof(gfc_offset) is on the
target. But rather than worry about teaching the frontend yet another
detail about the target, I'd suggest just using INTEGER(8) for
offsets, whether the target has LFS support or not. Unless we claim to
support targets that don't support 8 byte integer types at all?
We already have, both in the front-end and library, a type "I/O int"
(gfc_intio_kind in the front end; GFC_IO_INT in the library) for this
kind of thing. It's an integer(8) is this is supported, an integer(4)
otherwise.
That sounds like the good type to use.