ghc 8.0.2 compat about mafia

[erikd]

Once its bootstrapped it works mafia works fine with ghc-8.0.2. For instance, you can build mafia with ghc-7.10.3, copy the binary to ~/bin/ and it will then work as it should.

Reproduction with ghc-8.0.3:

• Clean checkout
• ./script/mafia upgrade
• ./script/mafia build

[erikd]

I've tried bootstrapping this manually in a clean checkout by doing:

git submodule update --init

cabal sandbox init

cabal sandbox add-source lib/p
cabal sandbox add-source lib/twine
cabal sandbox add-source lib/x/x-eithert
cabal sandbox add-source lib/x/x-optparse
cabal sandbox add-source lib/x/x-exception
cabal sandbox add-source lib/disorder/disorder-core

cabal install --dependencies-only

and I get the same error.

[erikd]

If I add --force-reinstalls to that final cabal install command everything is fine and it should be safe because we're installing into a local sandbox anyway.

[thumphries]

It builds fine using cabal install --dependencies-only --allow-newer.

Just need to poke some upper bounds.

[erikd-ambiata]

It seems --allow-newer does fix that warning, but I can't figure out what dependency is causing cabal to want to re-install the ghc package.

Wait, no, --allow-newer makes all sorts of bad things happen, like x-optparse failing because it tries to build against optparse-applicative version 0.13.*.

[HuwCampbell]

Will push a 0.13.2 with process today.

[erikd-ambiata]

@HuwCampbell Its process that's doing this (via optparse-applicative)?