Merge branch 'ds/more-index-cleanups'

Cleaning various codepaths up.

* ds/more-index-cleanups:
  t1092: test interesting sparse-checkout scenarios
  test-lib: test_region looks for trace2 regions
  sparse-checkout: load sparse-checkout patterns
  name-hash: use trace2 regions for init
  repository: add repo reference to index_state
  fsmonitor: de-duplicate BUG()s around dirty bits
  cache-tree: extract subtree_pos()
  cache-tree: simplify verify_cache() prototype
  cache-tree: clean up cache_tree_update()

15 files changed, 408 insertions, 53 deletions

diff --git a/builtin/checkout.c b/builtin/checkout.c
index c9ba23c279..2d6550bc3c 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -821,9 +821,6 @@ static int merge_working_tree(const struct checkout_opts *opts,
 		}
 	}
 
-	if (!active_cache_tree)
-		active_cache_tree = cache_tree();
-
 	if (!cache_tree_fully_valid(active_cache_tree))
 		cache_tree_update(&the_index, WRITE_TREE_SILENT | WRITE_TREE_REPAIR);
 
diff --git a/builtin/sparse-checkout.c b/builtin/sparse-checkout.c
index e3140db2a0..2306a9ad98 100644
--- a/builtin/sparse-checkout.c
+++ b/builtin/sparse-checkout.c
@@ -22,11 +22,6 @@ static char const * const builtin_sparse_checkout_usage[] = {
 	NULL
 };
 
-static char *get_sparse_checkout_filename(void)
-{
-	return git_pathdup("info/sparse-checkout");
-}
-
 static void write_patterns_to_file(FILE *fp, struct pattern_list *pl)
 {
 	int i;
diff --git a/cache-tree.c b/cache-tree.c
index 3f1a8d4f1b..2fb483d3c0 100644
--- a/cache-tree.c
+++ b/cache-tree.c
@@ -45,7 +45,7 @@ static int subtree_name_cmp(const char *one, int onelen,
 	return memcmp(one, two, onelen);
 }
 
-static int subtree_pos(struct cache_tree *it, const char *path, int pathlen)
+int cache_tree_subtree_pos(struct cache_tree *it, const char *path, int pathlen)
 {
 	struct cache_tree_sub **down = it->down;
 	int lo, hi;
@@ -72,7 +72,7 @@ static struct cache_tree_sub *find_subtree(struct cache_tree *it,
 					   int create)
 {
 	struct cache_tree_sub *down;
-	int pos = subtree_pos(it, path, pathlen);
+	int pos = cache_tree_subtree_pos(it, path, pathlen);
 	if (0 <= pos)
 		return it->down[pos];
 	if (!create)
@@ -123,7 +123,7 @@ static int do_invalidate_path(struct cache_tree *it, const char *path)
 	it->entry_count = -1;
 	if (!*slash) {
 		int pos;
-		pos = subtree_pos(it, path, namelen);
+		pos = cache_tree_subtree_pos(it, path, namelen);
 		if (0 <= pos) {
 			cache_tree_free(&it->down[pos]->cache_tree);
 			free(it->down[pos]);
@@ -151,16 +151,15 @@ void cache_tree_invalidate_path(struct index_state *istate, const char *path)
 		istate->cache_changed |= CACHE_TREE_CHANGED;
 }
 
-static int verify_cache(struct cache_entry **cache,
-			int entries, int flags)
+static int verify_cache(struct index_state *istate, int flags)
 {
-	int i, funny;
+	unsigned i, funny;
 	int silent = flags & WRITE_TREE_SILENT;
 
