[julia-users] Is JL_GC_PUSH not allowed to be nested?

[K leo]

I tried to nest the GC pairs (JL_GC_PUSH, JL_GC_POP), but got some compile 
errors regarding julia.h.

In file included from test6.cpp:11:0:
> test6.cpp: In function ‘int main(int, char**)’:
> /home/xxx/Software/julia-9c76c3e89a/include/julia/julia.h:609:19: error: 
> redeclaration of ‘void* __gc_stkf []’
>    void *__gc_stkf[] = {(void*)3, jl_pgcstack, arg1};                     
>  \
>                    ^
> test6.cpp:44:5: note: in expansion of macro ‘JL_GC_PUSH1’
>      JL_GC_PUSH1(&ret);
>      ^
> /home/xxx/Software/julia-9c76c3e89a/include/julia/julia.h:613:9: note: 
> ‘void* __gc_stkf [4]’ previously declared here
>    void *__gc_stkf[] = {(void*)5, jl_pgcstack, arg1, arg2};               
>  \
>          ^
> test6.cpp:35:5: note: in expansion of macro ‘JL_GC_PUSH2’
>      JL_GC_PUSH2(&a,&b);


So is nesting them not allowed, or is it a bug in julia.h?

My test C++ code is here:

#include <julia.h>
#include <julia_threads.h>
#include <iostream>
using namespace std;
#include <julia.h>
#include <iostream>
using namespace std;
struct TestType {
    double a;
    double b;
};
int main(int argc, char *argv[])
{
    TestType A, *ret;
    A.a=2.;
    A.b=3.;
    jl_init(NULL);
    jl_load("TestArg.jl");
    jl_value_t * mod = (jl_value_t*)jl_eval_string("TestArg");
    jl_value_t* a=NULL;
    jl_value_t* b=NULL;
    JL_GC_PUSH2(&a,&b);
    a = jl_box_float64(A.a);
    b = jl_box_float64(A.b);
    jl_value_t* jl_A = 
jl_new_struct((jl_datatype_t*)jl_get_function((jl_module_t*)mod, 
"TestType"), a, b);
   // construct a TestType instance
    jl_function_t * func = jl_get_function((jl_module_t*)mod,"TestFunc");
    ret = (TestType*) jl_call1(func, jl_A);
    JL_GC_PUSH1(&ret);
    cout<<ret->a<<" "<<ret->b<<endl;
    JL_GC_POP();
    JL_GC_POP();
    jl_atexit_hook(0);
    return 0;
}