ext/standard: improve explode() error message for empty separator

NEWS

@@ -224,6 +224,8 @@ PHP                                                                        NEWS
     (Weilin Du)
   . getenv() and putenv() now raises a ValueError when the first argument
     contains null bytes. (Weilin Du)
+  . Improved explode() ValueError message when $separator is empty; suggests
+    str_split() or mb_str_split(). (diegoasales)
   . parse_str() now raises a ValueError when the $string argument contains
     null bytes. (Weilin Du)
   . proc_open() now raises a ValueError when the $cwd argument contains

UPGRADING

@@ -281,6 +281,8 @@ PHP 8.6 UPGRADE NOTES
     constants).
 
 - Standard:
+  . explode() ValueError message when $separator is empty now suggests
+    str_split() or mb_str_split().
   . ini_get_all() now includes a "builtin_default_value" element for each
     directive when $details is true. It holds the built-in default value of
     the directive (or null if it has none), independent of values set in

ext/standard/string.c

@@ -914,7 +914,7 @@ PHP_FUNCTION(explode)
 	ZEND_PARSE_PARAMETERS_END();
 
 	if (ZSTR_LEN(delim) == 0) {
-		zend_argument_must_not_be_empty_error(1);
+		zend_argument_value_error(1, "must not be empty. Use str_split() or mb_str_split() to split a string into characters");
 		RETURN_THROWS();
 	}
 

ext/standard/tests/strings/explode.phpt

@@ -62,9 +62,9 @@ array (
   4 => 'd',
 )
 d6bee42a771449205344c0938ad4f035
-explode(): Argument #1 ($separator) must not be empty
-explode(): Argument #1 ($separator) must not be empty
-explode(): Argument #1 ($separator) must not be empty
+explode(): Argument #1 ($separator) must not be empty. Use str_split() or mb_str_split() to split a string into characters
+explode(): Argument #1 ($separator) must not be empty. Use str_split() or mb_str_split() to split a string into characters
+explode(): Argument #1 ($separator) must not be empty. Use str_split() or mb_str_split() to split a string into characters
 array(1) {
   [0]=>
   string(0) ""
@@ -79,7 +79,7 @@ array(1) {
   [0]=>
   string(0) ""
 }
-explode(): Argument #1 ($separator) must not be empty
+explode(): Argument #1 ($separator) must not be empty. Use str_split() or mb_str_split() to split a string into characters
 array(1) {
   [0]=>
   string(3) "acb"

ext/standard/tests/strings/explode1.phpt

@@ -91,15 +91,15 @@ var_dump( explode("b", $obj) );
 --EXPECT--
 *** Testing explode() for basic operations ***
 -- Iteration 1 --
-explode(): Argument #1 ($separator) must not be empty
-explode(): Argument #1 ($separator) must not be empty
-explode(): Argument #1 ($separator) must not be empty
-explode(): Argument #1 ($separator) must not be empty
+explode(): Argument #1 ($separator) must not be empty. Use str_split() or mb_str_split() to split a string into characters
+explode(): Argument #1 ($separator) must not be empty. Use str_split() or mb_str_split() to split a string into characters
+explode(): Argument #1 ($separator) must not be empty. Use str_split() or mb_str_split() to split a string into characters
+explode(): Argument #1 ($separator) must not be empty. Use str_split() or mb_str_split() to split a string into characters
 -- Iteration 2 --
-explode(): Argument #1 ($separator) must not be empty
-explode(): Argument #1 ($separator) must not be empty
-explode(): Argument #1 ($separator) must not be empty
-explode(): Argument #1 ($separator) must not be empty
+explode(): Argument #1 ($separator) must not be empty. Use str_split() or mb_str_split() to split a string into characters
+explode(): Argument #1 ($separator) must not be empty. Use str_split() or mb_str_split() to split a string into characters
+explode(): Argument #1 ($separator) must not be empty. Use str_split() or mb_str_split() to split a string into characters
+explode(): Argument #1 ($separator) must not be empty. Use str_split() or mb_str_split() to split a string into characters
 -- Iteration 3 --
 array(1) {
   [0]=>
@@ -201,10 +201,10 @@ array(2) {
   string(56) "234NULL23abcd00000TRUEFALSE-11.234444true-11.24%PHP%ZEND"
 }
 -- Iteration 7 --
-explode(): Argument #1 ($separator) must not be empty
-explode(): Argument #1 ($separator) must not be empty
-explode(): Argument #1 ($separator) must not be empty
-explode(): Argument #1 ($separator) must not be empty
+explode(): Argument #1 ($separator) must not be empty. Use str_split() or mb_str_split() to split a string into characters
+explode(): Argument #1 ($separator) must not be empty. Use str_split() or mb_str_split() to split a string into characters
+explode(): Argument #1 ($separator) must not be empty. Use str_split() or mb_str_split() to split a string into characters
+explode(): Argument #1 ($separator) must not be empty. Use str_split() or mb_str_split() to split a string into characters
 -- Iteration 8 --
 array(2) {
   [0]=>