I hear ya. In fact, I got burned by that problem enough times to make a test for it in my PHPCS 'coding standard'... which is basically a handful of standards that look for my stupid, repeated, coding errors :)

My own standard is this:

    foreach ($array as & $ref) {
        // Do something with $ref
    } unset ($ref);

i.e. put the `unset()` call on the same line as the closing brace, forever "welding" it to that block.

Why do you even use references in the first place?

Data structures like trees, etc. are pretty hard to do without them, due to default array by-value semantics.