How to scope/limit the effect of Enter-VsDevShell? - visual-studio

Question

I am scripting the build of a third-party piece of software, which also is the reason why I need to accommodate its needs. The third-party software expects nmake to be available along with compiler, linker, librarian and other tools found in the MSVC toolchain.
So I thought I'd use Enter-VsDevShell from Microsoft.VisualStudio.DevShell and be done with it. Here's my minimal script to show the issue:
Set-StrictMode -Version Latest
function Get-VSBasePath
{
Param($vsrange = "[16.0,18.0)")
$vswhere = "${env:ProgramFiles(x86)}\Microsoft Visual Studio\Installer\vswhere.exe"
$vspath = & $vswhere -products "*" -format value -property installationPath -latest -version "$vsrange"
return $vspath
}
function Do-Stuff
{
Param($arch = "x64")
$vspath = Get-VSBasePath
if (-not (Get-Command Enter-VsDevShell -CommandType Cmdlet -ErrorAction silentlycontinue))
{
Import-Module "$vspath\Common7\Tools\Microsoft.VisualStudio.DevShell.dll" -Force|Out-Host
}
Enter-VsDevShell -VsInstallPath "$vspath" -DevCmdArguments "-arch=$arch -no_logo" -SkipAutomaticLocation|Out-Host
}
echo "Do we know cl.exe now? (#1)"
Get-Command cl -CommandType Application -ErrorAction silentlycontinue|Out-Host
echo "Calling Do-Stuff"
Do-Stuff
echo "Do we know cl.exe now? (#2)"
Get-Command cl -CommandType Application -ErrorAction silentlycontinue|Out-Host
After the Import-Module I can see there is no counterpart cmdlet to Enter-VsDevShell in that module:
$ Get-Command -Module Microsoft.VisualStudio.DevShell
CommandType Name Version Source
----------- ---- ------- ------
Cmdlet Enter-VsDevShell 17.0.0.0 Microsoft.VisualStudio.DevShell
Cmdlet Send-VsDevShellTelemetry 17.0.0.0 Microsoft.VisualStudio.DevShell
Issuing a Remove-Module Microsoft.VisualStudio.DevShell also doesn't undo the effect of Enter-VsDevShell, unfortunately. My guess is that for the most part it affects environment variables. It even leaks its effect into the calling PowerShell.
So how can I limit the effect of Enter-VsDevShell to only the Do-Stuff function, say?
I need to run several builds back to back in order to build for all my desired target platforms. And that's why I want to limit the effect of Enter-VsDevShell.
I have also tried issuing another Enter-VsDevShell with a different target platform, but it doesn't work reliably.