Better return types for getBackingType

[SamMousa]

The only backing types for Enums are int and string. The proper return type for ReflectionEnum::getBackingType() is thus null|ReflectionNamedType.

See also php/doc-en#1608

[SamMousa]

Note that some changes to the C source might also be required to more formally guarantee this stricter contract. Unfortunately my C and my php source knowledge is not fluent enough to propose those changes.

I think we need to define a new return type somewhere:

ZEND_BEGIN_ARG_WITH_RETURN_OBJ_INFO_EX(arginfo_class_ReflectionEnum_getBackingType, 0, 0, ReflectionNamedType, 1)
ZEND_END_ARG_INFO()

[cmb69]

It seems to me that restricting the return type might not work well with tagged unions or other extensions to the current enumerations.

@iluuu1994, @Crell, thoughts?

[iluuu1994]

Tagged unions can't be backed so that's not a concern. The type would change if we supported more types as backing types but I'm not sure if that's likely to happen. I'm ok with this change, an assert in ZEND_METHOD(ReflectionEnum, getBackingType) might make sense.

[SamMousa]

I'm ok with this change, an assert in ZEND_METHOD(ReflectionEnum, getBackingType) might make sense.

While I think the assert would go between lines 6869 and 6870 I'm not actually sure what it would look like. (C is not a language I use)

ZEND_ASSERT(ce->enum_backing_type != ...)

Would you mind proposing the code change?

Edit: as far as I can tell the pipeline failing is a CI problem, not a code problem.

[iluuu1994]

@SamMousa Something like ZEND_ASSERT(Z_OBJCE_P(return_value) == reflection_named_type_ptr); right after the reflection_type_factory to ensure the value is actually of that type. But it's actually fine, we do return type checks for internal functions in debug builds.