[PATCH 3/3] sparse-checkout: refuse to add to bad patterns

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

From: Derrick Stolee <dstolee@microsoft.com>

When in cone mode sparse-checkout, it is unclear how 'git
sparse-checkout add <dir1> ...' should behave if the existing
sparse-checkout file does not match the cone mode patterns. Change the
behavior to fail with an error message about the existing patterns.

Also, all cone mode patterns start with a '/' character, so add that
restriction. This is necessary for our example test 'cone mode: warn on
bad pattern', but also requires modifying the example sparse-checkout
file we use to test the warnings related to recognizing cone mode
patterns.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
---
 builtin/sparse-checkout.c          |  3 +++
 dir.c                              |  2 +-
 t/t1091-sparse-checkout-builtin.sh | 11 +++++++----
 3 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/builtin/sparse-checkout.c b/builtin/sparse-checkout.c
index fe76c3eedda..2492ae828a9 100644
--- a/builtin/sparse-checkout.c
+++ b/builtin/sparse-checkout.c
@@ -513,6 +513,9 @@ static void add_patterns_cone_mode(int argc, const char **argv,
 		die(_("unable to load existing sparse-checkout patterns"));
 	free(sparse_filename);
 
+	if (!existing.use_cone_patterns)
+		die(_("existing sparse-checkout patterns do not use cone mode"));
+
 	hashmap_for_each_entry(&existing.recursive_hashmap, &iter, pe, ent) {
 		if (!hashmap_contains_parent(&pl->recursive_hashmap,
 					pe->pattern, &buffer) ||
diff --git a/dir.c b/dir.c
index 03c4d212672..93136442103 100644
--- a/dir.c
+++ b/dir.c
@@ -727,7 +727,7 @@ static void add_pattern_to_hashsets(struct pattern_list *pl, struct path_pattern
 	}
 
 	if (given->patternlen < 2 ||
-	    *given->pattern == '*' ||
+	    *given->pattern != '/' ||
 	    strstr(given->pattern, "**")) {
 		/* Not a cone pattern. */
 		warning(_("unrecognized pattern: '%s'"), given->pattern);
diff --git a/t/t1091-sparse-checkout-builtin.sh b/t/t1091-sparse-checkout-builtin.sh
index af0acd32bd9..780c6a1aaae 100755
--- a/t/t1091-sparse-checkout-builtin.sh
+++ b/t/t1091-sparse-checkout-builtin.sh
@@ -108,14 +108,17 @@ test_expect_success 'switching to cone mode with non-cone mode patterns' '
 	git -C bad-patterns sparse-checkout init &&
 	git -C bad-patterns sparse-checkout add dir &&
 	git -C bad-patterns config core.sparseCheckoutCone true &&
-	git -C bad-patterns sparse-checkout add dir &&
+
+	test_must_fail git -C bad-patterns sparse-checkout add dir 2>err &&
+	grep "existing sparse-checkout patterns do not use cone mode" err &&
 
 	git -C bad-patterns sparse-checkout init --cone &&
 	cat >expect <<-\EOF &&
 	/*
 	!/*/
 	EOF
-	test_cmp expect bad-patterns/.git/info/sparse-checkout
+	test_cmp expect bad-patterns/.git/info/sparse-checkout &&
+	git -C bad-patterns sparse-checkout add dir
 '
 
 test_expect_success 'interaction with clone --no-checkout (unborn index)' '
@@ -182,9 +185,9 @@ test_expect_success 'set sparse-checkout using --stdin' '
 test_expect_success 'add to sparse-checkout' '
 	cat repo/.git/info/sparse-checkout >expect &&
 	cat >add <<-\EOF &&
-	pattern1
+	/pattern1
 	/folder1/
-	pattern2
+	/pattern2
 	EOF
 	cat add >>expect &&
 	git -C repo sparse-checkout add --stdin <add &&
-- 
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