@mavogel @wadackel I would also like to generate changelog notes based on a pair of commit references, in my case the head and base refs of a Pull Request

my use case is to generate a release note fragment in a pull request based just on the changes in that pull request as a way to provide feedback to the developers on my team how their commit messages will render in the customer-facing release notes we intend to generate later (based on tags in our release branch).

if this capability is aligned with this project's goals and vision I would be willing to prepare a contribution to implement.

I look forward to your thoughts and direction.

it looks like the functionality I'm looking for is already present in this method https://github.com/git-chglog/git-chglog/blob/v0.15.4/chglog.go#L226-L253

there is no real reason that I can tell for this readUnreleased(..) method to take in a slice of *Tag; if instead we pushed the responsibility for forming the rev list out so that this method could accept any rev list, that would probably move us towards being able to generate release fragments for an arbitrary range of commits by standard git ref syntax.

func (gen *Generator) readUnreleased(tags []*Tag) (*Unreleased, error) {
	if gen.config.Options.NextTag != "" {
		return &Unreleased{}, nil
	}

	rev := "HEAD"

	if len(tags) > 0 {
		rev = tags[0].Name + "..HEAD"
	}

	commits, err := gen.commitParser.Parse(rev)
	if err != nil {
		return nil, err
	}

	commitGroups, mergeCommits, revertCommits, noteGroups := gen.commitExtractor.Extract(commits)

	unreleased := &Unreleased{
		CommitGroups:  commitGroups,
		Commits:       commits,
		MergeCommits:  mergeCommits,
		RevertCommits: revertCommits,
		NoteGroups:    noteGroups,
	}

	return unreleased, nil
}

maybe supporting generating unreleased notes about any arbitrary commits while still requiring tags to be in use for the standard use case is a nice compromise?