Difference between string increment typing and reality

[zonuexe]

Bug report

The result of incrementing a string is not necessarily a string.

function inc(string $n): string
{
	$before = $n;
	$after = ++$n;
	assertType('array{string|int, string, string|int}', [$n, $before, $after]));

	return (string)$after; // No warnings expected here
}

inc('10'); // => '11'
inc('a');  // => 'b'

This behavior is consistent between PHP 8.3 and earlier: https://3v4l.org/i4rru

There seems to be a problem with InitializerExprTypeResolver::getPlusType().

Code snippet that reproduces the problem

https://phpstan.org/r/110b3926-f4c5-4f51-b4ab-537fa2be3fb6

Expected output

No errors.

Did PHPStan help you today? Did it make you happy in any way?

I'm excited to see that PHPStan is working consistently even with PHP 8.3.

[ondrejmirtes]

Fixed phpstan/phpstan-src#2797

[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.