Fix issue handling transitive framework references for pruning in VS design-time builds, and add tests

Author: dsplaisted

src/Tasks/Microsoft.NET.Build.Tasks/GetPackagesToPrune.cs

@@ -65,11 +65,18 @@ public override int GetHashCode()
 
         protected override void ExecuteCore()
         {
+
+            //  Filter out transitive framework references.  Normally they wouldn't be passed to this task, but in Visual Studio design-time builds
+            //  the ResolvePackageAssets and AddTransitiveFrameworkReferences targets may have already run.  Filtering these references out should
+            //  avoid a bug similar to https://github.com/dotnet/sdk/issues/14641
+            var filteredFrameworkReferences = FrameworkReferences.Where(
+                i => i.GetMetadata("IsTransitiveFrameworkReference") is string transitiveVal && !transitiveVal.Equals("true", StringComparison.OrdinalIgnoreCase)).ToList();
+
             CacheKey key = new()
             {
                 TargetFrameworkIdentifier = TargetFrameworkIdentifier,
                 TargetFrameworkVersion = TargetFrameworkVersion,
-                FrameworkReferences = FrameworkReferences.Select(i => i.ItemSpec).ToHashSet()
+                FrameworkReferences = filteredFrameworkReferences.Select(i => i.ItemSpec).ToHashSet()
             };
 
             //  Cache framework package values per build
@@ -84,7 +91,7 @@ protected override void ExecuteCore()
 
             Dictionary<string, NuGetVersion> packagesToPrune = new();
 
-            var frameworkPackages = FrameworkPackages.GetFrameworkPackages(nugetFramework, FrameworkReferences.Select(fr => fr.ItemSpec).ToArray(), TargetingPackRoot)
+            var frameworkPackages = FrameworkPackages.GetFrameworkPackages(nugetFramework, filteredFrameworkReferences.Select(fr => fr.ItemSpec).ToArray(), TargetingPackRoot)
                 .SelectMany(packages => packages);
 
             foreach (var kvp in frameworkPackages)

test/Microsoft.NET.Build.Tests/GivenThatWeWantToResolveConflicts.cs

@@ -1,6 +1,7 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.Text.Json.Nodes;
 using System.Text.RegularExpressions;
 using NuGet.Common;
 using NuGet.Frameworks;
@@ -301,5 +302,55 @@ public void PlatformPackagesCanBePruned(bool prunePackages)
                 lockFileTarget.Libraries.Should().Contain(library => library.Name.Equals("System.Text.Json", StringComparison.OrdinalIgnoreCase));
             }
         }
+
+        [Fact]
+        public void TransitiveFrameworkReferencesDoNotAffectPruning()
+        {
+            var referencedProject = new TestProject("ReferencedProject")
+            {
+                TargetFrameworks = ToolsetInfo.CurrentTargetFramework,
+                IsExe = false
+            };
+            referencedProject.PackageReferences.Add(new TestPackageReference("System.Text.Json", "8.0.0"));
+            referencedProject.FrameworkReferences.Add("Microsoft.AspNetCore.App");
+
+            var testProject = new TestProject()
+            {
+                TargetFrameworks = ToolsetInfo.CurrentTargetFramework
+            };
+
+            testProject.AdditionalProperties["RestoreEnablePackagePruning"] = "True";
+            testProject.ReferencedProjects.Add(referencedProject);
+
+            var testAsset = _testAssetsManager.CreateTestProject(testProject);
+
+            new BuildCommand(testAsset).Execute().Should().Pass();
+
+            var getItemsCommand1 = new MSBuildCommand(testAsset, "AddPrunePackageReferences");
+            var itemsResult1 = getItemsCommand1.Execute("-getItem:PrunePackageReference");
+            itemsResult1.Should().Pass();
+
+            var items1 = ParseItemsJson(itemsResult1.StdOut);
+
+            var getItemsCommand2 = new MSBuildCommand(testAsset, "ResolvePackageAssets;AddTransitiveFrameworkReferences;AddPrunePackageReferences");
+            var itemsResult2 = getItemsCommand2.Execute("-getItem:PrunePackageReference");
+            itemsResult2.Should().Pass();
+
+            var items2 = ParseItemsJson(itemsResult2.StdOut);
+
+            items2.Should().BeEquivalentTo(items1);
+
+            static List<KeyValuePair<string,string>> ParseItemsJson(string json)
+            {
+                List<KeyValuePair<string, string>> ret = new();
+                var root = JsonNode.Parse(json);
+                var items = (JsonArray) root["Items"]["PrunePackageReference"];
+                foreach (var item in items)
+                {
+                    ret.Add(new KeyValuePair<string, string>((string)item["Identity"], (string)item["Version"]));
+                }
+                return ret;
+            }
+        }
     }
 }