Add option to use MSBuild's graph to discover projects (#56)

Directory.Packages.props

@@ -2,6 +2,7 @@
   <ItemGroup>
     <PackageVersion Include="CommandLineParser" Version="2.9.1" />
     <PackageVersion Include="Microsoft.Build" Version="17.10.4" />
+    <PackageVersion Include="Microsoft.Build.Locator" Version="1.7.8" />
     <PackageVersion Include="Microsoft.Extensions.Logging" Version="8.0.0" />
     <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="17.10.0" />
     <PackageVersion Include="NuGet.Commands" Version="6.10.1" />

src/PackagesConfigConverter/PackagesConfigConverter.csproj

@@ -5,7 +5,8 @@
   </PropertyGroup>
   <ItemGroup>
     <PackageReference Include="CommandLineParser" />
-    <PackageReference Include="Microsoft.Build" />
+    <PackageReference Include="Microsoft.Build" ExcludeAssets="runtime" />
+    <PackageReference Include="Microsoft.Build.Locator" />
     <PackageReference Include="Microsoft.Extensions.Logging" />
     <PackageReference Include="NuGet.Commands" />
     <PackageReference Include="Serilog" />

src/PackagesConfigConverter/Program.cs

@@ -7,6 +7,7 @@
 using System.IO;
 using System.Threading;
 using CommandLine;
+using Microsoft.Build.Locator;
 using Microsoft.Extensions.Logging;
 using NuGet.Frameworks;
 using Serilog;
@@ -62,15 +63,24 @@ public static void Run(ProgramArguments arguments)
             using ILoggerFactory factory = LoggerFactory.Create(builder => builder.AddSerilog());
             ILogger logger = factory.CreateLogger("PackagesConfigConverter");
 
+            MSBuildLocator.RegisterDefaults();
+
             ProjectConverterSettings settings = new ProjectConverterSettings
             {
                 RepositoryRoot = arguments.RepoRoot,
                 Include = arguments.Include.ToRegex(),
                 Exclude = arguments.Exclude.ToRegex(),
+                Graph = arguments.Graph,
                 Log = logger,
                 TrimPackages = arguments.Trim,
             };
 
+            if (settings.Graph && settings.Include != null)
+            {
+                logger.LogError("Cannot specify using graph discovery and specific project inclusion.");
+                return;
+            }
+
             if (arguments.DefaultTargetFramework != null)
             {
                 settings.DefaultTargetFramework = NuGetFramework.Parse(arguments.DefaultTargetFramework);
@@ -79,6 +89,7 @@ public static void Run(ProgramArguments arguments)
             logger.LogInformation($" RepositoryRoot: '{settings.RepositoryRoot}'");
             logger.LogInformation($"  Include regex: '{settings.Include}'");
             logger.LogInformation($"  Exclude regex: '{settings.Exclude}'");
+            logger.LogInformation($"  Graph discovery: '{settings.Graph}'");
             logger.LogInformation(string.Empty);
 
             if (!arguments.Yes)

src/PackagesConfigConverter/ProgramArguments.cs

@@ -17,6 +17,9 @@ public class ProgramArguments
         [Option('i', HelpText = "Regex for project files to include", MetaValue = "regex")]
         public string Include { get; set; }
 
+        [Option('g', HelpText = "Whether to use the MSBuild graph to discover project files")]
+        public bool Graph { get; set; }
+
         [Option('l', HelpText = "Log file to write to", MetaValue = "log")]
         public string LogFile { get; set; }
 

src/PackagesConfigConverter/ProjectConverter.cs

@@ -11,6 +11,7 @@
 using System.Xml.Linq;
 using Microsoft.Build.Construction;
 using Microsoft.Build.Evaluation;
+using Microsoft.Build.Graph;
 using Microsoft.Extensions.Logging;
 using NuGet.Commands;
 using NuGet.Common;
@@ -87,9 +88,13 @@ public void ConvertRepository(CancellationToken cancellationToken)
 
             Log.LogInformation($"  NuGet configuration file : \"{_converterSettings.NuGetConfigPath}\"");
 
-            foreach (string file in Directory.EnumerateFiles(_converterSettings.RepositoryRoot, "*.csproj", SearchOption.AllDirectories)
-                .TakeWhile(_ => !cancellationToken.IsCancellationRequested))
+            foreach (string file in GetProjectFiles())
             {
+                if (cancellationToken.IsCancellationRequested)
+                {
+                    break;
+                }
+
                 if (_converterSettings.Exclude != null && _converterSettings.Exclude.IsMatch(file))
                 {
                     Log.LogDebug($"  Excluding file \"{file}\"");
@@ -142,6 +147,63 @@ private static ISettings GetNuGetSettings(ProjectConverterSettings converterSett
             return Settings.LoadDefaultSettings(converterSettings.RepositoryRoot, Settings.DefaultSettingsFileName, new XPlatMachineWideSetting());
         }
 
+        private IEnumerable<string> GetProjectFiles()
+        {
+            if (_converterSettings.Graph)
+            {
+                string entryProjectFile;
+
+                string[] rootSolutionFiles = Directory.GetFiles(_converterSettings.RepositoryRoot, "*.sln", SearchOption.TopDirectoryOnly);
+                if (rootSolutionFiles.Length > 1)
+                {
+                    Log.LogError("Found more than one sln file in the repo root. Cannot use graph discovery");
+                    return Array.Empty<string>();
+                }
+
+                if (rootSolutionFiles.Length == 1)
+                {
+                    entryProjectFile = rootSolutionFiles[0];
+                }
+                else
+                {
+                    string[] rootProjectFiles = Directory.GetFiles(_converterSettings.RepositoryRoot, "*.*proj", SearchOption.TopDirectoryOnly);
+                    if (rootProjectFiles.Length > 1)
+                    {
+                        Log.LogError("Found more than one project file in the repo root. Cannot use graph discovery");
+                        return Array.Empty<string>();
+                    }
+
+                    if (rootProjectFiles.Length == 1)
+                    {
+                        entryProjectFile = rootProjectFiles[0];
+                    }
+                    else
+                    {
+                        Log.LogError("Did not find any solutions or projects in the repo root. Cannot use graph discovery");
+                        return Array.Empty<string>();
+                    }
+                }
+
+                // Using a set to avoid duplicates due to inner/outer builds. Sorting for a consistent ordering.
+                SortedSet<string> projectFiles = new(StringComparer.OrdinalIgnoreCase);
+                ProjectGraph graph = new(entryProjectFile);
+                foreach (ProjectGraphNode node in graph.ProjectNodes)
+                {
+                    string projectFile = node.ProjectInstance.FullPath;
+                    if (projectFile.EndsWith(".csproj", StringComparison.OrdinalIgnoreCase))
+                    {
+                        projectFiles.Add(projectFile);
+                    }
+                }
+
+                return projectFiles;
+            }
+            else
+            {
+                return Directory.EnumerateFiles(_converterSettings.RepositoryRoot, "*.csproj", SearchOption.AllDirectories);
+            }
+        }
+
         private ProjectItemElement AddPackageReference(ProjectItemGroupElement itemGroupElement, PackageUsage package, LockFileTargetLibrary lockFileTargetLibrary, bool isDevelopmentDependency)
         {
             LibraryIncludeFlags existingAssets = LibraryIncludeFlags.None;

src/PackagesConfigConverter/ProjectConverterSettings.cs

@@ -14,6 +14,8 @@ public sealed class ProjectConverterSettings
 
         public Regex Include { get; set; }
 
+        public bool Graph { get; set; }
+
         public ILogger Log { get; set; }
 
         public string NuGetConfigPath { get; set; } = "(Default)";