It would be great if the following definition actually worked. Having a native event fire with multiple execution pins makes a lot of sense for our implementation.
The autogenerated code attempts to recompile this using TEnumAsByte. However if you switch out the Enum for the TEnumAsByte version, although it compiles, the function is not visible to the blueprint.
UFUNCTION(BlueprintNativeEvent, Meta = (ExpandEnumAsExecs = p))
void Test(EBlah& p);
void Test_Implementation(EBlah& p);