Example of how install errors look like on the parbuild-better-output branch

error.log

$ cabal install -j 2 Win32
Resolving dependencies...
Downloading Win32-2.2.2.0...
Configuring Win32-2.2.2.0...
Failed to install Win32-2.2.2.0
Last 10 lines of the build log (
/home/cabal-test/.cabal/logs/Win32-2.2.2.0.log ):
setup-Cabal-1.14.0-ghc-7.4.2: Missing dependencies on foreign libraries:
* Missing (or bad) header file: HsWin32.h
* Missing C libraries: user32, gdi32, winmm, advapi32, shell32, shfolder
This problem can usually be solved by installing the system packages that
provide these libraries (you may need the "-dev" versions). If the libraries
are already installed but in a non-standard location then you can use the
flags --extra-include-dirs= and --extra-lib-dirs= to specify where they are.
If the header file does exist, it may contain errors that are caught by the C
compiler at the preprocessing stage. In this case you can re-run configure
with the verbosity flag -v3 to see the error messages.
cabal: Error: some packages failed to install:
Win32-2.2.2.0 failed during the configure step. The exception was:
ExitFailure 1