Fix warnings in deSugar/Check.lhs
Fix warnings in deSugar/Check.lhs

forked-upstream-packages-for-ghcjs/ghc,holzensp/ghc,nathyong/microghc-ghc,bitemyapp/ghc,tibbe/ghc,wxwxwwxxx/ghc,gcampax/ghc,hferreiro/replay,shlevy/ghc,tjakway/ghcjvm,TomMD/ghc,da-x/ghc,bitemyapp/ghc,nkaretnikov/ghc,olsner/ghc,GaloisInc/halvm-ghc,urbanslug/ghc,nkaretnikov/ghc,GaloisInc/halvm-ghc,da-x/ghc,spacekitteh/smcghc,shlevy/ghc,lukexi/ghc,nushio3/ghc,ekmett/ghc,ryantm/ghc,sgillespie/ghc,snoyberg/ghc,green-haskell/ghc,bitemyapp/ghc,wxwxwwxxx/ghc,ghc-android/ghc,nomeata/ghc,ghc-android/ghc,ml9951/ghc,nkaretnikov/ghc,jstolarek/ghc,oldmanmike/ghc,GaloisInc/halvm-ghc,AlexanderPankiv/ghc,christiaanb/ghc,ekmett/ghc,mfine/ghc,gcampax/ghc,AlexanderPankiv/ghc,ml9951/ghc,ml9951/ghc,ekmett/ghc,forked-upstream-packages-for-ghcjs/ghc,sdiehl/ghc,vTurbine/ghc,lukexi/ghc-7.8-arm64,jstolarek/ghc,vTurbine/ghc,GaloisInc/halvm-ghc,sdiehl/ghc,vTurbine/ghc,tibbe/ghc,tibbe/ghc,ryantm/ghc,fmthoma/ghc,lukexi/ghc,christiaanb/ghc,tjakway/ghcjvm,ghc-android/ghc,mcschroeder/ghc,snoyberg/ghc,holzensp/ghc,mcmaniac/ghc,elieux/ghc,forked-upstream-packages-for-ghcjs/ghc,ghc-android/ghc,green-haskell/ghc,tjakway/ghcjvm,oldmanmike/ghc,forked-upstream-packages-for-ghcjs/ghc,ghc-android/ghc,fmthoma/ghc,hferreiro/replay,nushio3/ghc,acowley/ghc,wxwxwwxxx/ghc,sgillespie/ghc,nomeata/ghc,holzensp/ghc,frantisekfarka/ghc-dsi,vikraman/ghc,anton-dessiatov/ghc,tjakway/ghcjvm,frantisekfarka/ghc-dsi,acowley/ghc,jstolarek/ghc,christiaanb/ghc,gcampax/ghc,mettekou/ghc,frantisekfarka/ghc-dsi,wxwxwwxxx/ghc,nushio3/ghc,mcschroeder/ghc,gcampax/ghc,mettekou/ghc,oldmanmike/ghc,oldmanmike/ghc,GaloisInc/halvm-ghc,ezyang/ghc,nathyong/microghc-ghc,tibbe/ghc,olsner/ghc,gridaphobe/ghc,ekmett/ghc,green-haskell/ghc,oldmanmike/ghc,gridaphobe/ghc,mcschroeder/ghc,urbanslug/ghc,da-x/ghc,ilyasergey/GHC-XAppFix,snoyberg/ghc,nushio3/ghc,acowley/ghc,mcschroeder/ghc,sdiehl/ghc,gcampax/ghc,ezyang/ghc,ilyasergey/GHC-XAppFix,christiaanb/ghc,tjakway/ghcjvm,anton-dessiatov/ghc,hferreiro/replay,gridaphobe/ghc,acowley/ghc,ryantm/ghc,ezyang/ghc,vTurbine/ghc,lukexi/ghc-7.8-arm64,christiaanb/ghc,siddhanathan/ghc,mcmaniac/ghc,mettekou/ghc,nomeata/ghc,AlexanderPankiv/ghc,ezyang/ghc,sdiehl/ghc,elieux/ghc,elieux/ghc,da-x/ghc,anton-dessiatov/ghc,tjakway/ghcjvm,ghc-android/ghc,green-haskell/ghc,