How to evaluate a project while resolving its imports?

[teo-tsirpanis]

MSBuild has APIs to just evaluate a project's properties and items without building it (being aware of the disclaimers of #1285) but these do not take into accound any properties that are defined in any of the project's Imports.

I have thought of the following workaround: I will tell the BuildManager to build a nonexistent target, while passing BuildRequestDataFlags.SkipNonexistentTargets in the BuildRequestData.

My questions are:

1. Is there anything problematic with the approach I described? MSBuild will fully evaluate the project file and "run" a target that does not exist, ignoring it as I told. The default target will be prevented from running.

2. How about concurrency? It seems to me that the BuildManager class is not thread-safe. So instead of locking around its use, I have thought of creating and reusing BuildManager per thread. Is that good? Documentation says that "Normally there is only one build manager in a process, and it is the default build manager." but doesn't say what would happen if more than one build managers exist.

[rainersigwald]

these do not take into accound any properties that are defined in any of the project's Imports

What makes you think that?

[teo-tsirpanis]

I tested it with a project file of mine.

Perhaps it wasn't fully evaluated because the imports were implicitly defined from the SDK; not an Imports declaration.

Edit: Yes, regular Imports are recognized from the Project class.

[rainersigwald]

@teo-tsirpanis How are you loading the MSBuild API? Are you using MSBuildLocator? I don't see that behavior:

using System;
using Microsoft.Build.Evaluation;

namespace _5819
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Hello World!");

            Microsoft.Build.Locator.MSBuildLocator.RegisterDefaults();

            LoadProject();
        }

        private static void LoadProject()
        {
            Project p = new Project(@"S:\repro\dotnet\msbuild\issues\5819\5819.csproj");

            Console.WriteLine($" {p.Properties.Count} total properties");
        }
    }
}

On its own project produces

❯ dotnet run -f net48
Hello World!
 339 total properties

even though only 3 are defined in the project file itself.

[teo-tsirpanis]

@rainersigwald, yes I am using MSBuildLocator.

I ran my code again and it works. MSBuild finds the SDK imports even when the project is not restored. I don't know what had gone wrong in my first attempt.

For my use case (ionide/proj-info#87) I will keep using ProjectInstance instead of Project because sometimes we might need to run some targets on the project, but I won't keep doing the dummy target trick.

Still I would like to know whether my approach to concurrency I illustrated in my second bullet point in OP has any problems.