 	/* Verify that the tree is merged */
 	funny = 0;
-	for (i = 0; i < entries; i++) {
-		const struct cache_entry *ce = cache[i];
+	for (i = 0; i < istate->cache_nr; i++) {
+		const struct cache_entry *ce = istate->cache[i];
 		if (ce_stage(ce)) {
 			if (silent)
 				return -1;
@@ -180,13 +179,13 @@ static int verify_cache(struct cache_entry **cache,
 	 * stage 0 entries.
 	 */
 	funny = 0;
-	for (i = 0; i < entries - 1; i++) {
+	for (i = 0; i + 1 < istate->cache_nr; i++) {
 		/* path/file always comes after path because of the way
 		 * the cache is sorted.  Also path can appear only once,
 		 * which means conflicting one would immediately follow.
 		 */
-		const struct cache_entry *this_ce = cache[i];
-		const struct cache_entry *next_ce = cache[i + 1];
+		const struct cache_entry *this_ce = istate->cache[i];
+		const struct cache_entry *next_ce = istate->cache[i + 1];
 		const char *this_name = this_ce->name;
 		const char *next_name = next_ce->name;
 		int this_len = ce_namelen(this_ce);
@@ -436,16 +435,20 @@ static int update_one(struct cache_tree *it,
 
 int cache_tree_update(struct index_state *istate, int flags)
 {
-	struct cache_tree *it = istate->cache_tree;
-	struct cache_entry **cache = istate->cache;
-	int entries = istate->cache_nr;
-	int skip, i = verify_cache(cache, entries, flags);
+	int skip, i;
+
+	i = verify_cache(istate, flags);
 
 	if (i)
 		return i;
+
+	if (!istate->cache_tree)
+		istate->cache_tree = cache_tree();
+
 	trace_performance_enter();
 	trace2_region_enter("cache_tree", "update", the_repository);
-	i = update_one(it, cache, entries, "", 0, &skip, flags);
+	i = update_one(istate->cache_tree, istate->cache, istate->cache_nr,
+		       "", 0, &skip, flags);
 	trace2_region_leave("cache_tree", "update", the_repository);
 	trace_performance_leave("cache_tree_update");
 	if (i < 0)
@@ -635,9 +638,6 @@ static int write_index_as_tree_internal(struct object_id *oid,
 		cache_tree_valid = 0;
 	}
 
-	if (!index_state->cache_tree)
-		index_state->cache_tree = cache_tree();
-
 	if (!cache_tree_valid && cache_tree_update(index_state, flags) < 0)
 		return WRITE_TREE_UNMERGED_INDEX;
 
diff --git a/cache-tree.h b/cache-tree.h
index 639bfa5340..8efeccebfc 100644
--- a/cache-tree.h
+++ b/cache-tree.h
@@ -27,6 +27,8 @@ void cache_tree_free(struct cache_tree **);
 void cache_tree_invalidate_path(struct index_state *, const char *);
 struct cache_tree_sub *cache_tree_sub(struct cache_tree *, const char *);
 
+int cache_tree_subtree_pos(struct cache_tree *it, const char *path, int pathlen);
+
 void cache_tree_write(struct strbuf *, struct cache_tree *root);
 struct cache_tree *cache_tree_read(const char *buffer, unsigned long size);
 
diff --git a/cache.h b/cache.h
index f22d12ecb0..d928149614 100644
--- a/cache.h
+++ b/cache.h
@@ -328,6 +328,7 @@ struct index_state {
 	struct ewah_bitmap *fsmonitor_dirty;
 	struct mem_pool *ce_mem_pool;
 	struct progress *progress;
+	struct repository *repo;
 };
 
 /* Name hashing */
diff --git a/dir.c b/dir.c
index d637461da5..d153a63bbd 100644
--- a/dir.c
+++ b/dir.c
@@ -2998,6 +2998,23 @@ void setup_standard_excludes(struct dir_struct *dir)
 	}
 }
 
+char *get_sparse_checkout_filename(void)
+{
+	return git_pathdup("info/sparse-checkout");
+}
+
+int get_sparse_checkout_patterns(struct pattern_list *pl)
+{
+	int res;
+	char *sparse_filename = get_sparse_checkout_filename();
+
+	pl->use_cone_patterns = core_sparse_checkout_cone;
+	res = add_patterns_from_file_to_list(sparse_filename, "", 0, pl, NULL);
+
+	free(sparse_filename);
+	return res;
+}
+
 int remove_path(const char *name)
 {
 	char *slash;
diff --git a/dir.h b/dir.h
index a3c40dec51..facfae4740 100644
--- a/dir.h
+++ b/dir.h
@@ -448,6 +448,8 @@ int is_empty_dir(const char *dir);
 
 void setup_standard_excludes(struct dir_struct *dir);
 
