Install Metal toolchain for Xcode 26 and newer (#268)

* Install Metal toolchain when Xcode version is 26 or newer

* Define a variable rather than using a regex

* Provide the Xcode components as a list

* Use “shell” rather than “provisioner”

* Update .ci/cirrus.xcode.yml

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

---------

Co-authored-by: Fedor Korotkov <fedor.korotkov@gmail.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

.ci/cirrus.xcode.yml

@@ -5,6 +5,7 @@ task:
     matrix:
       - MACOS_VERSION: tahoe
         XCODE_VERSION: 26-beta-6
+        XCODE_COMPONENTS: "MetalToolchain"
         LATEST: true
       - MACOS_VERSION: sequoia
         XCODE_VERSION: 16.4
@@ -32,7 +33,7 @@ task:
     - tart pull ghcr.io/cirruslabs/macos-$MACOS_VERSION-base:latest
   build_xcode_script:
     - packer init templates/xcode.pkr.hcl
-    - packer build -var macos_version="$MACOS_VERSION" -var xcode_version="[\"$XCODE_VERSION\"]" templates/xcode.pkr.hcl
+    - packer build -var macos_version="$MACOS_VERSION" -var xcode_version="[\"$XCODE_VERSION\"]" -var xcode_components="[\"$XCODE_COMPONENTS\"]" templates/xcode.pkr.hcl
   push_script: |
     if [[ -z "$LATEST" ]]
     then

templates/xcode.pkr.hcl

@@ -20,6 +20,12 @@ variable "additional_ios_builds" {
   default = []
 }
 
+variable "xcode_components" {
+  type    = list(string)
+  default = []
+  description = "Additional Xcode components to download."
+}
+
 variable "expected_runtimes_file" {
   type    = string
   default = ""
@@ -194,6 +200,15 @@ build {
     )
   }
 
+  dynamic "shell" {
+    inline = concat(
+      ["source ~/.zprofile"],
+      [
+        for component in var.xcode_components : "xcodebuild -downloadComponent ${component}"
+      ]
+    )
+  }
+
   provisioner "shell" {
     inline = [
       "source ~/.zprofile",