Description:
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I was trying to debug a database error and after many minutes eventually realized that I had misspelled a variable passed to mysqli_stmt_bind_param (which, of course, was not set). I think it should really throw an error, or at least give a warning if a variable is undefined.

I downloaded PHP from windows.php.net. I have error_reporting set to E_ALL and display_errors is enabled. My php.ini file looks essentially just like the included php.ini-development file; the only difference is that I've enabled the mysqli and mbstring extensions.

Test script:
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<?php

    $Db = mysqli_connect('host', 'user', 'pass', 'database');

    $Query = "SELECT `field1` FROM `table` WHERE `field2` = ? LIMIT 1";

    $Statement = mysqli_stmt_init($Db);

    mysqli_stmt_prepare($Stmt, $Query);

    /* I would expect this to throw a warning or error */
    mysqli_stmt_bind_param($Stmt, 's', $UndefinedVariable);

?>

Expected result:
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A warning or error.

Actual result:
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No warning or error is given.