Small fix and a test case to prove it's right

ext/mysqli/tests/mysqli_stmt_bind_param_check_param_no_change.phpt

@@ -0,0 +1,148 @@
+--TEST--
+mysqli_stmt_bind_param() - checking whether the parameters are modified (bug#44390)
+--SKIPIF--
+<?php
+require_once('skipif.inc');
+require_once('skipifemb.inc');
+require_once('skipifconnectfailure.inc');
+?>
+--FILE--
+<?php
+	include "connect.inc";
+	require('table.inc');
+
+	class foo {
+	  // @var $bar string
+	  public $bar;
+	}
+
+	$foo = new foo;
+	$foo->bar = "фубар";
+
+	echo "Test 1: \n";
+	$stmt = $link->prepare("SELECT ? FOO");
+	var_dump($foo); // here you can see the bar member var beeing a string
+	$stmt->bind_param("s", $foo->bar);
+	var_dump($foo); // this will show $foo->bar beeing a reference string
+	$stmt->bind_result($one);
+	$stmt->execute();
+	$stmt->fetch();
+	$stmt->free_result();
+	echo("$one\n\n");
+
+	// it is getting worse. Binding the same var twice with different 
+	// types you can get unexpected results (e.g. binary trash for the
+	// string and misc data for the integer. See next 2 tests.
+
+	echo "Test 2: \n";
+	$stmt = $link->prepare("SELECT ? FOO, ? BAR");
+	var_dump($foo);
+	$stmt->bind_param("si", $foo->bar, $foo->bar);
+	echo "---\n";
+	var_dump($foo);
+	echo "---\n";
+	$stmt->execute();
+	var_dump($foo);
+	echo "---\n";
+	$stmt->bind_result($one, $two);
+	$stmt->fetch();
+	$stmt->free_result();
+	echo("$one - $two\n\n");
+
+
+	echo "Test 3: \n";
+	$stmt = $link->prepare("SELECT ? FOO, ? BAR");
+	var_dump($foo);
+	$stmt->bind_param("is", $foo->bar, $foo->bar);
+	var_dump($foo);
+	$stmt->bind_result($one, $two);
+	$stmt->execute();
+	$stmt->fetch();
+	$stmt->free_result();
+	echo("$one - $two\n\n");
+	echo "done!\n";
+?>
+--EXPECTF--
+Test 1: 
+object(foo)#3 (1) {
+  ["bar"]=>
+  string(10) "фубар"
+}
+object(foo)#3 (1) {
+  ["bar"]=>
+  &string(10) "фубар"
+}
+фубар
+
+Test 2: 
+object(foo)#3 (1) {
+  ["bar"]=>
+  string(10) "фубар"
+}
+---
+object(foo)#3 (1) {
+  ["bar"]=>
+  &string(10) "фубар"
+}
+---
+object(foo)#3 (1) {
+  ["bar"]=>
+  &string(10) "фубар"
+}
+---
+фубар - 0
+
+Test 3: 
+object(foo)#3 (1) {
+  ["bar"]=>
+  string(10) "фубар"
+}
+object(foo)#3 (1) {
+  ["bar"]=>
+  &string(10) "фубар"
+}
+0 - фубар
+
+done!
+--UEXPECTF--
+Test 1: 
+object(foo)#3 (1) {
+  [u"bar"]=>
+  unicode(5) "фубар"
+}
+object(foo)#3 (1) {
+  [u"bar"]=>
+  &unicode(5) "фубар"
+}
+фубар
+
+Test 2: 
+object(foo)#3 (1) {
+  [u"bar"]=>
+  unicode(5) "фубар"
+}
+---
+object(foo)#3 (1) {
+  [u"bar"]=>
+  &unicode(5) "фубар"
+}
+---
+object(foo)#3 (1) {
+  [u"bar"]=>
+  &unicode(5) "фубар"
+}
+---
+фубар - 0
+
+Test 3: 
+object(foo)#3 (1) {
+  [u"bar"]=>
+  unicode(5) "фубар"
+}
+object(foo)#3 (1) {
+  [u"bar"]=>
+  &unicode(5) "фубар"
+}
+0 - фубар
+
+done!

ext/mysqlnd/mysqlnd_ps_codec.c

@@ -828,14 +828,7 @@ mysqlnd_stmt_execute_store_params(MYSQLND_STMT *stmt, zend_uchar **buf, zend_uch
 						*p = php_mysqlnd_net_store_length(*p, 0);
 					}
 					break;
-				case MYSQL_TYPE_VAR_STRING:
-					/*
-					  If the user uses refs, it could be that the type has
-					  has changed and we need to convert, again. Which is noop,
-					  if the type hasn't changed.
-					*/
-					convert_to_string_ex(&stmt->param_bind[i].zv);
-					{
+				case MYSQL_TYPE_VAR_STRING:{
 						unsigned int len = Z_STRLEN_P(data);
 						/* to is after p. The latter hasn't been moved */
 						*p = php_mysqlnd_net_store_length(*p, len);