Refresh copy marker when implementation output changes

src/Tasks.UnitTests/RegressionTests.cs

@@ -3,9 +3,11 @@
 
 using System;
 using System.IO;
+using System.Threading;
 using Microsoft.Build.Evaluation;
 using Microsoft.Build.Shared;
 using Microsoft.Build.UnitTests;
+using Shouldly;
 using Xunit;
 
 #nullable disable
@@ -102,5 +104,99 @@ public void IsWellKnownAttributeValuePreserved()
             MockLogger logger = new MockLogger(_output);
             ObjectModelHelpers.BuildTempProjectFileExpectSuccess("Myapp.proj", logger);
         }
+
+        /// <summary>
+        /// Test for https://github.com/dotnet/msbuild/issues/13478.
+        /// </summary>
+        [Fact]
+        public void CopyUpToDateMarkerTracksImplementationAssemblyWrites()
+        {
+            ObjectModelHelpers.DeleteTempProjectDirectory();
+            CreateCopyMarkerTestProject(produceReferenceAssembly: true);
+
+            MockLogger logger = new MockLogger(_output);
+
+            ObjectModelHelpers.BuildTempProjectFileExpectSuccess("MarkerTest.csproj", logger);
+
+            string markerPath = Path.Combine(ObjectModelHelpers.TempProjectDir, "obj", "Debug", "MarkerTest.csproj.Up2Date");
+            File.Exists(markerPath).ShouldBeTrue($"Expected marker to exist at {markerPath}");
+            DateTime markerAfterFirstBuild = File.GetLastWriteTimeUtc(markerPath);
+
+            ObjectModelHelpers.BuildTempProjectFileExpectSuccess("MarkerTest.csproj", logger);
+
+            DateTime markerAfterNoOpBuild = File.GetLastWriteTimeUtc(markerPath);
+            markerAfterNoOpBuild.ShouldBe(markerAfterFirstBuild);
+
+            string intermediateRefAssemblyPath = Path.Combine(ObjectModelHelpers.TempProjectDir, "obj", "Debug", "refint", "MarkerTest.dll");
+            File.Exists(intermediateRefAssemblyPath).ShouldBeTrue($"Expected intermediate reference assembly to exist at {intermediateRefAssemblyPath}");
+
+            Thread.Sleep(TimeSpan.FromSeconds(2));
+            File.WriteAllText(intermediateRefAssemblyPath, "Reference output changed");
+
+            ObjectModelHelpers.BuildTempProjectFileExpectSuccess("MarkerTest.csproj", logger);
+
+            DateTime markerAfterReferenceAssemblyOnlyChange = File.GetLastWriteTimeUtc(markerPath);
+            markerAfterReferenceAssemblyOnlyChange.ShouldBe(markerAfterNoOpBuild);
+
+            Thread.Sleep(TimeSpan.FromSeconds(2));
+            File.WriteAllText(Path.Combine(ObjectModelHelpers.TempProjectDir, "input.txt"), "changed");
+
+            ObjectModelHelpers.BuildTempProjectFileExpectSuccess("MarkerTest.csproj", logger);
+
+            DateTime markerAfterImplementationChange = File.GetLastWriteTimeUtc(markerPath);
+            (markerAfterImplementationChange > markerAfterReferenceAssemblyOnlyChange).ShouldBeTrue(
+                $"Expected marker to advance from {markerAfterReferenceAssemblyOnlyChange:O}, but it was {markerAfterImplementationChange:O}.");
+        }
+
+        /// <summary>
+        /// Test for https://github.com/dotnet/msbuild/issues/13478.
+        /// </summary>
+        [Fact]
+        public void CopyUpToDateMarkerIsNotCreatedForMainAssemblyWritesWhenReferenceAssembliesAreNotProduced()
+        {
+            ObjectModelHelpers.DeleteTempProjectDirectory();
+            CreateCopyMarkerTestProject(produceReferenceAssembly: false);
+
+            MockLogger logger = new MockLogger(_output);
+
+            ObjectModelHelpers.BuildTempProjectFileExpectSuccess("MarkerTest.csproj", logger);
+
+            string markerPath = Path.Combine(ObjectModelHelpers.TempProjectDir, "obj", "Debug", "MarkerTest.csproj.Up2Date");
+            File.Exists(markerPath).ShouldBeFalse($"Did not expect marker to exist at {markerPath}");
+        }
+
+        private static void CreateCopyMarkerTestProject(bool produceReferenceAssembly)
+        {
+            ObjectModelHelpers.CreateFileInTempProjectDirectory("input.txt", "initial");
+            ObjectModelHelpers.CreateFileInTempProjectDirectory("MarkerTest.csproj", $@"
+<Project DefaultTargets=""Build"" xmlns=""msbuildnamespace"" ToolsVersion=""msbuilddefaulttoolsversion"">
+  <Import Project=""$(MSBuildToolsPath)\Microsoft.Common.props"" />
+
+  <PropertyGroup>
+    <AssemblyName>MarkerTest</AssemblyName>
+    <OutputType>Library</OutputType>
+    <TargetFrameworkVersion>{MSBuildConstants.StandardTestTargetFrameworkVersion}</TargetFrameworkVersion>
+    <ProduceReferenceAssembly>{produceReferenceAssembly.ToString().ToLowerInvariant()}</ProduceReferenceAssembly>
+  </PropertyGroup>
+
+  <Import Project=""$(MSBuildToolsPath)\Microsoft.CSharp.targets"" />
+
+  <Target Name=""GetReferenceAssemblyPaths"" />
+  <Target Name=""ResolveAssemblyReferences"" />
+
+  <Target Name=""CoreCompile""
+          Inputs=""input.txt""
+          Outputs=""@(IntermediateAssembly)"">
+    <MakeDir Directories=""@(IntermediateAssembly->'%(RootDir)%(Directory)');@(IntermediateRefAssembly->'%(RootDir)%(Directory)')"" />
+    <WriteLinesToFile File=""@(IntermediateAssembly)""
+                      Lines=""Implementation output""
+                      Overwrite=""true"" />
+    <WriteLinesToFile File=""@(IntermediateRefAssembly)""
+                      Lines=""Reference output""
+                      Overwrite=""true""
+                      Condition=""'@(IntermediateRefAssembly)' != '' and !Exists('@(IntermediateRefAssembly)')"" />
+  </Target>
+</Project>");
+        }
     }
 }

