msbuild-resolve.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices;
using Microsoft.VisualStudio.Setup.Configuration;
 
namespace LocateMSBuild
{
    public class Instance
    {
 
        private static ISetupConfiguration GetSetupConfiguration()
        {
            ISetupConfiguration setupConfiguration;
 
            try
            {
                setupConfiguration = new SetupConfiguration();
            }
            catch (COMException comException) when (comException.HResult == unchecked((int)0x80040154))
            {
                Console.WriteLine("COM registration is missing, Visual Studio may not be installed correctly");
                throw;
            }
 
            return setupConfiguration;
        }
 
        private static IEnumerable<ISetupInstance> EnumerateVisualStudioInstances()
        {
            var setupConfiguration = GetSetupConfiguration() as ISetupConfiguration2;
 
            var instanceEnumerator = setupConfiguration.EnumAllInstances();
            var instances = new ISetupInstance[3];
 
            var instancesFetched = 0;
            instanceEnumerator.Next(instances.Length, instances, out instancesFetched);
 
            if (instancesFetched == 0)
            {
                throw new Exception("There were no instances of Visual Studio 15.0 or later found.");
            }
 
            do
            {
                for (var index = 0; index < instancesFetched; index++)
                {
                    yield return instances[index];
                }
 
                instanceEnumerator.Next(instances.Length, instances, out instancesFetched);
            }
            while (instancesFetched != 0);
        }
 
        private static ISetupInstance LocateVisualStudioInstance(string vsProductVersion, HashSet<string> requiredPackageIds)
        {
            var instances = EnumerateVisualStudioInstances().Where((instance) => instance.GetInstallationVersion().StartsWith(vsProductVersion));
 
            var instanceFoundWithInvalidState = false;
 
            foreach (ISetupInstance2 instance in instances.OrderByDescending(i => i.GetInstallationVersion()))
            {
                var packages = instance.GetPackages()
                                        .Where((package) => requiredPackageIds.Contains(package.GetId()));
 
                if (packages.Count() != requiredPackageIds.Count)
                {
                    continue;
                }
 
                const InstanceState minimumRequiredState = InstanceState.Local | InstanceState.Registered;
 
                var state = instance.GetState();
 
                if ((state & minimumRequiredState) == minimumRequiredState)
                {
                    return instance;
                }
 
                Console.WriteLine($"An instance matching the specified requirements but had an invalid state. (State: {state})");
                instanceFoundWithInvalidState = true;
            }
 
            throw new Exception(instanceFoundWithInvalidState ?
                                "An instance matching the specified requirements was found but it was in an invalid state." :
                                "There were no instances of Visual Studio 15.0 or later found that match the specified requirements.");
        }
 
        public static string GetMsBuildInstallPath()
        {
            var instance = LocateVisualStudioInstance("15.0", new HashSet<string>(new[] { "Microsoft.Component.MSBuild" })) as ISetupInstance2;
            var installationPath = instance.GetInstallationPath();
            return Path.Combine(installationPath, "MSBuild", "15.0");
        }
    }
}

Using in Powershell

function Locate-MsBuildInstallPath {
  $locateVsApi = Locate-LocateMsBuildApi
  Add-Type -path $locateVsApi
  $vsInstallPath = [LocateMSBuild.Instance]::GetMsBuildInstallPath()
  return Resolve-Path -path $vsInstallPath
}