Merge branch 'ws/single-file-cone' into jch

The logic to see if we are using the "cone" mode by checking the
sparsity patterns has been tightened to avoid mistaking a pattern
that names a single file as specifying a cone.

* ws/single-file-cone:
  dir: check for single file cone patterns

dir.c

@@ -732,6 +732,13 @@ static void add_pattern_to_hashsets(struct pattern_list *pl, struct path_pattern
 		goto clear_hashmaps;
 	}
 
+	if (!(given->flags & PATTERN_FLAG_MUSTBEDIR) &&
+	    strcmp(given->pattern, "/*")) {
+		/* Not a cone pattern. */
+		warning(_("unrecognized pattern: '%s'"), given->pattern);
+		goto clear_hashmaps;
+	}
+
 	prev = given->pattern;
 	cur = given->pattern + 1;
 	next = given->pattern + 2;

t/t1091-sparse-checkout-builtin.sh

@@ -238,7 +238,7 @@ test_expect_success 'cone mode: match patterns' '
 test_expect_success 'cone mode: warn on bad pattern' '
 	test_when_finished mv sparse-checkout repo/.git/info/ &&
 	cp repo/.git/info/sparse-checkout . &&
-	echo "!/deep/deeper/*" >>repo/.git/info/sparse-checkout &&
+	echo "!/deep/deeper/*/" >>repo/.git/info/sparse-checkout &&
 	git -C repo read-tree -mu HEAD 2>err &&
 	test_i18ngrep "unrecognized negative pattern" err
 '
@@ -667,6 +667,15 @@ test_expect_success 'pattern-checks: starting "*"' '
 	check_read_tree_errors repo "a deep" "disabling cone pattern matching"
 '
 
+test_expect_success 'pattern-checks: non directory pattern' '
+	cat >repo/.git/info/sparse-checkout <<-\EOF &&
+	/deep/deeper1/a
+	EOF
+	check_read_tree_errors repo deep "disabling cone pattern matching" &&
+	check_files repo/deep deeper1 &&
+	check_files repo/deep/deeper1 a
+'
+
 test_expect_success 'pattern-checks: contained glob characters' '
 	for c in "[a]" "\\" "?" "*"
 	do