[ci] Fail build if any git tracked files were modified. (#1288)

Context: dotnet/android@208c529

Scenarios where the build unintentionally modifies git tracked files
on some platforms are frustrating, so let's prevent them from
happening in the first place.

Add a CI check to fail a build if any git tracked files were modified.

Also contains a fix for the `<GenAPITask/>` task, which always
generates files with Windows line endings, which causes
`git status` to show the file as modified on other platforms.

Author: jpobst

build-tools/automation/azure-pipelines.yaml

@@ -61,6 +61,8 @@ jobs:
       nativeAotRid: win-x64
       platformName: .NET - Windows
 
+  - template: templates\fail-on-dirty-tree.yaml
+
   - template: templates\fail-on-issue.yaml
 
   - task: PublishPipelineArtifact@1
@@ -92,6 +94,8 @@ jobs:
       nativeAotRid: osx-x64
       platformName: .NET - MacOS
 
+  - template: templates\fail-on-dirty-tree.yaml
+
   - template: templates\fail-on-issue.yaml
 
 

build-tools/automation/templates/fail-on-dirty-tree.yaml

@@ -0,0 +1,22 @@
+# Ensure the build did not produce any modified checked in files
+
+parameters:
+  condition: succeeded()
+
+steps:
+- powershell: |
+    # Run this to log the output for the user
+    git status
+
+    # Run this to error the build if untracked files
+    $process= git status --porcelain --untracked-files=no
+
+    if ($process)
+    {
+        Write-Host "##vso[task.logissue type=error]git tree has modified tracked files."
+        Write-Host "##vso[task.complete result=Failed;]"
+    }
+    
+    git diff
+  displayName: Ensure no modified committed files
+  condition: ${{ parameters.condition }}

src/Java.Base/Java.Base.targets

@@ -84,4 +84,18 @@
     </PropertyGroup>
   </Target>
 
+  <!--
+    The <GenAPITask/> task always generates files with WIndows line endings,
+    which causes `git status` to show the file as modified.
+
+    Update `$(GenAPITargetPath)` so that it contains Unix line endings..
+    -->
+  <Target Name="_FixGenApiLineEndings"
+      Condition=" !$([MSBuild]::IsOSPlatform ('windows')) "
+      AfterTargets="GenerateReferenceAssemblySource">
+    <Move SourceFiles="$(GenAPITargetPath)" DestinationFiles="$(GenAPITargetPath).crlf" />
+    <Exec Command="tr -d '\015' &lt; $(GenAPITargetPath).crlf > $(GenAPITargetPath)" />
+    <Delete Files="$(GenAPITargetPath).crlf" />
+  </Target>
+
 </Project>