#7931: Deriving Read of an empty datatype crashes -----------------------------+---------------------------------------------- Reporter: monoidal | Owner: Type: bug | Status: patch Priority: normal | Component: Compiler Version: 7.6.3 | Keywords: Os: Unknown/Multiple | Architecture: Unknown/Multiple Failure: None/Unknown | Blockedby: Blocking: | Related: -----------------------------+---------------------------------------------- Comment(by monoidal): @parcs: What I get is: {{{ g@g-lap:~/haskell/head$ ghc-7.7.20130515 X [1 of 1] Compiling Main ( X.hs, X.o ) ghc: panic! (the 'impossible' happened) (GHC version 7.7.20130515 for x86_64-unknown-linux): Prelude.foldr1: empty list Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug g@g-lap:~/haskell/head$ ghci-7.7.20130515 X GHCi, version 7.7.20130515: http://www.haskell.org/ghc/ :? for help Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... done. [1 of 1] Compiling Main ( X.hs, interpreted ) *** Exception: Prelude.foldr1: empty list }}} -- Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/7931#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler