From 0a0217fe0cdd3654105d1c46be4e43eeae9c163e Mon Sep 17 00:00:00 2001
From: Matt Mitchell <mmitche@microsoft.com>
Date: Mon, 11 Dec 2023 13:12:17 -0800
Subject: [PATCH] Enable Vertical build PoC as a more first-class concept
 (#14274)

Co-authored-by: Viktor Hofer <viktor.hofer@microsoft.com>
---
 eng/common/build.ps1                          |   3 +
 eng/common/build.sh                           |   8 ++
 eng/common/tools.ps1                          |   3 +-
 .../Microsoft.DotNet.Arcade.Sdk.csproj        |   2 +-
 .../tools/Build.proj                          |  11 +-
 ...cludeFromBuild.BeforeCommonTargets.targets |   6 +-
 .../tools/Publish.proj                        |   2 +-
 .../tools/SourceBuild/AfterSourceBuild.proj   |   4 +-
 .../SourceBuildArcadeBuild.targets            |  29 +++--
 .../tools/SourceBuild/git-clone-to-dir.ps1    | 111 ++++++++++++++++++
 .../tools/Tests.props                         |   2 +
 .../tools/Tools.proj                          |   2 +-
 .../Microsoft.DotNet.AsmDiff.csproj           |   2 +
 13 files changed, 165 insertions(+), 20 deletions(-)
 create mode 100644 src/Microsoft.DotNet.Arcade.Sdk/tools/SourceBuild/git-clone-to-dir.ps1

diff --git a/eng/common/build.ps1 b/eng/common/build.ps1
index 33a6f2d0e24..066044f62f2 100644
--- a/eng/common/build.ps1
+++ b/eng/common/build.ps1
@@ -19,6 +19,7 @@ Param(
   [switch] $pack,
   [switch] $publish,
   [switch] $clean,
+  [switch] $verticalBuild,
   [switch][Alias('bl')]$binaryLog,
   [switch][Alias('nobl')]$excludeCIBinarylog,
   [switch] $ci,
@@ -58,6 +59,7 @@ function Print-Usage() {
   Write-Host "  -sign                   Sign build outputs"
   Write-Host "  -publish                Publish artifacts (e.g. symbols)"
   Write-Host "  -clean                  Clean the solution"
+  Write-Host "  -verticalBuild          Run in 'vertical build' infra mode."
   Write-Host ""
 
   Write-Host "Advanced settings:"
@@ -120,6 +122,7 @@ function Build {
     /p:Deploy=$deploy `
     /p:Test=$test `
     /p:Pack=$pack `
+    /p:ArcadeBuildVertical=$verticalBuild `
     /p:IntegrationTest=$integrationTest `
     /p:PerformanceTest=$performanceTest `
     /p:Sign=$sign `
diff --git a/eng/common/build.sh b/eng/common/build.sh
index 2c17ba529b9..5ce01dd161a 100755
--- a/eng/common/build.sh
+++ b/eng/common/build.sh
@@ -59,6 +59,7 @@ scriptroot="$( cd -P "$( dirname "$source" )" && pwd )"
 restore=false
 build=false
 source_build=false
+vertical_build=false
 rebuild=false
 test=false
 integration_test=false
@@ -129,6 +130,12 @@ while [[ $# > 0 ]]; do
       restore=true
       pack=true
       ;;
+    -verticalbuild|-vb)
+      build=true
+      vertical_build=true
+      restore=true
+      pack=true
+      ;;
     -test|-t)
       test=true
       ;;
@@ -220,6 +227,7 @@ function Build {
     /p:Restore=$restore \
     /p:Build=$build \
     /p:ArcadeBuildFromSource=$source_build \
+    /p:ArcadeBuildVertical=$vertical_build \
     /p:Rebuild=$rebuild \
     /p:Test=$test \
     /p:Pack=$pack \
diff --git a/eng/common/tools.ps1 b/eng/common/tools.ps1
index e8def7e6a85..162dee2b936 100644
--- a/eng/common/tools.ps1
+++ b/eng/common/tools.ps1
@@ -827,7 +827,8 @@ function MSBuild-Core() {
     }
   }
 
