address feedback

Author: nkolev92

src/NuGet.Core/NuGet.Commands/RestoreCommand/LockFileBuilder.cs

@@ -162,7 +162,7 @@ public LockFile CreateLockFile(LockFile previousLockFile,
                 .OrderBy(graph => graph.Framework.ToString(), StringComparer.Ordinal)
                 .ThenBy(graph => graph.RuntimeIdentifier, StringComparer.Ordinal))
             {
-                var target = lockFile.Version >= 4 ?
+                var target = lockFile.Version >= LockFileFormat.AliasedVersion ?
                     new LockFileTarget
                     {
                         TargetFramework = targetGraph.Framework,
@@ -399,7 +399,7 @@ private static string GetFallbackFrameworkString(NuGetFramework framework)
 
         private static void AddProjectFileDependenciesForPackageReference(PackageSpec project, LockFile lockFile, List<RestoreTargetGraph> targetGraphs)
         {
-            bool isV4LockFile = lockFile.Version >= 4;
+            bool isAliasedLockFile = lockFile.Version >= LockFileFormat.AliasedVersion;
 
             foreach (var frameworkInfo in project.TargetFrameworks
                 .OrderBy(framework => framework.TargetAlias,
@@ -440,7 +440,7 @@ private static void AddProjectFileDependenciesForPackageReference(PackageSpec pr
                 }
 
                 // Add entry
-                string framework = (isV4LockFile && !string.IsNullOrEmpty(frameworkInfo.TargetAlias)) ? frameworkInfo.TargetAlias : frameworkInfo.FrameworkName.ToString();
+                string framework = (isAliasedLockFile && !string.IsNullOrEmpty(frameworkInfo.TargetAlias)) ? frameworkInfo.TargetAlias : frameworkInfo.FrameworkName.ToString();
                 var dependencyGroup = new ProjectFileDependencyGroup(
                     framework,
                     uniqueDependencies.Select(x => x.ToLockFileDependencyGroupString())

src/NuGet.Core/NuGet.Commands/RestoreCommand/RequestFactory/RestoreArgs.cs

@@ -205,8 +205,8 @@ public void ApplyStandardProperties(RestoreRequest request)
 
             request.RequestedRuntimes.UnionWith(Runtimes);
             request.FallbackRuntimes.UnionWith(FallbackRuntimes);
-            // Use v3 for classic csproj.
-            request.LockFileVersion = request.Project.RestoreMetadata?.UsingMicrosoftNETSdk == true ? LockFileFormat.Version : 3;
+            // Use legacy version for classic csproj.
+            request.LockFileVersion = request.Project.RestoreMetadata?.UsingMicrosoftNETSdk == true ? LockFileFormat.Version : LockFileFormat.LegacyVersion;
 
             // Run runtime asset checks for project.json, and for other types if enabled.
             if (ValidateRuntimeAssets == null)

src/NuGet.Core/NuGet.Commands/RestoreCommand/RestoreCommand.cs

@@ -153,12 +153,12 @@ public RestoreCommand(RestoreRequest request)
             _request = request ?? throw new ArgumentNullException(nameof(request));
             _lockFileBuilderCache = request.LockFileBuilderCache;
 
-            // Validate the lock file version requested
-            if (_request.LockFileVersion < 3 || _request.LockFileVersion > LockFileFormat.Version)
+            // Validate the assets file version requested
+            if (_request.LockFileVersion < LockFileFormat.LegacyVersion || _request.LockFileVersion > LockFileFormat.Version)
             {
                 throw new ArgumentOutOfRangeException(
                     paramName: nameof(request),
-                    message: $"Lock file version {_request.LockFileVersion} is not supported.");
+                    message: $"Assets file version {_request.LockFileVersion} is not supported.");
             }
 
             var collectorLoggerHideWarningsAndErrors = request.Project.RestoreSettings.HideWarningsAndErrors

src/NuGet.Core/NuGet.Commands/RestoreCommand/SourceRepositoryDependencyProvider.cs

@@ -341,8 +341,8 @@ public Task<LibraryDependencyInfo> GetDependenciesAsync(
 
             cancellationToken.ThrowIfCancellationRequested();
 
-            // Pass an empty alias since aliases are not supported for packages.
-            LibraryRangeCacheKey key = new(libraryIdentity, targetFramework, alias: string.Empty);
+            // Aliases are not supported for packages.
+            LibraryRangeCacheKey key = new(libraryIdentity, targetFramework, alias: null);
 
             return _dependencyInfoCache.GetOrAddAsync(
                 key,

src/NuGet.Core/NuGet.Commands/RestoreCommand/Utility/SpecValidationUtility.cs

@@ -216,11 +216,13 @@ private static void ValidateProjectSpecPackageReference(PackageSpec spec, IEnume
                 throw RestoreSpecException.Create(message, files);
             }
 
