Use correct MSBuild SDK folder for .NET Core 3.0 and newer.

tintoy/msbuild-project-tools-vscode#46

.appveyor.yml

@@ -1,4 +1,4 @@
-version: 0.2.50.{build}
+version: 0.2.51.{build}
 image: Visual Studio 2017
 build_script:
 - ps: >-

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Change Log
 
+## v0.2.51
+
+* Use correct MSBuild SDK folder for .NET Core 3.0 and newer (tintoy/msbuild-project-tools-vscode#46).
+
 ## v0.2.50
 
 * Enable per-workspace override of `MSBuildExtensionsPath` and `MSBuildExtensionsPath32` (tintoy/msbuild-project-tools-vscode#35).

src/LanguageServer.Common/Utilities/MSBuildHelper.cs

@@ -1,6 +1,7 @@
 using Microsoft.Build.Construction;
 using Microsoft.Build.Evaluation;
 using Microsoft.Build.Exceptions;
+using NuGet.Versioning;
 using System;
 using System.Collections.Generic;
 using System.IO;
@@ -82,10 +83,16 @@ public static ProjectCollection CreateProjectCollection(string solutionDirectory
 
             ProjectCollection projectCollection = new ProjectCollection(globalProperties) { IsBuildEnabled = false };
 
+            SemanticVersion netcoreVersion;
+            if (!SemanticVersion.TryParse(runtimeInfo.Version, out netcoreVersion))
+                throw new FormatException($"Cannot parse .NET Core version '{runtimeInfo.Version}' (does not appear to be a valid semantic version).");
+
+            // For .NET Core 3.0 and newer, toolset version is simply "Current" instead of "15.0" (tintoy/msbuild-project-tools-vscode#46).
+            string toolsVersion = netcoreVersion.Major < 3 ? "15.0" : "Current";
+
             // Override toolset paths (for some reason these point to the main directory where the dotnet executable lives).
-            Toolset toolset = projectCollection.GetToolset("15.0");
-            toolset = new Toolset(
-                toolsVersion: "15.0",
+            Toolset toolset = projectCollection.GetToolset(toolsVersion);
+            toolset = new Toolset(toolsVersion,
                 toolsPath: runtimeInfo.BaseDirectory,
                 projectCollection: projectCollection,
                 msbuildOverrideTasksPath: ""