-  $env:ARCADE_BUILD_TOOL_COMMAND = "$($buildTool.Path) $cmdArgs"
+  # Be sure quote the path in case there are spaces in the dotnet installation location.
+  $env:ARCADE_BUILD_TOOL_COMMAND = "`"$($buildTool.Path)`" $cmdArgs"
 
   $exitCode = Exec-Process $buildTool.Path $cmdArgs
 
diff --git a/src/Microsoft.DotNet.Arcade.Sdk/Microsoft.DotNet.Arcade.Sdk.csproj b/src/Microsoft.DotNet.Arcade.Sdk/Microsoft.DotNet.Arcade.Sdk.csproj
index 9dc910778ea..08bfeaa4120 100644
--- a/src/Microsoft.DotNet.Arcade.Sdk/Microsoft.DotNet.Arcade.Sdk.csproj
+++ b/src/Microsoft.DotNet.Arcade.Sdk/Microsoft.DotNet.Arcade.Sdk.csproj
@@ -16,7 +16,7 @@
 
     <EnableDefaultNoneItems>false</EnableDefaultNoneItems>
     <_GeneratedVersionFilePath>$(IntermediateOutputPath)DefaultVersions.Generated.props</_GeneratedVersionFilePath>
-    <NoWarn>$(NoWarn);3021;NU5105;SYSLIB0013</NoWarn>
+    <NoWarn>$(NoWarn);3021;NU5105;NU5111;SYSLIB0013</NoWarn>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/src/Microsoft.DotNet.Arcade.Sdk/tools/Build.proj b/src/Microsoft.DotNet.Arcade.Sdk/tools/Build.proj
index 2bae0717032..29e73cbe51f 100644
--- a/src/Microsoft.DotNet.Arcade.Sdk/tools/Build.proj
+++ b/src/Microsoft.DotNet.Arcade.Sdk/tools/Build.proj
@@ -10,6 +10,7 @@
     Configuration                   Build configuration: "Debug", "Release", etc.
 
     DotNetBuildFromSource           Building the entire stack from source with no external dependencies.
+    DotNetBuildVertical             Building the entire stack in "Vertical" PoC mode. This is a superset of DotNetBuildFromSource.
     DotNetOutputBlobFeedDir         Directory to publish Source Build assets to (packages, symbol packages, installers, etc.).
     DotNetPublishUsingPipelines     Publish assets to Build Asset Registry.
     DotNetSymbolServerTokenMsdl     Personal access token for MSDL symbol server. Available from variable group DotNet-Symbol-Server-Pats.	
@@ -47,7 +48,7 @@
 
   <Import Project="RepoLayout.props"/>
 
-  <Import Project="SourceBuild/SourceBuildArcadeBuild.targets" Condition="'$(ArcadeBuildFromSource)' == 'true'" />
+  <Import Project="SourceBuild/SourceBuildArcadeBuild.targets" Condition="'$(ArcadeBuildFromSource)' == 'true' or '$(ArcadeBuildVertical)' == 'true'" />
 
   <!-- Allow for repo specific Build properties such as the list of Projects to build -->
   <Import Project="$(RepositoryEngineeringDir)Build.props" Condition="Exists('$(RepositoryEngineeringDir)Build.props')" />
@@ -121,10 +122,10 @@
       <_CommonProps Include="VersionsPropsPath=$(VersionsPropsPath)"/>
 
       <!--
-        When building from source we suppress restore for projects that set ExcludeFromSourceBuild=true.
+        When building from source we suppress restore for projects that set ExcludeFromSourceBuild=true or ExcludeFromVerticalBuild.
         NuGet Restore task reports a warning for such projects, which we suppress here.
       -->
-      <_CommonProps Include="DisableWarnForInvalidRestoreProjects=true" Condition="'$(DotNetBuildFromSource)' == 'true'"/>
+      <_CommonProps Include="DisableWarnForInvalidRestoreProjects=true" Condition="'$(DotNetBuildFromSource)' == 'true' or '$(DotNetBuildVertical)' == 'true'"/>
 
       <!--
         C++ projects expect VCTargetsPath property to be set. MSBuild generates this property to solution
@@ -296,7 +297,7 @@
     -->
     <MSBuild Projects="SourceBuild\AfterSourceBuild.proj"
              Properties="@(_CommonProps);_NETCORE_ENGINEERING_TELEMETRY=AfterSourceBuild"
-             Condition="'$(ArcadeBuildFromSource)' == 'true'"/>
+             Condition="'$(ArcadeBuildFromSource)' == 'true' or '$(ArcadeBuildVertical)' == 'true'"/>
 
