Cannot transitively reference a csproj+project.json

[gulbanana]

Steps to reproduce

1. Clone https://github.com/gulbanana/repro-transitive-projectjson
2. dotnet build
3. error MSB4025: The project file could not be loaded. Data at the root level is invalid. Line 1, position 1.

The bug also occurs when building in Visual Studio.

[gulbanana]

I've verified that the problem also happens when building with full-framework commandline MSBuild (version 15.1.1012.6693)

[livarcocc]

@AndyGerlicher @rainersigwald can you guys help take a look?

@gulbanana please note that this will not work through dotnet build, as the CLI does not support old style csproj files.

[rainersigwald]

I don't see this with msbuild /t:restore && msbuild in that repo. Can you share a diagnostic log? What file is allegedly invalid, and what are its contents?

[gulbanana]

Oh wow, i had unpushed commits in my local copy of the repo.. sorry, it should reproduce now!

Here's the output of msbuld /t:restore && msbuild /v:diag: https://gist.github.com/gulbanana/40d54c41f83a73bfc7aa6ad8c68ffef5

The content of the project.json file which is claimed to be invalid:

{
  "runtimes": {
    "win": {}
  },

  "frameworks": {
    "net461": {}
  },

  "dependencies": {
    "Newtonsoft.Json": "9.0.1"
  }
}

My guess is that the MSB4025 error indicates it's trying to load the project.json as an msbuild project file, which of course won't work.

[rainersigwald]

With that I'm now able to reproduce this, thanks.

You're right--the SDK includes transitive project references as ProjectReferences, which are then built with the <MSBuild> task, which then errors because in this case, the reference is a path to the project.json file, rather than the %(ResolvedPath), which is the path to the .csproj. See 11821-11833 in your log.

It looks like this was done intentionally in #478, but I don't know the full implications. @emgarten, is this a problem in the SDK layer, or is NuGet reporting bad information here?

[emgarten]

This looks like the same issue as #922

The error there is:

3>E:\dotnetsdkerror\ClassLibrary1\project.json(1,1): error MSB4025: The project file could not be loaded. Data at the root level is invalid. Line 1, position 1.
3>Done building project "project.json" -- FAILED.

The workaround for this is to reference the project directly instead of getting it as a transitive project reference.

[gulbanana]

That workaround works (around) for me.

[livarcocc]

Let's track it though #922.