Unused function parameter in lambda function

[ghnp5]

Consider this code:

$type = in_array_cb($_GET['type'], TYPES, fn(&$array, $needle) => $array[2] === $needle);

The parameter $needle is marked as an error:

Unused function parameter $needle.PHPCS(VariableAnalysis.CodeAnalysis.VariableAnalysis.UnusedVariable)

[sirbrillig]

Interesting! It looks like something to do with the array access which is breaking this. The bug does occur in the expression:

do_something(fn($array, $needle) => $array[2] === $needle);

But it does not occur in:

do_something(fn($array, $needle) => $array === $needle);

I think that there's a bug in how we detect the scope of an arrow function which contains a bracket.

[sirbrillig]

https://github.com/sirbrillig/phpcs-variable-analysis/pull/296 should fix this.

[ghnp5]

Thanks @sirbrillig - that was a quick fix & release!! Working perfectly now.

[sirbrillig]

Turns out the fix was really easy: just stop letting phpcs do its own scope detection for arrow functions. 😁