Comment 1:

A possible workaround is:
epevent.Events |= syscall.EPOLLET & 0xffffffff
but maybe something can be done in the syscall package or the language to make this bit 
mask unnecessary.

Comment 2:

This is not a language or compiler problem, the value syscall.EPOLLET is negative
(-0x80000000) and thus 
cannot be represented as (or'ed to) a uint32 w/o loss of precision.
Your "work-around" is the correct approach in this case, in Go one has to be explicit
about loosing precision 
with constants.
Alternatively, perhaps the constant syscall.EPOLLET shouldn't be negative in the first
place - but that would be 
an issue with godefs as this package is automatically generated.
Closing for now as this works as intended.

Status changed to WorkingAsIntended.