`cabal build package-name` builds more than asked in multipackage project

[vrom911]

I am working on the co-log project which is a multipackage project. It has the following cabal.project file:

packages:
    co-log-core
    co-log
    co-log-polysemy
    co-log-benchmark

I want to build only co-log-core, co-log and co-log-polysemy packages on Appveyor's Windows machines (as co-log-benchmark is using unix library as a dependency). The command I run:

cabal v2-build co-log-core co-log co-log-polysemy

However, it starts to build co-log-benchmark:

[__2] trying: co-log-benchmark-0.0.0.0 (user goal)

and obviously fails.

How could I restrict the build of a certain package with Cabal?

Expected behaviour

Cabal builds only those packages of the multipackage project that I specified in the command.

System information

• Operating system: Windows
• cabal-3.0.0.0, ghc-8.8.1

Additional context

Appveyor full output: https://ci.appveyor.com/project/kowainik/co-log/builds/29774908
Corresponding co-log PR: co-log/co-log#160

[phadej]

Cabal doesn’t try to build co-log-benchmark, it tries to come with build plan which includes everything. We want that behaviour, so the build plan is stable even you change targets. Having conditionals in cabal.project is known wanted feature (so co-log-benchmarks won’t be in the project on windows), but we don’t have that yet. I’d recommend having appveyor/windows specific cabal.project variant until that.