+            List<string> aliases = (spec.TargetFrameworks.Count > 1 || spec.RestoreMetadata.TargetFrameworks.Count > 1) ?
+                spec.TargetFrameworks.Select(e => e.TargetAlias).ToList()
+                : [];
+
             //OriginalTargetFrameworks must match the aliases.
             if (spec.RestoreMetadata.TargetFrameworks.Count > 1)
             {
-                var aliases = spec.TargetFrameworks.Select(e => e.TargetAlias).ToList();
-
                 if (!EqualityUtility.OrderedEquals(aliases, spec.RestoreMetadata.OriginalTargetFrameworks, e => e, StringComparer.OrdinalIgnoreCase, StringComparer.OrdinalIgnoreCase))
                 {
                     var message = string.Format(
@@ -235,7 +237,6 @@ private static void ValidateProjectSpecPackageReference(PackageSpec spec, IEnume
 
             if (spec.TargetFrameworks.Count > 1)
             {
-                var aliases = spec.TargetFrameworks.Select(e => e.TargetAlias).ToList();
                 var uniqueAliases = new HashSet<string>(aliases, StringComparer.OrdinalIgnoreCase);
 
                 if (uniqueAliases.Count != aliases.Count)

src/NuGet.Core/NuGet.DependencyResolver.Core/LibraryRangeCacheKey.cs

@@ -17,7 +17,7 @@ namespace NuGet.DependencyResolver
         public LibraryRangeCacheKey(LibraryRange range, NuGetFramework framework, string? alias)
         {
             Framework = framework;
-            Alias = alias;
+            Alias = alias ?? string.Empty;
             LibraryRange = range;
         }
 
@@ -52,7 +52,7 @@ public bool Equals(LibraryRangeCacheKey other)
         {
             return LibraryRange.Equals(other.LibraryRange)
                 && Framework.Equals(other.Framework)
-                && StringComparer.Ordinal.Equals(Alias, other.Alias);
+                && StringComparer.OrdinalIgnoreCase.Equals(Alias, other.Alias);
         }
 
         public override string ToString()

src/NuGet.Core/NuGet.DependencyResolver.Core/Remote/RemoteDependencyWalker.cs

@@ -93,7 +93,7 @@ private async ValueTask<GraphNode<RemoteResolveResult>> CreateGraphNodeAsync(
                 libraryRange,
                 framework,
                 runtimeName,
-                string.Empty,
+                targetAlias: null,
                 _context,
                 CancellationToken.None);
 
@@ -171,7 +171,7 @@ private async ValueTask<GraphNode<RemoteResolveResult>> CreateGraphNodeAsync(
                                     dependencyLibraryRange,
                                     framework,
                                     runtimeName,
-                                    string.Empty,
+                                    targetAlias: null,
                                     _context,
                                     CancellationToken.None);
 

src/NuGet.Core/NuGet.ProjectModel/LockFile/LockFileFormat.cs

@@ -18,6 +18,8 @@ namespace NuGet.ProjectModel
     public class LockFileFormat
     {
         public static readonly int Version = 4;
+        public static readonly int AliasedVersion = 4;
+        public static readonly int LegacyVersion = 3;
         // If this is ever renamed, you should also rename NoOpRestoreUtilities.NoOpCacheFileName to keep them in sync.
         public static readonly string AssetsFileName = "project.assets.json";
 

src/NuGet.Core/NuGet.ProjectModel/LockFile/Utf8JsonStreamLockFileTargetConverterV4.cs

@@ -27,13 +27,6 @@ public LockFileTarget Read(ref Utf8JsonStreamReader reader)
             var propertyName = reader.GetString();
             var (targetFramework, runTimeFramework) = propertyName.SplitInTwo(LockFile.DirectorySeparatorChar);
 
-            // How do we differentiate between targetAlias and targetFramework here?
-            // Legacy is really supposed to be 3.
-
-            // PackageSpec probably doesn't need to be versioned to be honest.
-            // But the lock file does.
-            // This gets fucking shit.
-
             var lockFileTarget = new LockFileTarget
             {
                 TargetAlias = targetFramework,

src/NuGet.Core/NuGet.ProjectModel/PublicAPI.Unshipped.txt

@@ -1,3 +1,5 @@
 #nullable enable
 static NuGet.ProjectModel.PackageSpecExtensions.GetNearestTargetFramework(this NuGet.ProjectModel.PackageSpec! project, NuGet.Frameworks.NuGetFramework! targetFramework, string! targetAlias) -> NuGet.ProjectModel.TargetFrameworkInformation!
+static readonly NuGet.ProjectModel.LockFileFormat.AliasedVersion -> int
+static readonly NuGet.ProjectModel.LockFileFormat.LegacyVersion -> int
 ~NuGet.ProjectModel.PackageSpecReferenceDependencyProvider.GetLibrary(NuGet.LibraryModel.LibraryRange libraryRange, NuGet.Frameworks.NuGetFramework targetFramework, string alias) -> NuGet.LibraryModel.Library