Use script to install ARM version of .NET on ARM because of a UseDotNet bug

eng/pipelines/common/templates/jobs/ci-run-tests-job.yml

@@ -217,26 +217,17 @@ jobs:
         referenceType: ${{ parameters.buildType }}
         testSet: ${{ parameters.testSet }}
         operatingSystem: ${{ parameters.operatingSystem }}
-  
+
   - ${{ if and(eq(parameters.enableX86Test, true), eq(parameters.operatingSystem, 'Windows')) }}: # run x86 tests
-    - powershell: |
-        dotnet --info
-
-        Invoke-WebRequest https://dot.net/v1/dotnet-install.ps1 -OutFile dotnet-install.ps1
-
-        # install .net x86
-        $version = "LTS"
-        if (!"${{parameters.targetFramework }}".StartsWith("net4"))
-        {
-            $version = "${{parameters.targetFramework }}".Substring(3, "${{parameters.targetFramework }}".Length-3)
-        }
-
-        .\dotnet-install.ps1 -Channel $version -Architecture x86 -InstallDir "$(dotnetx86RootPath)"
-
-        $(dotnetx86RootPath)dotnet.exe --info
-      displayName: 'Install .NET x86 '
-      condition: ne(variables['dotnetx86RootPath'], '')
-
+    - ${{ if ne(variables['dotnetx86RootPath'], '') }}:
+      - template: ../steps/ensure-dotnet-version.yml
+        parameters:
+          sdk: true
+          ${{ if not(startsWith(parameters.targetFramework, 'net4')) }}:
+            version: ${{ split(replace(parameters.targetFramework, 'net', ''), '.')[0] }}
+          windowsArchitecture: x86
+          installDir: $(dotnetx86RootPath)
+
     - template: ../steps/run-all-tests-step.yml@self
       parameters:
         debug: ${{ parameters.debug }}

eng/pipelines/common/templates/steps/ci-prebuild-step.yml

@@ -20,17 +20,15 @@ parameters:
       - Package
 
 steps:
-- task: UseDotNet@2
-  displayName: 'Use .NET 9.x sdk'
-  inputs:
-    packageType: sdk
-    version: '9.x'
+- template: ensure-dotnet-version.yml
+  parameters:
+    sdk: true
+    version: 9
 
-- task: UseDotNet@2
-  displayName: 'Install .NET 8.x runtime'
-  inputs:
-    packageType: runtime
-    version: '8.x'
+- template: ensure-dotnet-version.yml
+  parameters:
+    sdk: false
+    version: 8
 
 - ${{if eq(parameters.debug, true)}}:
   - powershell: |

eng/pipelines/common/templates/steps/ci-project-build-step.yml

@@ -34,18 +34,6 @@ parameters:
       - all
 
 steps:
-- task: UseDotNet@2
-  displayName: 'Use .NET 9.x sdk'
-  inputs:
-    packageType: sdk
-    version: '9.x'
-
-- task: UseDotNet@2
-  displayName: 'Install .NET 8.x runtime'
-  inputs:
-    packageType: runtime
-    version: '8.x'
-
 - ${{ if or(eq(parameters.operatingSystem, 'Windows'), eq(parameters.operatingSystem, 'deferedToRuntime')) }}:
   - ${{ if or(eq(parameters.build, 'MDS'), eq(parameters.build, 'all')) }}:
     - task: MSBuild@1

eng/pipelines/common/templates/steps/ensure-dotnet-version.yml

@@ -0,0 +1,77 @@
+#################################################################################
+# Licensed to the .NET Foundation under one or more agreements.                 #
+# The .NET Foundation licenses this file to you under the MIT license.          #
+# See the LICENSE file in the project root for more information.                #
+#################################################################################
+parameters:
+- name: version
+  type: number
+  default: 9
+- name: sdk
+  type: boolean
+  default: false
+- name: windowsArchitecture # This is only used on Windows
+  type: string
+  default: '<auto>'
+  values:
+    - '<auto>'
+    - 'x86'
+    - 'x64'
+    - 'arm'
+    - 'arm64'
+- name: installDir
+  type: string
+  default: ''
+- name: usePreview
+  type: boolean
+  default: false
+
+# Reason for not using UseDotNet task:
+# "[BUG]: UseDotNet task installs x86 build on Windows arm64"
+# https://github.com/microsoft/azure-pipelines-tasks/issues/20300
+#
+# Borrowed from: https://github.com/microsoft/PowerToys/blob/main/.pipelines/v2/templates/steps-ensure-dotnet-version.yml
+steps:
+- powershell: |-
+    Invoke-WebRequest -Uri "https://dot.net/v1/dotnet-install.ps1" -OutFile "dotnet-install.ps1"
+    $NEW_DOTNET_ROOT = "${{parameters.installDir}}"
+
+    if ('${{parameters.installDir}}' -eq '') {
+      $NEW_DOTNET_ROOT = "$(Agent.ToolsDirectory)\dotnet"
+    } else {
+      $NEW_DOTNET_ROOT = "${{parameters.installDir}}"
+    }
+
+    if (!$${{parameters.sdk}}) {
+      $runtime = "dotnet"
+    }
+
+    $quality = "GA"
+    if ($${{parameters.usePreview}}) {
+      $quality = "preview"
+    }
+
+    & ./dotnet-install.ps1 -Channel "${{parameters.version}}.0" -Quality $quality -InstallDir $NEW_DOTNET_ROOT -Runtime $runtime -Architecture "${{parameters.windowsArchitecture}}"
+    Write-Host "##vso[task.setvariable variable=DOTNET_ROOT]${NEW_DOTNET_ROOT}"
+    Write-Host "##vso[task.prependpath]${NEW_DOTNET_ROOT}"
+    Remove-Item dotnet-install.ps1 -ErrorAction:Ignore
+  condition: and(succeeded(), eq(variables['Agent.OS'], 'Windows_NT'))
+  ${{ if eq(parameters.sdk, true) }}:
+    displayName: "Install .NET ${{parameters.version}} SDK (Win)"
+  ${{ else }}:
+    displayName: "Install .NET ${{parameters.version}} (Win)"
+- task: UseDotNet@2
+  inputs:
+    ${{ if eq(parameters.sdk, true) }}:
+      packageType: sdk
+    ${{ else }}:
+      packageType: runtime
+    version: '${{parameters.version}}.x'
+    ${{ if ne(parameters.installDir, '') }}:
+      installationPath: '${{parameters.installDir}}'
+    includePreviewVersions: ${{parameters.usePreview}}
+  condition: and(succeeded(), ne(variables['Agent.OS'], 'Windows_NT'))
+  ${{ if eq(parameters.sdk, true) }}:
+    displayName: "Install .NET ${{parameters.version}} SDK (non-Win)"
+  ${{ else }}:
+    displayName: "Install .NET ${{parameters.version}} (non-Win)"