4 files changed, 42 insertions, 13 deletions
diff --git a/ext/mbstring/mbstring.c b/ext/mbstring/mbstring.c
index b9a07b2f55..46c09d3e8c 100644
--- a/ext/mbstring/mbstring.c
+++ b/ext/mbstring/mbstring.c
@@ -1862,6 +1862,7 @@ static int mbfl_split_output(int c, void *data)
     return 0;
 }
 
+/* TODO Document this function on php.net */
 PHP_FUNCTION(mb_str_split)
 {
 	zend_string *str, *encoding = NULL;
@@ -1879,8 +1880,8 @@ PHP_FUNCTION(mb_str_split)
 	ZEND_PARSE_PARAMETERS_END();
 
 	if (split_length <= 0) {
-		php_error_docref(NULL, E_WARNING, "The length of each segment must be greater than zero");
-		RETURN_FALSE;
+		zend_argument_value_error(2, "must be greater than 0");
+		RETURN_THROWS();
 	}
 
 	/* fill mbfl_string structure */
@@ -1945,10 +1946,8 @@ PHP_FUNCTION(mb_str_split)
 				mbfl_memory_device_output,
 				NULL,
 				&device);
-		/* if something wrong with the decoded */
-		if (decoder == NULL) {
-			RETURN_FALSE;
-		}
+		/* assert that nothing is wrong with the decoder */
+		ZEND_ASSERT(decoder != NULL);
 
 		/* wchar filter */
 		mbfl_string_init(&result_string); /* mbfl_string to store chunk in the callback */
@@ -1966,11 +1965,8 @@ PHP_FUNCTION(mb_str_split)
 				mbfl_split_output,
 				NULL,
 				&params);
-		/* if something wrong with the filter */
-		if (filter == NULL){
-			mbfl_convert_filter_delete(decoder); /* this will free allocated memory for the decoded */
-			RETURN_FALSE;
-		}
+		/* assert that nothing is wrong with the filter */
+		ZEND_ASSERT(filter != NULL);
 
 		while (p < last - 1) { /* cycle each byte except last with callback function */
 			(*filter->filter_function)(*p++, filter);
diff --git a/ext/mbstring/mbstring.stub.php b/ext/mbstring/mbstring.stub.php
index 5598aa8c12..6fccd72449 100644
--- a/ext/mbstring/mbstring.stub.php
+++ b/ext/mbstring/mbstring.stub.php
@@ -19,7 +19,7 @@ function mb_parse_str(string $encoded_string, &$result): bool {}
 
 function mb_output_handler(string $contents, int $status): string {}
 
-function mb_str_split(string $str, int $split_length = 1, string $encoding = UNKNOWN): array|false {}
+function mb_str_split(string $str, int $split_length = 1, string $encoding = UNKNOWN): array {}
 
 function mb_strlen(string $str, string $encoding = UNKNOWN): int|false {}
 
diff --git a/ext/mbstring/mbstring_arginfo.h b/ext/mbstring/mbstring_arginfo.h
index 8d37ae1cbe..69d50f581a 100644
--- a/ext/mbstring/mbstring_arginfo.h
+++ b/ext/mbstring/mbstring_arginfo.h
@@ -36,7 +36,7 @@ ZEND_BEGIN_ARG_WITH_RETURN_TYPE_INFO_EX(arginfo_mb_output_handler, 0, 2, IS_STRI
 	ZEND_ARG_TYPE_INFO(0, status, IS_LONG, 0)
 ZEND_END_ARG_INFO()
 
-ZEND_BEGIN_ARG_WITH_RETURN_TYPE_MASK_EX(arginfo_mb_str_split, 0, 1, MAY_BE_ARRAY|MAY_BE_FALSE)
+ZEND_BEGIN_ARG_WITH_RETURN_TYPE_INFO_EX(arginfo_mb_str_split, 0, 1, IS_ARRAY, 0)
 	ZEND_ARG_TYPE_INFO(0, str, IS_STRING, 0)
 	ZEND_ARG_TYPE_INFO(0, split_length, IS_LONG, 0)
 	ZEND_ARG_TYPE_INFO(0, encoding, IS_STRING, 0)
diff --git a/ext/mbstring/tests/mb_str_split_error_conditions.phpt b/ext/mbstring/tests/mb_str_split_error_conditions.phpt
new file mode 100644
index 0000000000..77f04aad09
--- /dev/null
+++ b/ext/mbstring/tests/mb_str_split_error_conditions.phpt
@@ -0,0 +1,33 @@
+--TEST--
+mb_str_split() error conditions
+--SKIPIF--
+<?php extension_loaded('mbstring') or die('skip mbstring not available'); ?>
+--FILE--
+<?php
+
+$string = "日本"; /* 2 chars */
+
+// Invalid split length
+try {
+    mb_str_split($string, 0);
+} catch (\ValueError $e) {
+    echo $e->getMessage() . \PHP_EOL;
+}
+try {
+    mb_str_split($string, -5);
+} catch (\ValueError $e) {
+    echo $e->getMessage() . \PHP_EOL;
+}
+
+//Invalid Encoding
+try {
+    mb_str_split($string, 1, "BAD_ENCODING");
+} catch (\ValueError $e) {
+    echo $e->getMessage() . \PHP_EOL;
+}
+
+?>
+--EXPECT--
+mb_str_split(): Argument #2 ($split_length) must be greater than 0
+mb_str_split(): Argument #2 ($split_length) must be greater than 0
+mb_str_split(): Argument #3 ($encoding) must be a valid encoding, "BAD_ENCODING" given