Explore structure with member offsets #14821

Feature Request

This is an attempt to reopen the old request #13544.
That request was closed as duplicate to a similar one (13034). The 13034 is solved in version 1.35.3, but the 13544 is not solved. Hence a new request repeating an old one:

I'd like to have a command (probably in a Peek menu) which would open a window for a struct and show offsets of all struct members. Something similar to gdb's ptype /o command.

For example, for a code like:

typedef struct {
   char a;
   int b;
   char c[5];
} s1_t;

typedef struct __attribute__((packed)) {
   char a;
   int b;
   char c[5];
} s2_t;

int main() {
   s1_t s1;
   s2_t s2;
   return 0;
}

We can see offsets in gdb:

(gdb) ptype /o s1_t
type = struct {
/*      0      |       1 */    char a;
/* XXX  3-byte hole      */
/*      4      |       4 */    int b;
/*      8      |       5 */    char c[5];
/* XXX  3-byte padding   */

                               /* total size (bytes):   16 */
                             }
(gdb) ptype /o s2_t
type = struct {
/*      0      |       1 */    char a;
/*      1      |       4 */    int b;
/*      5      |       5 */    char c[5];

                               /* total size (bytes):   10 */
                             }
(gdb)

I would love to have something similar, but without compiling and running gdb

The solution implemented in 1.35.3 shows the total size of a structure. That is nice, but not enough. My original request is to see member offsets and gaps in the struct. The information which is shown by gdb as response to ptype /o

The show of alignment implemented in 1.35.3 is probably nice, but it is not very useful. It gives an idea of do we use a packed or unpacked structure, but member offsets still have to be calculated manually (or with gdb), and existence and size of gaps still requires gdb or a lot of manual work.