It would be nice to be able to use defctype to make aliases for struct types that can be used as if they were actual struct types.

for example

(cffi:defcstruct foo)
(cffi:defctype bar foo)
(cffi:foreign-type-size '(:struct bar))

currently the defctype complains

WARNING: bare references to struct types are deprecated.
Please use (:POINTER (:STRUCT FOO)) or (:STRUCT FOO) instead.

and using it as a struct type fails with

Unknown CFFI type (:STRUCT BAR)

Vulkan renames structs as they are promoted from extensions to 'core' types, but keeps around the old names so old code doesn't break. It would be nice to do so for the CL version as well, but as far as I can see it will need duplicated defcstruct definitions to keep existing code with (:struct bar) working after bar is renamed to foo.