B0_srcs
type sel = [
| `Dir of B0_std.Fpath.t
| `Dir_rec of B0_std.Fpath.t
| `File of B0_std.Fpath.t
| `Fut of B0_build.t -> B0_std.Fpath.Set.t B0_std.Fut.t
| `X of B0_std.Fpath.t
]
type sels = sel list
val select : B0_build.t -> sels -> t B0_std.Fut.t
val by_ext : t -> B00_fexts.map