Don't publish MSBuild assemblies in the NuGet package

[AndyGerlicher]

https://developercommunity.visualstudio.com/content/problem/208668/the-finddependenciesofexternallyresolvedreferences.html

Customers are reporting issues with projects that use SimpleStubs. We added a parameter to Resolve Assembly References (RAR) in 15.6 and the common targets were updated to use the new parameter. Since Etg.SimpleStubs packages MSBuild (currently 15.5.180) it will load DLLs from that location but common targets/toolset from the installed location.

Options:

1. Redistribute all of MSBuild. You need to define a toolset (see msbuild.exe.config) for things can be found. It would need all targets/tasks needed to do what you're trying to do. This is really hard to get right since VS installs stuff to the MSBuild extensions folder.
2. Dynamically load MSBuild at run-time. See https://www.nuget.org/packages/Microsoft.Build.Locator/1.0.7-preview-ge60d679b53
   Code/samples available here: https://github.com/Microsoft/MSBuildLocator

If you choose one, we'll continue to have this issue where we add features and things are out of sync. I can help out with 2 if needed. If you build the repo the sample app shows a simple build and prompts which VS to use (you probably don't want to prompt, but something similar).

[nehmebilal]

The reason I package MSBuild is because Roslyn needs the MSBuild dlls to work. I am not an MSBuild expert but there should be a way to allow Roslyn to link to the MSBuild dlls in the installed location directly. However, the problem would be for users who don't have that version of MSBuild installed.

[AndyGerlicher]

Can you at minimum publish a package with MSBuild 15.6 to unblock people?

[nehmebilal]

Yes, if Roslyn can work with 15.6. I will try to upgrade as soon as I find time and give it a try.

[DustinCampbell]

@nehmebilal: If you use the Microsoft.Build.Locator package that @AndyGerlicher mentioned, you do not need to deploy the MSBuild assemblies to make MSBuildWorkspace function. Instead, the locator will install an assembly resolution hook that will load the MSBuild assemblies from instance of MSBuild that you register. This will make your tool more resilient to changes in VS.

[nehmebilal]

@DustinCampbell my experience with Roslyn is that if I don’t add assembly redirects to specific version of MSBuild, it usually fails. That said, I will give it a try and see what happens.

[DustinCampbell]

I will look at producing a small sample app for you to demonstrate if it would help.

[nehmebilal]

That would definitely help. Thanks.

[DustinCampbell]

Here you go!

MSBuildWorkspaceSample.zip

This is just a simple WinForms app. It does the following:

1. Uses the Microsoft.Build.Locator package to register the default MSBuild instance on the machine.
2. Uses MSBuildWorkspace to open solutions and projects.
3. Dumps information to a text box.

You should be able to unzip the file, open MSBuildWorkspaceSample.sln in VS 2017, restore packages and F5. Note that it has a custom post-build step to delete the following assemblies from the output:

• Microsoft.Build.dll
• Microsoft.Build.Framework.dll
• Microsoft.Build.Tasks.Core.dll
• Microsoft.Build.Utilities.Core.dll

Let me know if you need additional help to get this up-and-running. Also, I should let you know that we are in the process of overhauling MSBuildWorkspace. This will be a major (and breaking!) update and is in PR here: dotnet/roslyn#21670.

[nehmebilal]

Thanks @DustinCampbell. I tried the tool and this is what I am seeing when I try to open a csproj:

Loading solution: C:\projects\SimpleStubs\test\TestClassLibraryTest\TestClassLibraryTest.csproj...
Loaded: 00:00:04.1057035

Errors:
[Failure] Msbuild failed when processing the file 'C:\projects\SimpleStubs\src\SimpleStubs\SimpleStubs.csproj' with message: The SDK 'Microsoft.NET.Sdk' specified could not be found.  C:\projects\SimpleStubs\src\SimpleStubs\SimpleStubs.csproj

Project: TestClassLibraryTest (8 document(s))

I tried on other projects and solutions and I see a similar message.

[DustinCampbell]

Could you provide the full output?

[DustinCampbell]

Note that the instance of MSBuild that is registered is important. If that particular MSBuild doesn't have all of the workloads installed that the project you're loading requires, MSBuild won't be able to process the project.

[nehmebilal]

MSBuild instances discovered:
1. Visual Studio Enterprise 2017 - 15.6.27428.2011

Registered: Visual Studio Enterprise 2017 - 15.6.27428.2011

Loading solution: C:\projects\SimpleStubs\test\TestClassLibraryTest\TestClassLibraryTest.csproj...
Loaded: 00:00:04.1057035

Errors:
[Failure] Msbuild failed when processing the file 'C:\projects\SimpleStubs\src\SimpleStubs\SimpleStubs.csproj' with message: The SDK 'Microsoft.NET.Sdk' specified could not be found.  C:\projects\SimpleStubs\src\SimpleStubs\SimpleStubs.csproj

Project: TestClassLibraryTest (8 document(s))

I recently updated visual studio to 15.6. I'll try to create a brand new project and test on.

[DustinCampbell]

Did you restore that project first? MSBuildWorkspace will not run a dotnet restore.