C++20 module does not export certain vulkan.h types used by its API

[teschnei]

Some of the exported types in vulkan_hpp directly use types from vulkan.h (Vk* instead of vk::) which don't get exported by the module. This makes working with these types pretty cumbersome, as you can't instantiate or cast to them.

I noticed this mostly with vk::DebugUtilsMessengerCreateInfoEXT, which has a member of type PFN_vkDebugUtilsMessengerCallbackEXT (not exported), which itself is a function pointer for a type involving several types that are not exported either. I also noticed this with vk::AccelerationStructureInstanceKHR, where flags is a VkGeometryInstanceFlagsKHR instead of a vk::GeometryInstanceFlagsKHR (I suppose because of the bit-packing), where assigning to .flags appears to be impossible because (as far as I can figure out) there's no way to cast to a VkGeometryInstanceFlagsKHR without the type being exported.

I can work around this by just including vulkan.h of course, but I assume a goal of the module is not requiring that? If not, then I suppose this is resolved with the include.

[asuessenbach]

#2020 and #2022 resolved half of this issue: the callback types.
Handling of the VkGeometryInstanceFlagsKHR will follow soon.