Build on Windows fails

[David Macek]

Hi all. My build fails, log: https://gist.github.com/elieux/2b2a074e03005f7754d6

I'm working on Windows x64, using msys2 with mingw64-x86_64 4.9.1. What I did:

download the official 7.6.3 x64 build without included toolchain
download x64 msys2, install x64 toolchain and set ghc to use it
build Cabal, install Alex and Happy
set paths to relevant binaries

download http://www.haskell.org/ghc/dist/7.8.3/ghc-7.8.3-src.tar.xz
extract
cp mk/build.mk.sample mk/build.mk
./boot
patch configure to remove the in-tree toolchain
./configure with some parameters
make

I have a PKGBUILD, but since I'm bootstrapping with the manually configured ghc, the environment is not 100% reproducible at the moment.

Can you point me at what should I try changing to build successfully?

-- 
David Macek