For example
type
Attr {.bitmask.} = enum
Attr1 = 1 shl 0
Attr2 = 1 shl 63
Attrs = set[Attr]
const AllAttr = {Attr1, Attr2}
doAssert sizeof(Attrs) == 8
Not that hard.
type
Attr = enum
Attr1 = 0
Attr2 = 63
Attrs = set[Attr]
const AllAttr = {Attr1, Attr2}
doAssert sizeof(Attrs) == 8