The official way of building PowerShell requires PowerShell (nice dogfooding idea, like Roslyn requires previous version of Roslyn with runtime and BCL to compile).

For new platforms bootstrap, it is a problem however: #6367 (comment)

Please add a build script for new platform and then add PowerShell submodule to source-build repo: https://github.com/dotnet/source-build, so we have a scripting capability on new system.

@dseefeld, @weshaggard to comment on the idea of adding PowerShell as one of the source-build target.