[PATCH v2 1/2] update-index: optionally leave skip-worktree entries alone

From: Johannes Schindelin via GitGitGadget <gitgitgadget@gmail.com>
Date: Oct 28, 2019, 11:20 UTC
Message-ID: <86dbb11f159375da281acd6266df019106abeadb.1572261615.git.gitgitgadget@gmail.com>
In-Reply-To: <pull.355.v2.git.1572261615.gitgitgadget@gmail.com>

From: Johannes Schindelin <johannes.schindelin@gmx.de>

While `git update-index` mostly ignores paths referring to index entries whose skip-worktree bit is set, in b4d1690df11 (Teach Git to respect skip-worktree bit (reading part), 2009-08-20), for reasons that are not entirely obvious, the `--remove` option was made special: it _does_ remove index entries even if their skip-worktree bit is set.

Seeing as this behavior has been in place for a decade now, it does not make sense to change it.

However, in preparation for fixing a bug in `git stash` where it pretends that skip-worktree entries have actually been removed, we need a mode where `git update-index` leaves all skip-worktree entries alone, even if the `--remove` option was passed.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 Documentation/git-update-index.txt |  6 ++++++
 builtin/update-index.c             |  6 +++++-
 t/t7012-skip-worktree-writing.sh   | 14 ++++++++++++++
 3 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/Documentation/git-update-index.txt b/Documentation/git-update-index.txt
index 1c4d146a41..08393445e7 100644
--- a/Documentation/git-update-index.txt
+++ b/Documentation/git-update-index.txt
@@ -16,6 +16,7 @@ SYNOPSIS
 	     [--chmod=(+|-)x]
 	     [--[no-]assume-unchanged]
 	     [--[no-]skip-worktree]
+	     [--[no-]ignore-skip-worktree-entries]
 	     [--[no-]fsmonitor-valid]
 	     [--ignore-submodules]
 	     [--[no-]split-index]
@@ -113,6 +114,11 @@ you will need to handle the situation manually.
 	set and unset the "skip-worktree" bit for the paths. See
 	section "Skip-worktree bit" below for more information.
 
+
+--[no-]ignore-skip-worktree-entries::
+	Do not remove skip-worktree (AKA "index-only") entries even when
+	the `--remove` option was specified.
+
 --[no-]fsmonitor-valid::
 	When one of these flags is specified, the object name recorded
 	for the paths are not updated. Instead, these options
diff --git a/builtin/update-index.c b/builtin/update-index.c
index dff2f4b837..074d563df0 100644
--- a/builtin/update-index.c
+++ b/builtin/update-index.c
@@ -35,6 +35,7 @@ static int verbose;
 static int mark_valid_only;
 static int mark_skip_worktree_only;
 static int mark_fsmonitor_only;
+static int ignore_skip_worktree_entries;
 #define MARK_FLAG 1
 #define UNMARK_FLAG 2
 static struct strbuf mtime_dir = STRBUF_INIT;
@@ -381,7 +382,8 @@ static int process_path(const char *path, struct stat *st, int stat_errno)
 		 * so updating it does not make sense.
 		 * On the other hand, removing it from index should work
 		 */
-		if (allow_remove && remove_file_from_cache(path))
+		if (!ignore_skip_worktree_entries && allow_remove &&
+		    remove_file_from_cache(path))
 			return error("%s: cannot remove from the index", path);
 		return 0;
 	}
@@ -1013,6 +1015,8 @@ int cmd_update_index(int argc, const char **argv, const char *prefix)
 		{OPTION_SET_INT, 0, "no-skip-worktree", &mark_skip_worktree_only, NULL,
 			N_("clear skip-worktree bit"),
 			PARSE_OPT_NOARG | PARSE_OPT_NONEG, NULL, UNMARK_FLAG},
+		OPT_BOOL(0, "ignore-skip-worktree-entries", &ignore_skip_worktree_entries,
+			 N_("do not touch index-only entries")),
 		OPT_SET_INT(0, "info-only", &info_only,
 			N_("add to index only; do not add content to object database"), 1),
 		OPT_SET_INT(0, "force-remove", &force_remove,
diff --git a/t/t7012-skip-worktree-writing.sh b/t/t7012-skip-worktree-writing.sh
index 9d1abe50ef..28b1b0b2b9 100755
--- a/t/t7012-skip-worktree-writing.sh
+++ b/t/t7012-skip-worktree-writing.sh
@@ -134,6 +134,20 @@ test_expect_success 'git-clean, dirty case' '
 	test_i18ncmp expected result
 '
 
+test_expect_success '--ignore-skip-worktree-entries leaves worktree alone' '
+	test_commit geroff-me &&
+	git update-index --skip-worktree geroff-me.t &&
+	rm geroff-me.t &&
+
+	: ignoring the worktree &&
+	git update-index --remove --ignore-skip-worktree-entries geroff-me.t &&
+	git diff-index --cached --exit-code HEAD &&
+
+	: not ignoring the worktree, a deletion is staged &&
+	git update-index --remove geroff-me.t &&
+	test_must_fail git diff-index --cached --exit-code HEAD
+'
+
 #TODO test_expect_failure 'git-apply adds file' false
 #TODO test_expect_failure 'git-apply updates file' false
 #TODO test_expect_failure 'git-apply removes file' false

-- 
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