acowley/ghc,forked-upstream-packages-for-ghcjs/ghc,frantisekfarka/ghc-dsi,da-x/ghc,nkaretnikov/ghc,nkaretnikov/ghc,spacekitteh/smcghc,mettekou/ghc,lukexi/ghc,siddhanathan/ghc,vikraman/ghc,mettekou/ghc,forked-upstream-packages-for-ghcjs/ghc,mcschroeder/ghc,urbanslug/ghc,ml9951/ghc,sdiehl/ghc,TomMD/ghc,urbanslug/ghc,vikraman/ghc,sgillespie/ghc,gcampax/ghc,mcmaniac/ghc,jstolarek/ghc,siddhanathan/ghc,vTurbine/ghc,nathyong/microghc-ghc,ekmett/ghc,elieux/ghc,shlevy/ghc,anton-dessiatov/ghc,olsner/ghc,fmthoma/ghc,gridaphobe/ghc,ezyang/ghc,siddhanathan/ghc,ilyasergey/GHC-XAppFix,wxwxwwxxx/ghc,nathyong/microghc-ghc,snoyberg/ghc,nathyong/microghc-ghc,snoyberg/ghc,ghc-android/ghc,oldmanmike/ghc,fmthoma/ghc,TomMD/ghc,siddhanathan/ghc,nomeata/ghc,olsner/ghc,snoyberg/ghc,olsner/ghc,da-x/ghc,mfine/ghc,fmthoma/ghc,vTurbine/ghc,nathyong/microghc-ghc,jstolarek/ghc,urbanslug/ghc,tibbe/ghc,fmthoma/ghc,acowley/ghc,nushio3/ghc,urbanslug/ghc,AlexanderPankiv/ghc,nkaretnikov/ghc,mettekou/ghc,forked-upstream-packages-for-ghcjs/ghc,tjakway/ghcjvm,vikraman/ghc,lukexi/ghc-7.8-arm64,urbanslug/ghc,mfine/ghc,anton-dessiatov/ghc,nushio3/ghc,ml9951/ghc,nushio3/ghc,ezyang/ghc,snoyberg/ghc,bitemyapp/ghc,sgillespie/ghc,anton-dessiatov/ghc,sgillespie/ghc,sdiehl/ghc,frantisekfarka/ghc-dsi,spacekitteh/smcghc,olsner/ghc,spacekitteh/smcghc,vikraman/ghc,shlevy/ghc,TomMD/ghc,fmthoma/ghc,shlevy/ghc,mfine/ghc,ml9951/ghc,green-haskell/ghc,gcampax/ghc,elieux/ghc,mfine/ghc,acowley/ghc,bitemyapp/ghc,nkaretnikov/ghc,AlexanderPankiv/ghc,ml9951/ghc,gridaphobe/ghc,vTurbine/ghc,lukexi/ghc-7.8-arm64,siddhanathan/ghc,lukexi/ghc,hferreiro/replay,elieux/ghc,shlevy/ghc,wxwxwwxxx/ghc,christiaanb/ghc,lukexi/ghc-7.8-arm64,GaloisInc/halvm-ghc,mettekou/ghc,olsner/ghc,gridaphobe/ghc,christiaanb/ghc,ezyang/ghc,mcschroeder/ghc,ilyasergey/GHC-XAppFix,nathyong/microghc-ghc,mfine/ghc,lukexi/ghc,holzensp/ghc,TomMD/ghc,mcschroeder/ghc,da-x/ghc,holzensp/ghc,TomMD/ghc,mcmaniac/ghc,sdiehl/ghc,ryantm/ghc,GaloisInc/halvm-ghc,nomeata/ghc,gridaphobe/ghc,hferreiro/replay,elieux/ghc,TomMD/ghc,wxwxwwxxx/ghc,hferreiro/replay,hferreiro/replay,ml9951/ghc,spacekitteh/smcghc,anton-dessiatov/ghc,sgillespie/ghc,vikraman/ghc,sgillespie/ghc,oldmanmike/ghc,AlexanderPankiv/ghc,shlevy/ghc,AlexanderPankiv/ghc,siddhanathan/ghc,mfine/ghc,vikraman/ghc,mcmaniac/ghc,ryantm/ghc