hard to detect bug when capn_setp not called.

[slayercat]

If capn_setp not been called. data serialized shell not contain it. or an assert shell emit at least.

It's really hard to debug it.

eg.

file a.capnp

@0xb5c2cbd0a1ee9f74;

struct Person{
    name @0 :Text;
}

#include <unistd.h>
#include<sys/types.h>
#include<fcntl.h>
#include <capnp_c.h>

#include "a.capnp.h"


void x(){

};

int main() {
    struct capn capn;
    struct capn_segment *seg;
    capn_init_malloc(&capn);
    capn_ptr root = capn_root(&capn);
    Person_ptr personobj=new_Person(root.seg);
    printf("root->type %d\n",root.type);
    struct capn_text ustr={
        3,"aaa", NULL
    };  
    Person_set_name(personobj, ustr);
    int fd=open("aaa.data",O_CREAT|O_RDWR);
    capn_write_fd(&capn, write , fd, 0); 
    close(fd);
}

this will generate file aaa.data, content:

[root@7e6235426e5d bbb]# od -x aaa.data 
0000000 0000 0000 0003 0000 0000 0000 0000 0000
0000020 0001 0000 0022 0000 6161 0061 0000 0000
0000040
[root@7e6235426e5d bbb]# capnp decode a.capnp Person < aaa.data 
()

[root@7e6235426e5d test-go-capnp]# od -x good.data
0000000 0000 0000 0003 0000 0000 0000 0000 0001
0000020 0001 0000 0022 0000 6161 0061 0000 0000
0000040
[root@7e6235426e5d test-go-capnp]# capnp decode a.capnp Person < good.data 
(name = "aaa")

[eqvinox]

Hm. Need to look at this in more detail...

Warning probably needs to be on unused data, not on a "null" pointer - null pointers are useful and explicitly desirable in some situations, but here there is data allocated that isn't used. Not sure how & where to do this...