Detect what cpu flag was given to the build process

[obones]

Hello,

Inside an implementation method, I'm using the symlink method from the repository context to "map" a set of files into an expected location, like this:

repo_ctx.symlink(location + "\\Lib\\x64", "lib")

The issue is that x64 is hardcoded and thus not desirable as I'm trying to cross build for x86 targets with the --cpu x64_x86_windows flag.
At first, I thought about using repo_ctx.os.arch but this is not working because it's returning the operating system architecture, not the one I'm targeting with the --cpu flag.

Is it something that I can find in the repo_ctx.attr field? If yes, would you have an example?

Thanks for your help.