From 3908a78286454058c6642b1873e08f5f82afb19e Mon Sep 17 00:00:00 2001
From: Klaus Loffelmann <klaus.loeffelmann@microsoft.com>
Date: Fri, 3 Jul 2026 09:30:42 -0700
Subject: [PATCH] Refactor build.cmd for ARM64 and add build.cmd.ps1

* Refactored build.cmd to delegate to a new PowerShell script (build.cmd.ps1) for improved argument parsing and platform detection.

* Added support for building on Windows ARM64 via the -platform arm64 option, which sets TargetArchitecture and disables NativeToolsOnMachine.

* Updated documentation to reflect the new ARM64 build instructions.
---
 build.cmd         |  2 +-
 docs/building.md  |  1 +
 eng/build.cmd.ps1 | 65 +++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 67 insertions(+), 1 deletion(-)
 create mode 100644 eng/build.cmd.ps1

diff --git a/build.cmd b/build.cmd
index 9852a061a26..c25a3fbebe1 100755
--- a/build.cmd
+++ b/build.cmd
@@ -1,3 +1,3 @@
 @echo off
-powershell -ExecutionPolicy ByPass -NoProfile -command "& """%~dp0eng\common\Build.ps1""" -NativeToolsOnMachine -restore -build -bl %*"
+powershell -ExecutionPolicy ByPass -NoProfile -File "%~dp0eng\build.cmd.ps1" %*
 exit /b %ErrorLevel%
diff --git a/docs/building.md b/docs/building.md
index 25f26541301..da5a785bb75 100644
--- a/docs/building.md
+++ b/docs/building.md
@@ -10,6 +10,7 @@ Follow the prerequisites listed at [Developer Guide](developer-guide.md).
 
 * Run `.\build.cmd` from the repository root. This builds the `Winforms.sln` using the default config (Debug|Any CPU).
 * To specify a build configuration, add `-configuration` followed by the config such as `.\build -configuration Release`.
+* To build on Windows ARM64, use `.\build -platform arm64`. This maps the solution platform to `TargetArchitecture=arm64` without promoting local Visual Studio native tool paths.
 
 Note that this does **not** build using your machine-wide installed version of the dotnet sdk. It builds using the repo-local .NET SDK specified in the global.json in the repository root.
 
diff --git a/eng/build.cmd.ps1 b/eng/build.cmd.ps1
new file mode 100644
index 00000000000..50ab390e38b
--- /dev/null
+++ b/eng/build.cmd.ps1
@@ -0,0 +1,65 @@
+[CmdletBinding(PositionalBinding = $false)]
+param(
+    [Parameter(ValueFromRemainingArguments = $true)]
+    [string[]] $BuildArgs
+)
+
+$forwardArgs = [System.Collections.Generic.List[string]]::new()
+$useNativeTools = $true
+$isArm64Platform = $false
+$hasTargetArchitecture = $false
+
+for ($i = 0; $i -lt $BuildArgs.Length; $i++) {
+    $arg = $BuildArgs[$i]
+
+    if ($arg.StartsWith('/p:TargetArchitecture=', [StringComparison]::OrdinalIgnoreCase) -or
+        $arg.StartsWith('-p:TargetArchitecture=', [StringComparison]::OrdinalIgnoreCase)) {
+        $hasTargetArchitecture = $true
+    }
+
+    if ($arg.Equals('-platform', [StringComparison]::OrdinalIgnoreCase) -and
+        $i + 1 -lt $BuildArgs.Length -and
+        $BuildArgs[$i + 1].Equals('arm64', [StringComparison]::OrdinalIgnoreCase)) {
+        $isArm64Platform = $true
+        $i++
+        continue
+    }
+
+    if ($arg.Equals('/p:Platform=arm64', [StringComparison]::OrdinalIgnoreCase) -or
+        $arg.Equals('-p:Platform=arm64', [StringComparison]::OrdinalIgnoreCase)) {
+        $isArm64Platform = $true
+        continue
+    }
+
+    $forwardArgs.Add($arg)
+}
+
+if ($isArm64Platform) {
+    $useNativeTools = $false
+
+    if (!$hasTargetArchitecture) {
+        $forwardArgs.Add('/p:TargetArchitecture=arm64')
+    }
+}
+
+$buildScript = Join-Path $PSScriptRoot 'common\Build.ps1'
+$baseArgs = @()
+
+if ($useNativeTools) {
+    $baseArgs += '-NativeToolsOnMachine'
+}
+
+$processArgs = @(
+    '-ExecutionPolicy'
+    'ByPass'
+    '-NoProfile'
+    '-File'
+    $buildScript
+) + $baseArgs + @(
+    '-restore'
+    '-build'
+    '-bl'
+) + $forwardArgs
+
+& powershell @processArgs
+exit $LASTEXITCODE