From b4d01f339c2c81d6548d86ceec4c168afdf44a85 Mon Sep 17 00:00:00 2001
From: "Matt Mitchell (.NET)" <mmitche@microsoft.com>
Date: Fri, 15 Dec 2023 08:32:51 -0800
Subject: [PATCH] Do not call Unsubst if it is not available due to argument
 processing If argument processing fails, the script will not import the
 utility methods, and Subst won't be called. This will cause the script to
 fail in non-helpful ways. In addition, fix an issue where the TEMP dir
 remains at T: after unsubst is called.

---
 eng/build-utils.ps1 | 5 +++++
 eng/build.ps1       | 4 +++-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/eng/build-utils.ps1 b/eng/build-utils.ps1
index 34490cf2d56fa..953697e851614 100644
--- a/eng/build-utils.ps1
+++ b/eng/build-utils.ps1
@@ -15,6 +15,7 @@ $nodeReuse = if (Test-Path variable:nodeReuse) { $nodeReuse } else { $false }
 $bootstrapDir = if (Test-Path variable:bootstrapDir) { $bootstrapDir } else { "" }
 $bootstrapConfiguration = if (Test-Path variable:bootstrapConfiguration) { $bootstrapConfiguration } else { "Release" }
 $properties = if (Test-Path variable:properties) { $properties } else { @() }
+$originalTemp = $env:TEMP;
 
 function GetProjectOutputBinary([string]$fileName, [string]$projectName = "", [string]$configuration = $script:configuration, [string]$tfm = "net472", [string]$rid = "", [bool]$published = $false) {
   $projectName = if ($projectName -ne "") { $projectName } else { [System.IO.Path]::GetFileNameWithoutExtension($fileName) }
@@ -358,5 +359,9 @@ function Subst-TempDir() {
 function Unsubst-TempDir() {
   if ($ci) {
     Exec-Command "subst" "T: /d"
+
+    # Restore the original temp directory
+    $env:TEMP=$originalTemp
+    $env:TMP=$originalTemp
   }
 }
diff --git a/eng/build.ps1 b/eng/build.ps1
index 5c4014a4096e4..1a53d89c05983 100644
--- a/eng/build.ps1
+++ b/eng/build.ps1
@@ -798,6 +798,8 @@ finally {
     Stop-Processes
   }
 
-  Unsubst-TempDir
+  if (Test-Path Function:\Unsubst-TempDir) {
+    Unsubst-TempDir
+  }
   Pop-Location
 }