Hello Ganesh, You should go ahead and file a bug on the Cabal tracker; the dep solver folks will be able to help you there. ~> indicates "linking". In the code comments: -- The modular solver has a number of package goals to solve for, and can only -- pick a single package version for a single goal. In order to allow to -- install multiple versions of the same package as part of a single solution -- the solver uses qualified goals. For example, @0.P@ and @1.P@ might both -- be qualified goals for @P@, allowing to pick a difference version of package -- @P@ for @0.P@ and @1.P@. -- -- Linking is an essential part of this story. In addition to picking a specific -- version for @1.P@, the solver can also decide to link @1.P@ to @0.P@ (or -- vice versa). It means that @1.P@ and @0.P@ really must be the very same package -- (and hence must have the same build time configuration, and their -- dependencies must also be the exact same). -- -- See http://www.well-typed.com/blog/2015/03/qualified-goals/ for details. I haven't studied the actual error you have too closely. Hope that helps, Edward Excerpts from Ganesh Sittampalam's message of 2016-12-03 18:45:24 +0000:
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