Imply UTF8 validity in implode function

Author: mvorisek

ext/zend_test/tests/strings_marked_as_utf8.phpt

@@ -115,6 +115,25 @@ $string = "\xff";
 $string_concat = str_repeat($string, 100);
 var_dump(zend_test_is_string_marked_as_valid_utf8($string_concat));
 
+echo "implode:\n";
+$arr = ['a', 'b'];
+$string_concat = implode('', $arr);
+var_dump(zend_test_is_string_marked_as_valid_utf8($string_concat));
+$string_concat = implode('|', [...$arr]);
+var_dump(zend_test_is_string_marked_as_valid_utf8($string_concat));
+$string_concat = implode('', ['c', ...$arr]);
+var_dump(zend_test_is_string_marked_as_valid_utf8($string_concat));
+$string_concat = implode('', [...$arr, 'c']);
+var_dump(zend_test_is_string_marked_as_valid_utf8($string_concat));
+$string_concat = implode('', [...$arr, "\xff"]);
+var_dump(zend_test_is_string_marked_as_valid_utf8($string_concat));
+$string_concat = implode("\xff", $arr);
+var_dump(zend_test_is_string_marked_as_valid_utf8($string_concat));
+$string_concat = implode('', []);
+var_dump(zend_test_is_string_marked_as_valid_utf8($string_concat));
+$string_concat = implode("\xff", []);
+var_dump(zend_test_is_string_marked_as_valid_utf8($string_concat));
+
 ?>
 --EXPECT--
 Empty strings:
@@ -159,3 +178,12 @@ bool(true)
 str_repeat:
 bool(true)
 bool(false)
+implode:
+bool(true)
+bool(true)
+bool(true)
+bool(true)
+bool(false)
+bool(false)
+bool(true)
+bool(true)