% cabal build -v3
Using external setup method with build-type Custom
creating dist/setup
Using Cabal library version 1.18.1.2
Using ./Setup.lhs as setup script.
./dist/setup/setup build --verbose=3 --builddir=dist
("darcs",["changes","-a","--from-tag","2.8.4","--count"])
darcs returned ExitFailure 2 with error message:

darcs failed: Not a repository: . (./_darcs/inventory does not exist)

HINT: Do you have the right URI for the repository?

If so, check with the repository owner to see if the following files
are readable:

1. _darcs/format - might not exist; that's OK
2. _darcs/inventory - should exist if #1 is missing
3. _darcs/hashed_inventory - should exist if #2 is missing

creating dist/build/autogen
Component build order: library, executable 'darcs'
creating dist/build
creating dist/build/autogen
Building darcs-2.8.4...
Preprocessing library darcs-2.8.4...
Building library...
("/usr/local/bin/ghc",["--info"])
("/usr/local/bin/ghc",["--info"])
creating dist/build
<...>
<...>
*** C pre-processor:
'/usr/bin/ghc-clang-wrapper' '-E' '-undef' '-traditional' '-m64' '-fno-stack-protector' '-m64' '-I' 'dist/build' '-I' 'dist/build' '-I' 'dist/build/autogen' '-I' 'dist/build' '-I' 'src' '-I' '/usr/local/Cellar/haskell-platform/2013.2.0.0/lib/ghc/vector-0.10.0.1/ghc-7.6.3/include' '-I' '/usr/local/Cellar/haskell-platform/2013.2.0.0/lib/ghc/primitive-0.5.0.1/ghc-7.6.3/include' '-I' '/usr/local/Cellar/ghc/7.6.3/lib/ghc-7.6.3/process-1.1.0.2/include' '-I' '/usr/local/Cellar/ghc/7.6.3/lib/ghc-7.6.3/directory-1.2.0.1/include' '-I' '/usr/local/Cellar/ghc/7.6.3/lib/ghc-7.6.3/old-time-1.1.0.1/include' '-I' '/usr/local/Cellar/haskell-platform/2013.2.0.0/lib/ghc/network-2.4.1.2/ghc-7.6.3/include' '-I' '/usr/local/Cellar/ghc/7.6.3/lib/ghc-7.6.3/unix-2.6.0.1/include' '-I' '/usr/local/Cellar/ghc/7.6.3/lib/ghc-7.6.3/time-1.4.0.1/include' '-I' '/usr/local/Cellar/ghc/7.6.3/lib/ghc-7.6.3/bytestring-0.10.0.2/include' '-I' '/usr/local/Cellar/ghc/7.6.3/lib/ghc-7.6.3/base-4.6.0.1/include' '-I' '/usr/local/Cellar/ghc/7.6.3/lib/ghc-7.6.3/include' '-D__GLASGOW_HASKELL__=706' '-Ddarwin_BUILD_OS=1' '-Dx86_64_BUILD_ARCH=1' '-Ddarwin_HOST_OS=1' '-Dx86_64_HOST_ARCH=1' '-U __PIC__' '-D__PIC__' '-DPACKAGE_VERSION="2.8.4"' '-DPACKAGE_VERSION_STATE="+ 1 patch"' '-DHAVE_HTTP' '-DUSE_COLOR' '-DGADT_WITNESSES=1' '-DFORCE_CHAR8_ENCODING' '-DHAVE_CURL' '-DHAVE_HTTP' '-DHAVE_MMAP' '-DHAVE_TERMINFO' '-include' 'dist/build/autogen/cabal_macros.h' '-x' 'c' 'src/CommandLine.hs' '-o' '/var/folders/7h/dvj6502s107dkmgnrm2rr0j40000gn/T/ghc75005_0/ghc75005_0.hscpp'
clang: error: no such file or directory: '1'
clang: error: no such file or directory: 'patch"'
*** Deleting temp files:
Deleting: /var/folders/7h/dvj6502s107dkmgnrm2rr0j40000gn/T/ghc75005_0/ghc75005_0.hscpp
Warning: deleting non-existent /var/folders/7h/dvj6502s107dkmgnrm2rr0j40000gn/T/ghc75005_0/ghc75005_0.hscpp
*** Deleting temp dirs:
Deleting: /var/folders/7h/dvj6502s107dkmgnrm2rr0j40000gn/T/ghc75005_0
/usr/local/bin/ghc returned ExitFailure 1