     <!--
       Publish artifacts.
@@ -304,6 +305,6 @@
     <MSBuild Projects="Publish.proj"
              Properties="@(_PublishProps);_NETCORE_ENGINEERING_TELEMETRY=Publish"
              Targets="Publish"
-             Condition="'$(Publish)' == 'true' and '$(DotNetBuildFromSource)' != 'true'"/>
+             Condition="'$(Publish)' == 'true' and '$(DotNetBuildFromSource)' != 'true' and '$(DotNetBuildVertical)' != 'true'"/>
   </Target>
 </Project>
diff --git a/src/Microsoft.DotNet.Arcade.Sdk/tools/ExcludeFromBuild.BeforeCommonTargets.targets b/src/Microsoft.DotNet.Arcade.Sdk/tools/ExcludeFromBuild.BeforeCommonTargets.targets
index d9b93b00a28..29e3f06568a 100644
--- a/src/Microsoft.DotNet.Arcade.Sdk/tools/ExcludeFromBuild.BeforeCommonTargets.targets
+++ b/src/Microsoft.DotNet.Arcade.Sdk/tools/ExcludeFromBuild.BeforeCommonTargets.targets
@@ -4,6 +4,7 @@
   <!--  This file sets properties that enable skipping of a project build if desired.
         Cases where we might skip include:
         - Source-build mode and "ExcludeFromSourceBuild" is set.
+        - Vertical-build mode and "ExcludeFromVerticalBuild" is set.
         - Non source-build mode and "ExcludeFromBuild" is set
         - Target filtering is used and the target filters set "ExcludeFromBuild".
 
@@ -26,8 +27,8 @@
           In that case, Sdk.targets imports it explicitly. -->
 
   <!--
-    If a project specifies ExcludeFromSourceBuild=true during a source build suppress all targets and emulate a no-op
-    (empty common targets like Restore, Build, Pack, etc.).
+    If a project specifies ExcludeFromSourceBuild=true or ExcludeFromVerticalBuild=true during a source build/vertical
+    build suppress all targets and emulate a no-op (empty common targets like Restore, Build, Pack, etc.).
 
     It's also possible to set ExcludeFromBuild prior to importing the Sdk.targets
     to skip building as desired in non-source build scenarios. This might be done to
@@ -36,6 +37,7 @@
   <PropertyGroup>
     <_SuppressAllTargets>false</_SuppressAllTargets>
     <_SuppressAllTargets Condition="'$(DotNetBuildFromSource)' == 'true' and '$(ExcludeFromSourceBuild)' == 'true'">true</_SuppressAllTargets>
+    <_SuppressAllTargets Condition="'$(DotNetBuildVertical)' == 'true' and '$(ExcludeFromVerticalBuild)' == 'true'">true</_SuppressAllTargets>
     <_SuppressAllTargets Condition="'$(ExcludeFromBuild)' == 'true'">true</_SuppressAllTargets>
 
     <!-- If excluding, then disable a restore warning, which will fire on newer SDKs, as well as set the NuGetRestoreTargets property to empty,
diff --git a/src/Microsoft.DotNet.Arcade.Sdk/tools/Publish.proj b/src/Microsoft.DotNet.Arcade.Sdk/tools/Publish.proj
index 94b576eee5d..a7daec23b74 100644
--- a/src/Microsoft.DotNet.Arcade.Sdk/tools/Publish.proj
+++ b/src/Microsoft.DotNet.Arcade.Sdk/tools/Publish.proj
@@ -286,6 +286,6 @@
     <FileSignInfo Update="@(FileSignInfo->WithMetadataValue('CertificateName','Microsoft400'))" CertificateName="$(DotNetCertificateName)" />
   </ItemGroup>
 
-  <Import Project="SourceBuild/SourceBuildArcadePublish.targets" Condition="'$(ArcadeBuildFromSource)' == 'true'" />
+  <Import Project="SourceBuild/SourceBuildArcadePublish.targets" Condition="'$(ArcadeBuildFromSource)' == 'true' or '$(ArcadeBuildVertical)' == 'true'" />
 
