Won't see as function declaration

I'm getting some mysterious syntax errors. Anywhere I declare grid::region& as the return type of a function, I get trouble. I expect it's some little typo mistake, but I can't find it after combing a while.

Code:

---

simulator.h:25: error: ‘region’ declared as a ‘virtual’ field
simulator.h:25: error: expected ‘;’ before ‘(’ token
simulator.h:48: error: expected ‘;’ before ‘(’ token
simulator.h:53: error: expected `;' before ‘private’
simulator.h:72: error: expected ‘;’ before ‘(’ token
simulator.h:73: error: expected `;' before ‘}’ token

---

Code:

---

class thread_method
{
  public:
    virtual bool wait() = 0;
    virtual grid::data_type get_sum(const grid::data_type & piece) = 0;
    virtual grid::data_type get_max(const grid::data_type & piece) = 0;
    virtual grid::region & region(std::vector<grid::region>::size_t index) = 0;
};

class single_thread : public thread_method
{
    public:
        bool wait() { return true; }
        grid::data_type get_sum(const grid::data_type & piece) { return piece; }
        grid::data_type get_max(const grid::data_type & piece) { return piece; }
        grid::region & region(std::vector<grid::region>::size_t index)
        {
            if(index) throw std::string("single_thread requested region index other than 0");
            return r;
        }
    private:
        grid::region r;
};

---

Code:

---

class grid
{
  .  .  .
      typedef std::vector<span> region;
  .  .  .
};

---

Is the grid class visible? Have you made sure you have included the proper header?

Yes, it is visible.

And public?

--
Mats

And you say it only happens when the return type is grid::region and not any of the parameters?

Correct. Here's grid, for good measure:

Code:

---

class grid : public array2d<GRID_DATA_TYPE, uword>
{
public:
    typedef array2d<grid::data_type,uword> base_type;
        typedef array2d<grid::data_type,uword>* base_pointer_type;
        grid(size_type w_in, size_type h_in, data_type fill = 0.0); //see declaration of array2d for 'data_type'

        struct span;  //POD type
        typedef std::vector<span> region;
        static size_type num_points(const region & r, size_type until = std::numeric_limits<size_type>::max());

        bool iterate_region(const region & reg, func2d & f);
        void write_file(const std::string & path);
};

---

I think you have to define span before you can typedef it? IIRC, typedefs don't change when you redefine names, so right now region is a vector of an incomplete type.

However, I think it's time for "minimal, complete example that shows the problem". Reduce it down to one file, check that you still get the problem, and post it here.

--
Mats

Here's a gentle program that completely rapes my compiler. How is span an incomplete type?

Code:

---

#include <vector>
#include <iostream>

class grid
{
  public:
    struct span
    {
        int x; int y; int dy;
    };
    typedef std::vector<span> region;
};

class thread_method
{
  public:
    grid::region & region(std::vector<grid::region>::size_t index) = 0;
};

class single_thread : public thread_method
{
    grid::region r;
  public:
    grid::region & region(std::vector<grid::region>::size_t index) { return r; }
};

int main()
{
    thread_method * tmeth = new single_thread();
    std::cout << tmeth->region(0).size() << std::endl;
    delete tmeth;
}

---

Code:

---

david@david-laptop:~/Desktop$ g++ prob.cpp -o prob
prob.cpp:19: error: expected ‘;’ before ‘(’ token
prob.cpp:26: error: expected ‘;’ before ‘(’ token
prob.cpp:27: error: expected `;' before ‘}’ token
prob.cpp: In function ‘int main()’:
prob.cpp:32: error: ‘class thread_method’ has no member named ‘region’
/usr/include/c++/4.2/bits/stl_vector.h: In destructor ‘std::_Vector_base<_Tp, _Alloc>::~_Vector_base() [with _Tp = grid::span, _Alloc = std::allocator<grid::span>]’:
/usr/include/c++/4.2/bits/stl_vector.h:199:  instantiated from ‘std::vector<_Tp, _Alloc>::vector(const _Alloc&) [with _Tp = grid::span, _Alloc = std::allocator<grid::span>]’
prob.cpp:23:  instantiated from here
/usr/include/c++/4.2/bits/stl_vector.h:120: error: invalid use of incomplete type ‘struct grid::span’
prob.cpp:7: error: forward declaration of ‘struct grid::span’
/usr/include/c++/4.2/bits/stl_construct.h: In function ‘void std::__destroy_aux(_ForwardIterator, _ForwardIterator, std::__false_type) [with _ForwardIterator = grid::span*]’:
/usr/include/c++/4.2/bits/stl_construct.h:155:  instantiated from ‘void std::_Destroy(_ForwardIterator, _ForwardIterator) [with _ForwardIterator = grid::span*]’
/usr/include/c++/4.2/bits/stl_construct.h:182:  instantiated from ‘void std::_Destroy(_ForwardIterator, _ForwardIterator, std::allocator<_T2>) [with _ForwardIterator = grid::span*, _Tp = grid::span]’
/usr/include/c++/4.2/bits/stl_vector.h:268:  instantiated from ‘std::vector<_Tp, _Alloc>::~vector() [with _Tp = grid::span, _Alloc = std::allocator<grid::span>]’
prob.cpp:23:  instantiated from here
/usr/include/c++/4.2/bits/stl_construct.h:121: error: cannot increment a pointer to incomplete type ‘grid::span’
/usr/include/c++/4.2/bits/stl_construct.h: In function ‘void std::_Destroy(_Tp*) [with _Tp = grid::span]’:
/usr/include/c++/4.2/bits/stl_construct.h:122:  instantiated from ‘void std::__destroy_aux(_ForwardIterator, _ForwardIterator, std::__false_type) [with _ForwardIterator = grid::span*]’
/usr/include/c++/4.2/bits/stl_construct.h:155:  instantiated from ‘void std::_Destroy(_ForwardIterator, _ForwardIterator) [with _ForwardIterator = grid::span*]’
/usr/include/c++/4.2/bits/stl_construct.h:182:  instantiated from ‘void std::_Destroy(_ForwardIterator, _ForwardIterator, std::allocator<_T2>) [with _ForwardIterator = grid::span*, _Tp = grid::span]’
/usr/include/c++/4.2/bits/stl_vector.h:268:  instantiated from ‘std::vector<_Tp, _Alloc>::~vector() [with _Tp = grid::span, _Alloc = std::allocator<grid::span>]’
prob.cpp:23:  instantiated from here
/usr/include/c++/4.2/bits/stl_construct.h:107: error: invalid use of incomplete type ‘struct grid::span’
prob.cpp:7: error: forward declaration of ‘struct grid::span’
david@david-laptop:~/Desktop$

---

The problem is not with span or region. Vector does not have a nested typedef called size_t, it's size_type.

Comeau online told me that.

Quote:

---

Originally Posted by CodeMonkey

I expect it's some little typo mistake, but I can't find it after combing a while.

---

It was.

Code:

---

class thread_method
{
  public:
    virtual grid::region & region(std::vector<grid::region>::size_type index) = 0;
};

class single_thread : public thread_method
{
    public:
        grid::region & region(std::vector<grid::region>::size_type index)
        {
            if(index) throw std::string("single_thread requested region index other than 0");
            return r;
        }
    private:
        grid::region r;
};

---

Yes, that fixed it. Also, I had been saving to prob.txt and compiling prob.cpp..... it's no wonder none of the proposed solutions were working!

Thanks.