safecopy-0.8.3 broken with GHC 7.10 about safecopy

[en-em]

I too wonder what's going on here.

[Qinka]

Me too. I build hackage-server , when this happened.

[Qinka]

I guess that we were missing something just like {-# LANGUAGE XX #-}. But what XX is ?

[sirlensalot]

I did -ddump-splices on this as it's breaking log-domain, which I presume is where the example above comes from. Replacing the TH code with the following emitted code has the same problem:

instance SafeCopy Log where
      putCopy (Exp arg_afqB)
        = contain
            (do { safePut_a_afqC <- getSafePut;
                  safePut_a_afqC arg_afqB;
                  return () })
      getCopy
        = contain
            (label
               "Numeric.Log.Log:"
               (do { safeGet_a_afqD <- getSafeGet;
                     ((return Exp) <*> safeGet_a_afqD) }))
      version = 1
      kind = base
      errorTypeName _ = "Numeric.Log.Log"

src/Numeric/Log.hs:77:19-21: Expecting one more argument to ‘Log’ …
    The first argument of ‘SafeCopy’ should have kind ‘*’,
      but ‘Log’ has kind ‘* -> *’
    In the instance declaration for ‘SafeCopy Log’
Compilation failed.

To fix the code, change the instance decl to instance SafeCopy a => SafeCopy (Log a) where. This compiles.

I think the TH code would need to be changed to fix this, I'll take a look.

[stepcut]

The snippet works for me with GHC 7.10.3 and safecopy 0.9.0.1. I'm guessing this patch fixed it:

899152c