Coding-standard: UselessParentheses false positive with arrow functions (PHP 7.4)

Created on 23 Jul 2019 · 4Comments · Source: slevomat/coding-standard

Starting with PHP 7.4 we'll have the ability to create arrow functions. The stable version will be available at the end of the year, but right now I'm testing the alpha2 release.

An arrow function with only one argument triggers a unwanted error Useless parentheses (SlevomatCodingStandard.PHP.UselessParentheses.UselessParentheses):

$firstName = 'John';
$name  = fn($firstName) => 'FirstName: ' . $firstName;

Zero or two or more arguments does not trigger an error - as expected.

// arrow function without arguments
$fullName = fn() => 'John Doe';

// arrow function with two or more arguments
$firstName = 'John';
$lastName  = 'Doe';
$fullName  = fn($firstName, $lastName) => $firstName . $lastName;

Environment: