Add a rule to force-add or force-remove ? on nullable types

[nicolas-grekas]

Sorry if this already exists, I didn't find it with a quick lookup,

Since PHP 7.1, nullable arguments can be written with or without the ? prefix:
Form 1: function (string $s = null) {}
vs
Form 2: function (?string $s = null) {}

It would be great to have a rule to normalize to either form 1 or 2.
(On Symfony, we would stick to Form 1 for consistency with branches that still support PHP 5.5)

[SpacePossum]

Hi,
Sounds like a good idea, we currently don't have a rule for this nor an open request for it, so all good 👍

[keradus]

note that
function (?string $s = null, $b) {}
shall be later autofixed into
function (?string $s, $b) {}

so, I would even say
Form 3: function (?string $s) {}

(as often, = null was provided not with intention to make argument optional (in terms of number of args), but to make it nullable)

[gharlan]

@keradus I think for this case the NoUnreachableDefaultArgumentValueFixer should be updated.

https://github.com/FriendsOfPHP/PHP-CS-Fixer/blob/2.12/src/Fixer/FunctionNotation/NoUnreachableDefaultArgumentValueFixer.php#L102

isTypehintedNullableVariable should be replaced by
isNonNullableTypehintedNullableVariable

[keradus]

Closing due to merge of #4401