I figured I’d just add another intrinsic which returns a

Snapshot

, and if I do, I get told 38 times that

(AddressFamily, [Select(AddressMapper), Select(Dir)], [Get(Snapshot, PathGlobs), Get(Collection.of(FileContent), DirectoryDigest)], parse_address_family):
    no rule was available to compute Dir with parameter types (Address+BuildFileAddress+BuildFileAddresses+DirectoryDigest+ExecuteProcessRequest+LLVM+NativeToolchain+OptionsBootstrapper+PathGlobs+Specs)

and similarly for many other rules

the error messaging around this could be better (although it's better than i remember!). the "parameter types" part is a good start but i think this message specifically can be improved only because i rememember staring at it too many times when first writing rules