Looking for a way to reference different versions of FSharp.Core in multi-targeted projects

[eiriktsarpalis]

Description

Multi-targeting provides an excellent means to author libraries that target both .NET classic and .NET standard frameworks. However, I am missing a way to specify different versions of FSharp.Core per target using paket. This is an important requirement, since I do not want to force FSharp.Core >= 4.2 on consumers of the net4x build.

Repro steps

Using the code from this commit, run paket install.

Expected behavior

Should complete successfully.

Actual behavior

Fails with the following error:

Paket failed with
-> Installation Errors :
   Package FSharp.Core is referenced in different versions in C:\Users\eirik.tsarpalis\Source\Repos\Repro\Library\Library.fsproj (4.3.1 vs 4.0.0.1), (inspect the lockfile for details) to resolve this either add all dependencies to a single group (to get a unified resolution) or use a condition on both groups and control compilation yourself.

Known workarounds

Either stop using multi-targetting, or use the nuget client.

[forki]

see #3046

[eiriktsarpalis]

Awesome, thanks!