From 24f68585c33672b4848cd6b7c8df73e243ec4b89 Mon Sep 17 00:00:00 2001
From: Davis Goodin <dagood@microsoft.com>
Date: Thu, 21 Oct 2021 17:39:47 -0500
Subject: [PATCH 1/4] Prepare source-build for prebuiltless build

---
 eng/Versions.props                                  | 13 +++++++++++++
 .../Arcade/tools/SourceBuildArcadeTarball.targets   |  4 +++-
 src/SourceBuild/tarball/content/build.proj          |  3 ++-
 .../tarball/content/tools-local/init-build.proj     |  9 ++++++++-
 4 files changed, 26 insertions(+), 3 deletions(-)

diff --git a/eng/Versions.props b/eng/Versions.props
index 2cc105534..9a3d37288 100644
--- a/eng/Versions.props
+++ b/eng/Versions.props
@@ -159,6 +159,19 @@
          removed.  See https://github.com/dotnet/source-build/issues/2295 -->
     <MicrosoftBuildFrameworkVersion>15.7.179</MicrosoftBuildFrameworkVersion>
     <MicrosoftBuildUtilitiesCoreVersion>15.7.179</MicrosoftBuildUtilitiesCoreVersion>
+    <!--
+      Building .NET from source depends on one or two tar.gz files depending on the branch's current
+      source-buildability status.
+
+      PrivateSourceBuiltArtifactsPackageVersion is a tar.gz of .NET build outputs from a previous
+      build needed to build the current version of .NET. This is always defined, because .NET needs
+      to be bootstrappable at any point in time.
+
+      PrivateSourceBuiltPrebuiltsPackageVersion is a tar.gz of assets downloaded from the internet
+      that are needed to build the current version of .NET. Early in the lifecycle of a .NET major
+      or minor release, prebuilts may be needed. When the release is mature, prebuilts are not
+      necessary, and this property is removed from the file.
+    -->
     <PrivateSourceBuiltArtifactsPackageVersion>0.1.0-6.0.100-bootstrap.29</PrivateSourceBuiltArtifactsPackageVersion>
     <PrivateSourceBuiltPrebuiltsPackageVersion>0.1.0-6.0.100-36</PrivateSourceBuiltPrebuiltsPackageVersion>
   </PropertyGroup>
diff --git a/src/SourceBuild/Arcade/tools/SourceBuildArcadeTarball.targets b/src/SourceBuild/Arcade/tools/SourceBuildArcadeTarball.targets
index 7203b401b..c970f04cc 100644
--- a/src/SourceBuild/Arcade/tools/SourceBuildArcadeTarball.targets
+++ b/src/SourceBuild/Arcade/tools/SourceBuildArcadeTarball.targets
@@ -292,7 +292,9 @@
 
     <ItemGroup>
       <ArtifactUrls Include="$(SourceBuiltArtifactsTarballUrl)$(SourceBuiltArtifactsTarballName).$(PrivateSourceBuiltArtifactsPackageVersion).tar.gz" />
-      <ArtifactUrls Include="$(SourceBuiltArtifactsTarballUrl)$(SourceBuiltPrebuiltsTarballName).$(PrivateSourceBuiltPrebuiltsPackageVersion).tar.gz" />
+      <ArtifactUrls
+        Include="$(SourceBuiltArtifactsTarballUrl)$(SourceBuiltPrebuiltsTarballName).$(PrivateSourceBuiltPrebuiltsPackageVersion).tar.gz"
+        Condition="'$(PrivateSourceBuiltPrebuiltsPackageVersion)' != ''" />
     </ItemGroup>
 
     <WriteLinesToFile
diff --git a/src/SourceBuild/tarball/content/build.proj b/src/SourceBuild/tarball/content/build.proj
index 117a13675..80e6fd939 100644
--- a/src/SourceBuild/tarball/content/build.proj
+++ b/src/SourceBuild/tarball/content/build.proj
@@ -133,7 +133,8 @@
   </Target>
 
   <Target Name="CreatePrebuiltsTarball"
-          AfterTargets="Build">
+          AfterTargets="Build"
+          Condition="Exists('$(ResultingPrebuiltPackagesDir)')">
 
     <PropertyGroup>
       <TarballFileVersion>$(PrivateSourceBuiltPrebuiltsPackageVersionPrefix)$([MSBuild]::Add($(PrivateSourceBuiltPrebuiltsPackageVersionSuffix), 1))</TarballFileVersion>
diff --git a/src/SourceBuild/tarball/content/tools-local/init-build.proj b/src/SourceBuild/tarball/content/tools-local/init-build.proj
index 3835e019c..ee7a1bdb8 100644
--- a/src/SourceBuild/tarball/content/tools-local/init-build.proj
+++ b/src/SourceBuild/tarball/content/tools-local/init-build.proj
@@ -46,7 +46,14 @@
           WorkingDirectory="$(PrebuiltSourceBuiltPackagesPath)"
           Condition="'$(CustomPrebuiltSourceBuiltPackagesPath)' == ''" />
 
