Comment by Joker_vD

> Now you have a naming problem. You need a naming convention that every user of the list library must follow, or else their types will be incompatible.

Oh, that's simple: just have empty struct tags.

> And what about typedefs?

The names introduced by the typedefs are irrelevant.

> A and B are typedef-related (their normal forms, obtained by following all typedefs, are the same), lists of A and B will be incompatible unless users agree on a common name.

Huh?

    typedef struct { int x; } A;
    typedef struct { int x; } B;

    typedef struct { header_list header; A payload; } list_of_A;
    typedef struct { header_list header; B payload; } list_of_B;

The structs list_of_A and list_of_B are compatible.