As it turns out, it was a somewhat subtle bug in the code. The compiler is fine.
Change the following code:
proc segsieve(Kn: int) = # for Kn resgroups in segment
for b in 0 .. <Kn*bprg: seg[b] = 0 # initialize seg bits to all prime '0'
to:
proc segsieve(Kn: int) = # for Kn resgroups in segment
for b in 0 .. <(Kn*bprg): seg[b] = 0 # initialize seg bits to all prime
'0'
Note the parentheses around `Kn*bprg`. Alternatively, just use `Kn*bprg-1`.
Operator precedence here _is_ surprising and we may want to think how to avoid
that this trips up other people, but the code seems to work fine with this
change.
