@matheusbsbs / matheus-bagliano / commits / 7ccdf65b63

rebase --rebase-merges: avoid "empty merges"

The `git merge` command does not allow merging commits that are already reachable from HEAD: `git merge HEAD^`, for example, will report that we are already up to date and not change a thing. In an interactive rebase, such a merge could occur previously, e.g. when competing (or slightly modified) versions of a patch series were applied upstream, and the user had to `git rebase --skip` all of the local commits, and the topic branch becomes "empty" as a consequence. Let's teach the todo command `merge` to behave the same as `git merge`. Seeing as it requires some low-level trickery to create such merges with Git's commands in the first place, we do not even have to bother to introduce an option to force `merge` to create such merge commits. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Johannes Schindelin committed Apr 25, 2018 at 14:29 UTC 7ccdf65b63f2f4a5e751d70b9788af3c9e16b6ab

2 files changed +15

sequencer.c

@@ -2810,6 +2810,13 @@ static int do_merge(struct commit *commit, const char *arg, int arg_len,

2810 write_message("no-ff", 5, git_path_merge_mode(), 0);

2811

2812 bases = get_merge_bases(head_commit, merge_commit);

2813 + if (bases && !oidcmp(&merge_commit->object.oid,

2814 + &bases->item->object.oid)) {

2815 + ret = 0;

2816 + /* skip merging an ancestor of HEAD */

2817 + goto leave_merge;

2818 + }

2819 +

2820 for (j = bases; j; j = j->next)

2821 commit_list_insert(j->item, &reversed);

2822 free_commit_list(bases);

t/t3430-rebase-merges.sh

@@ -215,4 +215,12 @@ test_expect_success 'post-rewrite hook and fixups work for merges' '

215 test_cmp expect actual

216 '

217

218 +test_expect_success 'refuse to merge ancestors of HEAD' '

219 + echo "merge HEAD^" >script-from-scratch &&

220 + test_config -C wt sequence.editor \""$PWD"/replace-editor.sh\" &&

221 + before="$(git rev-parse HEAD)" &&

222 + git rebase -i HEAD &&

223 + test_cmp_rev HEAD $before

224 +'

225 +

226 test_done