checking whether to use -liconv... setup: Unable to link against the iconv library.
Failed to install darcs-2.8.4
cabal: Error: some packages failed to install:
What is actually going on here? Iconv libraries already installed with libc6 package.
Running ubuntu, cabal-install-1.16.0.2.
Linux distinguishes between runtime and linkable libraries; you probably need to install the libc6-dev package to get the latter. (This is not a Haskell-specific issue; configure is using a C program to test the link.)