Enable specifying install search location options for published `apph…

…ost` (#42455)

- `AppHostDotNetSearch` allows selection of which search locations should be used
  - Errors on creating `apphost` if set to an invalid value
- `AppHostRelativeDotNet` allows specifying a relative path to the runtime
  - Setting implies `AppHostDotNetSearch=AppRelative` if `AppHostDotNetSearch` is not explicitly set
- Values are only embedded in `apphost` on `publish` (not `build`)

SDK side of https://github.com/dotnet/designs/blob/main/proposed/apphost-embed-install-location.md.

src/Tasks/Common/Resources/Strings.resx

@@ -956,5 +956,9 @@ You may need to build the project on another operating system or architecture, o
     <value>NETSDK1216: Package Microsoft.Net.Sdk.Compilers.Toolset is not downloaded but it is needed because your MSBuild and SDK versions are mismatched. Ensure version {0} of the package is available in your NuGet source feeds and then run NuGet package restore from Visual Studio or MSBuild.</value>
     <comment>{StrBegin="NETSDK1216: "}{Locked="Microsoft.Net.Sdk.Compilers.Toolset"} {0} is a NuGet package version and should not be translated.</comment>
   </data>
-  <!-- The latest message added is MicrosoftNetSdkCompilersToolsetNotFound. Please update this value with each PR to catch parallel PRs both adding a new message -->
+  <data name="InvalidAppHostDotNetSearch" xml:space="preserve">
+    <value>NETSDK1217: Invalid value in AppHostDotNetSearch: '{0}'.</value>
+    <comment>{StrBegin="NETSDK1217: "}</comment>
+  </data>
+  <!-- The latest message added is InvalidAppHostDotNetSearch. Please update this value with each PR to catch parallel PRs both adding a new message -->
 </root>

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

@@ -48,6 +48,10 @@ public class CreateAppHost : TaskBase
 
         public bool DisableCetCompat { get; set; } = false;
 
+        public ITaskItem[] DotNetSearchLocations { get; set; }
+
+        public string AppRelativeDotNet { get; set; } = null;
+
         protected override void ExecuteCore()
         {
             try
@@ -61,13 +65,38 @@ protected override void ExecuteCore()
                 {
                     try
                     {
+                        HostWriter.DotNetSearchOptions options = null;
+                        if (DotNetSearchLocations?.Length > 0)
+                        {
+                            HostWriter.DotNetSearchOptions.SearchLocation searchLocation = default;
+                            foreach (var locationItem in DotNetSearchLocations)
+                            {
+                                if (Enum.TryParse(locationItem.ItemSpec, out HostWriter.DotNetSearchOptions.SearchLocation location)
+                                    && Enum.IsDefined(typeof(HostWriter.DotNetSearchOptions.SearchLocation), location))
+                                {
+                                    searchLocation |= location;
+                                }
+                                else
+                                {
+                                    throw new BuildErrorException(Strings.InvalidAppHostDotNetSearch, locationItem.ItemSpec);
+                                }
+                            }
+
+                            options = new HostWriter.DotNetSearchOptions()
+                            {
+                                Location = searchLocation,
+                                AppRelativeDotNet = AppRelativeDotNet
+                            };
+                        }
+
                         HostWriter.CreateAppHost(appHostSourceFilePath: AppHostSourcePath,
                                                 appHostDestinationFilePath: AppHostDestinationPath,
                                                 appBinaryFilePath: AppBinaryName,
                                                 windowsGraphicalUserInterface: isGUI,
                                                 assemblyToCopyResourcesFrom: resourcesAssembly,
                                                 enableMacOSCodeSign: EnableMacOSCodeSign,
-                                                disableCetCompat: DisableCetCompat);
+                                                disableCetCompat: DisableCetCompat,
+                                                dotNetSearchOptions: options);
                         return;
                     }
                     catch (Exception ex) when (ex is IOException ||

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

@@ -719,6 +719,35 @@ Copyright (c) .NET Foundation. All rights reserved.
                    />
   </Target>
 
