strict types is ignored when mapping or filtering arrays due to the usage of PHP builtin functions

[azjezz]

This bug was introduced in #169 by mistake, the solution would be to wrap all callbacks provided by the end user in another closure to ensure that strict types is used.

Environment (please complete the following information):

• OS: *
• PHP version: 7.4, 8.0
• Version: 1.6, 1.7

Additional context

see Roave/BackwardCompatibilityCheck#306 (comment)

[azjezz]

we have to benchmark which solution is better:

1. wrap callbacks in a closure
2. re-implement array_* functions in userland.

[Ocramius]

re-implement array_* functions in userland.

I think we'll likely need to suck it up and keep using array_ functions here: assuming 100% type coverage on sources, we can assume that the given values are within the type boundaries of the provided callbacks.

The array_* functions are massively outperforming any iterative approach, as they can operate at zval level.

[azjezz]

fixed and released as 1.6.1 and 1.7.1