extern alias support for NuGet package references

[davkean]

• Design document

From @fubar-coder on April 5, 2017 15:59

Currently, when a NuGet package reference is added, there is no way to set the alias from the project system for the new style csproj projects.

This feature is needed, because NuGet package references don't result in direct assembly references any more and only those can have an alias.

My proposal is to add the alias(es) to all assemblies referenced for the NuGet package, but not the indirectly referenced NuGet packages.

Copied from original issue: dotnet/project-system#1930

notes

dotnet/sdk#10947 The build tasks on (.NET Core SDK side)
dotnet/NuGet.BuildTasks#70 The build tasks for the non-SDK based PackageReference
dotnet/project-system#6011 Nomination updates on project-system side.

[davkean]

Great suggestion. I'll move this over to the NuGet repo, they own the syntax for PackageReference.

[andymac4182]

This would be great since we are running into this issue due to https://www.nuget.org/packages/StackExchange.Redis/ and https://www.nuget.org/packages/StackExchange.Redis.StrongName/

[brianpos]

We have this issue to if we want to add both of these
https://www.nuget.org/packages/Hl7.Fhir.DSTU2
https://www.nuget.org/packages/Hl7.Fhir.STU3

[wburgers]

@brianpos exactly the same problem here.
We would like to run both fhir versions next to each other.

[brianpos]

@wburgers i have a project using the extern alias trick https://github.com/brianpos/FhirPathTester but do have to set manually after inclusion. So can't wait for this to be fixed.

[JoseFMP]

+1, can't wait for this. I think this is important because right now different packages implementing same namespaces.

@brianpos could you share your trick please?

[fubar-coder]

IIRC you can configure NuGet to store the NuGet packages in an packages folder instead of using the cache in the users home folder using the NuGet.config. This allows you to manually specify project-relative assembly references (via Reference Update) which can include the alias. The problem with this approach is, that you have to update the reference whenever the package version changes. However, you can restore the packages into folders without the package version of you don't have conflicting package versions.

[JoseFMP]

Ok, so basically referencing the .dll quasi-manually and including then the alias, right? I was also thinking about that as a work around

[davkean]

As a side note, a workaround is to write a target that does something like this: https://github.com/dotnet/project-system/blob/master/build/Targets/VSL.Imports.targets#L340.

Here we're setting the EmbedInteropTypes metadata, but the same could be applied to alias.

[andymac4182]

It would be great if someone on the NuGet team could point in the right direction of the repo that requires the change. I am sure people are happy to look if they know where to look.

[davkean]

I think they'll need a design first, I don't see a flushed out proposal on syntax/behavior. Once we do that, we'll then need to work with the project systems (http://github.com/dotnet/project-system) and SDK (http://github.com/dotnet/project-system) to add/respect the property so that it can be passed to NuGet/show in Properties, etc, added to the <REference/> when we dynamically produce them, and then plumbed through pack (what does an aliased set of references do when we add the package as a reference in the nuspec?). Just to set expectations, this isn't a couple of lines change.

[davkean]

I'll help sponsor, point to the locations that need to change in SDK, ProjectSystem (NuGet team will need to jump in on the nuget side, as I don't have context), and driving this through, if a community member wants to pick up the design/changes.

[gertjvr]

After some experimentation and got it to work.

Placed the below snippet into my csproj file where I had both references of StackExchange.Redis and StackExchange.Redis.StrongName nuget dependencies.

<Target Name="ChangeAliasesOfStrongNameAssemblies" BeforeTargets="FindReferenceAssembliesForReferences;ResolveReferences">
    <ItemGroup>
      <ReferencePath Condition="'%(FileName)' == 'StackExchange.Redis.StrongName'">
        <Aliases>signed</Aliases>
      </ReferencePath>
    </ItemGroup>
  </Target>