From 3585d0ea232b1a9c5498ab5785b11f61e93967c8 Mon Sep 17 00:00:00 2001 From: Elijah Newren Date: Wed, 30 Jun 2021 17:30:00 +0000 Subject: [PATCH] merge-recursive: handle rename-to-self case Directory rename detection can cause transitive renames, e.g. if the two different sides of history each do one half of: A/file -> B/file B/ -> C/ then directory rename detection transitively renames to give us A/file -> C/file However, when C/ == A/, note that this gives us A/file -> A/file. merge-recursive assumed that any rename D -> E would have D != E. While that is almost always true, the above is a special case where it is not. So we cannot do things like delete the rename source, we cannot assume that a file existing at path E implies a rename/add conflict and we have to be careful about what stages end up in the output. This change feels a bit hackish. It took me surprisingly many hours to find, and given merge-recursive's design causing it to attempt to enumerate all combinations of edge and corner cases with special code for each combination, I'm worried there are other similar fixes needed elsewhere if we can just come up with the right special testcase. Perhaps an audit would rule it out, but I have not the energy. merge-recursive deserves to die, and since it is on its way out anyway, fixing this particular bug narrowly will have to be good enough. Reported-by: Anders Kaseorg Signed-off-by: Elijah Newren Signed-off-by: Junio C Hamano --- merge-recursive.c | 19 +++++++++++++------ t/t6423-merge-rename-directories.sh | 6 +++--- 2 files changed, 16 insertions(+), 9 deletions(-) diff --git a/merge-recursive.c b/merge-recursive.c index d146bb116f..c895145a8f 100644 --- a/merge-recursive.c +++ b/merge-recursive.c @@ -2804,12 +2804,19 @@ static int process_renames(struct merge_options *opt, int renamed_stage = a_renames == renames1 ? 2 : 3; int other_stage = a_renames == renames1 ? 3 : 2; + /* + * Directory renames have a funny corner case... + */ + int renamed_to_self = !strcmp(ren1_src, ren1_dst); + /* BUG: We should only remove ren1_src in the base * stage and in other_stage (think of rename + * add-source case). */ - remove_file(opt, 1, ren1_src, - renamed_stage == 2 || !was_tracked(opt, ren1_src)); + if (!renamed_to_self) + remove_file(opt, 1, ren1_src, + renamed_stage == 2 || + !was_tracked(opt, ren1_src)); oidcpy(&src_other.oid, &ren1->src_entry->stages[other_stage].oid); @@ -2823,6 +2830,9 @@ static int process_renames(struct merge_options *opt, ren1->dir_rename_original_type == 'A') { setup_rename_conflict_info(RENAME_VIA_DIR, opt, ren1, NULL); + } else if (renamed_to_self) { + setup_rename_conflict_info(RENAME_NORMAL, + opt, ren1, NULL); } else if (oideq(&src_other.oid, null_oid())) { setup_rename_conflict_info(RENAME_DELETE, opt, ren1, NULL); @@ -3180,7 +3190,6 @@ static int handle_rename_normal(struct merge_options *opt, struct rename *ren = ci->ren1; struct merge_file_info mfi; int clean; - int side = (ren->branch == opt->branch1 ? 2 : 3); /* Merge the content and write it out */ clean = handle_content_merge(&mfi, opt, path, was_dirty(opt, path), @@ -3190,9 +3199,7 @@ static int handle_rename_normal(struct merge_options *opt, opt->detect_directory_renames == MERGE_DIRECTORY_RENAMES_CONFLICT && ren->dir_rename_original_dest) { if (update_stages(opt, path, - NULL, - side == 2 ? &mfi.blob : NULL, - side == 2 ? NULL : &mfi.blob)) + &mfi.blob, &mfi.blob, &mfi.blob)) return -1; clean = 0; /* not clean, but conflicted */ } diff --git a/t/t6423-merge-rename-directories.sh b/t/t6423-merge-rename-directories.sh index 316339cb6c..4d056f0465 100755 --- a/t/t6423-merge-rename-directories.sh +++ b/t/t6423-merge-rename-directories.sh @@ -5000,7 +5000,7 @@ test_setup_12i () { ) } -test_expect_merge_algorithm failure success '12i: Directory rename causes rename-to-self' ' +test_expect_success '12i: Directory rename causes rename-to-self' ' test_setup_12i && ( cd 12i && @@ -5058,7 +5058,7 @@ test_setup_12j () { ) } -test_expect_merge_algorithm failure success '12j: Directory rename to root causes rename-to-self' ' +test_expect_success '12j: Directory rename to root causes rename-to-self' ' test_setup_12j && ( cd 12j && @@ -5116,7 +5116,7 @@ test_setup_12k () { ) } -test_expect_merge_algorithm failure success '12k: Directory rename with sibling causes rename-to-self' ' +test_expect_success '12k: Directory rename with sibling causes rename-to-self' ' test_setup_12k && ( cd 12k &&