 </Project>
diff --git a/src/Microsoft.DotNet.Arcade.Sdk/tools/SourceBuild/AfterSourceBuild.proj b/src/Microsoft.DotNet.Arcade.Sdk/tools/SourceBuild/AfterSourceBuild.proj
index 37e9b4c4037..2ab404f985d 100644
--- a/src/Microsoft.DotNet.Arcade.Sdk/tools/SourceBuild/AfterSourceBuild.proj
+++ b/src/Microsoft.DotNet.Arcade.Sdk/tools/SourceBuild/AfterSourceBuild.proj
@@ -65,6 +65,8 @@
       <ContinueOnPrebuiltBaselineError Condition="'$(FailOnPrebuiltBaselineError)' != 'true'">true</ContinueOnPrebuiltBaselineError>
     </PropertyGroup>
 
+    <!-- Usage of prebuiltss against the baseline is not reported in vertical build modes,
+         as it is expected to be extensive. -->
     <ValidateUsageAgainstBaseline
       DataFile="$(PackageReportDataFile)"
       BaselineDataFile="$(PrebuiltBaselineDataFile)"
@@ -72,7 +74,7 @@
       OutputBaselineFile="$(SourceBuildSelfPrebuiltReportDir)generated-new-baseline.xml"
       OutputReportFile="$(SourceBuildSelfPrebuiltReportDir)baseline-comparison.xml"
       ContinueOnError="$(ContinueOnPrebuiltBaselineError)"
-      Condition="'$(DotNetBuildFromSourceFlavor)' != 'Product'" />
+      Condition="'$(DotNetBuildFromSourceFlavor)' != 'Product' and '$(ArcadeBuildVertical)' != 'true'" />
   </Target>
 
   <!--
diff --git a/src/Microsoft.DotNet.Arcade.Sdk/tools/SourceBuild/SourceBuildArcadeBuild.targets b/src/Microsoft.DotNet.Arcade.Sdk/tools/SourceBuild/SourceBuildArcadeBuild.targets
index eac7b26465c..00ec926b802 100644
--- a/src/Microsoft.DotNet.Arcade.Sdk/tools/SourceBuild/SourceBuildArcadeBuild.targets
+++ b/src/Microsoft.DotNet.Arcade.Sdk/tools/SourceBuild/SourceBuildArcadeBuild.targets
@@ -24,7 +24,7 @@
             RunInnerSourceBuildCommand;
             PackSourceBuildTarball"
           Condition="
-            '$(ArcadeBuildFromSource)' == 'true' and
+            ('$(ArcadeBuildFromSource)' == 'true' or '$(ArcadeBuildVertical)' == 'true') and
             '$(ArcadeInnerBuildFromSource)' != 'true'"
           BeforeTargets="Execute" />
 
@@ -40,7 +40,7 @@
   -->
   <Target Name="HookExecuteInnerSourceBuild"
           Condition="
-            '$(ArcadeBuildFromSource)' == 'true' and
+            ('$(ArcadeBuildFromSource)' == 'true' or '$(ArcadeBuildVertical)' == 'true') and
             '$(ArcadeInnerBuildFromSource)' == 'true'"
           DependsOnTargets="ExecuteInnerSourceBuild"
           BeforeTargets="Execute"/>
@@ -72,8 +72,9 @@
     <PropertyGroup>
       <!-- Track that this is the inner build to prevent infinite recursion. -->
       <InnerBuildArgs>$(InnerBuildArgs) /p:ArcadeInnerBuildFromSource=true</InnerBuildArgs>
-      <!-- Set DotNetBuildFromSource to avoid publishing. -->
-      <InnerBuildArgs>$(InnerBuildArgs) /p:DotNetBuildFromSource=true</InnerBuildArgs>
+      <!-- Turn on DotNetBuildFromSource or DotNetBuildVertical in the inner build -->
+      <InnerBuildArgs Condition="'$(ArcadeBuildFromSource)' == 'true'">$(InnerBuildArgs) /p:DotNetBuildFromSource=true</InnerBuildArgs>
+      <InnerBuildArgs Condition="'$(ArcadeBuildVertical)' == 'true'">$(InnerBuildArgs) /p:DotNetBuildVertical=true</InnerBuildArgs>
       <!-- Use a fresh clone of the repo so that source-build modifications are isolated. -->
       <InnerBuildArgs>$(InnerBuildArgs) /p:RepoRoot=$(InnerSourceBuildRepoRoot)</InnerBuildArgs>
       <!-- Override the artifacts dir to cleanly separate the inner build from outer build. -->
@@ -87,7 +88,7 @@
       <InnerBuildArgs>$(InnerBuildArgs) /p:SourceBuildOutputDir=$(SourceBuildOutputDir)</InnerBuildArgs>
       <InnerBuildArgs>$(InnerBuildArgs) /p:SourceBuiltBlobFeedDir=$(SourceBuiltBlobFeedDir)</InnerBuildArgs>
 
