Thank you! Could you make the new logic conditional on some property so people who want to use Zig that they already have installed can do so (and the NuGet doesn't download)? Would you mind updating the README.md too?

Done. PTAL.

I tried this out in a Windows Sandbox and it doesn't quite work (the package doesn't get downloaded and the property that should have path to the package is empty). I think it's because one cannot reference new NuGets from a .targets that is in a NuGet itself. NuGet restore doesn't see it and it kind of makes sense. NuGet restore is a different codepath from what the test project in this repo uses :/.

I'm wondering how does the Microsoft.DotNet.ILCompiler package handle this correctly to download the corresponding runtime package?

There's some special logic for that in the sdk.

I think nuget has a way to express this package depends on something else in the package metadata. That's the normal way. Ilcompiler is definitely not normal in this sense, don't look at that

AFAIK the (undocumented) runtime.json file in a NuGet package is the only way to express this notion. It's what e.g. LLVMSharp and ClangSharp do as well. This is for target RID, not host RID.

Adding a note of what I wrote on Discord: can we build this in a way that requires users to add Vezel.Zig.Toolsets.XXX manually? The targets can detect whether this nuget is present. If it is, use Zig from there. If it isn't, use zig from environment. If no zig is found, suggest to the user to either download zig manually and add to their path, or add a reference to the Vezel.Zig.Toolsets.XXX nuget.

Adding a note of what I wrote on Discord: can we build this in a way that requires users to add Vezel.Zig.Toolsets.XXX manually?

It seems like that's the least painful way forward. Those packages will set ZigExePath, which PublishAotCross can check for and use.

I think we'd need some docs to point to that would explain that the recommended usage pattern for those packages is something like:

<Project Sdk="Microsoft.NET.Sdk">
    ...

    <ItemGroup>
       <PackageReference Include="Vezel.Zig.Toolsets.$(NETCoreSdkPortableRuntimeIdentifier)"
                         Version="0.12.0.*"
                         PrivateAssets="all" />
    </ItemGroup>

    ...
</Project>

That can probably just go in the README or something.

Looks great, any progress on this PR?