Use shorter output paths to avoid max path issues on Windows

For example, "out/2" instead of "artifacts/stage2"

.gitignore

@@ -96,6 +96,7 @@ dlldata.c
 # DNX
 project.lock.json
 artifacts/
+out/
 
 *_i.c
 *_p.c

build/InitRepo.props

@@ -1,6 +1,6 @@
 <Project ToolsVersion="14.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <PropertyGroup>
-    <GeneratedPropsDir>$(RepoRoot)/artifacts/obj</GeneratedPropsDir>
+    <GeneratedPropsDir>$(RepoRoot)/out/obj</GeneratedPropsDir>
     <GitCommitInfoProps>$(GeneratedPropsDir)/GitCommitInfo.props</GitCommitInfoProps>
     <HostInfoProps>$(GeneratedPropsDir)/HostInfo.props</HostInfoProps>
     <BuildInfoProps>$(GeneratedPropsDir)/BuildInfo.props</BuildInfoProps>

build/OutputDirectories.props

@@ -6,7 +6,7 @@
       <!-- BaseOutputDirectory is the root output path for this stage and RID
            BaseOutputPath is the project-specific output folder that each project builds into.
            This is not confusing at all. -->
-      <BaseOutputDirectory>$(RepoRoot)/artifacts/stage$(CliBuildStage)/$(Rid)</BaseOutputDirectory>
+      <BaseOutputDirectory>$(RepoRoot)/out/$(CliBuildStage)/$(Rid)</BaseOutputDirectory>
       <BaseOutputPath>$([System.IO.Path]::GetFullPath('$(BaseOutputDirectory)/bin/$(MSBuildProjectName)'))</BaseOutputPath>
 
       <BaseIntermediateOutputPath>$([System.IO.Path]::GetFullPath('$(BaseOutputDirectory)/obj/$(MSBuildProjectName)'))</BaseIntermediateOutputPath>

build/Prepare.targets

@@ -100,7 +100,7 @@
 
   <Target Name="IsolateArtifactsFromDirectoryBuildFiles">
     <Copy SourceFiles="$(RepoRoot)TestAssets\Directory.Build.props"
-          DestinationFolder ="$(RepoRoot)artifacts"
+          DestinationFolder ="$(RepoRoot)out"
           SkipUnchangedFiles="true" />
   </Target>
 

test/Microsoft.DotNet.Tools.Tests.Utilities/RepoDirectoriesProvider.cs

@@ -63,7 +63,7 @@ public static string BuildRid
             {
                 if (string.IsNullOrEmpty(s_buildRid))
                 {
-                    var buildInfoPath = Path.Combine(RepoRoot, "artifacts", "obj", "BuildInfo.props");
+                    var buildInfoPath = Path.Combine(RepoRoot, "out", "obj", "BuildInfo.props");
                     var root = XDocument.Load(buildInfoPath).Root;
                     var ns = root.Name.Namespace;
 
@@ -99,7 +99,10 @@ public RepoDirectoriesProvider(
             string corehostDummyPackages = null,
             string pjDotnet = null)
         {
-            _artifacts = artifacts ?? Path.Combine(RepoRoot, "artifacts", "stage2", BuildRid);
+            _artifacts = artifacts ?? Path.Combine(RepoRoot,
+                                                   "out",
+                                                   "2",     //  Stage - ideally this would come from the "previous stage"
+                                                   BuildRid);
             _builtDotnet = builtDotnet ?? Path.Combine(_artifacts, "intermediate", "sharedFrameworkPublish");
             _nugetPackages = nugetPackages ?? Path.Combine(RepoRoot, ".nuget", "packages");
             _pjDotnet = pjDotnet ?? GetPjDotnetPath();