block_derive_type
type_t *void_ptr = block_derive_type(gettyp(VOID), PTR);
dsym->s_type = tp = block_derive_type(tp, t = PTR);
type_t *tp = block_derive_type(stp, PTR);
type_t *tp = block_derive_type(stp, ARRAY);
type_t *tp = block_derive_type(ret, FUNC);
sym->s_type = block_derive_type(subt, PTR);
sym->s_type = block_derive_type(sym->s_type, PTR);
*tpp = block_derive_type(
type_t *block_derive_type(type_t *, tspec_t);
sym->s_type = block_derive_type(gettyp(CHAR), ARRAY);
sym->s_type = block_derive_type(sym->s_type, FUNC);