Missing potential false on DateTime::modify

[yann-eugone]

Bug report

Both DateTime::modify & DateTimeImmutable::modify can return false, but got following message when testing result :

Strict comparison using === between DateTimeImmutable and false will always evaluate to false.
Strict comparison using === between DateTime and false will always evaluate to false.

I found #1934 which is about almost the same thing, but somehow the issue get closed.

Code snippet that reproduces the problem

https://phpstan.org/r/3b587421-aa5b-4c3f-ac48-7b5c20e1d61c

https://3v4l.org/sTN7A

Expected output

These 2 methods should consider that the return type is potentially false, as documented here :

• DateTime::modify : https://www.php.net/manual/en/datetime.modify.php#refsect1-datetime.modify-returnvalues
• DateTimeImmutable::modify : https://www.php.net/manual/en/datetimeimmutable.modify.php#refsect1-datetimeimmutable.modify-returnvalues

[pbourdet]

Hello, ran into this issue as well on version 1.5.2

[VincentLanglet]

This can be fixed by changing this line https://github.com/phpstan/phpstan-src/blob/1.6.x/resources/functionMap.php#L1607

But having an error because $dateTime->modify('+1 year') might be false will be disturbing.
So IMHO, it would required to add a dynamicReturnTypeExtension

[VincentLanglet]

Will be fixed by phpstan/phpstan-src#1267

[phpstan-bot]

@yann-eugone After the latest commit in 1.7.x, PHPStan now reports different result with your code snippet:

@@ @@
-3: Strict comparison using === between DateTimeImmutable and false will always evaluate to false.
-6: Strict comparison using === between DateTime and false will always evaluate to false.
+No errors

[ondrejmirtes]

Fixed: phpstan/phpstan-src#1267

[github-actions]

This thread has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.