cabal new-build: what does foo-setup~> mean?

[Ganesh Sittampalam]

Hi,

How should I interpret the following dependency solving error from cabal
new-build?

Resolving dependencies...
cabal: Could not resolve dependencies:
trying: time-setup.time~>entropy-setup.time-1.1.2.3 (dependency of
time-1.1.2.3)
trying: time-setup.Cabal~>entropy-setup.Cabal-1.20.0.4 (dependency of
time-1.1.2.3)
Dependency tree exhaustively searched.

FWIW I'm trying to build the HTTP package with GHC 7.0 and the following
options. The solver takes ~10 minutes before failing.

--constraint 'time==1.1.2.3' --constraint 'entropy<0.2.2.4'
-f-warp-tests --constraint 'HUnit<1.4'

cabal configure does seem to be able to find a solution.

Cheers,

Ganesh