-      <InnerBuildArgs>$(InnerBuildArgs) /p:DotNetBuildOffline=true</InnerBuildArgs>
+      <InnerBuildArgs Condition="'$(ArcadeBuildVertical)' != 'true'">$(InnerBuildArgs) /p:DotNetBuildOffline=true</InnerBuildArgs>
       <InnerBuildArgs Condition=" '$(DotNetPackageVersionPropsPath)' != '' ">$(InnerBuildArgs) /p:DotNetPackageVersionPropsPath=$(DotNetPackageVersionPropsPath)</InnerBuildArgs>
 
       <InnerBuildArgs>$(InnerBuildArgs) /p:FullAssemblySigningSupported=$(FullAssemblySigningSupported)</InnerBuildArgs>
@@ -96,7 +97,7 @@
     <ItemGroup>
       <!-- Override package cache to separate source-built packages from upstream. -->
       <InnerBuildEnv Include="NUGET_PACKAGES=$(CurrentRepoSourceBuildPackageCache)" />
-      <InnerBuildEnv Include="DotNetTargetFrameworkFilter=$(SourceBuildTargetFrameworkFilter)" />
+      <InnerBuildEnv Include="DotNetTargetFrameworkFilter=$(SourceBuildTargetFrameworkFilter)" Condition="'$(ArcadeBuildVertical)' != 'true'" />
     </ItemGroup>
   </Target>
 
@@ -140,15 +141,27 @@
       <CopyWipIntoInnerSourceBuildRepo Condition="'$(CopyWipIntoInnerSourceBuildRepo)' == ''">true</CopyWipIntoInnerSourceBuildRepo>
 
       <_GitCloneToDirArgs />
+    </PropertyGroup>
+
+    <PropertyGroup Condition="$([MSBuild]::IsOSPlatform(Windows))">
+      <_GitCloneToDirArgs>$(_GitCloneToDirArgs) -Source '$(RepoRoot)'</_GitCloneToDirArgs>
+      <_GitCloneToDirArgs>$(_GitCloneToDirArgs) -Dest '$(InnerSourceBuildRepoRoot)'</_GitCloneToDirArgs>
+      <_GitCloneToDirArgs Condition="'$(CopyWipIntoInnerSourceBuildRepo)' == 'true'">$(_GitCloneToDirArgs) -CopyWip</_GitCloneToDirArgs>
+      <_GitCloneToDirArgs Condition="'$(CleanInnerSourceBuildRepoRoot)' == 'true'">$(_GitCloneToDirArgs) -Clean</_GitCloneToDirArgs>
+
+      <_GitCloneToDirScriptCommand>powershell -ExecutionPolicy Unrestricted -NoProfile -command "&amp; $(MSBuildThisFileDirectory)git-clone-to-dir.ps1 $(_GitCloneToDirArgs)"</_GitCloneToDirScriptCommand>
+    </PropertyGroup>
+
+    <PropertyGroup Condition="!$([MSBuild]::IsOSPlatform(Windows))">
       <_GitCloneToDirArgs>$(_GitCloneToDirArgs) --source &quot;$(RepoRoot)&quot;</_GitCloneToDirArgs>
       <_GitCloneToDirArgs>$(_GitCloneToDirArgs) --dest &quot;$(InnerSourceBuildRepoRoot)&quot;</_GitCloneToDirArgs>
       <_GitCloneToDirArgs Condition="'$(CopyWipIntoInnerSourceBuildRepo)' == 'true'">$(_GitCloneToDirArgs) --copy-wip</_GitCloneToDirArgs>
       <_GitCloneToDirArgs Condition="'$(CleanInnerSourceBuildRepoRoot)' == 'true'">$(_GitCloneToDirArgs) --clean</_GitCloneToDirArgs>
 
