I am using the answer found at https://stackoverflow.com/a/25749660 in order to sort the $_SERVER['HTTP_ACCEPT_LANGUAGE'] array by the most preferred language.
In that answer (which is working great by the way), one line is:
list($a, $b) = explode('-', $match[1]) + array('', '');
Within PhpStorm, I get the following error for that line:
"Unused local variable $b: The value of the variable is overwritten immediately".
I'm a little confused as to what this line is doing exactly, so I don't know if I should just keep it the same, or if I should modify it to:
list($a) = explode('-', $match[1]) + array('', '');
... which also seems to be working fine.
Should it be changed?
You can't join arrays with the arithmetic operator +. Basically you are telling PHP to convert the arrays to scalar types and then sum them, which yields you a number (probably arrays evaluate to 1 if it has elements and 0 if it doesn't).
The result is that effectively you are doing something like:
list($a, $b) = 2;
And the conclusion PHP reaches is that you haven't specified enough elements to define all the variables in the list.
To join two arrays together, use array_merge().
list($a, $b) = array_merge(explode('-', $match[1]), array('', ''));
The wording is confusing because it's a full explanation for an inspection that covers two situations and the initial tooltip only displays the first line, which happens to describe the other situation. If you hit Ctl+F1 you can read the complete text, which kind of makes more sense (emphasis mine):
Unused local variable 'b'. The value of the variable is overwritten immediately. less... (Ctrl+F1)
Inspection info: A variable is considered unused in the following cases:
- The value of the variable is not used anywhere or is overwritten immediately.
- The reference stored in the variable is not used anywhere or is overwritten immediately.
That's exactly what happens here:
list($a, $b) = …
$a is used later but $b is not. Since $b is never used, this works as well:
list($a) = explode('-', $match[1]) + array('', '');
(Remember these inspections are hints to prevent potential bugs, not necessarily errors.)