Simon Peyton Jones via ghc-devs
I see that anything involving ghci fails:
/c/code/HEAD/inplace/bin/ghc-stage2 --interactive
GHCi, version 8.1.20161209: http://www.haskell.org/ghc/ :? for help
ghc-stage2.exe: unable to load package `base-4.9.0.0'
ghc-stage2.exe: C:\code\HEAD\inplace\mingw\x86_64-w64-mingw32\lib\libmingwex.a: unknown symbol `_lock_file'
Yes, Tamar and I were working on tracking this down over the last few days. The patch (which I will merge after a running validation finishes) is D2817. In short, the problem is that we recently upgraded the Windows toolchain. For better or worse, the new mingw-w64 toolchain now has an atomic printf implementation, which requires the use of the _lock_file function provided by Microsoft's C runtime. However, the _lock_file symbol is only exported by certain variants of msvcrt (e.g. msvcrt90.dll), but not the distribution which mingw-w64 uses (apparently due to license considerations [1], although the exact reason isn't clear). To hack around this, mingw-w64 ships a static library, msvcrt.a, which wraps msvcrt.dll and provides hand-rolled implementations of some needed symbols, including _lock_file. However, this means that the static library msvcrt.a, and the dynamic library msvcrt.dll don't export the same set of symbols, which causes GHCi to blow up if dynamically linked. Consequently we need to All of this coupled with another recent but quite unrelated cleanup (D2579) breaking the Windows build when bootstrapped with GHC 7.10, the recent testsuite debacle, as well as a number of other Windows quirks I've discovered in the past few weeks, meant that figuring all of this out took quite some time (which is why the Windows builder *still* isn't quite up). On the bright side, one happy side-effort of this is that it prompted me to write down some notes on the interactions between the many components of our Windows toolchain [2]. Anyways, we are getting quite close. I expect we'll finally have the Windows builder up by next week. Hopefully from that point forth it will be considerably harder to break the Windows build. Cheers, - Ben [1] https://sourceforge.net/p/mingw-w64/discussion/723797/thread/55520785/ [2] https://ghc.haskell.org/trac/ghc/wiki/SurvivingWIndows