src/Tasks/Microsoft.Common.CurrentVersion.targets

@@ -4931,6 +4931,7 @@ Copyright (C) Microsoft Corporation. All rights reserved.
 
       <Output TaskParameter="DestinationFiles" ItemName="MainAssembly"/>
       <Output TaskParameter="DestinationFiles" ItemName="FileWrites"/>
+      <Output TaskParameter="WroteAtLeastOneFile" PropertyName="_WroteMainAssemblyToOutputDirectory"/>
 
     </Copy>
 
@@ -4948,6 +4949,25 @@ Copyright (C) Microsoft Corporation. All rights reserved.
 
     <Message Importance="High" Text="$(MSBuildProjectName) -&gt; @(MainAssembly->'%(FullPath)')" Condition="'$(CopyBuildOutputToOutputDirectory)' == 'true' and '$(SkipCopyBuildProduct)'!='true'" />
 
+    <!--
+      Advance the marker considered by projects that reference this one during their up-to-date
+      checks. It must move forward when either:
+        * this project produces reference assemblies and its implementation assembly changed on
+          this build (referencing projects may need to copy the updated implementation), or
+        * copy-local (possibly transitive) references were actually copied on this build, as
+          captured by _CopyFilesMarkedCopyLocal in $(_CopyLocalReferencesCopiedInThisBuild).
+      Both signals are OR'd into this single Touch so the marker is written at most once per
+      build. _CopyFilesMarkedCopyLocal is a DependsOnTargets dependency of this target, so its
+      capture always runs before this Touch.
+    -->
+    <Touch Files="@(CopyUpToDateMarker)"
+      AlwaysCreate="true"
+      Condition="('$(ProduceReferenceAssembly)' == 'true' and '$(_WroteMainAssemblyToOutputDirectory)' == 'true') or '$(_CopyLocalReferencesCopiedInThisBuild)' == 'true'" />
+
+    <ItemGroup Condition="'$(ProduceReferenceAssembly)' == 'true'">
+      <FileWrites Include="@(CopyUpToDateMarker)" />
+    </ItemGroup>
+
     <!-- Copy the additional modules. -->
     <Copy
         SourceFiles="@(AddModules)"
@@ -5111,13 +5131,13 @@ Copyright (C) Microsoft Corporation. All rights reserved.
 
     </Copy>
 
-    <!-- If this project produces reference assemblies *and* copied (possibly transitive)
-         references on this build, subsequent builds of projects that depend on it must
-         not be considered up to date, so touch this marker file that is considered an
-         input to projects that reference this one. -->
-    <Touch Files="@(CopyUpToDateMarker)"
-      AlwaysCreate="true"
-      Condition="'@(ReferencesCopiedInThisBuild)' != '' and '$(WroteAtLeastOneFile)' == 'true'" />
+    <!-- Record whether copy-local (possibly transitive) references were actually copied on this
+         build. When they were, projects that depend on this one must not be considered up to date.
+         The marker file that carries that signal is touched once, later, in CopyFilesToOutputDirectory
+         (which depends on this target), so the same file isn't written twice in a normal build. -->
+    <PropertyGroup>
+      <_CopyLocalReferencesCopiedInThisBuild Condition="'@(ReferencesCopiedInThisBuild)' != '' and '$(WroteAtLeastOneFile)' == 'true'">true</_CopyLocalReferencesCopiedInThisBuild>
+    </PropertyGroup>
 
     <ItemGroup>
       <FileWrites Include="@(CopyUpToDateMarker)" />