Resolving dependencies...
cabal: Could not resolve dependencies:
next goal: protocol-buffers (user goal)
rejecting: protocol-buffers-2.4.0, protocol-buffers-2.3.1,
protocol-buffers-2.3.0, protocol-buffers-2.2.0, protocol-buffers-2.1.12,
protocol-buffers-2.1.11, protocol-buffers-2.1.10, protocol-buffers-2.1.9
(constraint from user target requires ==2.1.8)
trying: protocol-buffers-2.1.8
next goal: base (dependency of protocol-buffers-2.1.8)
rejecting: base-4.9.0.0/installed-4.9... (conflict: protocol-buffers =>
base>=4.7.0 && <4.9)
rejecting: base-4.9.0.0, base-4.8.2.0, base-4.8.1.0, base-4.8.0.0,
base-4.7.0.2, base-4.7.0.1, base-4.7.0.0, base-4.6.0.1, base-4.6.0.0,
base-4.5.1.0, base-4.5.0.0, base-4.4.1.0, base-4.4.0.0, base-4.3.1.0,
base-4.3.0.0, base-4.2.0.2, base-4.2.0.1, base-4.2.0.0, base-4.1.0.0,
base-4.0.0.0, base-3.0.3.2, base-3.0.3.1 (constraint from non-upgradeable
package requires installed instance)
Dependency tree exhaustively searched.