Permalink
Reply
Hi,
I'm following this example:
https://dlang.org/spec/cpp_interface.html#using_cpp_classes_from_d
and try to wrap a std::list
base.cpp
#include <iostream>
#include <list>
using namespace std;
class Base
{
public:
virtual void print3i(int a, int b, int c) = 0;
};
class Derived : public Base
{
public:
int field;
Derived(int field) : field(field) {}
void print3i(int a, int b, int c)
{
cout << "a = " << a << endl;
cout << "b = " << b << endl;
cout << "c = " << c << endl;
}
int mul(int factor);
};
template<class T> class std_list : public std::list<T> {};
void getInts(std_list<int>* list);
int Derived::mul(int factor)
{
return field * factor;
}
Derived *createInstance(int i)
{
// get list of ints from D side
std_list<int> list;
list.push_back(911);
::getInts(&list);
for (int i : list) {
cout << "i = " << i << endl;
}
return new Derived(i);
}
void deleteInstance(Derived *&d)
{
delete d;
d = 0;
}
main.c
extern(C++)
{
abstract class Base
{
void print3i(int a, int b, int c);
}
class Derived : Base
{
int field;
@disable this();
override void print3i(int a, int b, int c);
final int mul(int factor);
}
Derived createInstance(int i);
void deleteInstance(ref Derived d);
}
extern(C++) {
class std_list(T) {
@disable this();
void push_back(const ref T value);
}
void getInts(std_list!(int) list) {
foreach (int i; 0 .. 10) {
list.push_back(i);
}
}
}
void main()
{
import std.stdio;
auto d1 = createInstance(5);
writeln(d1.field);
writeln(d1.mul(4));
Base b1 = d1;
b1.print3i(1, 2, 3);
deleteInstance(d1);
assert(d1 is null);
auto d2 = createInstance(42);
writeln(d2.field);
deleteInstance(d2);
assert(d2 is null);
}
Makefile
c2d:
g++ -c -g -ggdb base.cpp
ldmd2 -g main.d base.o -L-lstdc++ && ./main
if I use LCD (ldmd2), it segfaults:
$ make
g++ -c -g -ggdb base.cpp
ldmd2 -g main.d base.o -L-lstdc++ && ./main
Segmentation fault (core dumped)
and gdb shows it fails at: main.d:29 list.push_back(i);
if I use DMD, it cannot link:
$ make
g++ -c -g -ggdb base.cpp
dmd -g main.d base.o -L-lstdc++ && ./main
/usr/bin/ld: main.o:(.data._D4main__T8std_listTiZQm6__vtblZ+0x0): undefined reference to `std_list<int>::push_back(int const&)'
collect2: error: ld returned 1 exit status
Error: linker exited with status 1
Looks like something wrong with the push_back().
So, how to fix this DMD link error, and LDC segfaults?
Thanks.
