On Thu, Dec 26, 2013 at 8:37 PM, Kazu Yamamoto
When I tried to build the SHA library with GHC head on on 32bit Linux, GHC head got panic. GHC 7.4.2 can build SHA on the same machine.
[1 of 1] Compiling Data.Digest.Pure.SHA ( Data/Digest/Pure/SHA.hs, dist/dist-sandbox-ef3aaa11/build/Data/Digest/Pure/SHA.o ) ghc: panic! (the 'impossible' happened) (GHC version 7.7.20131202 for i386-unknown-linux): regSpill: out of spill slots! regs to spill = 1129 slots left = 677
I ran into this a while ago. Turns out it’s a known bug[0], but it seems like it’s been hard to reproduce. FWIW, I also hit it on 32bit Linux. You can probably work around it with `-fno-regs-graph`. [0]: https://ghc.haskell.org/trac/ghc/ticket/5361