Constant string param template type is generalized to string

[axlon]

Bug report

It seems that PHPStan generalizes template types somewhat when no clear bound is defined. In my example I pass a constant string which is not empty, a union between this template type and another that is bound to non-empty-string should result in non-empty-string but instead PHPStan reports string

Code snippet that reproduces the problem

https://phpstan.org/r/3c8a8a00-c08f-405d-9d98-b603d00b5631

Expected output

No errors.

The $default parameter to getOrDefault() is a constant string in the example, so we know both sides of the return type are not going to be empty.

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

No response

[axlon]

As always, am happy to fix this myself if pointed in the right direction. 🙂

[mad-briller]

template generalization comes up quite often and it's hard problem to solve as there is no one-size-fits-all solution, take a look at this issue for some more information and possible inspiration for fixing it:
phpstan/phpstan-src#1038

[axlon]

@mad-briller thanks for the link, seems this might be a bit more complicated than I had initially thought. If I'm understanding the situation correctly it would be quite easy to make my use case work but it may create problems for others as templates might suddenly be stricter than they should be.

[ondrejmirtes]

Your specific case is already fixed, if you enable bleeding edge: https://phpstan.org/r/ca05f1e3-d908-48a4-8b1e-5d4006687a97

(I figured out most of "generics generalization" problems are happening inside generic objects - if you were to to something like Foo<TDefault> and not just TDefault, it would still be generalized.)

[github-actions]

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