+char *get_sparse_checkout_filename(void);
+int get_sparse_checkout_patterns(struct pattern_list *pl);
 
 /* Constants for remove_dir_recursively: */
 
diff --git a/fsmonitor.c b/fsmonitor.c
index ca031c3abb..fe9e9d7baf 100644
--- a/fsmonitor.c
+++ b/fsmonitor.c
@@ -13,14 +13,19 @@
 
 struct trace_key trace_fsmonitor = TRACE_KEY_INIT(FSMONITOR);
 
+static void assert_index_minimum(struct index_state *istate, size_t pos)
+{
+	if (pos > istate->cache_nr)
+		BUG("fsmonitor_dirty has more entries than the index (%"PRIuMAX" > %u)",
+		    (uintmax_t)pos, istate->cache_nr);
+}
+
 static void fsmonitor_ewah_callback(size_t pos, void *is)
 {
 	struct index_state *istate = (struct index_state *)is;
 	struct cache_entry *ce;
 
-	if (pos >= istate->cache_nr)
-		BUG("fsmonitor_dirty has more entries than the index (%"PRIuMAX" >= %u)",
-		    (uintmax_t)pos, istate->cache_nr);
+	assert_index_minimum(istate, pos + 1);
 
 	ce = istate->cache[pos];
 	ce->ce_flags &= ~CE_FSMONITOR_VALID;
@@ -82,10 +87,8 @@ int read_fsmonitor_extension(struct index_state *istate, const void *data,
 	}
 	istate->fsmonitor_dirty = fsmonitor_dirty;
 
-	if (!istate->split_index &&
-	    istate->fsmonitor_dirty->bit_size > istate->cache_nr)
-		BUG("fsmonitor_dirty has more entries than the index (%"PRIuMAX" > %u)",
-		    (uintmax_t)istate->fsmonitor_dirty->bit_size, istate->cache_nr);
+	if (!istate->split_index)
+		assert_index_minimum(istate, istate->fsmonitor_dirty->bit_size);
 
 	trace_printf_key(&trace_fsmonitor, "read fsmonitor extension successful");
 	return 0;
@@ -110,10 +113,8 @@ void write_fsmonitor_extension(struct strbuf *sb, struct index_state *istate)
 	uint32_t ewah_size = 0;
 	int fixup = 0;
 
-	if (!istate->split_index &&
-	    istate->fsmonitor_dirty->bit_size > istate->cache_nr)
-		BUG("fsmonitor_dirty has more entries than the index (%"PRIuMAX" > %u)",
-		    (uintmax_t)istate->fsmonitor_dirty->bit_size, istate->cache_nr);
+	if (!istate->split_index)
+		assert_index_minimum(istate, istate->fsmonitor_dirty->bit_size);
 
 	put_be32(&hdr_version, INDEX_EXTENSION_VERSION2);
 	strbuf_add(sb, &hdr_version, sizeof(uint32_t));
@@ -335,9 +336,7 @@ void tweak_fsmonitor(struct index_state *istate)
 			}
 
 			/* Mark all previously saved entries as dirty */
-			if (istate->fsmonitor_dirty->bit_size > istate->cache_nr)
-				BUG("fsmonitor_dirty has more entries than the index (%"PRIuMAX" > %u)",
-				    (uintmax_t)istate->fsmonitor_dirty->bit_size, istate->cache_nr);
+			assert_index_minimum(istate, istate->fsmonitor_dirty->bit_size);
 			ewah_each_bit(istate->fsmonitor_dirty, fsmonitor_ewah_callback, istate);
 
 			refresh_fsmonitor(istate);
diff --git a/name-hash.c b/name-hash.c
index 5d3c7b12c1..4e03fac9bb 100644
--- a/name-hash.c
+++ b/name-hash.c
@@ -7,6 +7,7 @@
  */
 #include "cache.h"
 #include "thread-utils.h"
+#include "trace2.h"
 
 struct dir_entry {
 	struct hashmap_entry ent;
@@ -577,6 +578,7 @@ static void lazy_init_name_hash(struct index_state *istate)
 	if (istate->name_hash_initialized)
 		return;
 	trace_performance_enter();
+	trace2_region_enter("index", "name-hash-init", istate->repo);
 	hashmap_init(&istate->name_hash, cache_entry_cmp, NULL, istate->cache_nr);
 	hashmap_init(&istate->dir_hash, dir_entry_cmp, NULL, istate->cache_nr);
 
