I just noticed that GHC 7.10.3 (latest release version) fails to build with version 7.3 of Xcode (which just came out of beta). Maybe this is due to https://ghc.haskell.org/trac/ghc/ticket/11744 The problem manifests in the form of a SEGV when dll-split is invoked for the first time — specifically lldb has the following to say, Process 17348 launched: '../lib/bin/dll-split' (x86_64) Process 17348 stopped * thread #1: tid = 0x4a821e, 0x0000000100e26357 libHSrts-ghc7.10.3.dylib`stg_returnToStackTop + 7, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x1e) frame #0: 0x0000000100e26357 libHSrts-ghc7.10.3.dylib`stg_returnToStackTop + 7 libHSrts-ghc7.10.3.dylib`stg_returnToStackTop: -> 0x100e26357 <+7>: movq 0x1e(%rax), %rbx 0x100e2635b <+11>: movq 0x10(%rbx), %rbp 0x100e2635f <+15>: leaq 0x126(%rbx), %r15 0x100e26366 <+22>: movq $0x0, 0x904(%r13) Interestingly, the GHC 8.0.1-rc2 build does not exhibit that same failure. It does, however, fail to build due to an undefined symbol: Undefined symbols for architecture x86_64: "_stg_sel_18_upd_info", referenced from: _sc9J_info in Monad.dyn_o ld: symbol(s) not found for architecture x86_64 clang: error: linker command failed with exit code 1 (use -v to see invocation) `gcc' failed in phase `Linker'. (Exit code: 1) make[1]: *** [ghc/stage2/build/tmp/ghc-stage2] Error 1 make: *** [all] Error 2 (This may be unrelated to Xcode 7.3 and a known problem on OS X with that RC. I didn’t follow the 8.0.1-rc2 tickets in detail.) As I assume that there will be no further 7.10 release, I am posting this here just to save others the time to track the problem down. Manuel PS: I wish I had the time to check GHC builds with Xcode beta releases, but alas, I usually don’t.