PHP error on testing server - php

Question

I have a bit of PHP code that works fine on my production server but not on my test server. Here is the code:
function callProcedure0(&$connection, $procname, $dofunction)
{
mysqli_multi_query($connection, "CALL " . $procname . "();");
$first_result = 1;
do
{
$query_result = mysqli_store_result($connection);
if ($first_result)
{
$dofunction($query_result);
$first_result = 0;
}
if ($query_result)
{
mysqli_free_result($query_result);
}
$query_result = NULL;
} while(mysqli_next_result($connection));
}
...
function doGenres($in_result)
{
global $genre_array, $game_array, $genre_order_array;
$genre_count = 1;
// foreach is necessary when retrieving values since gaps may appear in the primary key
while ($genre_row = mysqli_fetch_row($in_result)) // line 81 is here!
{
$genre_array[] = $genre_row[0];
$genre_order_array[$genre_row[1] - 1] = $genre_count;
$game_array[] = [[],[]];
$genre_count += 1;
}
}
...
callProcedure0($con, "get_genres_front", doGenres); // line 138 is here!
The "get_genres_front" bit refers to a stored procedure on my database. Here are the errors:
Notice: Use of undefined constant doGenres - assumed 'doGenres' in /opt/lampp/htdocs/keyboard/keyboard.php on line 138
Again, there are no problems on the production server which is using Apache 2.2.23, MySQL 5.1.73-cll, PHP 5.4.26. The test server where things are broken is running Apache 2.4.10, MySQL 5.6.21, PHP 5.5.19.
Did something change in recent software versions? Thanks.
[edit]
This is not a duplicate question. I'm worried about the first error. I already know what to do about the second error which I have deleted.

Answer 1

The code you have posted is wrong, you must pass function name as string and then use call_user_func to invoke this function.
In your callProcedure0 function change
$dofunction($query_result);
to
call_user_func($dofunction, $query_result);
And then call it with the function name as string like this
callProcedure0($con, "get_genres_front", "doGenres");
The above code could work also with invoking the function with
$dofunction($query_result);
on some php versions, but the line where you pass the function name it should be string, otherwise PHP assumes it is a constant.