@@ -597,6 +599,7 @@ static void lazy_init_name_hash(struct index_state *istate)
 	}
 
 	istate->name_hash_initialized = 1;
+	trace2_region_leave("index", "name-hash-init", istate->repo);
 	trace_performance_leave("initialize name hash");
 }
 
diff --git a/repository.c b/repository.c
index a4174ddb06..c98298acd0 100644
--- a/repository.c
+++ b/repository.c
@@ -264,6 +264,12 @@ int repo_read_index(struct repository *repo)
 	if (!repo->index)
 		repo->index = xcalloc(1, sizeof(*repo->index));
 
+	/* Complete the double-reference */
+	if (!repo->index->repo)
+		repo->index->repo = repo;
+	else if (repo->index->repo != repo)
+		BUG("repo's index should point back at itself");
+
 	return read_index_from(repo->index, repo->index_file, repo->gitdir);
 }
 
diff --git a/sequencer.c b/sequencer.c
index 264d494a64..d2332d3e17 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -679,9 +679,6 @@ static int do_recursive_merge(struct repository *r,
 
 static struct object_id *get_cache_tree_oid(struct index_state *istate)
 {
-	if (!istate->cache_tree)
-		istate->cache_tree = cache_tree();
-
 	if (!cache_tree_fully_valid(istate->cache_tree))
 		if (cache_tree_update(istate, 0)) {
 			error(_("unable to update cache tree"));
diff --git a/t/t0500-progress-display.sh b/t/t0500-progress-display.sh
index 1ed1df351c..84cce345e7 100755
--- a/t/t0500-progress-display.sh
+++ b/t/t0500-progress-display.sh
@@ -303,8 +303,7 @@ test_expect_success 'progress generates traces' '
 		"Working hard" <in 2>stderr &&
 
