fix: reject deleted prior checkout branches#2610
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Repository::rev_parse_single("@{-1}") could return the previous object id from
HEAD's reflog after the prior checkout branch had been deleted. Git treats @{-N}
as the previous checkout name and reparses that name, so a deleted branch no
longer names a single revision.
The regression adds deleted prior-checkout fixtures and asserts that @{-1}
follows the Git baseline failure for deleted branch names while still accepting
previous checkout names that are full object ids.
The fix keeps resolving existing prior checkout references as before, but only
falls back to a direct object id when the reflog name itself is a full object id
for the repository hash kind.
Git baseline: Git 2.50.1 rejects the deleted branch scenario with `git rev-parse
--verify @{-1}` reporting "Needed a single revision" and exiting 128. The
reference implementation in object-name.c expands @{-N} to the previous checkout
text before normal revision lookup.
Co-authored-by: Sebastian Thiel <sebastian.thiel@icloud.com>
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Pull request overview
This PR fixes gix::Repository::rev_parse_single("@{-1}") to match Git’s behavior when the previous checkout target was a branch that has since been deleted: instead of resolving via the stale object id recorded in HEAD’s reflog, it now fails unless the prior checkout name itself is a full object id.
Changes:
- Update prior-checkout (
@{-N}) resolution to error on deleted branch names instead of falling back to the reflog’s recorded object id. - Preserve Git-compatible behavior for prior checkout names that are full object ids by accepting them even if they don’t correspond to an existing ref.
- Add fixtures + tests covering both the deleted-branch failure case and the “branch named like full object id” acceptance case.
Reviewed changes
Copilot reviewed 3 out of 4 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
| gix/src/revision/spec/parse/delegate/revision.rs | Adjusts @{-N} handling to re-resolve the previous checkout name and reject deleted branches, only allowing fallback for full object ids. |
| gix/tests/gix/revision/spec/from_bytes/reflog.rs | Adds regression tests for deleted prior-checkout branches and the full-object-id-name exception. |
| gix/tests/fixtures/make_rev_spec_parse_repos.sh | Adds new fixture repos to exercise the deleted-branch and full-object-id-name prior-checkout scenarios. |
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Tasks
Created by Codex on behalf of Byron. Byron will review before this is ready to merge.
Summary
Fixes #2609.
Repository::rev_parse_single("@{-1}")now rejects a deleted prior checkout branch instead of resolving it through the stale object id stored in the HEAD reflog.The change keeps Git-compatible full-object-id behavior for previous checkout names that are themselves complete object ids.
Git Baseline
Git 2.50.1 rejects the deleted branch scenario with
git rev-parse --verify @{-1}reporting "Needed a single revision" and exiting 128.The Git reference implementation in
object-name.cexpands@{-N}to the previous checkout text before normal revision lookup.Validation
GIX_TEST_IGNORE_ARCHIVES=1 cargo test -p gix --test gix revision::spec::from_bytes::reflog::nth_prior_checkout_to_deleted_branch_fails_like_git --features revisionGIX_TEST_IGNORE_ARCHIVES=1 cargo test -p gix --test gix revision::spec::from_bytes::reflog --features revisioncargo test -p gix --test gix revision::spec::from_bytes::reflog --features revisionGIX_TEST_IGNORE_ARCHIVES=1 cargo test -p gix --test gix revision::spec::from_bytes --features revisioncargo test -p gix --test gix revision::spec::from_bytes --features revision