GHC API 7.10 -> 8.0.1 (unusable due to missing or recursive dependencies)

[Edward Z. Yang]

Hi A.M.,

It's very possible that the list in DynFlags are accumulated in
reverse order to the flags that were provided.  The manual is
just talking about user provided flags.

You may also be interested in
https://downloads.haskell.org/~ghc/master/users-guide/extending_ghc.html#frontend-plugins

Edward

Excerpts from A.M.'s message of 2017-01-07 10:54:56 -0500:
> On 01/06/2017 10:37 PM, Edward Z. Yang wrote:
> > Hello A.M.,
> > 
> > In 8.0.1 package databases must be specified in the correct order,
> > whereas in 7.10 they could be done in any order. This problem
> > was fixed in 8.0.2, give it a try.
> 
> Thanks for the tip, Edward. That was it!
> 
> Following https://ghc.haskell.org/trac/ghc/ticket/12485 to
> https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/packages.html#package-databases,
> I read:
> 
> "By default, the stack contains just the global and the user’s package
> databases, in that order."
> 
> However, the order that works for me is:
> 
> extraPkgConfs = const (localPkgPaths ++ [GlobalPkgConf])
> 
> so is the description flipped or is the stack head at the end of the
> list? In any case, it's rather confusing, though I recognize that the
> above sentence is not referring to the GHC API in particular.
> 
> I now see that the wrong ordering caused me to be unable to load *any*
> packages from my sandbox.
> 
> Thanks for the fix!
> 
> Cheers,
> M