 	# t0212/parse_events.perl intentionally omits regions and data.
-	grep -e "region_enter" -e "\"category\":\"progress\"" trace.event &&
-	grep -e "region_leave" -e "\"category\":\"progress\"" trace.event &&
+	test_region progress "Working hard" trace.event &&
 	grep "\"key\":\"total_objects\",\"value\":\"40\"" trace.event &&
 	grep "\"key\":\"total_bytes\",\"value\":\"409600\"" trace.event
 '
diff --git a/t/t1092-sparse-checkout-compatibility.sh b/t/t1092-sparse-checkout-compatibility.sh
new file mode 100755
index 0000000000..8cd3e5a8d2
--- /dev/null
+++ b/t/t1092-sparse-checkout-compatibility.sh
@@ -0,0 +1,301 @@
+#!/bin/sh
+
+test_description='compare full workdir to sparse workdir'
+
+. ./test-lib.sh
+
+test_expect_success 'setup' '
+	git init initial-repo &&
+	(
+		cd initial-repo &&
+		echo a >a &&
+		echo "after deep" >e &&
+		echo "after folder1" >g &&
+		echo "after x" >z &&
+		mkdir folder1 folder2 deep x &&
+		mkdir deep/deeper1 deep/deeper2 &&
+		mkdir deep/deeper1/deepest &&
+		echo "after deeper1" >deep/e &&
+		echo "after deepest" >deep/deeper1/e &&
+		cp a folder1 &&
+		cp a folder2 &&
+		cp a x &&
+		cp a deep &&
+		cp a deep/deeper1 &&
+		cp a deep/deeper2 &&
+		cp a deep/deeper1/deepest &&
+		cp -r deep/deeper1/deepest deep/deeper2 &&
+		git add . &&
+		git commit -m "initial commit" &&
+		git checkout -b base &&
+		for dir in folder1 folder2 deep
+		do
+			git checkout -b update-$dir &&
+			echo "updated $dir" >$dir/a &&
+			git commit -a -m "update $dir" || return 1
+		done &&
+
+		git checkout -b rename-base base &&
+		echo >folder1/larger-content <<-\EOF &&
+		matching
+		lines
+		help
+		inexact
+		renames
+		EOF
+		cp folder1/larger-content folder2/ &&
+		cp folder1/larger-content deep/deeper1/ &&
+		git add . &&
+		git commit -m "add interesting rename content" &&
+
+		git checkout -b rename-out-to-out rename-base &&
+		mv folder1/a folder2/b &&
+		mv folder1/larger-content folder2/edited-content &&
+		echo >>folder2/edited-content &&
+		git add . &&
+		git commit -m "rename folder1/... to folder2/..." &&
+
+		git checkout -b rename-out-to-in rename-base &&
+		mv folder1/a deep/deeper1/b &&
+		mv folder1/larger-content deep/deeper1/edited-content &&
+		echo >>deep/deeper1/edited-content &&
+		git add . &&
+		git commit -m "rename folder1/... to deep/deeper1/..." &&
+
+		git checkout -b rename-in-to-out rename-base &&
+		mv deep/deeper1/a folder1/b &&
+		mv deep/deeper1/larger-content folder1/edited-content &&
+		echo >>folder1/edited-content &&
+		git add . &&
+		git commit -m "rename deep/deeper1/... to folder1/..." &&
+
+		git checkout -b deepest base &&
+		echo "updated deepest" >deep/deeper1/deepest/a &&
+		git commit -a -m "update deepest" &&
+
+		git checkout -f base &&
+		git reset --hard
+	)
+'
+
+init_repos () {
+	rm -rf full-checkout sparse-checkout sparse-index &&
+
+	# create repos in initial state
+	cp -r initial-repo full-checkout &&
+	git -C full-checkout reset --hard &&
+
+	cp -r initial-repo sparse-checkout &&
+	git -C sparse-checkout reset --hard &&
+	git -C sparse-checkout sparse-checkout init --cone &&
+
+	# initialize sparse-checkout definitions
+	git -C sparse-checkout sparse-checkout set deep
+}
+
+run_on_sparse () {
+	(
+		cd sparse-checkout &&
+		$* >../sparse-checkout-out 2>../sparse-checkout-err
+	)
+}
+
+run_on_all () {
+	(
+		cd full-checkout &&
+		$* >../full-checkout-out 2>../full-checkout-err
+	) &&
+	run_on_sparse $*
+}
+
+test_all_match () {
+	run_on_all $* &&
+	test_cmp full-checkout-out sparse-checkout-out &&
+	test_cmp full-checkout-err sparse-checkout-err
+}
+
+test_expect_success 'status with options' '
+	init_repos &&
+	test_all_match git status --porcelain=v2 &&
+	test_all_match git status --porcelain=v2 -z -u &&
