Bug report

Given generic instance with specific template type T (eg. string), this instance can't be passed to generic parameter which specifies T as compatible union (eg. string|int).

Code snippet that reproduces the problem

https://phpstan.org/r/280fa009-69dc-4515-8b09-5bbaee07eb61

Expected output

Considering the more specific instance is clearly subset of the parameter type, I believe it should be accepted.

My real-life union was actually about nullable instance, eg. Foo|NULL.