-      <_GitCloneToDirScriptFile>$(MSBuildThisFileDirectory)git-clone-to-dir.sh</_GitCloneToDirScriptFile>
+      <_GitCloneToDirScriptCommand>$(MSBuildThisFileDirectory)git-clone-to-dir.sh $(_GitCloneToDirArgs)</_GitCloneToDirScriptCommand>
     </PropertyGroup>
 
-    <Exec Command="$(_GitCloneToDirScriptFile) $(_GitCloneToDirArgs)" />
+    <Exec Command="$(_GitCloneToDirScriptCommand)" />
 
     <!--
       If the repo has submodules, use 'git clone' on each submodule to put it in the inner repo. We
diff --git a/src/Microsoft.DotNet.Arcade.Sdk/tools/SourceBuild/git-clone-to-dir.ps1 b/src/Microsoft.DotNet.Arcade.Sdk/tools/SourceBuild/git-clone-to-dir.ps1
new file mode 100644
index 00000000000..dad8e9f47bc
--- /dev/null
+++ b/src/Microsoft.DotNet.Arcade.Sdk/tools/SourceBuild/git-clone-to-dir.ps1
@@ -0,0 +1,111 @@
+<#
+.SYNOPSIS
+Creates a git clone of <source> into <dest> directory, optionally saving WIP changes.
+
+.PARAMETER Source
+The source Git directory
+
+.PARAMETER Dest
+The destination Git directory. Created if doesn't exist.
+
+.PARAMETER Clean
+If dest directory already exists, delete it.
+
+.PARAMETER CopyWip
+Transfer most types of uncommitted change into the destination directory. Useful for dev workflows.
+
+#>
+
+param (
+  [Parameter(Mandatory=$true)]
+  [string]$Source,
+  [Parameter(Mandatory=$true)]
+  [string]$Dest,
+  [switch]$Clean,
+  [switch]$CopyWip
+)
+
+if (-not (Test-Path $Source -PathType Container)) {
+  Write-Host "-Source not a directory: $Source"
+  exit 1
+}
+
+Write-Host "Cloning repository at: $Source -> $Dest ..."
+
+if (Test-Path $Dest) {
+  Write-Host "Destination already exists!"
+  if (Test-Path $Dest -PathType Leaf) {
+    Write-Host "Existing destination is a regular file, not a directory. This is unusual: aborting."
+    exit 1
+  }
+  elseif ($Clean) {
+    Write-Host "Clean is enabled: removing $dest and continuing..."
+    Remove-Item -Path $Dest -Recurse -Force
+  }
+  else {
+    Write-Host "Clean is not enabled: aborting."
+    exit 1
+  }
+}
+
+Push-Location -Path $Source
+
+if (-not (Test-Path $Dest)) {
+  New-Item -Path $Dest -ItemType Directory | Out-Null
+
+  if ($CopyWip) {
+    # Copy over changes that haven't been committed, for dev inner loop.
+    # This gets changes (whether staged or not) but misses untracked files.
+    $stashCommit = (git stash create)
+
+    if ($stashCommit) {
+      Write-Host "WIP changes detected: created temporary stash $stashCommit to transfer to inner repository..."
+    }
+    else {
+      Write-Host "No WIP changes detected..."
+    }
+  }
+
+  Write-Host "Creating empty clone at: $Dest"
+
+  # Combine the results of git rev-parse --git-dir with the "shallow" subdirectory
+  # to get the full path to the shallow file.
+
+  $shallowFile = Join-Path (git rev-parse --git-dir) "shallow"
+
+  if (Test-Path $shallowFile) {
+    Write-Host "Source repository is shallow..."
+    if ($stashCommit) {
+      Write-Host "WIP stash is not supported in a shallow repository: aborting."
+      exit 1
+    }
+
+    # If source repo is shallow, old versions of Git refuse to clone it to another directory. First,
+    # remove the 'shallow' file to trick Git into allowing the clone.
+    $shallowContent = Get-Content -Path $shallowFile
+    Remove-Item -Path $shallowFile
+
+    # Then, run the clone:
+      # * 'depth=1' avoids encountering the leaf commit in the shallow repo that points to a parent
+      #   that doesn't exist. (The commit marked "grafted".) Git would fail here, otherwise.
+      # * '--no-local' allows a shallow clone from a git dir on the same filesystem. This means the
+      #   clone will not use hard links and takes up more space. However, since we're doing a shallow
+      #   clone anyway, the difference is probably not significant. (This has not been measured.)
+      # * '-c protocol.file.allow=alwyas allows cloning from the local filesystem even on newer versions
+      #   of git which have disabled this for security reasons.
+    git clone -c protocol.file.allow=always --depth=1 --no-local --no-checkout "$Source" "$Dest"
+
+    # Restore the 'shallow' file
+    Set-Content -Path $shallowFile -Value $shallowContent
+  } else {
+    git clone -c protocol.file.allow=always --no-checkout "$Source" "$Dest"
+  }
+
+  echo "Checking out sources..."
+  # If no changes were stashed, stashCommit is empty string, and this is a simple checkout.
+  git -C $Dest checkout $stashCommit
+  echo "Clone complete: $Source -> $Dest"
+
+}
+
+Pop-Location
diff --git a/src/Microsoft.DotNet.Arcade.Sdk/tools/Tests.props b/src/Microsoft.DotNet.Arcade.Sdk/tools/Tests.props
index 127debe2220..271b679ce84 100644
--- a/src/Microsoft.DotNet.Arcade.Sdk/tools/Tests.props
+++ b/src/Microsoft.DotNet.Arcade.Sdk/tools/Tests.props
@@ -39,5 +39,7 @@
 
