WIP: Enable source-build through arcade

This enables 'source-build', which makes it easier to build the entire
shipping .NET SDK from source.

This is the first and second step of arcade-powered-source-build:
https://github.com/dotnet/source-build/blob/master/Documentation/planning/arcade-powered-source-build/README.md

See dotnet/sourcelink#692 for a similar PR, that this is based on.

The `LICENSE` to `LICENSE.txt` rename is hack to work around
NuGet/Home#7601 for now.

build.cmd

@@ -1,2 +1,2 @@
 @echo off
-powershell -ExecutionPolicy ByPass -NoProfile -command "& """%~dp0eng\common\Build.ps1""" -projects """%~dp0illink.sln""" -restore -build %*"
+powershell -ExecutionPolicy ByPass -NoProfile -command "& """%~dp0eng\common\Build.ps1""" -restore -build %*"

build.sh

@@ -13,4 +13,4 @@ while [[ -h $source ]]; do
 done
 
 scriptroot="$( cd -P "$( dirname "$source" )" && pwd )"
-"$scriptroot/eng/common/build.sh" --projects "$scriptroot/illink.sln" --build --restore $@
+"$scriptroot/eng/common/build.sh" --build --restore $@

eng/Build.props

@@ -0,0 +1,17 @@
+<Project>
+  <ItemGroup>
+
+    <ProjectToBuild Include="$(RepoRoot)src\linker\Mono.Linker.csproj" />
+    <ProjectToBuild Include="$(RepoRoot)src\ILLink.Tasks\ILLink.Tasks.csproj" />
+    <ProjectToBuild Condition="'$(DotNetBuildFromSource)' != 'true'" Include="$(RepoRoot)test\Mono.Linker.Tests\Mono.Linker.Tests.csproj" />
+    <ProjectToBuild Condition="'$(DotNetBuildFromSource)' != 'true'" Include="$(RepoRoot)test\Mono.Linker.Tests.Cases\Mono.Linker.Tests.Cases.csproj" />
+    <ProjectToBuild Condition="'$(DotNetBuildFromSource)' != 'true'" Include="$(RepoRoot)test\Mono.Linker.Tests.Cases.Expectations\Mono.Linker.Tests.Cases.Expectations.csproj" />
+    <ProjectToBuild Condition="'$(DotNetBuildFromSource)' != 'true'" Include="$(RepoRoot)src\analyzer\analyzer.csproj" />
+    <ProjectToBuild Condition="'$(DotNetBuildFromSource)' != 'true'" Include="$(RepoRoot)test\ILLink.Tasks.Tests\ILLink.Tasks.Tests.csproj" />
+    <ProjectToBuild Include="$(RepoRoot)src\ILLink.RoslynAnalyzer\ILLink.RoslynAnalyzer.csproj" />
+    <ProjectToBuild Include="$(RepoRoot)test\ILLink.RoslynAnalyzer.Tests\ILLink.RoslynAnalyzer.Tests.csproj" />
+    <ProjectToBuild Include="$(RepoRoot)src\linker\ref\Mono.Linker.csproj" />
+    <ProjectToBuild Include="$(RepoRoot)src\tlens\tlens.csproj" />
+
+  </ItemGroup>
+</Project>

eng/SourceBuild.props

@@ -0,0 +1,8 @@
+<Project>
+
+  <PropertyGroup>
+    <GitHubRepositoryName>linker</GitHubRepositoryName>
+    <SourceBuildManagedOnly>true</SourceBuildManagedOnly>
+  </PropertyGroup>
+
+</Project>

eng/SourceBuildPrebuiltBaseline.xml

@@ -0,0 +1,5 @@
+<UsageData>
+  <IgnorePatterns>
+    <UsagePattern IdentityGlob="*/*" />
+  </IgnorePatterns>
+</UsageData>

eng/Version.Details.xml

@@ -6,6 +6,7 @@
     <Dependency Name="Microsoft.DotNet.Arcade.Sdk" Version="6.0.0-beta.21105.5">
       <Uri>https://github.com/dotnet/arcade</Uri>
       <Sha>fc83e59329203724d4a63c4f6c843be62983a35e</Sha>
+      <SourceBuild RepoName="arcade" ManagedOnly="true" />
     </Dependency>
     <Dependency Name="Microsoft.DotNet.ApiCompat" Version="6.0.0-beta.21105.5">
       <Uri>https://github.com/dotnet/arcade</Uri>
@@ -14,6 +15,10 @@
     <Dependency Name="Microsoft.NET.Sdk.IL" Version="6.0.0-preview.2.21108.2">
       <Uri>https://github.com/dotnet/runtime</Uri>
       <Sha>a66b4e3bf5e3c5ecb2e9fba771f69b177bd3844e</Sha>
+      <!--
+      This would introduce a cyclic dependency, so it's explictly not enabled for now
+      <SourceBuild RepoName="runtime" />
+      -->
     </Dependency>
   </ToolsetDependencies>
 </Dependencies>

eng/azure-pipelines.yml

@@ -44,6 +44,8 @@ stages:
       testResultsFormat: vstest
       enablePublishBuildAssets: true # generate build manifests and publish to BAR in internal builds
       enableMicrobuild: true # only affects internal builds
+      # See https://github.com/dotnet/source-build/issues/2049
+      # enableSourceBuild: true
 
       jobs:
 
@@ -84,6 +86,21 @@ stages:
           ${{ if eq(variables.officialBuild, 'true') }}:
             displayName: Build and publish illink.sln $(_BuildConfig)
 
+      - job: SourceBuild_Managed
+        displayName: Source-Build (Managed)
+        pool:
+          vmImage: ubuntu-20.04
+        container: 'mcr.microsoft.com/dotnet-buildtools/prereqs:centos-7-3e800f1-20190501005343'
+        workspace:
+          clean: all
+        variables:
+        - name: _BuildConfig
+          value: Release
+        steps:
+        - checkout: self
+          submodules: true
+        - template: /eng/common/templates/steps/source-build.yml
+
       - ${{ if eq(variables.officialBuild, 'false') }}:
         - job: Linux
           condition: eq(variables.officialBuild, 'false')

src/linker/Mono.Linker.csproj

@@ -2,6 +2,8 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
+    <!-- This apphost is not necessary for source-build. Remove it to avoid a prebuilt. See https://github.com/dotnet/source-build/issues/1905 -->
+    <UseAppHost Condition="'$(DotNetBuildFromSource)' == 'true'">false</UseAppHost>
     <Nullable>disable</Nullable>
     <ServerGarbageCollection>true</ServerGarbageCollection>
   </PropertyGroup>