NuGet Static graph restore invoked on a slnf file restores excluded projects

[ViktorHofer]

NuGet Product Used

dotnet.exe

Product Version

8.0.100

Worked before?

no

Impact

I'm unable to use this version

Repro Steps & Context

Repro:
dotnet restore ttt.slnf -> only the projects listed in the slnf file are restored
dotnet restore ttt.slnf /p:RestoreUseStaticGraphEvaluation=true -> all projects listed in the sln file are restored

restorediff.zip

This impacts changes like dotnet/msbuild#9555 as when building from source, we must not restore more projects than necessary to not bring in prebuilts.

cc @jeffkl

Verbose Logs

No response

[nkolev92]

Team Triage: @jeffkl what would be the cost of fixing this?

[jeffkl]

Unfortunately, MSBuild does not expose the path to the solution filter during the build (dotnet/msbuild#6162). The way it currently works for regular restore is that MSBuild generates an in-memory .metaproj that contains a <ProjectReference /> to just the projects to build. Regular restore then walks those projects.

For static graph-based restore, MSBuild only passes along the path to the solution file and the path to the in-memory .metaproj:

For regular restore, since its running in the same process it has access to the in-memory .metaproj. Since static graph-based restore runs out-of-proc, it would need to either write the .metaproj to disk or pass along the path to the solution filter instead. It could also use reflection to get the path to the solution filter:

object buildRequest = BuildEngine.GetType().GetField("_requestEntry", BindingFlags.NonPublic | BindingFlags.Instance).GetValue(BuildEngine);
object buildRequestConfiguration = buildRequest.GetType().GetProperty("RequestConfiguration", BindingFlags.Public | BindingFlags.Instance).GetValue(buildRequest);
string solutionFilterFileFullPath = buildRequestConfiguration.GetType().GetProperty("ProjectFullPath", BindingFlags.Public | BindingFlags.Instance).GetValue(buildRequestConfiguration) as string;

So we need to either:

1. Update MSBuild to indicate the path to the solution filter being restored
2. Use reflection to get the path to the solution filter being restored

[nkolev92]

We use reflection in nuget.exe, but the bar is arguably lower there: https://github.com/NuGet/NuGet.Client/blob/d7607e2f08721498801ace7fe47933d4e6dfeffd/src/NuGet.Clients/NuGet.CommandLine/Common/Solution.cs#L120.