GHC 8.8 heap overflow regression
The following program throws a heap overflow if you compile it with optimization on GHC 8.8 and HEAD:
module Bug where import Data.Bits (setBit) f :: Int f = foldl setter 0 $ zip [0..] [()] where setter v (ix, _) = setBit v ix
$ ~/Software/ghc3/inplace/bin/ghc-stage2 -fforce-recomp -O Bug.hs [1 of 1] Compiling Bug ( Bug.hs, Bug.o ) ghc-stage2: panic! (the 'impossible' happened) (GHC version 8.9.20190309 for x86_64-unknown-linux): heap overflow
This does not happen with GHC 8.6.4.
FontyFruity package on Hackage fails to build on GHC HEAD due to this regression.