On Sunday, 27 November 2016 at 12:59:32 UTC, Timoses wrote:
Hi there,
I've got a problem interfacing to a C library.
The following structs are used by the library's .d file that
I've written.
--------------------
struct neo4j_map_entry_t
{
neo4j_value_t key;
neo4j_value_t value;
};
struct neo4j_value_t
{
uint8_t _vt_off;
uint8_t _type; /*TODO: combine with _vt_off? (both always
have same value)*/
uint16_t _pad1;
uint32_t _pad2;
_neo4j_value_data _vdata;
};
union _neo4j_value_data
{
uint64_t _int;
uintptr_t _ptr;
double _dbl;
};
--------------------
Now I'd also like to use them in my own code. However, I fail
at generating an array of map entries:
--------------------
void test()
{
// These work
neo4j_map_entry_t[] mapa2; // yes
neo4j_map_entry_t entry1 = { key: neo4j_string("prop1"),
value: neo4j_string("testprop1")}; // yes
neo4j_map_entry_t entry2 = { key: neo4j_string("prop2"),
value: neo4j_string("testprop2")}; // yes
neo4j_map_entry_t* mapp; // yes
// These don't
neo4j_map_entry_t[2] mapa1; // no
mapa2.length = 2; // no
mapa2 ~= entry1; // no
neo4j_map_entry_t[] mapa3 = [{ key: neo4j_null, value:
neo4j_null}]; // no
}
--------------------
The output is:
______________________
myprogram ~master: building configuration "unittest"...
Linking...
Undefined symbols for architecture x86_64:
"_D10neo4jTypes17neo4j_map_entry_t6__initZ", referenced from:
_D6myprogram6myprogram5test2MFZv in myprogram.o
ld: symbol(s) not found for architecture x86_64
______________________
Why is it a linker problem? I'm not linking to the c interface
but merely using D structs...
The missing symbol is the struct initialiser for
neo4j_map_entry_t. Not sure why is not being generated (it
should), possibly because of the union.
That seems like a bug please report it. http://issues.dlang.org/
