[PATCH 19/27] status: skip sparse-checkout percentage with sparse-index

["Derrick Stolee via GitGitGadget" <gitgitgadget@gmail.com>]

From: Derrick Stolee <dstolee@microsoft.com>

'git status' began reporting a percentage of populated paths when
sparse-checkout is enabled in 051df3cf (wt-status: show sparse
checkout status as well, 2020-07-18). This percentage is incorrect when
the index has sparse directories. It would also be expensive to
calculate as we would need to parse trees to count the total number of
possible paths.

Avoid the expensive computation by simplifying the output to only report
that a sparse checkout exists, without the percentage.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
---
 t/t1092-sparse-checkout-compatibility.sh |  8 ++++++++
 wt-status.c                              | 14 +++++++++++---
 wt-status.h                              |  1 +
 3 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/t/t1092-sparse-checkout-compatibility.sh b/t/t1092-sparse-checkout-compatibility.sh
index a3521cdc310..09650f0755c 100755
--- a/t/t1092-sparse-checkout-compatibility.sh
+++ b/t/t1092-sparse-checkout-compatibility.sh
@@ -190,6 +190,14 @@ test_expect_success 'status with options' '
 	test_all_match git status --porcelain=v2 -uno
 '
 
+test_expect_success 'status reports sparse-checkout' '
+	init_repos &&
+	git -C sparse-checkout status >full &&
+	git -C sparse-index status >sparse &&
+	test_i18ngrep "You are in a sparse checkout with " full &&
+	test_i18ngrep "You are in a sparse checkout." sparse
+'
+
 test_expect_success 'add, commit, checkout' '
 	init_repos &&
 
diff --git a/wt-status.c b/wt-status.c
index 5366d336938..46c9d71068e 100644
--- a/wt-status.c
+++ b/wt-status.c
@@ -1492,9 +1492,12 @@ static void show_sparse_checkout_in_use(struct wt_status *s,
 	if (s->state.sparse_checkout_percentage == SPARSE_CHECKOUT_DISABLED)
 		return;
 
-	status_printf_ln(s, color,
-			 _("You are in a sparse checkout with %d%% of tracked files present."),
-			 s->state.sparse_checkout_percentage);
+	if (s->state.sparse_checkout_percentage == SPARSE_CHECKOUT_SPARSE_INDEX)
+		status_printf_ln(s, color, _("You are in a sparse checkout."));
+	else
+		status_printf_ln(s, color,
+				_("You are in a sparse checkout with %d%% of tracked files present."),
+				s->state.sparse_checkout_percentage);
 	wt_longstatus_print_trailer(s);
 }
 
@@ -1652,6 +1655,11 @@ static void wt_status_check_sparse_checkout(struct repository *r,
 		return;
 	}
 
+	if (r->index->sparse_index) {
+		state->sparse_checkout_percentage = SPARSE_CHECKOUT_SPARSE_INDEX;
+		return;
+	}
+
 	for (i = 0; i < r->index->cache_nr; i++) {
 		struct cache_entry *ce = r->index->cache[i];
 		if (ce_skip_worktree(ce))
diff --git a/wt-status.h b/wt-status.h
index 35b44c388ed..3cb0c200244 100644
--- a/wt-status.h
+++ b/wt-status.h
@@ -80,6 +80,7 @@ enum wt_status_format {
 #define HEAD_DETACHED_AT _("HEAD detached at ")
 #define HEAD_DETACHED_FROM _("HEAD detached from ")
 #define SPARSE_CHECKOUT_DISABLED -1
+#define SPARSE_CHECKOUT_SPARSE_INDEX -2
 
 struct wt_status_state {
 	int merge_in_progress;
-- 
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