nupkgs produced by building .NET 10 alpha are unusable

[arrowd]

Describe the Bug

I'm building dotnet/dotnet@ceda881 using .NET 9.0.10 (see below why I'm doing this). The process successfully produces the Private.SourceBuilt.Artifacts.10.0.100-alpha.1.24530.1 archive. Then I use these 10.0.100-alpha.1.24530.1 artifacts and SDK to build the latest 10.0 RC, but it quickly fails with errors like

/wrkdirs/usr/ports/lang/dotnet-devel/work/dotnet-10.0.100-rc.2.25502.107/eng/tools/tasks/Microsoft.DotNet.UnifiedBuild.MSBuildSdkResolver/Microsoft.DotNet.UnifiedBuild.MSBuildSdkResolver.csproj : error NU1103: Unable to find a stable package System.CodeDom with version (>= 9.0.9)
/wrkdirs/usr/ports/lang/dotnet-devel/work/dotnet-10.0.100-rc.2.25502.107/eng/tools/tasks/Microsoft.DotNet.UnifiedBuild.MSBuildSdkResolver/Microsoft.DotNet.UnifiedBuild.MSBuildSdkResolver.csproj : error NU1103:   - Found 4 version(s) in /wrkdirs/usr/ports/lang/dotnet-devel/work/packages/ [ Nearest version: 10.0.0-alpha.1.24528.7 ]
/wrkdirs/usr/ports/lang/dotnet-devel/work/dotnet-10.0.100-rc.2.25502.107/eng/tools/tasks/Microsoft.DotNet.UnifiedBuild.MSBuildSdkResolver/Microsoft.DotNet.UnifiedBuild.MSBuildSdkResolver.csproj : error NU1103:   - Found 0 version(s) in /wrkdirs/usr/ports/lang/dotnet-devel/work/bootstrap_sdk/library-packs
/wrkdirs/usr/ports/lang/dotnet-devel/work/dotnet-10.0.100-rc.2.25502.107/eng/tools/tasks/Microsoft.DotNet.UnifiedBuild.MSBuildSdkResolver/Microsoft.DotNet.UnifiedBuild.MSBuildSdkResolver.csproj : error NU1103:   - Found 0 version(s) in /wrkdirs/usr/ports/lang/dotnet-devel/work/dotnet-10.0.100-rc.2.25502.107/prereqs/packages/prebuilt/

From what I read in NU1103 error's description, this happens because -alpha versions are not considered during the dependency resolution. However, unpacking some .nupkgs from Private.SourceBuilt.Artifacts.10.0.100-alpha.1.24530.1 reveals, that dependencies listed in their .nuspecs have 9.0.9 for some reason:

Microsoft.Build.Tasks.Core.17.13.0-preview-24529-04.nupkg/Microsoft.Build.Tasks.Core.nuspec:        <dependency id="System.CodeDom" version="9.0.9" exclude="Build,Analyzers" />

Why I'm doing this

The platform I'm compiling on is FreeBSD. We do not have a luxury of using prebuilt .NET binaries that are usually used for bootstrapping the VMR build. Since it isn't possible to build the latest .NET 10 RC using the latest .NET 9, I tried to perform the bootstrapping in multiple steps. The ceda881686f48350dc079304ff15edcbeda6c5e3 can be built with .NET 9, but using it for further builds results in a problem described above.

[MichaelSimons]

@arrowd, What you are attempting is not supported. There is not a supported path where you can build 10 from previously source-built 9.0 assets. The .NET team allows the use of the in-development features before they are released during previews. This requires distro maintainers to have to re-bootstrap on every major release.

[arrowd]

How do I proceed, then? How were the first v10 Linux prebuilts produced anyways?

[MichaelSimons]

How do I proceed, then? How were the first v10 Linux prebuilts produced anyways?

You would have to bootstrap with the Microsoft SDK and artifacts.

https://github.com/dotnet/source-build/blob/main/Documentation/bootstrapping-guidelines.md#building-on-a-supported-platform-using-rid-known-to-net

[arrowd]

There are no SDKs for FreeBSD produced by Microsoft. How are these SDKs produced?

[MichaelSimons]

There are no SDKs for FreeBSD produced by Microsoft. How are these SDKs produced?

Would likely have to build your own since it is community supported or utilize others mentioned in #1139 (comment) and dotnet/runtime#102377