Resolving dependencies...
cabal: Could not resolve dependencies:
trying: llvm-ffi-3.1.0 (user goal)
trying: llvm-ffi-3.1.0:-buildtools
rejecting: llvm-ffi-3.1.0:+specificpkgconfig (conflict: requires pkg-config
package llvm-3.1==3.1, not found in the pkg-config database)
rejecting: llvm-ffi-3.1.0:-specificpkgconfig (conflict: requires pkg-config
package llvm==3.1, not found in the pkg-config database)
Dependency tree exhaustively searched.