sparse-checkout: disable sparse-index

We use 'git sparse-checkout init --cone --sparse-index' to toggle the
sparse-index feature. It makes sense to also disable it when running
'git sparse-checkout disable'. This is particularly important because it
removes the extensions.sparseIndex config option, allowing other tools
to use this Git repository again.

This does mean that 'git sparse-checkout init' will not re-enable the
sparse-index feature, even if it was previously enabled.

While testing this feature, I noticed that the sparse-index was not
being written on the first run, but by a second. This was caught by the
call to 'test-tool read-cache --table'. This requires adjusting some
assignments to core_apply_sparse_checkout and pl.use_cone_patterns in
the sparse_checkout_init() logic.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/sparse-checkout.c

@@ -280,6 +280,9 @@ static int set_config(enum sparse_checkout_mode mode)
 				      "core.sparseCheckoutCone",
 				      mode == MODE_CONE_PATTERNS ? "true" : NULL);
 
+	if (mode == MODE_NO_PATTERNS)
+		set_sparse_index_config(the_repository, 0);
+
 	return 0;
 }
 
@@ -341,10 +344,11 @@ static int sparse_checkout_init(int argc, const char **argv)
 		the_repository->index->updated_workdir = 1;
 	}
 
+	core_apply_sparse_checkout = 1;
+
 	/* If we already have a sparse-checkout file, use it. */
 	if (res >= 0) {
 		free(sparse_filename);
-		core_apply_sparse_checkout = 1;
 		return update_working_directory(NULL);
 	}
 
@@ -366,6 +370,7 @@ static int sparse_checkout_init(int argc, const char **argv)
 	add_pattern(strbuf_detach(&pattern, NULL), empty_base, 0, &pl, 0);
 	strbuf_addstr(&pattern, "!/*/");
 	add_pattern(strbuf_detach(&pattern, NULL), empty_base, 0, &pl, 0);
+	pl.use_cone_patterns = init_opts.cone_mode;
 
 	return write_patterns_and_update(&pl);
 }
@@ -632,6 +637,9 @@ static int sparse_checkout_disable(int argc, const char **argv)
 	strbuf_addstr(&match_all, "/*");
 	add_pattern(strbuf_detach(&match_all, NULL), empty_base, 0, &pl, 0);
 
+	prepare_repo_settings(the_repository);
+	the_repository->settings.sparse_index = 0;
+
 	if (update_working_directory(&pl))
 		die(_("error while refreshing working directory"));
 

t/t1091-sparse-checkout-builtin.sh

@@ -205,6 +205,19 @@ test_expect_success 'sparse-checkout disable' '
 	check_files repo a deep folder1 folder2
 '
 
+test_expect_success 'sparse-index enabled and disabled' '
+	git -C repo sparse-checkout init --cone --sparse-index &&
+	test_cmp_config -C repo true index.sparse &&
+	test-tool -C repo read-cache --table >cache &&
+	grep " tree " cache &&
+
+	git -C repo sparse-checkout disable &&
+	test-tool -C repo read-cache --table >cache &&
+	! grep " tree " cache &&
+	git -C repo config --list >config &&
+	! grep index.sparse config
+'
+
 test_expect_success 'cone mode: init and set' '
 	git -C repo sparse-checkout init --cone &&
 	git -C repo config --list >config &&