The libphutil repository does not ship a Windows binary for XHPAST by default. This can make it difficult to write and maintain Arcanist extensions for Windows.
This document provides information on how to set up your environment to build XHPAST on Windows
You'll need to install the msysGit environment so that you have a Bash shell available. The easiest way to download and install Git from https://git-scm.com/download/win.
Download MINGW32 from http://www.mingw.org/download/installer and install it. Once the main install has finished, it'll prompt you for the packages to install. You'll want to install these packages and then hit "Apply Changes":
mingw32-base, mingw32-gcc-g++ and msys-base is what you want to install.
You will need to add Git and MINGW32 to your PATH like this:
(Git is in the system PATH so it's not shown in that list, but it does need to be there)
The provided scripts won't work on Windows, because Make is called mingw32-make. Open up Git Bash and then run (modify the path to libphutil as needed):
$ "mingw32-make" -C "C:\Tools\Arcanist\libphutil\support\xhpast" "SKIP_PARSER=1" "SKIP_SCANNER=1" "clean" "all" "install"
After this, arc liberate should work as intended.