Req #78401 [Csd]: DateTime::modify signature change

Edit report at https://bugs.php.net/bug.php?id=78401&edit=1 ID: 78401 Updated by: nikic@php.net Reported by: kylekatarnls at gmail dot com Summary: DateTime::modify signature change Status: Closed Type: Feature/Change Request Package: Compile Failure Operating System: Linux PHP Version: Next Major Version -Assigned To: +Assigned To: nikic Block user comment: N Private report: N New Comment: While both DateTime and DateTimeImmutable have a modify() method, the behavior is not compatible, so it's not part of the interface. If you accept a generic DateTimeInterface parameter, it's generally only safe to call the read-only methods on it, not the mutating methods, as these may exhibit differing behavior. Previous Comments: ------------------------------------------------------------------------ [2019-08-12 06:21:32] kylekatarnls at gmail dot com Hi, sorry, my mistake, the method was not implemented. In fact I relied on the fact that both DateTime and DateTimeImmutable have the modify() method, but as it's not declared in DateTimeInterface (I don't know why, it would have seem logical), I had to declare it in my own interface. Now due to this change in PHP 8, I have to add ``` public function modify($modify) { return parent::modify((string) $modify); } ``` So question for curiosity. Why DateTimeInterface does not declare all common methods of DateTime and DateTimeImmutable. ------------------------------------------------------------------------ [2019-08-11 20:42:46] nikic@php.net I can't reproduce this. ------------------------------------------------------------------------ [2019-08-11 20:06:30] kylekatarnls at gmail dot com Description: ------------ My last Travis-CI test failed (while same code worked until there) for PHP 8.0.0-dev with the following message: Declaration of DateTime::modify(string $modify) must be compatible with I::modify($modify) Test script: --------------- interface I extends DateTimeInterface { modify($modify); } class A extends DateTime implements I { modify($modify) {} } Expected result: ---------------- I would expect my interface to be compatible with DateTime since it's covariant. I accept more types but string is included so it should pass as there is no reason to forbid this extension. Then I would be compatible with both PHP 7 and 8 but if I change the signature to a the string typing, it will fail on PHP 7. Actual result: -------------- Declaration of DateTime::modify(string $modify) must be compatible with I::modify($modify) ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=78401&edit=1