     <!-- exclude test projects from source-build by default -->
     <ExcludeFromSourceBuild Condition="'$(ExcludeFromSourceBuild)' == ''">true</ExcludeFromSourceBuild>
+    <!-- Vertical Build PoC. Exclude test projects. -->
+    <ExcludeFromVerticalBuild Condition="'$(ExcludeFromVerticalBuild)' == ''">true</ExcludeFromVerticalBuild>
   </PropertyGroup>
 </Project>
diff --git a/src/Microsoft.DotNet.Arcade.Sdk/tools/Tools.proj b/src/Microsoft.DotNet.Arcade.Sdk/tools/Tools.proj
index 5d978ade3af..b7f3831ed7b 100644
--- a/src/Microsoft.DotNet.Arcade.Sdk/tools/Tools.proj
+++ b/src/Microsoft.DotNet.Arcade.Sdk/tools/Tools.proj
@@ -56,7 +56,7 @@
     <Exec Command='"$(DotNetTool)" tool restore' WorkingDirectory="$(RepoRoot)" />
   </Target>
 
-  <Import Project="SourceBuild/SourceBuildArcadeTools.targets" Condition="'$(ArcadeBuildFromSource)' == 'true' or '$(SetUpSourceBuildIntermediateNupkgCache)' == 'true'" />
+  <Import Project="SourceBuild/SourceBuildArcadeTools.targets" Condition="'$(ArcadeBuildFromSource)' == 'true' or '$(ArcadeBuildVertical)' == 'true' or '$(SetUpSourceBuildIntermediateNupkgCache)' == 'true'" />
 
   <!-- Repository extensibility point -->
   <Import Project="$(RepositoryEngineeringDir)Tools.props" Condition="Exists('$(RepositoryEngineeringDir)Tools.props')" />
diff --git a/src/Microsoft.DotNet.AsmDiff/Microsoft.DotNet.AsmDiff.csproj b/src/Microsoft.DotNet.AsmDiff/Microsoft.DotNet.AsmDiff.csproj
index 66c20be3a6b..3607971b8a4 100644
--- a/src/Microsoft.DotNet.AsmDiff/Microsoft.DotNet.AsmDiff.csproj
+++ b/src/Microsoft.DotNet.AsmDiff/Microsoft.DotNet.AsmDiff.csproj
@@ -8,6 +8,8 @@
     <PackAsTool>true</PackAsTool>
     <ToolCommandName>dotnet-asmdiff</ToolCommandName>
     <ExcludeFromSourceBuild>true</ExcludeFromSourceBuild>
+    <!-- Vertical PoC - in-tree use of the tool causes some race? -->
+    <ExcludeFromVerticalBuild>true</ExcludeFromVerticalBuild>
     <StrongNameKeyId>Open</StrongNameKeyId>
     <UsingToolXliff>true</UsingToolXliff>
     <!-- Use xliff localization. -->