From ca4e3ca029def86b7b29451d4ba77ef76574949e Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?SZEDER=20G=C3=A1bor?= Date: Wed, 30 Mar 2016 10:35:07 +0200 Subject: [PATCH] diffcore: fix iteration order of identical files during rename detection MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit If the two paths 'dir/A/file' and 'dir/B/file' have identical content and the parent directory is renamed, e.g. 'git mv dir other-dir', then diffcore reports the following exact renames: renamed: dir/B/file -> other-dir/A/file renamed: dir/A/file -> other-dir/B/file While technically not wrong, this is confusing not only for the user, but also for git commands that make decisions based on rename information, e.g. 'git log --follow other-dir/A/file' follows 'dir/B/file' past the rename. This behavior is a side effect of commit v2.0.0-rc4~8^2~14 (diffcore-rename.c: simplify finding exact renames, 2013-11-14): the hashmap storing sources returns entries from the same bucket, i.e. sources matching the current destination, in LIFO order. Thus the iteration first examines 'other-dir/A/file' and 'dir/B/file' and, upon finding identical content and basename, reports an exact rename. Other hashmap users are apparently happy with the current iteration order over the entries of a bucket. Changing the iteration order would risk upsetting other hashmap users and would increase the memory footprint of each bucket by a pointer to the tail element. Fill the hashmap with source entries in reverse order to restore the original exact rename detection behavior. Reported-by: Bill Okara Signed-off-by: SZEDER Gábor Signed-off-by: Junio C Hamano --- diffcore-rename.c | 6 ++++-- t/t4001-diff-rename.sh | 11 +++++++++++ 2 files changed, 15 insertions(+), 2 deletions(-) diff --git a/diffcore-rename.c b/diffcore-rename.c index af1fe08861..69fcf77be0 100644 --- a/diffcore-rename.c +++ b/diffcore-rename.c @@ -340,9 +340,11 @@ static int find_exact_renames(struct diff_options *options) int i, renames = 0; struct hashmap file_table; - /* Add all sources to the hash table */ + /* Add all sources to the hash table in reverse order, because + * later on they will be retrieved in LIFO order. + */ hashmap_init(&file_table, NULL, rename_src_nr); - for (i = 0; i < rename_src_nr; i++) + for (i = rename_src_nr-1; i >= 0; i--) insert_file_table(&file_table, i, rename_src[i].p->one); /* Walk the destinations and find best source match */ diff --git a/t/t4001-diff-rename.sh b/t/t4001-diff-rename.sh index 2f327b7495..ed90c6c6f9 100755 --- a/t/t4001-diff-rename.sh +++ b/t/t4001-diff-rename.sh @@ -77,6 +77,17 @@ test_expect_success 'favour same basenames even with minor differences' ' git show HEAD:path1 | sed "s/15/16/" > subdir/path1 && git status | test_i18ngrep "renamed: .*path1 -> subdir/path1"' +test_expect_success 'two files with same basename and same content' ' + git reset --hard && + mkdir -p dir/A dir/B && + cp path1 dir/A/file && + cp path1 dir/B/file && + git add dir && + git commit -m 2 && + git mv dir other-dir && + git status | test_i18ngrep "renamed: .*dir/A/file -> other-dir/A/file" +' + test_expect_success 'setup for many rename source candidates' ' git reset --hard && for i in 0 1 2 3 4 5 6 7 8 9;