I am unable to build current HEAD. I'm getting a build error in Outputable module: compiler/utils/Outputable.hs:1046:28: Not in scope: type constructor or class ‘CallStack’ compiler/utils/Outputable.hs:1047:23: Not in scope: ‘showCallStack’ The most likely culprit is 80d7ce8038a100f6797a89755c893c6f67f18a30, which added this: #if __GLASGOW_HASKELL__ >= 710 pprSTrace :: (?location :: CallStack) => SDoc -> a -> a pprSTrace = pprTrace (showCallStack ?location) #else pprSTrace :: SDoc -> a -> a pprSTrace = pprTrace "no callstack info" #endif The most interesting thing is that if I change the definition of pprSTrace in the first branch of #if to be identical to the definition in the second branch, then I get warnings that GHC.Stack and GHC.Exception imports are redundant. Any ideas what might be going on here? I'm compiling using GHC 7.10.1. This happens in a clean build tree. Janek --- Politechnika Łódzka Lodz University of Technology Treść tej wiadomości zawiera informacje przeznaczone tylko dla adresata. Jeżeli nie jesteście Państwo jej adresatem, bądź otrzymaliście ją przez pomyłkę prosimy o powiadomienie o tym nadawcy oraz trwałe jej usunięcie. This email contains information intended solely for the use of the individual to whom it is addressed. If you are not the intended recipient or if you have received this message in error, please notify the sender and delete it from your system.