= DataTyCon {
data_cons = cons,
is_enum = -- We define datatypes with no constructors to not be
- -- enumerations; this fixes trac #2578
+ -- enumerations; this fixes trac #2578, Otherwise we
+ -- end up generating an empty table for
+ -- <mod>_<type>_closure_tbl
+ -- which is used by tagToEnum# to map Int# to constructors
+ -- in an enumeration. The empty table apparently upset
+ -- the linker.
not (null cons) &&
all isNullarySrcDataCon cons
}