Function diff_sets 

pub fn diff_sets(old: &[Package], new: &[Package]) -> DiffReport

Compares two sets of resolved packages, matching by package name. A package present only on one side is a Category::DeclRemoved or Category::DeclAdded; matched packages are walked pairwise.

diff_sets_in with no context: a type from a package outside new, such as ridl.std, which no snapshot carries, does not resolve, and a type the diff cannot resolve is reported as breaking.