Build failure with Cabal 2.0/GHC 8.2

[snoyberg]

Configuring now fails when trying to find the clang library:

> /tmp/stackage-build14$ stack unpack clang-pure-0.2.0.2@gitsha1:9e1e30660eae21019295683e11f326529aec17c1
Unpacked clang-pure-0.2.0.2 to /tmp/stackage-build14/clang-pure-0.2.0.2/
> /tmp/stackage-build14/clang-pure-0.2.0.2$ ghc -clear-package-db -global-package-db -package-db=/var/stackage/work/builds/nightly/pkgdb Setup
[1 of 1] Compiling Main             ( Setup.hs, Setup.o )
Linking Setup ...
> /tmp/stackage-build14/clang-pure-0.2.0.2$ ./Setup configure --package-db=clear --package-db=global --package-db=/var/stackage/work/builds/nightly/pkgdb --libdir=/var/stackage/work/builds/nightly/lib --bindir=/var/stackage/work/builds/nightly/bin --datadir=/var/stackage/work/builds/nightly/share --libexecdir=/var/stackage/work/builds/nightly/libexec --sysconfdir=/var/stackage/work/builds/nightly/etc --docdir=/var/stackage/work/builds/nightly/doc/clang-pure-0.2.0.2 --htmldir=/var/stackage/work/builds/nightly/doc/clang-pure-0.2.0.2 --haddockdir=/var/stackage/work/builds/nightly/doc/clang-pure-0.2.0.2 --flags= --extra-lib-dirs /usr/lib/llvm-3.7/lib --extra-include-dirs /usr/lib/llvm-3.7/include
Configuring clang-pure-0.2.0.2...
Setup: Missing dependency on a foreign library:
* Missing C library: clang
This problem can usually be solved by installing the system package that
provides this library (you may need the "-dev" version). If the library is
already installed but in a non-standard location then you can use the flags
--extra-include-dirs= and --extra-lib-dirs= to specify where it is.

[kenta2]

This issue went away for me after I installed llvm (include cfe), and had llvm-config in my PATH so that Setup could find the libraries.