General Idea

Using typedef allows us to rename a data type, and I follow these ideas:

• Sticking to the current coding convention.
• Using typedef for encapsulated structs (i.e. hidden, opaque).
• Using it for function pointers.
• Avoiding it for any other case, including normal structs and enums.

Example

/* The .h file */
struct position {
    int x;
    int y;
};

typedef struct ctx ctx;

typedef int (*context_cb)(ctx *ctx, struct position *position);

ctx *new_context(context_cb cb);

/* The .c file */

struct ctx {
    context_cb cb;
    /*...*/
};

Explanation

I kind of avoid typedef, the main problem I see is that it hides the actual type. However, if you have an encapsulated struct then it makes sense to hide it, because you can't use it as a struct.

I prefer to know that the type is an enum, or an struct. This way, when it is an struct I know that I can access its elements, and that doing it should be safe. If the struct is meant to be accessed only by functions, then it should be opaque and typedef should be used.

Also, it allows you to use the same name for related things, like stat that is a function and also the struct used in that function.