Function bump_of 

pub fn bump_of(changes: &[Change]) -> Bump

What a set of conventional commits says about itself.

The rule is the conventional-commit rule and nothing more: a breaking change is major, a feature is minor, anything else is patch, and no commits at all is none.

This is evidence, not authority

It used to decide what release bump wrote, and that was the defect this subsystem exists to remove. A commit message is a label a person chose, and a capability deleted under a refactor: heading was a patch to this function and a broken caller to everyone else. The compatibility level is now measured from the public contract by crate::release::compat::analyze; this answer is carried beside it as crate::release::compat::CommitEvidence, and when the two disagree the plan says which one understated the change. Nothing decides a version from this alone.