The shim is hardcoded in ghcup currently. So if there is a bug, then we need to tell people to 'ghcup upgrade'. That could be a problem imo.
the shim does some additional work, I'm not sure if this will in fact slow down compilation processes? A cat call and a [ -f file ] check.
the local feature only works for the current directory (and only the current directory), there is no recursive upwards check performed, so if you are in a subdirectory of your project, it will not work
TODO:
I think there was some logic checking for ghc etc being dangling symlinks, clean that up