TypeResolver resolve ?string|null|?boolean|?int as Nullable instead of Compound

[steevanb]

Hi,

When i want to resolve a variable type, there is a little bug when it begin with ?: it should return a Compound object, but it return a Nullable object, with Compound as realType. As you can see in example below, in ?string|null|?boolean , ?boolean is well parsed, cause it's not the first one.

$typeResolver = new TypeResolver();
print_r($typeResolver->resolve('?string|null|?boolean'));

phpDocumentor\Reflection\Types\Nullable Object
(
    [realType:phpDocumentor\Reflection\Types\Nullable:private] => phpDocumentor\Reflection\Types\Compound Object
        (
            [types:phpDocumentor\Reflection\Types\Compound:private] => Array
                (
                    [0] => phpDocumentor\Reflection\Types\String_ Object
                        (
                        )
                    [1] => phpDocumentor\Reflection\Types\Null_ Object
                        (
                        )
                    [2] => phpDocumentor\Reflection\Types\Nullable Object
                        (
                            [realType:phpDocumentor\Reflection\Types\Nullable:private] => phpDocumentor\Reflection\Types\Boolean Object
                                (
                                )
                        )
                )
        )
)

Another example, that works well, without ? as first character:

$typeResolver = new TypeResolver();
print_r($typeResolver->resolve('string|null|?boolean'));

phpDocumentor\Reflection\Types\Compound Object
(
    [types:phpDocumentor\Reflection\Types\Compound:private] => Array
        (
            [0] => phpDocumentor\Reflection\Types\String_ Object
                (
                )
            [1] => phpDocumentor\Reflection\Types\Null_ Object
                (
                )
            [2] => phpDocumentor\Reflection\Types\Nullable Object
                (
                    [realType:phpDocumentor\Reflection\Types\Nullable:private] => phpDocumentor\Reflection\Types\Boolean Object
                        (
                        )
                )
        )
)

[jaapio]

The hard part about this is how we should interpret this. I remember a discussion about this in the PSR-5 context.

I think from a usage perspective the following typehints are equal:

?string|null|?boolean
string|null|?boolean
?string|null|boolean
?string|boolean
string|?boolean
string|null|boolean

Since the ? sign states that the passed value might be a null null is a valid value. There is no difference between a null that could have been a string or boolean value.

Most important thing is that we need to be sure when we are resolving the types of ?string|null|boolean the to string method of the resulting Compound type should be equal to the resolved type. And that it does mean the same thing that was resolved. It is unclear to me if this is the case at the moment. So I will add a test with this use-case to check that.