[release/9.0.1xx] Fix incorrect apphost being used when publishing for self-contained single-file with NoBuild=true (#45400)

The `_GetAppHostCreationConfiguration` target sets the `_UseSingleFileHostForPublish` property, which determines if we (re-)create the app using `singlefilehost` on publish. When publishing with `NoBuild=true`, the target was not being run, so we bundled using `apphost`, resulting in an app that was configured to be self-contained but did not actually have the runtime as part of itself.

This change chains the target into the computation for output paths to ensure that the target runs when publishing without building, so that the correct host is used.

Author: github-actions[bot]

src/Tasks/Microsoft.NET.Build.Tasks/targets/Microsoft.NET.Sdk.targets

@@ -790,9 +790,9 @@ Copyright (c) .NET Foundation. All rights reserved.
 
   <!--
     ============================================================
-                                        _GetAppHostPaths
-    Gets the path to apphost (restored via packages or in an apphost pack),
-    and computes the path for the destination apphost.
+                _GetAppHostCreationConfiguration
+    Computes the properties for configuration of apphost creation
+    during either build or publish
     ============================================================
      -->
   <Target Name="_GetAppHostCreationConfiguration"
@@ -981,7 +981,7 @@ Copyright (c) .NET Foundation. All rights reserved.
     ============================================================
     -->
   <Target Name="_ComputeNETCoreBuildOutputFiles"
-          DependsOnTargets="_GetAppHostPaths;_GetComHostPaths;_GetIjwHostPaths"
+          DependsOnTargets="_GetAppHostPaths;_GetAppHostCreationConfiguration;_GetComHostPaths;_GetIjwHostPaths"
           BeforeTargets="AssignTargetPaths"
           Condition="'$(ComputeNETCoreBuildOutputFiles)' == 'true'">
 

test/Microsoft.NET.Publish.Tests/GivenThatWeWantToPublishASingleFileApp.cs

@@ -551,6 +551,44 @@ public void It_does_not_rewrite_the_single_file_unnecessarily()
             fileWriteTimeAfterSecondRun.Should().Be(fileWriteTimeAfterFirstRun);
         }
 
+        [RequiresMSBuildVersionFact("16.8.0")]
+        public void It_uses_appropriate_host_on_selfcontained_publish_with_no_build()
+        {
+            var testProject = new TestProject()
+            {
+                Name = "SingleFileTest",
+                TargetFrameworks = ToolsetInfo.CurrentTargetFramework,
+                RuntimeIdentifier = RuntimeInformation.RuntimeIdentifier,
+                IsExe = true,
+            };
+            testProject.AdditionalProperties.Add("SelfContained", "true");
+            TestAsset testAsset = _testAssetsManager.CreateTestProject(testProject);
+
+            // Build will create app using apphost
+            var buildCommand = new BuildCommand(testAsset);
+            buildCommand
+                .Execute()
+                .Should()
+                .Pass();
+
+            // Publish without build should create app using singlefilehost
+            var publishCommand = new PublishCommand(testAsset);
+            publishCommand
+                .Execute(PublishSingleFile, "/p:NoBuild=true")
+                .Should()
+                .Pass();
+            string singleFilePath = Path.Combine(
+                GetPublishDirectory(publishCommand).FullName,
+                $"{testProject.Name}{Constants.ExeSuffix}");
+
+            // Make sure published app runs correctly
+            var command = new RunExeCommand(Log, singleFilePath);
+            command.Execute()
+                .Should()
+                .Pass()
+                .And.HaveStdOutContaining("Hello World");
+        }
+
         [RequiresMSBuildVersionFact("16.8.0")]
         public void It_rewrites_the_apphost_for_single_file_publish()
         {