Hmm no that doesn't seem familiar to me. It looks like some Windows style paths are being passed around but don't know why..
Are you running the non-emulating shells? E.g. The MinGW-w64 Win64 Shell bat?
From:
Michael Snoyman
Sent:
8/21/2015 8:27
To:
Tamar Christina
Cc:
ghc-devs@haskell.org
Subject:
Re: Building on Windows