I'm talking about unattended automated builds, so tweaking isn't an option. On the other hand breaking the package environment isn't so bad, because I'm throwing it away after each build.
I'm not convinced that we should try to build packages at any price. If they're likely to cause problems in a standard environment on a user machine, then isn't it better to see this reflected on Hackage?
So in short, no combination of flags will work in this case, I think. Failure is the best option.
Actually --force-reinstalls does work in this case, and this thread began with Levent being unhappy with the failure option for his package, so I'm tempted to use that flag on all hackage builds.
Does it produce a usable package and environment, or does it just work, but leave everything broken? I agree that using --force-reinstalls on Hackage might be an acceptable option, and it's probably better than using --avoid-reinstalls by default. However, it may still send the misleading message that a package "builds just fine" when it practice it doesn't. Cheers, Andres -- Andres Löh, Haskell Consultant Well-Typed LLP, http://www.well-typed.com