Type kinds (The CTF File Format)

2.3.3 Type kinds

Every type in CTF is of some kind. Each kind is some variety of C type: all structures are a single kind, as are all unions, all pointers, all arrays, all integers regardless of their bitfield width, etc. The kind of a type is given in the kind field of the ctt_info word (see section The info word, ctt_info).

The space of type kinds is only a quarter full so far, so there is plenty of room for expansion. It is likely that in future versions of the file format, types with smaller kinds will be more efficiently encoded than types with larger kinds, so their numerical value will actually start to matter in future. (So these IDs will probably change their numerical values in a later release of this format, to move more frequently-used kinds like structures and cv-quals towards the top of the space, and move rarely-used kinds like integers downwards. Yes, integers are rare: how many kinds of int are there in a program? They’re just very frequently referenced.)

Here’s the set of kinds so far. Each kind has a #define associated with it, also given here.

Kind	Macro	Purpose
0	`CTF_K_UNKNOWN`	Indicates a type that cannot be represented in CTF, or that is being skipped. It is very similar to type ID 0, except that you can have multiple, distinct types of kind `CTF_K_UNKNOWN`.
1	`CTF_K_INTEGER`	An integer type. See section Integer types.
2	`CTF_K_FLOAT`	A floating-point type. See section Floating-point types.
3	`CTF_K_POINTER`	A pointer. See section Pointers, typedefs, and cvr-quals.
4	`CTF_K_ARRAY`	An array. See section Arrays.
5	`CTF_K_FUNCTION`	A function pointer. See section Function pointers.
6	`CTF_K_STRUCT`	A structure. See section Structs and unions.
7	`CTF_K_UNION`	A union. See section Structs and unions.
8	`CTF_K_ENUM`	An enumerated type. See section Enums.
9	`CTF_K_FORWARD`	A forward. See section Forward declarations.
10	`CTF_K_TYPEDEF`	A typedef. See section Pointers, typedefs, and cvr-quals.
11	`CTF_K_VOLATILE`	A volatile-qualified type. See section Pointers, typedefs, and cvr-quals.
12	`CTF_K_CONST`	A const-qualified type. See section Pointers, typedefs, and cvr-quals.
13	`CTF_K_RESTRICT`	A restrict-qualified type. See section Pointers, typedefs, and cvr-quals.
14	`CTF_K_SLICE`	A slice, a change of the bit-width or offset of some other type. See section Slices.

Now we cover all type kinds in turn. Some are more complicated than others.