Visual Studio Build 不会在没有项目引用的情况下下载所有 NuGet 包

Question

I'm trying to understand why removing a project reference prevents my build from downloading all the NuGet packages it needs. This is with Visual Studio 2019

• Application A (.NET 5) holds a project reference to Assembly B.
• Assembly B uses a NuGet package C.
• When the build starts, NuGet Package C get downloaded automatically.

This is all vanilla expected, .NET stuff.

But then I realized that A does not actually use any B-specific types. B is a Prism Module that only loads dynamically if the user has a license for it and clicks a button. So A doesn't even always load "B".

So I removed A's project reference to B. I don't want some future developer to accidentally think they can start referring to types in B. (We don't ship all modules all the time). Technically now, there is no project in the solution that holds a reference to B. But it's still part of the build. I did set up the build dependencies so that B would still build before A but there's no longer a project reference..

Then I did a clean build. Visual Studio said it completed successfully. And I see Assembly B got built. But the build process did NOT retrieve NuGet package C (that B depends on). Testing has revealed it will not retrieve C unless application A actually holds a project reference to B.

Is there some way around this? If I'm building all assemblies, why would MSBuild not download all assemblies dependent NuGet packages. Is there some setting I can change to make it happen.

Answer 1

Answering my own question: I asked this question of Microsoft. They said that this behavior is by design: If a DLL-generating assembly ("B") uses a NuGet package, then the only way that package will be downloaded at build time is if an assembly that generates an EXE has a project reference to B. Merely having a build dependency is not enough.

No explanation as to why. I still think the behavior should be different for reasons I mentioned in the question and comments above. They said it is a question for the .NET team and referred it to them but I see no action on it so far. If I get a response, I'll post it here.