Function create_commit 

pub fn create_commit(
    repo: &Repository,
    req: &CommitRequest,
    progress: &mut dyn ProgressSink,
) -> Result<CommitOutcome>

Write a commit from the current index and advance the checked-out branch.

Loads the index from disk, builds the commit tree with an incremental cache-tree write-tree, writes the commit object, writes the index back with an updated cache-tree, then atomically updates the branch ref and reflogs (see crate::refs::update_branch_for_commit_on_store).

Parameters

• repo — open repository with a work tree and branch HEAD.
• req — message, author/committer identities, and empty-commit policy.
• progress — optional progress sink (single commit phase).

Errors

• Error::AmendUnborn when CommitRequest::amend is set but the branch has no commits yet.
• Error::NothingToCommit when the new tree is empty (unborn branch) or matches the parent tree and CommitRequest::allow_empty is false (not applied when amending).
• Error::IndexUnmerged when the index has conflict stages.
• Index write or diff failures before the branch is updated; the branch tip is not advanced.
• Ref/reflog failures from crate::refs::update_branch_for_commit_on_store; the branch tip is not left advanced without reflogs when logging is enabled.