PHP8 lint:container issue with isBuiltIn() use #39233
Description
Symfony version(s) affected: 5.2.0
Description
Run lint:container command and I get the error:
In CheckTypeDeclarationsPass.php line 288:
Attempted to call an undefined method named "isBuiltin" of class "ReflectionUnionType".
How to reproduce
Run lint:container
Possible Solution
Might be similar to this: #38836
Additional context
n/a