From: Siddharth Asthana Date: Wed, 18 Feb 2026 23:42:13 GMT Subject: [PATCH v3 0/2] replay: add --revert mode to reverse commit changes Message-ID: <20260218234215.89326-1-siddharthasthana31@gmail.com> In-Reply-To: <20251202201611.22137-1-siddharthasthana31@gmail.com> The `git replay` command performs server-side history rewriting without requiring a working tree. While it currently supports cherry-picking commits (--advance) and rebasing (--onto), it lacks the ability to revert them. At GitLab, we use replay in Gitaly for efficient server-side operations on bare repositories. Adding revert functionality enables us to reverse problematic commits directly on the server, eliminating client-side roundtrips and reducing network overhead. The implementation follows the same approach as sequencer.c where cherry-pick and revert are the same merge operation but with swapped arguments. For cherry-pick we merge(ancestor=parent, ours=current, theirs=commit), while for revert we merge(ancestor=commit, ours=current, theirs=parent). By swapping the base and pickme trees when calling merge_incore_nonrecursive(), we effectively reverse the diff direction. The series is structured as follows: Patch 1 extracts the revert message formatting logic into a shared sequencer_format_revert_header() function, eliminating code duplication between sequencer.c and the upcoming replay code. This follows Junio's suggestion to split the changes. Patch 2 adds the --revert mode to git replay. Following the architectural pattern suggested by Elijah and Phillip, --revert is a standalone mode (like --onto and --advance) that takes a branch argument and updates that branch with the revert commits. The series is based on top of 864f55e190 (The second batch, 2026-02-07). CI: https://gitlab.com/gitlab-org/git/-/pipelines/2329880894 The Windows CI failures (t4041, t4059, t4060, t4205, t6006) are pre-existing infrastructure issues (missing iconv, submodule pathspec errors) unrelated to this series. Signed-off-by: Siddharth Asthana --- Changes in v3: - Rebased on top of the latest upstream which refactored replay into a library (replay.c / replay.h). The --revert logic now lives in replay.c alongside the existing pick logic, while builtin/replay.c is a thin CLI wrapper. - sequencer_format_revert_header() now takes an optional oid parameter so it can handle the full commit reference internally, per Patrick's suggestion about refer_to_commit() - Removed now-unused `orig_subject` variable in do_pick_commit() - Switched to die_for_incompatible_opt3() for --onto/--advance/--revert mutual exclusivity, per Patrick - --contained now just checks "die(_("--contained requires --onto"))" instead of going through die_for_incompatible_opt2, per Phillip - Added BUG() guards for unhandled replay_mode values, per Patrick - Merged the separate advance/revert ref update blocks into one - author is set to NULL for revert commits so commit_tree_extended() picks up the current user, per Phillip - Factored out common --advance/--revert branch validation into a set_up_branch_mode() helper, per Phillip - Doc wording fixes: "reverted commits", "they are prefixed", "hash" instead of "SHA", per Phillip - Tests now reuse topic4 instead of creating new branches, use heredoc for test_commit_message, and the reflog check is folded into the main revert test - Added tests for bare repo revert, error cases (argument validation, multiple sources) - Link to v2: https://public-inbox.org/git/20251202201611.22137-1-siddharthasthana31@gmail.com/t/#u - Link to v1: https://public-inbox.org/git/20251125170056.34489-1-siddharthasthana31@gmail.com/t/#u --- Documentation/git-replay.adoc | 37 +++++++- builtin/replay.c | 25 ++++-- replay.c | 162 ++++++++++++++++++++++++---------- replay.h | 11 ++- sequencer.c | 47 ++++++---- sequencer.h | 11 +++ t/t3650-replay-basics.sh | 107 ++++++++++++++++++++-- 7 files changed, 319 insertions(+), 81 deletions(-) Siddharth Asthana (2): sequencer: extract revert message formatting into shared function replay: add --revert mode to reverse commit changes Range-diff versus v2: 1: bfd75484b4 ! 1: 9d686bcdfe sequencer: extract revert message formatting into shared function @@ Commit message Extract this logic into a new sequencer_format_revert_header() function that can be shared. The function handles both regular reverts ("Revert """) and revert-of-revert cases ("Reapply """). + When an oid is provided, the function appends the full commit hash and + period; otherwise the caller should append the commit reference. + Update do_pick_commit() to use the new helper, eliminating code duplication while preserving the special handling for commit_use_reference. Signed-off-by: Siddharth Asthana ## sequencer.c ## +@@ sequencer.c: static int do_pick_commit(struct repository *r, + */ + + if (command == TODO_REVERT) { +- const char *orig_subject; +- + base = commit; + base_label = msg.label; + next = parent; @@ sequencer.c: static int do_pick_commit(struct repository *r, if (opts->commit_use_reference) { strbuf_commented_addf(&ctx->message, comment_line_str, @@ sequencer.c: static int do_pick_commit(struct repository *r, - strbuf_addstr(&ctx->message, "Revert \""); - strbuf_addstr(&ctx->message, msg.subject); - strbuf_addstr(&ctx->message, "\"\n"); -+ sequencer_format_revert_header(&ctx->message, msg.subject); ++ sequencer_format_revert_header(&ctx->message, msg.subject, NULL); } - strbuf_addstr(&ctx->message, "\nThis reverts commit "); refer_to_commit(opts, &ctx->message, commit); @@ sequencer.c: int sequencer_pick_revisions(struct repository *r, return res; } -+void sequencer_format_revert_header(struct strbuf *out, const char *orig_subject) ++void sequencer_format_revert_header(struct strbuf *out, ++ const char *orig_subject, ++ const struct object_id *oid) +{ + const char *revert_subject; + @@ sequencer.c: int sequencer_pick_revisions(struct repository *r, + } + + strbuf_addstr(out, "\nThis reverts commit "); ++ if (oid) { ++ strbuf_addstr(out, oid_to_hex(oid)); ++ strbuf_addstr(out, ".\n"); ++ } +} + void append_signoff(struct strbuf *msgbuf, size_t ignore_footer, unsigned flag) @@ sequencer.h: int sequencer_determine_whence(struct repository *r, enum commit_wh int sequencer_get_update_refs_state(const char *wt_dir, struct string_list *refs); +/* -+ * Formats a revert commit message header following standard Git conventions. ++ * Formats a revert commit message following standard Git conventions. + * Handles both regular reverts ("Revert \"\"") and revert of revert -+ * cases ("Reapply \"\""). Adds "This reverts commit " at the end. -+ * The caller should append the commit OID after calling this function. ++ * cases ("Reapply \"\""). Adds "This reverts commit ." if oid ++ * is provided, otherwise just adds "This reverts commit " and the caller ++ * should append the commit reference. + */ -+void sequencer_format_revert_header(struct strbuf *out, const char *orig_subject); ++void sequencer_format_revert_header(struct strbuf *out, ++ const char *orig_subject, ++ const struct object_id *oid); + #endif /* SEQUENCER_H */ 2: a2f99bc8c2 < -: ---------- replay: add --revert mode to reverse commit changes -: ---------- > 2: a8eae7b802 replay: add --revert mode to reverse commit changes base-commit: 864f55e1906897b630333675a52874c0fec2a45c Thanks - Siddharth