Fix GH-8924 str_split of empty string must return empty array

Author: mvorisek

ext/standard/string.c

@@ -5882,9 +5882,14 @@ PHP_FUNCTION(str_split)
 		RETURN_THROWS();
 	}
 
-	if (0 == ZSTR_LEN(str) || (size_t)split_length >= ZSTR_LEN(str)) {
-		array_init_size(return_value, 1);
-		add_next_index_stringl(return_value, ZSTR_VAL(str), ZSTR_LEN(str));
+	if ((size_t)split_length >= ZSTR_LEN(str)) {
+        if (0 == ZSTR_LEN(str)) {
+            array_init_size(return_value, 0);
+        } else {
+            array_init_size(return_value, 1);
+            add_next_index_stringl(return_value, ZSTR_VAL(str), ZSTR_LEN(str));
+        }
+
 		return;
 	}
 

ext/standard/tests/strings/str_split_basic.phpt

@@ -16,7 +16,11 @@ var_dump( str_split($str,$split_length) );
 echo "-- With split_length as default argument --\n";
 var_dump( str_split($str) );
 
-echo "Done"
+echo "-- Empty string must always return empty array --\n";
+var_dump( str_split('') );
+var_dump( str_split('', 1) );
+var_dump( str_split('', 100) );
+
 ?>
 --EXPECT--
 *** Testing str_split() : basic functionality ***
@@ -80,4 +84,10 @@ array(22) {
   [21]=>
   string(1) "e"
 }
-Done
+-- Empty string must always return empty array --
+array(0) {
+}
+array(0) {
+}
+array(0) {
+}

ext/standard/tests/strings/str_split_variation3.phpt

@@ -39,9 +39,7 @@ echo "Done"
 --EXPECTF--
 *** Testing str_split() : double quoted strings for 'str' ***
 -- Iteration 1 --
-array(1) {
-  [0]=>
-  string(0) ""
+array(0) {
 }
 -- Iteration 2 --
 array(1) {

ext/standard/tests/strings/str_split_variation4.phpt

@@ -38,9 +38,7 @@ echo "Done"
 --EXPECT--
 *** Testing str_split() : single quoted strings for 'str' ***
 -- Iteration 1 --
-array(1) {
-  [0]=>
-  string(0) ""
+array(0) {
 }
 -- Iteration 2 --
 array(1) {

ext/standard/tests/strings/str_split_variation5.phpt

@@ -81,14 +81,10 @@ echo "Done"
 --EXPECT--
 *** Testing str_split() : heredoc strings as 'str' argument ***
 -- Iteration 1 --
-array(1) {
-  [0]=>
-  string(0) ""
+array(0) {
 }
 -- Iteration 2 --
-array(1) {
-  [0]=>
-  string(0) ""
+array(0) {
 }
 -- Iteration 3 --
 array(1) {