Preprocessing src/Foreign/Storable/Generic/Instances.hs fails for stack+OSX+ghc-8.0.1

[iand675]

derive-storable-0.1.0.3: configure
derive-storable-0.1.0.3: build
Progress: 1/2
--  While building package derive-storable-0.1.0.3 using:
      /Users/ian/.stack/setup-exe-cache/x86_64-osx/setup-Simple-Cabal-1.24.0.0-ghc-8.0.1 --builddir=.stack-work/dist/x86_64-osx/Cabal-1.24.0.0 build --ghc-options " -ddump-hi -ddump-to-file"
    Process exited with code: ExitFailure 1
    Logs have been written to: .stack-work/logs/derive-storable-0.1.0.3.log

    Configuring derive-storable-0.1.0.3...
    Building derive-storable-0.1.0.3...
    Preprocessing library derive-storable-0.1.0.3...
    [1 of 4] Compiling Foreign.Storable.Generic.Tools ( src/Foreign/Storable/Generic/Tools.hs, .stack-work/dist/x86_64-osx/Cabal-1.24.0.0/build/Foreign/Storable/Generic/Tools.o )
    [2 of 4] Compiling Foreign.Storable.Generic.Internal ( src/Foreign/Storable/Generic/Internal.hs, .stack-work/dist/x86_64-osx/Cabal-1.24.0.0/build/Foreign/Storable/Generic/Internal.o )
    [3 of 4] Compiling Foreign.Storable.Generic.Instances ( src/Foreign/Storable/Generic/Instances.hs, .stack-work/dist/x86_64-osx/Cabal-1.24.0.0/build/Foreign/Storable/Generic/Instances.o )

    /private/var/folders/v6/w9s25grj1xg_9tj3dg07cflc0000gn/T/stack2438/derive-storable-0.1.0.3/src/Foreign/Storable/Generic/Instances.hs:55:1: error:
        Parse error: naked expression at top level
        Perhaps you intended to use TemplateHaskell

[mkloczko]

I will look more into it when I'll have access to OSX.

In the meantime: does the error occur when building derive-storable as a dependency ? Or when built by itself ? I am quite curious why the 'naked expression' appears at line 55, and not before. Is there some noise in the source file ?

[codygman]

I have this issue as well. I did a bit of research and it may be related to this:

haskell/cabal#1740

root cause of that issue (basically preprocessing twice): https://gist.github.com/mzero/d4ba11c567977111749a

However using -optP-P did not fix this issue for me.

[mkloczko]

Thank you for your help!

It seems like the issue was with the white space between MakeGStorable and it's argument.

This should be fixed by now. The fix was uploaded to hackage.