Add support for file-based apps to the XPlat CLI

src/NuGet.Core/NuGet.CommandLine.XPlat/IVirtualProjectBuilder.cs

@@ -0,0 +1,40 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+#nullable enable
+
+using System;
+using System.IO;
+using System.Linq;
+using System.Reflection;
+using Microsoft.Build.Construction;
+using Microsoft.Build.Evaluation;
+
+namespace NuGet.CommandLine.XPlat;
+
+/// <summary>
+/// We cannot have a dependency on a package from SDK due to source build,
+/// hence we invert the relationship and define the interface here,
+/// SDK implements it and we load the implementation dynamically.
+/// </summary>
+public interface IVirtualProjectBuilder
+{
+    bool IsValidEntryPointPath(string entryPointFilePath);
+
+    ProjectRootElement CreateProjectRootElement(string entryPointFilePath, ProjectCollection projectCollection);
+
+    internal static IVirtualProjectBuilder? TryLoad()
+    {
+        var assemblyPath = Path.Join(AppContext.BaseDirectory, "dotnet.dll");
+
+        if (!File.Exists(assemblyPath))
+        {
+            return null;
+        }
+
+        var type = Assembly.LoadFile(assemblyPath)
+            .GetExportedTypes()
+            .FirstOrDefault(static t => t.IsAssignableTo(typeof(IVirtualProjectBuilder)));
+        return type != null ? (IVirtualProjectBuilder?)Activator.CreateInstance(type) : null;
+    }
+}

src/NuGet.Core/NuGet.CommandLine.XPlat/PublicAPI.Unshipped.txt

@@ -1 +1,4 @@
 #nullable enable
+NuGet.CommandLine.XPlat.IVirtualProjectBuilder
+NuGet.CommandLine.XPlat.IVirtualProjectBuilder.CreateProjectRootElement(string! entryPointFilePath, Microsoft.Build.Evaluation.ProjectCollection! projectCollection) -> Microsoft.Build.Construction.ProjectRootElement!
+NuGet.CommandLine.XPlat.IVirtualProjectBuilder.IsValidEntryPointPath(string! entryPointFilePath) -> bool

src/NuGet.Core/NuGet.CommandLine.XPlat/Utility/MSBuildAPIUtility.cs

@@ -725,7 +725,6 @@ internal static List<FrameworkPackages> GetResolvedVersions(
                 throw new ArgumentNullException(nameof(assetsFile));
             }
 
-            var projectPath = project.FullPath;
             var resultPackages = new List<FrameworkPackages>();
             var requestedTargetFrameworks = assetsFile.PackageSpec.TargetFrameworks;
             var requestedTargets = assetsFile.Targets;
@@ -781,7 +780,7 @@ internal static List<FrameworkPackages> GetResolvedVersions(
 
                 //The packages for the framework that were retrieved with GetRequestedVersions
                 var frameworkDependencies = tfmInformation.Dependencies;
-                var projectPackages = GetPackageReferencesFromTargets(projectPath, tfmInformation.ToString());
+                var projectPackages = GetPackageReferencesFromTargets(project, tfmInformation.ToString());
                 var topLevelPackages = new List<InstalledPackageReference>();
                 var transitivePackages = new List<InstalledPackageReference>();
 
@@ -808,7 +807,7 @@ internal static List<FrameworkPackages> GetResolvedVersions(
                             }
                             catch (Exception)
                             {
-                                throw new InvalidOperationException(string.Format(CultureInfo.CurrentCulture, Strings.ListPkg_ErrorReadingReferenceFromProject, projectPath));
+                                throw new InvalidOperationException(string.Format(CultureInfo.CurrentCulture, Strings.ListPkg_ErrorReadingReferenceFromProject, project.FullPath));
                             }
                         }
                         else
@@ -900,18 +899,18 @@ private static IEnumerable<ProjectItem> GetPackageReferences(Project project, Li
         /// <summary>
         /// Returns all package references after invoking the target CollectPackageReferences.
         /// </summary>
-        /// <param name="projectPath"> Path to the project for which the package references have to be obtained.</param>
+        /// <param name="project">The project for which the package references have to be obtained.</param>
         /// <param name="framework">Framework to get reference(s) for</param>
         /// <returns>List of Items containing the package reference for the package.
         /// If the libraryDependency is null then it returns all package references</returns>
-        private static IEnumerable<InstalledPackageReference> GetPackageReferencesFromTargets(string projectPath, string framework)
+        private static IEnumerable<InstalledPackageReference> GetPackageReferencesFromTargets(Project project, string framework)
         {
             var globalProperties = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
                 {
                     { "TargetFramework", framework },
                     { "ExcludeRestorePackageImports", bool.TrueString }
                 };
-            var newProject = new ProjectInstance(projectPath, globalProperties, null);
+            var newProject = new ProjectInstance(project.Xml, globalProperties, null, ProjectCollection.GlobalProjectCollection);
             newProject.Build(new[] { CollectPackageReferences, CollectCentralPackageVersions }, new List<Microsoft.Build.Framework.ILogger> { }, out var targetOutputs);
 
             // Find the first target output that matches `CollectPackageReferences`
@@ -1040,6 +1039,12 @@ private static IEnumerable<string> GetProjectFrameworks(Project project)
 
         private static ProjectRootElement TryOpenProjectRootElement(string filename)
         {
+            var virtualProjectBuilder = IVirtualProjectBuilder.TryLoad();
+            if (virtualProjectBuilder != null && virtualProjectBuilder.IsValidEntryPointPath(filename))
+            {
+                return virtualProjectBuilder.CreateProjectRootElement(filename, ProjectCollection.GlobalProjectCollection);
+            }
+
             try
             {
                 // There is ProjectRootElement.TryOpen but it does not work as expected