+	test_all_match git status --porcelain=v2 -uno &&
+	run_on_all "touch README.md" &&
+	test_all_match git status --porcelain=v2 &&
+	test_all_match git status --porcelain=v2 -z -u &&
+	test_all_match git status --porcelain=v2 -uno &&
+	test_all_match git add README.md &&
+	test_all_match git status --porcelain=v2 &&
+	test_all_match git status --porcelain=v2 -z -u &&
+	test_all_match git status --porcelain=v2 -uno
+'
+
+test_expect_success 'add, commit, checkout' '
+	init_repos &&
+
+	write_script edit-contents <<-\EOF &&
+	echo text >>$1
+	EOF
+	run_on_all "../edit-contents README.md" &&
+
+	test_all_match git add README.md &&
+	test_all_match git status --porcelain=v2 &&
+	test_all_match git commit -m "Add README.md" &&
+
+	test_all_match git checkout HEAD~1 &&
+	test_all_match git checkout - &&
+
+	run_on_all "../edit-contents README.md" &&
+
+	test_all_match git add -A &&
+	test_all_match git status --porcelain=v2 &&
+	test_all_match git commit -m "Extend README.md" &&
+
+	test_all_match git checkout HEAD~1 &&
+	test_all_match git checkout - &&
+
+	run_on_all "../edit-contents deep/newfile" &&
+
+	test_all_match git status --porcelain=v2 -uno &&
+	test_all_match git status --porcelain=v2 &&
+	test_all_match git add . &&
+	test_all_match git status --porcelain=v2 &&
+	test_all_match git commit -m "add deep/newfile" &&
+
+	test_all_match git checkout HEAD~1 &&
+	test_all_match git checkout -
+'
+
+test_expect_success 'checkout and reset --hard' '
+	init_repos &&
+
+	test_all_match git checkout update-folder1 &&
+	test_all_match git status --porcelain=v2 &&
+
+	test_all_match git checkout update-deep &&
+	test_all_match git status --porcelain=v2 &&
+
+	test_all_match git checkout -b reset-test &&
+	test_all_match git reset --hard deepest &&
+	test_all_match git reset --hard update-folder1 &&
+	test_all_match git reset --hard update-folder2
+'
+
+test_expect_success 'diff --staged' '
+	init_repos &&
+
+	write_script edit-contents <<-\EOF &&
+	echo text >>README.md
+	EOF
+	run_on_all "../edit-contents" &&
+
+	test_all_match git diff &&
+	test_all_match git diff --staged &&
+	test_all_match git add README.md &&
+	test_all_match git diff &&
+	test_all_match git diff --staged
+'
+
+test_expect_success 'diff with renames' '
+	init_repos &&
+
+	for branch in rename-out-to-out rename-out-to-in rename-in-to-out
+	do
+		test_all_match git checkout rename-base &&
+		test_all_match git checkout $branch -- .&&
+		test_all_match git diff --staged --no-renames &&
+		test_all_match git diff --staged --find-renames || return 1
+	done
+'
+
+test_expect_success 'log with pathspec outside sparse definition' '
+	init_repos &&
+
+	test_all_match git log -- a &&
+	test_all_match git log -- folder1/a &&
+	test_all_match git log -- folder2/a &&
+	test_all_match git log -- deep/a &&
+	test_all_match git log -- deep/deeper1/a &&
+	test_all_match git log -- deep/deeper1/deepest/a &&
+
+	test_all_match git checkout update-folder1 &&
+	test_all_match git log -- folder1/a
+'
+
+test_expect_success 'blame with pathspec inside sparse definition' '
+	init_repos &&
+
+	test_all_match git blame a &&
+	test_all_match git blame deep/a &&
+	test_all_match git blame deep/deeper1/a &&
+	test_all_match git blame deep/deeper1/deepest/a
+'
+
+# TODO: blame currently does not support blaming files outside of the
+# sparse definition. It complains that the file doesn't exist locally.
+test_expect_failure 'blame with pathspec outside sparse definition' '
+	init_repos &&
+
+	test_all_match git blame folder1/a &&
+	test_all_match git blame folder2/a &&
+	test_all_match git blame deep/deeper2/a &&
+	test_all_match git blame deep/deeper2/deepest/a
+'
+
+# TODO: reset currently does not behave as expected when in a
+# sparse-checkout.
