source: tests/exceptions/virtual-cast.cfa@ 8519fac

// Testing the virtual cast, as part of strict inheritance.

/* IMPORTANT: This test does not repersent the final feature set.
 * We are missing a number of important aspects such as:
 * + vtable type generation.
 * + vtable instance generation, that might use different resolution rules.
 * + Virtual syntax to force said generation on structures and traits.
 * + Trait references/pointers that do the virtual_table lookup.
 */

#include <stdlib.hfa>
#include <assert.h>



// Hand defined alpha virtual type:
struct __cfatid_struct_alpha {
        __cfavir_type_info parent;
};

__attribute__(( cfa_linkonce ))
struct __cfatid_struct_alpha __cfatid_alpha = {
        (__cfavir_type_info *)0,
};

struct alpha_vtable {
        struct __cfatid_struct_alpha const * const __cfavir_typeid;
        char (*code)(void);
};

struct alpha {
        alpha_vtable const * virtual_table;
};

char ret_a(void) {
        return 'a';
}



// Hand defined beta virtual type:
struct __cfatid_struct_beta {
        __cfatid_struct_alpha const * parent;
};

__attribute__(( section(".gnu.linkonce.__cfatid_beta") ))
struct __cfatid_struct_beta __cfatid_beta = {
        &__cfatid_alpha,
};

struct beta_vtable {
        struct __cfatid_struct_beta const * const __cfavir_typeid;
        char (*code)(void);
};

struct beta {
        beta_vtable const * virtual_table;
};

char ret_b(void) {
        return 'b';
}



// Hand defined gamma virtual type:
struct __cfatid_struct_gamma {
        __cfatid_struct_beta const * parent;
};

__attribute__(( section(".gnu.linkonce.__cfatid_gamma") ))
struct __cfatid_struct_gamma __cfatid_gamma = {
        &__cfatid_beta,
};

struct gamma_vtable {
        struct __cfatid_struct_gamma const * const __cfavir_typeid;
        char (*code)(void);
};

struct gamma {
        gamma_vtable const * virtual_table;
};

char ret_g(void) {
        return 'g';
}


extern "C" {
        alpha_vtable _alpha_vtable_instance = { &__cfatid_alpha, ret_a };
        beta_vtable _beta_vtable_instance = { &__cfatid_beta, ret_b };
        gamma_vtable _gamma_vtable_instance = { &__cfatid_gamma, ret_g };
}

int main (int argc, char * argv[]) {

        gamma * tri = malloc(); tri->virtual_table = &_gamma_vtable_instance;
        beta * mid = (virtual beta *)tri;
        assert( 'g' == mid->virtual_table->code() );

        alpha * top = malloc(); top->virtual_table = &_alpha_vtable_instance;
        mid = (virtual beta *)top;
        assert( ! mid );

        free(tri);
        free(top);
        printf( "done\n" );                             // non-empty .expect file
}