[Apple mobile] Stage the Helix R2R app payload outside the crossgen2 input directory

eng/Subsets.props

@@ -171,6 +171,7 @@
     <AllSubsetsExpansion>$(AllSubsetsExpansion)+clr.paltests+clr.paltestlist+clr.hosts+clr.jit+clr.alljits+clr.alljitscommunity+clr.spmi+clr.corelib+clr.nativecorelib+clr.tools+clr.toolstests+clr.packages</AllSubsetsExpansion>
     <AllSubsetsExpansion Condition="$([MSBuild]::IsOsPlatform(Windows))">$(AllSubsetsExpansion)+linuxdac+alpinedac</AllSubsetsExpansion>
     <AllSubsetsExpansion>$(AllSubsetsExpansion)+mono.runtime+provision.emsdk+mono.aotcross+mono.corelib+mono.manifests+mono.packages+mono.tools+mono.wasmruntime+mono.wasiruntime+mono.wasmworkload+mono.mscordbi</AllSubsetsExpansion>
+    <AllSubsetsExpansion>$(AllSubsetsExpansion)+apple.buildtests</AllSubsetsExpansion>
     <AllSubsetsExpansion>$(AllSubsetsExpansion)+tools.illink+tools.cdac+tools.illinktests+tools.cdactests+tools.cdacdumptests</AllSubsetsExpansion>
     <AllSubsetsExpansion>$(AllSubsetsExpansion)+host.native+host.pkg+host.tools+host.pretest+host.tests</AllSubsetsExpansion>
     <AllSubsetsExpansion>$(AllSubsetsExpansion)+libs.native+libs.sfx+libs.oob+libs.pretest+libs.tests</AllSubsetsExpansion>
@@ -253,6 +254,9 @@
     <SubsetName Include="Mono.WasmWorkload" Description="*Helper* subset for building some pre-requisites for wasm workload testing, useful on CI." />
     <SubsetName Include="Mono.MsCorDbi" Description="The implementation of ICorDebug interface." />
 
+    <!-- Apple build infrastructure -->
+    <SubsetName Include="Apple.BuildTests" OnDemand="true" Description="Unit tests for the Apple mobile MSBuild targets. Note that building this doesn't execute tests: you must also pass the '-test' argument." />
+
     <!-- Tools -->
     <SubsetName Include="Tools" Description="Additional runtime tools projects. Equivalent to: $(DefaultToolsSubsets)" />
     <SubsetName Include="Tools.ILLink" Description="The projects that produce illink and analyzer tools for trimming." />
@@ -656,6 +660,12 @@
     <ProjectToBuild Include="$(WasiProjectRoot)wasi.proj" Category="mono" />
   </ItemGroup>
 
+  <!-- Apple build infrastructure -->
+  <!-- The tests only drive MSBuild in a child process, so they need nothing else from the build. -->
+  <ItemGroup Condition="$(_subset.Contains('+apple.buildtests+'))">
+    <ProjectToBuild Include="$(MonoProjectRoot)msbuild\apple\tests\Apple.Build.Tests\Apple.Build.Tests.csproj" Test="true" />
+  </ItemGroup>
+
   <!-- Host sets -->
   <ItemGroup Condition="$(_subset.Contains('+host.native+'))">
     <CorehostProjectToBuild Include="$(SharedNativeRoot)corehost\corehost.proj" />

eng/pipelines/common/evaluate-default-paths.yml

@@ -182,6 +182,12 @@ jobs:
       - src/native/managed/cdac/*
       - src/coreclr/debug/runtimeinfo/*
 
+    # The Apple mobile MSBuild targets and the tests that cover them. The tests only drive MSBuild, so
+    # they run on ordinary build hosts and need none of the mobile or WebAssembly tooling.
+    - subset: applebuildtests
+      include:
+      - src/mono/msbuild/apple/*
+
     - subset: installer
       include:
       exclude:

eng/pipelines/runtime.yml

@@ -1057,6 +1057,29 @@ extends:
                 eq(stageDependencies.EvaluatePaths.evaluate_paths.outputs['SetPathVars_installer.containsChange'], true),
                 eq(variables['isRollingBuild'], true))
 
+      #
+      # Apple mobile MSBuild targets tests
+      # Only when the Apple MSBuild targets change
+      #
+      # These only drive MSBuild and file orchestration in a child process, so they run on an ordinary
+      # macOS build host and need no Apple mobile workload or device.
+      - template: /eng/pipelines/common/platform-matrix.yml
+        parameters:
+          jobTemplate: /eng/pipelines/common/global-build-job.yml
+          buildConfig: Release
+          platforms:
+          - osx_x64
+          jobParameters:
+            timeoutInMinutes: 30
+            nameSuffix: AppleBuildTests
+            buildArgs: -s apple.buildtests -c $(_BuildConfig) -test
+            enablePublishTestResults: true
+            testResultsFormat: 'xunit'
+            condition: >-
+              or(
+                eq(stageDependencies.EvaluatePaths.evaluate_paths.outputs['SetPathVars_applebuildtests.containsChange'], true),
+                eq(variables['isRollingBuild'], true))
+
       #
       # WebAssembly legs
       #

src/mono/msbuild/apple/data/ProxyProjectForAOTOnHelix.proj

@@ -160,25 +160,47 @@
 
     <PropertyGroup>
       <_R2ROutputPath>$(IntermediateOutputPath)R2R</_R2ROutputPath>
+      <!-- The app payload is staged outside the publish directory because publish is the pristine
+           crossgen2 input for every run in this work item, and AppleAppBuilder bundles every top level
+           entry of its AppDir, so staging inside publish would end up inside the app. -->
+      <_R2RAppPayloadDir>$([MSBuild]::NormalizeDirectory($(BaseIntermediateOutputPath), 'r2r-app-payload'))</_R2RAppPayloadDir>
     </PropertyGroup>
 