+  <!--
+    ============================================================
+    _CreateAppHostForPublish
+    Create the apphost for the publish scenario if app is configuring .NET install search behaviour
+    Because there is no SDK support yet for output with a layout conforming to the configuration,
+    only do this on publish, such that the inner dev loop is unaffected.
+    ============================================================
+     -->
+  <Target Name="_CreateAppHostForPublish"
+          Inputs="@(IntermediateAssembly);$(AppHostSourcePath)"
+          Outputs="$(AppHostForPublishIntermediatePath)"
+          DependsOnTargets="_GetAppHostPaths;_GetAppHostCreationConfiguration"
+          Condition="'$(_UpdateAppHostForPublish)' == 'true' and
+                     Exists('@(IntermediateAssembly)') and
+                     Exists('$(AppHostSourcePath)')">
+    <CreateAppHost AppHostSourcePath="$(AppHostSourcePath)"
+                   AppHostDestinationPath="$(AppHostForPublishIntermediatePath)"
+                   AppBinaryName="$(AssemblyName)$(TargetExt)"
+                   IntermediateAssembly="@(IntermediateAssembly->'%(FullPath)')"
+                   WindowsGraphicalUserInterface="$(_UseWindowsGraphicalUserInterface)"
+                   Retries="$(CopyRetryCount)"
+                   RetryDelayMilliseconds="$(CopyRetryDelayMilliseconds)"
+                   EnableMacOSCodeSign="$(_EnableMacOSCodeSign)"
+                   DisableCetCompat="$(_DisableCetCompat)"
+                   DotNetSearchLocations="$(AppHostDotNetSearch)"
+                   AppRelativeDotNet="$(AppHostRelativeDotNet)"
+                   />
+  </Target>
+
   <!--
     ============================================================
                                         _ComputeCopyToPublishDirectoryItems
@@ -762,6 +791,7 @@ Copyright (c) .NET Foundation. All rights reserved.
           DependsOnTargets="AssignTargetPaths;
                             DefaultCopyToPublishDirectoryMetadata;
                             _CreateSingleFileHost;
+                            _CreateAppHostForPublish;
                             _SplitProjectReferencesByFileExistence;
                             _GetProjectReferenceTargetFrameworkProperties">
 
@@ -861,6 +891,15 @@ Copyright (c) .NET Foundation. All rights reserved.
       <_SourceItemsToCopyToPublishDirectoryAlways Include="$(SingleFileHostIntermediatePath)" CopyToOutputDirectory="Always" TargetPath="$(AssemblyName)$(_NativeExecutableExtension)" />
     </ItemGroup>
 
+    <ItemGroup Condition="'$(_UpdateAppHostForPublish)' == 'true' and Exists('$(AppHostForPublishIntermediatePath)')">
+      <!-- Remove apphost from build from items to publish -->
+      <_SourceItemsToCopyToPublishDirectoryAlways Remove="$(AppHostIntermediatePath)" />
+      <_SourceItemsToCopyToPublishDirectory Remove="$(AppHostIntermediatePath)" />
+
+      <!-- Add the apphost created as part of publish -->
+      <_SourceItemsToCopyToPublishDirectoryAlways Include="$(AppHostForPublishIntermediatePath)" CopyToOutputDirectory="Always" TargetPath="$(AssemblyName)$(_NativeExecutableExtension)" />
+    </ItemGroup>
+
     <ItemGroup>
       <AllPublishItemsFullPathWithTargetPath Include="@(_SourceItemsToCopyToPublishDirectoryAlways->'%(FullPath)');@(_SourceItemsToCopyToPublishDirectory->'%(FullPath)')"/>
     </ItemGroup>

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

@@ -799,6 +799,11 @@ Copyright (c) .NET Foundation. All rights reserved.
                                                '$(TargetFrameworkIdentifier)' == '.NETCoreApp' and
                                                $([MSBuild]::VersionGreaterThanOrEquals($(TargetFrameworkVersion), 5.0))">true</_UseSingleFileHostForPublish>
       <_DisableCetCompat Condition="'$(CetCompat)' == 'false'">true</_DisableCetCompat>
+
+      <!-- Default to AppHostDotNetSearch=AppRelative if AppHostRelativeDotNet is set -->
+      <AppHostDotNetSearch Condition="'$(AppHostRelativeDotNet)' != '' and '$(AppHostDotNetSearch)' == ''">AppRelative</AppHostDotNetSearch>
+      <_UpdateAppHostForPublish Condition="'$(_UseSingleFileHostForPublish)' != 'true' and
+                                          ('$(AppHostRelativeDotNet)' != '' or '$(AppHostDotNetSearch)' != '')">true</_UpdateAppHostForPublish>
     </PropertyGroup>
   </Target>
 
@@ -851,6 +856,7 @@ Copyright (c) .NET Foundation. All rights reserved.
     </PropertyGroup>
     <PropertyGroup Condition="'$(UseAppHostFromAssetsFile)' == 'false' Or '@(_NativeRestoredAppHostNETCore)' != ''">
       <AppHostIntermediatePath>$([System.IO.Path]::GetFullPath('$(IntermediateOutputPath)apphost$(_NativeExecutableExtension)'))</AppHostIntermediatePath>
+      <AppHostForPublishIntermediatePath>$([System.IO.Path]::GetFullPath('$(IntermediateOutputPath)apphost_publish$(_NativeExecutableExtension)'))</AppHostForPublishIntermediatePath>
       <SingleFileHostIntermediatePath>$([System.IO.Path]::GetFullPath('$(IntermediateOutputPath)singlefilehost$(_NativeExecutableExtension)'))</SingleFileHostIntermediatePath>
     </PropertyGroup>