Speed up the build by only performing one restore, and parallelizing build (#1924)

build.proj

-<?xml version="1.0" encoding="utf-8"?>
-<Project ToolsVersion="14.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
-  <Import Project="Directory.Build.props" />
+<Project Sdk="Microsoft.Build.Traversal">
   
   <PropertyGroup>
     <BuildRestore Condition="'$(BuildRestore)'==''">true</BuildRestore>
@@ -9,80 +7,33 @@
     <SampleBuild Condition="'$(SampleBuild)'==''">true</SampleBuild>
     <BuildTests Condition="'$(BuildTests)'==''">true</BuildTests>
     <BuildPackages Condition="'$(BuildPackages)'==''">false</BuildPackages>
-
-    <BuildDependsOn Condition="'$(BuildRestore)'=='true'">$(BuildDependsOn);Restore</BuildDependsOn>
-    <BuildDependsOn Condition="'$(ProductBuild)'=='true'">$(BuildDependsOn);BuildProduct</BuildDependsOn>
-    <BuildDependsOn Condition="'$(ToolsBuild)'=='true'">$(BuildDependsOn);BuildTools</BuildDependsOn>
-    <BuildDependsOn Condition="'$(SampleBuild)'=='true'">$(BuildDependsOn);BuildSamples</BuildDependsOn>
-    <BuildDependsOn Condition="'$(BuildTests)'=='true'">$(BuildDependsOn);Test</BuildDependsOn>
-    <BuildDependsOn Condition="'$(BuildPackages)'=='true'">$(BuildDependsOn);Pack</BuildDependsOn>
   </PropertyGroup>
 
-  <Import Project="Directory.Build.targets" />
-
   <ItemGroup>
+      <!-- Build product -->
       <UnitTestProjects Include="$(MSBuildThisFileDirectory)src\devices\**\*.Tests.csproj" />
-  </ItemGroup>
-
-  <Target Name="BuildProduct">
-    <ItemGroup>
-      <_ExcludeBuildProductProjects Include="$(MSBuildThisFileDirectory)src\Native\build-native.proj" />
       <_BuildProductProjects Include="$(MSBuildThisFileDirectory)src\**\*.csproj" Exclude="@(_ExcludeBuildProductProjects);@(UnitTestProjects)" />
-    </ItemGroup>
       
-    <MSBuild Projects="@(_BuildProductProjects)" />
-  </Target>
+      <ProjectReference Condition="'$(ProductBuild)' == 'true'" Include="@(_BuildProductProjects)" />
 
-  <Target Name="BuildTools">
-    <ItemGroup>
+      <!-- Build tools -->
       <_BuildToolProjects Include="$(MSBuildThisFileDirectory)tools\**\*.csproj" />
-    </ItemGroup>
 
-    <MSBuild Projects="@(_BuildToolProjects)" />
-  </Target>
+      <ProjectReference Condition="'$(ToolsBuild)' == 'true'" Include="@(_BuildToolProjects)" />
 
-  <Target Name="BuildSamples">
-    <ItemGroup>
+      <!-- Build samples -->
       <_ExcludeBuildSampleProjects Include="$(MSBuildThisFileDirectory)samples\serialport-arduino\arduino-demo.csproj" />
       <_BuildSampleProjects Include="$(MSBuildThisFileDirectory)samples\**\*.csproj" Exclude="@(_ExcludeBuildSampleProjects)" />
-    </ItemGroup>
 
-    <MSBuild Projects="@(_BuildSampleProjects)" />
-  </Target>
+      <ProjectReference Condition="'$(SampleBuild)' == 'true'" Include="@(_BuildSampleProjects)" />
 
-  <Target Name="Restore">
-    <ItemGroup>
-      <_ExcludeProjectsToRestore Include="$(MSBuildThisFileDirectory)samples\serialport-arduino\arduino-demo.csproj" />
-      <_ExcludeProjectsToRestore Include="$(MSBuildThisFileDirectory)eng\**\*.csproj" />
-      <_ProjectsToRestore Include="$(MSBuildThisFileDirectory)**\*.csproj" Exclude="@(_ExcludeProjectsToRestore)" />
-    </ItemGroup>
-
-    <MSBuild Projects="@(_ProjectsToRestore)" Targets="Restore" />
-  </Target>
+      <!-- Build tests -->
+      <ProjectReference Condition="'$(BuildTests)' == 'true'" Include="@(UnitTestProjects)" Targets="VSTest" />
 
-  <Target Name="Test">
-    <MSBuild Projects="@(UnitTestProjects)" Targets="VSTest"
-        ContinueOnError="ErrorAndContinue" />
-    <Error Condition="$(MSBuildLastTaskResult) != 'true'"
-        Text="Unit tests failed. Please check the detailed log to find out which ones failed." />
-  </Target>
-
-  <Target Name="Pack">
-    <ItemGroup>
+      <!-- Run Pack -->
       <_ProjectsToPackage Include="$(MSBuildThisFileDirectory)src\Iot.Device.Bindings\Iot.Device.Bindings.csproj" />
       <_ProjectsToPackage Include="$(MSBuildThisFileDirectory)src\System.Device.Gpio\System.Device.Gpio.csproj" />
-    </ItemGroup>
-
-    <MSBuild Projects="@(_ProjectsToPackage)" Targets="Pack" />
-  </Target>
-
-  <Target Name="Build" DependsOnTargets="$(BuildDependsOn)" />
 
-  <Target Name="Clean">
-    <RemoveDir Directories="$(ArtifactsObjDir)" />
-    <RemoveDir Directories="$(ArtifactsBinDir)" />
-    <RemoveDir Directories="$(ArtifactsPackagesDir)" />
-  </Target>
-
-  <Target Name="Rebuild" DependsOnTargets="Clean;Build" />
+      <ProjectReference Condition="'$(BuildPackages)' == 'true'" Include="@(_ProjectsToPackage)" Targets="Pack" />
+  </ItemGroup>
 </Project>

eng/Versions.external.props

 <Project>
-  <!-- These references to third-party libraries are included in all projects except System.Device.Gpio -->
-  <ItemGroup Condition="'$(MSBuildProjectName)' != 'System.Device.Gpio'">
+  <!-- These references to third-party libraries are included in all projects except System.Device.Gpio and the build wrapper project -->
+  <ItemGroup Condition="'$(MSBuildProjectName)' != 'System.Device.Gpio' And '$(MSBuildProjectName)' != 'build'">
     <PackageReference Include="UnitsNet" Version="4.77.0" />
     <PackageReference Include="SixLabors.ImageSharp" Version="1.0.2" />
   </ItemGroup>

global.json

@@ -12,7 +12,8 @@
     "version": "7.0.100-preview.7.22377.5"
   },
   "msbuild-sdks": {
-    "Microsoft.DotNet.Arcade.Sdk": "8.0.0-beta.22452.1",
-    "Microsoft.DotNet.Helix.Sdk": "8.0.0-beta.22452.1"
+    "Microsoft.DotNet.Arcade.Sdk": "8.0.0-beta.22463.1",
+    "Microsoft.DotNet.Helix.Sdk": "8.0.0-beta.22463.1",
+    "Microsoft.Build.Traversal": "3.1.6"
   }
 }