-    <Exec Command="tar -xzf $(ExternalTarballsDir)$(SourceBuiltPrebuiltsTarballName).*.tar.gz"
+    <!--
+      Check for a prebuilt dependency tarball and extract if exists. If there isn't one, we expect
+      the build to be working without prebuilts.
+    -->
+    <ItemGroup>
+      <SourceBuiltPrebuiltsTarballFile Include="$(ExternalTarballsDir)$(SourceBuiltPrebuiltsTarballName).*.tar.gz" />
+    </ItemGroup>
+    <Exec Command="tar -xzf %(SourceBuiltPrebuiltsTarballFile.FullPath)"
           WorkingDirectory="$(PrebuiltPackagesPath)" />
 
     <!-- Move SBRP packages to reference packages location -->

From c46dcb7fca280f33a23050cb275de8bb60d57037 Mon Sep 17 00:00:00 2001
From: Davis Goodin <dagood@microsoft.com>
Date: Thu, 21 Oct 2021 18:14:47 -0500
Subject: [PATCH 2/4] Fix empty SourceBuiltPrebuiltsTarballFile batch behavior

---
 src/SourceBuild/tarball/content/tools-local/init-build.proj | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/SourceBuild/tarball/content/tools-local/init-build.proj b/src/SourceBuild/tarball/content/tools-local/init-build.proj
index ee7a1bdb8..c5494dedd 100644
--- a/src/SourceBuild/tarball/content/tools-local/init-build.proj
+++ b/src/SourceBuild/tarball/content/tools-local/init-build.proj
@@ -54,7 +54,8 @@
       <SourceBuiltPrebuiltsTarballFile Include="$(ExternalTarballsDir)$(SourceBuiltPrebuiltsTarballName).*.tar.gz" />
     </ItemGroup>
     <Exec Command="tar -xzf %(SourceBuiltPrebuiltsTarballFile.FullPath)"
-          WorkingDirectory="$(PrebuiltPackagesPath)" />
+          WorkingDirectory="$(PrebuiltPackagesPath)"
+          Condition="'@(SourceBuiltPrebuiltsTarballFile)' != ''" />
 
     <!-- Move SBRP packages to reference packages location -->
     <MakeDir Directories="$(ReferencePackagesDir)" />

From 17feead1afcdd9dab8d039babf806fc18bb3c6a2 Mon Sep 17 00:00:00 2001
From: Davis Goodin <dagood@microsoft.com>
Date: Fri, 22 Oct 2021 14:10:15 -0500
Subject: [PATCH 3/4] Remove PrivateSourceBuiltPrebuiltsPackageVersion: no
 prebuilts used

---
 eng/Versions.props | 1 -
 1 file changed, 1 deletion(-)

diff --git a/eng/Versions.props b/eng/Versions.props
index 9a3d37288..8c25cd8b8 100644
--- a/eng/Versions.props
+++ b/eng/Versions.props
@@ -173,7 +173,6 @@
       necessary, and this property is removed from the file.
     -->
     <PrivateSourceBuiltArtifactsPackageVersion>0.1.0-6.0.100-bootstrap.29</PrivateSourceBuiltArtifactsPackageVersion>
-    <PrivateSourceBuiltPrebuiltsPackageVersion>0.1.0-6.0.100-36</PrivateSourceBuiltPrebuiltsPackageVersion>
   </PropertyGroup>
   <!-- Workload manifest package versions -->
   <PropertyGroup>

From 563bb4b721a76d97f4567cbb3462b30d21b51346 Mon Sep 17 00:00:00 2001
From: Davis Goodin <dagood@microsoft.com>
Date: Fri, 22 Oct 2021 14:17:35 -0500
Subject: [PATCH 4/4] Skip building prebuilt tarball if directory exists but is
 empty

---
 src/SourceBuild/tarball/content/build.proj | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/src/SourceBuild/tarball/content/build.proj b/src/SourceBuild/tarball/content/build.proj
index 80e6fd939..3a43b32ab 100644
--- a/src/SourceBuild/tarball/content/build.proj
+++ b/src/SourceBuild/tarball/content/build.proj
@@ -134,8 +134,21 @@
 
   <Target Name="CreatePrebuiltsTarball"
           AfterTargets="Build"
-          Condition="Exists('$(ResultingPrebuiltPackagesDir)')">
+          DependsOnTargets="
+            CheckIfPrebuiltsExistToPack;
+            CreatePrebuiltsTarballIfPrebuiltsExist"/>
 
+  <Target Name="CheckIfPrebuiltsExistToPack">
+    <!-- Directory existence doesn't mean there are files inside. Use a pattern to find files. -->
+    <ItemGroup>
+      <PrebuiltFile Include="$(ResultingPrebuiltPackagesDir)**" />
+    </ItemGroup>
+
+    <Message Text="Found @(PrebuiltFile->Count()) files in prebuilt packages dir." Importance="High" />
+  </Target>
+
+  <Target Name="CreatePrebuiltsTarballIfPrebuiltsExist"
+          Condition="'@(PrebuiltFile->Count())' != '0'">
     <PropertyGroup>
       <TarballFileVersion>$(PrivateSourceBuiltPrebuiltsPackageVersionPrefix)$([MSBuild]::Add($(PrivateSourceBuiltPrebuiltsPackageVersionSuffix), 1))</TarballFileVersion>
       <TarballFilePath>$(OutputPath)$(SourceBuiltPrebuiltsTarballName).$(TarballFileVersion).tar.gz</TarballFilePath>