     <ItemGroup>
       <_R2RCompiledAssemblies Include="$(_R2ROutputPath)\*.dll" />
       <_R2RDylibFiles Include="$(_R2ROutputPath)\*.r2r.dylib" />
     </ItemGroup>
 
+    <Warning Condition="'@(_R2RCompiledAssemblies)' == ''" Text="No R2R compiled assemblies found at $(_R2ROutputPath)." />
     <Warning Condition="'@(_R2RDylibFiles)' == ''" Text="No R2R dylib files found at $(_R2ROutputPath)." />
 
-    <Copy SourceFiles="@(_R2RCompiledAssemblies)"
-          DestinationFolder="$(OriginalPublishDir)"
-          OverwriteReadOnlyFiles="true" />
+    <!-- Recreated on every run so that a Helix retry in the same work item cannot inherit stale dylibs
+         or app builder output from a previous attempt. -->
+    <RemoveDir Directories="$(_R2RAppPayloadDir)" />
+    <MakeDir Directories="$(_R2RAppPayloadDir)" />
+
+    <ItemGroup>
+      <_R2RAppPayloadSourceFiles Include="$(OriginalPublishDir)**\*" />
+    </ItemGroup>
+
+    <Copy SourceFiles="@(_R2RAppPayloadSourceFiles)"
+          DestinationFiles="@(_R2RAppPayloadSourceFiles->'$(_R2RAppPayloadDir)%(RecursiveDir)%(Filename)%(Extension)')" />
 
-    <Copy SourceFiles="@(_R2RDylibFiles)"
-          DestinationFolder="$(OriginalPublishDir)"
+    <Copy SourceFiles="@(_R2RCompiledAssemblies);@(_R2RDylibFiles)"
+          DestinationFolder="$(_R2RAppPayloadDir)"
           OverwriteReadOnlyFiles="true" />
 
+    <PropertyGroup>
+      <AppleBuildDir>$(_R2RAppPayloadDir)</AppleBuildDir>
+    </PropertyGroup>
+
     <ItemGroup>
-      <AppleNativeFilesToBundle Include="@(_R2RDylibFiles->'$(OriginalPublishDir)%(Filename)%(Extension)')" />
+      <AppleAssembliesToBundle Remove="@(AppleAssembliesToBundle)" />
+      <AppleAssembliesToBundle Include="$(_R2RAppPayloadDir)*.dll" Exclude="$(_R2RAppPayloadDir)*.resources.dll" />
+
+      <AppleNativeFilesToBundle Remove="@(AppleNativeFilesToBundle)" />
+      <AppleNativeFilesToBundle Include="@(_ExtraFiles)" />
+      <AppleNativeFilesToBundle Include="$(_R2RAppPayloadDir)**\*.*" Exclude="$(_R2RAppPayloadDir)*.dll" />
     </ItemGroup>
   </Target>
 
@@ -188,6 +210,11 @@
       <RuntimeIdentifier>$(TargetOS)-$(TargetArchitecture)</RuntimeIdentifier>
     </PropertyGroup>
 
+    <!-- The compilation is skipped whenever the tracked output, the composite image, is newer than the
+         inputs, and the per assembly outputs written next to it are not tracked at all, so an attempt
+         that was killed mid write can look up to date to the next one. Always compile from scratch. -->
+    <RemoveDir Directories="$(IntermediateOutputPath)R2R" />
+
     <ItemGroup>
       <ResolvedFileToPublish Remove="@(ResolvedFileToPublish)" />
       <_R2RPublishAssembly Include="$(OriginalPublishDir)*.dll" Exclude="$(OriginalPublishDir)*.resources.dll" />

src/mono/msbuild/apple/tests/Apple.Build.Tests/Apple.Build.Tests.csproj

@@ -0,0 +1,18 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <!-- Use the tool TFM so the tests run on the SDK's own runtime, the way Wasm.Build.Tests and
+         ILAssembler.Tests do. Nothing here needs the runtime that is being built. -->
+    <TargetFramework>$(NetCoreAppToolCurrent)</TargetFramework>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <!-- The tests drive the real proxy project, so it has to travel with the test payload. It is laid
+         out under 'data' to mirror the directory it is shipped from. -->
+    <None Include="..\..\data\ProxyProjectForAOTOnHelix.proj"
+          Link="data\ProxyProjectForAOTOnHelix.proj"
+          CopyToOutputDirectory="PreserveNewest" />
+  </ItemGroup>
+
+</Project>