+test_expect_failure 'checkout and reset (mixed)' '
+	init_repos &&
+
+	test_all_match git checkout -b reset-test update-deep &&
+	test_all_match git reset deepest &&
+	test_all_match git reset update-folder1 &&
+	test_all_match git reset update-folder2
+'
+
+test_expect_success 'merge' '
+	init_repos &&
+
+	test_all_match git checkout -b merge update-deep &&
+	test_all_match git merge -m "folder1" update-folder1 &&
+	test_all_match git rev-parse HEAD^{tree} &&
+	test_all_match git merge -m "folder2" update-folder2 &&
+	test_all_match git rev-parse HEAD^{tree}
+'
+
+test_expect_success 'merge with outside renames' '
+	init_repos &&
+
+	for type in out-to-out out-to-in in-to-out
+	do
+		test_all_match git reset --hard &&
+		test_all_match git checkout -f -b merge-$type update-deep &&
+		test_all_match git merge -m "$type" rename-$type &&
+		test_all_match git rev-parse HEAD^{tree} || return 1
+	done
+'
+
+test_expect_success 'clean' '
+	init_repos &&
+
+	echo bogus >>.gitignore &&
+	run_on_all cp ../.gitignore . &&
+	test_all_match git add .gitignore &&
+	test_all_match git commit -m ignore-bogus-files &&
+
+	run_on_sparse mkdir folder1 &&
+	run_on_all touch folder1/bogus &&
+
+	test_all_match git status --porcelain=v2 &&
+	test_all_match git clean -f &&
+	test_all_match git status --porcelain=v2 &&
+
+	test_all_match git clean -xf &&
+	test_all_match git status --porcelain=v2 &&
+
+	test_all_match git clean -xdf &&
+	test_all_match git status --porcelain=v2 &&
+
+	test_path_is_dir sparse-checkout/folder1
+'
+
+test_done
diff --git a/t/test-lib-functions.sh b/t/test-lib-functions.sh
index 6bca002316..aca17f8945 100644
--- a/t/test-lib-functions.sh
+++ b/t/test-lib-functions.sh
@@ -1683,3 +1683,45 @@ test_subcommand () {
 		grep "\[$expr\]"
 	fi
 }
+
+# Check that the given command was invoked as part of the
+# trace2-format trace on stdin.
+#
+#	test_region [!] <category> <label> git <command> <args>...
+#
+# For example, to look for trace2_region_enter("index", "do_read_index", repo)
+# in an invocation of "git checkout HEAD~1", run
+#
+#	GIT_TRACE2_EVENT="$(pwd)/trace.txt" GIT_TRACE2_EVENT_NESTING=10 \
+#		git checkout HEAD~1 &&
+#	test_region index do_read_index <trace.txt
+#
+# If the first parameter passed is !, this instead checks that
+# the given region was not entered.
+#
+test_region () {
+	local expect_exit=0
+	if test "$1" = "!"
+	then
+		expect_exit=1
+		shift
+	fi
+
+	grep -e	'"region_enter".*"category":"'"$1"'","label":"'"$2"\" "$3"
+	exitcode=$?
+
+	if test $exitcode != $expect_exit
+	then
+		return 1
+	fi
+
+	grep -e	'"region_leave".*"category":"'"$1"'","label":"'"$2"\" "$3"
+	exitcode=$?
+
+	if test $exitcode != $expect_exit
+	then
+		return 1
+	fi
+
+	return 0
+}
diff --git a/unpack-trees.c b/unpack-trees.c
index af6e9b9c2f..f5f668f532 100644
--- a/unpack-trees.c
+++ b/unpack-trees.c
@@ -1549,14 +1549,10 @@ static void mark_new_skip_worktree(struct pattern_list *pl,
 static void populate_from_existing_patterns(struct unpack_trees_options *o,
 					    struct pattern_list *pl)
 {
-	char *sparse = git_pathdup("info/sparse-checkout");
-
-	pl->use_cone_patterns = core_sparse_checkout_cone;
-	if (add_patterns_from_file_to_list(sparse, "", 0, pl, NULL) < 0)
+	if (get_sparse_checkout_patterns(pl) < 0)
 		o->skip_sparse_checkout = 1;
 	else
 		o->pl = pl;
-	free(sparse);
 }
 
 
@@ -1726,8 +1722,6 @@ int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options
 		if (!ret) {
 			if (git_env_bool("GIT_TEST_CHECK_CACHE_TREE", 0))
 				cache_tree_verify(the_repository, &o->result);
-			if (!o->result.cache_tree)
-				o->result.cache_tree = cache_tree();
 			if (!cache_tree_fully_valid(o->result.cache_tree))
 				cache_tree_update(&o->result,
 						  WRITE_TREE_SILENT |