Hi all, I recently ran into the following interesting bug (reproducible on Mac; I used ghcup to install GHC and cabal-install): cabal unpack aeson-1.2.1.0 cabal build -w ghc-8.0.2 (yields this error log) Configuring library for aeson-1.2.1.0.. Preprocessing library for aeson-1.2.1.0.. Building library for aeson-1.2.1.0.. [ 1 of 23] Compiling Data.Attoparsec.Time.Internal ( attoparsec-iso8601/Data/Attoparsec/Time/Internal.hs, dist/build/Data/Attoparsec/Time/Internal.o ) [ 2 of 23] Compiling Data.Attoparsec.Time ( attoparsec-iso8601/Data/Attoparsec/Time.hs, dist/build/Data/Attoparsec/Time.o ) [ 3 of 23] Compiling Data.Aeson.Types.Internal ( Data/Aeson/Types/Internal.hs, dist/build/Data/Aeson/Types/Internal.o ) [ 4 of 23] Compiling Data.Aeson.Types.Generic ( Data/Aeson/Types/Generic.hs, dist/build/Data/Aeson/Types/Generic.o ) [ 5 of 23] Compiling Data.Aeson.Parser.UnescapePure ( pure/Data/Aeson/Parser/UnescapePure.hs, dist/build/Data/Aeson/Parser/UnescapePure.o ) [ 6 of 23] Compiling Data.Aeson.Parser.Unescape ( Data/Aeson/Parser/Unescape.hs, dist/build/Data/Aeson/Parser/Unescape.o ) [ 7 of 23] Compiling Data.Aeson.Parser.Time ( Data/Aeson/Parser/Time.hs, dist/build/Data/Aeson/Parser/Time.o ) [ 8 of 23] Compiling Data.Aeson.Parser.Internal ( Data/Aeson/Parser/Internal.hs, dist/build/Data/Aeson/Parser/Internal.o ) <command line>: can't load .so/.DLL for: /Users/vmchale/.cabal/store/ghc-8.0.2/lib/libHStm-lcl-cmpt-0.1.1.5-83154f89-ghc8.0.2.dylib (dlopen(/Users/vmchale/.cabal/store/ghc-8.0.2/lib/libHStm-lcl-cmpt-0.1.1.5-83154f89-ghc8.0.2.dylib, 5): REBASE_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB has segment 2 which is not a writable segment (__LINKEDIT) in /Users/vmchale/.cabal/store/ghc-8.0.2/lib/libHStm-lcl-cmpt-0.1.1.5-83154f89-ghc8.0.2.dylib) Seems to be new; I guess the past libraries didn’t trigger it? I can’t tell if it’s a cabal-install bug, GHC bug, mac novelty… Cheers, Vanessa McHale