C++/CLI tests fail on VS 2026 Helix machines - MSB8020 v143 platform toolset not found

[MichaelSimons]

Description

Multiple C++/CLI tests fail on the windows.amd64.vs2026.pre.scout.open Helix queue with:

error MSB8020: The build tools for Visual Studio 2022 (Platform Toolset = 'v143') cannot be found.
To build using the v143 build tools, please install Visual Studio 2022 build tools.

The C++/CLI test asset .vcxproj files target the v143 (VS 2022) platform toolset, but the VS 2026 Helix scout images only have v180 installed.

Affected Tests

• Microsoft.NET.Build.Tests.SourceLinkTests.Cpp
• Microsoft.NET.Build.Tests.GivenThatWeWantToBuildACppCliProject (all methods)
• Microsoft.NET.Build.Tests.GivenThatWeWantToBuildACppCliProjectWithTransitiveDeps (all methods)
• Microsoft.NET.Pack.Tests.GivenThatWeWantToPackACppCliProject (all methods)
• Microsoft.NET.Publish.Tests.GivenThatWeWantToPublishACppCliProject (all methods)

Affected Test Assets

• test/TestAssets/TestProjects/NetCoreCsharpAppReferenceCppCliLib/NETCoreCppCliTest/NETCoreCppCliTest.vcxproj
• test/TestAssets/TestProjects/NetCoreCppCliLibWithTransitiveDeps/NETCoreCppCliTest/NETCoreCppCliTest.vcxproj
• test/TestAssets/TestProjects/NetCoreCppCliLibWithTransitiveDeps/NETCoreCppCliTestB/NETCoreCppCliTestB.vcxproj
• test/TestAssets/TestProjects/NetCoreCppCliLibWithTransitiveDeps/NETCoreCppCliTestC/NETCoreCppCliTestC.vcxproj

Build

https://dev.azure.com/dnceng-public/public/_build/results?buildId=1372766
Helix job: 698f4ee1-5121-4424-b30c-db78b1f1c0d9, work item: Microsoft.NET.Build.Tests.dll.16

Options

• Update the test asset .vcxproj files to use a newer platform toolset (v180)
• Request v143 build tools be installed on the VS 2026 Helix scout images