Restore with static graph evaluation fails with an NRE when a `TargetFramework` is specified

[nkolev92]

Take the following project for example:

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

  <PropertyGroup>
    <TargetFrameworks>netstandard2.0;net5.0</TargetFrameworks>
  </PropertyGroup>

</Project>

Run the following command:

msbuild /t:restore /p:TargetFramework="net5.0" /p:RestoreUseStaticGraphEvaluation="true"

Actual

See output below.

C:\Code\Temp\MultiTargetted [master]> msbuild /t:restore /p:TargetFramework="net5.0" /p:RestoreUseStaticGraphEvaluation="true"
Microsoft (R) Build Engine version 17.2.0-preview-22116-01+7d926d7ab for .NET Framework
Copyright (C) Microsoft Corporation. All rights reserved.

Build started 20-Apr-22 5:09:34 PM.
Project "C:\Code\Temp\MultiTargetted\MultiTargetted.csproj" on node 1 (Restore target(s)).
Restore:
  Determining projects to restore...
  Evaluated 1 project(s) in 1259ms (1 builds, 0 failures).
C:\Program Files\Microsoft Visual Studio\2022\Preview\Common7\IDE\CommonExtensions\Microsoft\NuGet\NuGet.RestoreEx.targets(19,5): error : Object reference not set to an instance of an object. [C:\Code\Temp\MultiTargetted\MultiTargetted.
csproj]
Done Building Project "C:\Code\Temp\MultiTargetted\MultiTargetted.csproj" (Restore target(s)) -- FAILED.


Build FAILED.

"C:\Code\Temp\MultiTargetted\MultiTargetted.csproj" (Restore target) (1) ->
(Restore target) ->
  C:\Program Files\Microsoft Visual Studio\2022\Preview\Common7\IDE\CommonExtensions\Microsoft\NuGet\NuGet.RestoreEx.targets(19,5): error : Object reference not set to an instance of an object. [C:\Code\Temp\MultiTargetted\MultiTargette
d.csproj]

    0 Warning(s)
    1 Error(s)

Time Elapsed 00:00:02.11

Run it without static graph, and note that there's no failure.

msbuild /t:restore /p:TargetFramework="net5.0"

Expected

C:\Code\Temp\MultiTargetted [master]> msbuild /t:restore /p:TargetFramework="net5.0"
Microsoft (R) Build Engine version 17.2.0-preview-22116-01+7d926d7ab for .NET Framework
Copyright (C) Microsoft Corporation. All rights reserved.

Build started 20-Apr-22 5:09:39 PM.
Project "C:\Code\Temp\MultiTargetted\MultiTargetted.csproj" on node 1 (Restore target(s)).
_GetAllRestoreProjectPathItems:
  Determining projects to restore...
Restore:
  Assets file has not changed. Skipping assets file writing. Path: C:\Code\Temp\MultiTargetted\obj\project.assets.json
  Restored C:\Code\Temp\MultiTargetted\MultiTargetted.csproj (in 81 ms).

  NuGet Config files used:
      C:\Code\NuGet.Config
      C:\Users\Roki2\AppData\Roaming\NuGet\NuGet.Config
      C:\Program Files (x86)\NuGet\Config\Microsoft.VisualStudio.FallbackLocation.config
      C:\Program Files (x86)\NuGet\Config\Microsoft.VisualStudio.Offline.config

  Feeds used:
      https://api.nuget.org/v3/index.json
      C:\Program Files\dotnet\library-packs
  All projects are up-to-date for restore.
Done Building Project "C:\Code\Temp\MultiTargetted\MultiTargetted.csproj" (Restore target(s)).


Build succeeded.
    0 Warning(s)
    0 Error(s)

Time Elapsed 00:00:00.79

Discovered this while working on #11653.

Note that when fixing this, we might need to do the same thing as the fix in #11653

[nkolev92]

cc @jeffkl

Did some quick debugging, and we basically end up with a project with nodes, but no outer node as TargetFramework is always set globally, so technically we can't discover an outer build project.

[jeffkl]

Possible duplicate of #11680. Basically, static graph doesn't give NuGet the full representation of the project graph when you specify a TargetFramework because it doesn't think it needs to enumerate the values of TargetFrameworks. I think we'll need to update MSBuild static graph to have a mode where it always loads the full graph even if it could get a scoped version.

[jeffkl]

@nkolev92 can you try this and tell me what happens?

msbuild /t:restore /Property:TargetFramework=net472 /RestoreProperty:Foo=bar

By specifying a /RestoreProperty, MSBuild does not pass the /Property global property to restore, only Foo=Bar.

[nkolev92]

That does workaround it.

[jeffkl]

Maybe for implicity restore /restore in MSBuild, we can block certain global properties from getting through which we know aren't really applicable. Or on NuGet's side we could ignore these properties that don't apply.

[nkolev92]

Not sure what you mean by ignoring certain properties.

I have a PR that might provide you some context about how I discovered this: NuGet/NuGet.Client#4587