GCC 4.2 Template strange error.

Question

Hello, i have the following code compiled with GCC 4.2 / XCode.

template <typename T>
class irrProcessBufferAllocator
{
public:

    T* allocate(size_t cnt)
    {
        return allocProcessBufferOfType<T>(cnt);
    }

    void deallocate(T* ptr)
    {
        if (ptr)
        {
            releaseProcessBuffer(ptr);
        }
    }

    void construct(T* ptr, const T& e)
    {
        new ((void*)ptr) T(e);//"error: expected type-specifier before 'e' " and
//error: expected `;' before 'e'
    }

    void destruct(T* ptr)
    {
        ptr->~T();//error: expected class-name before ';' token
    }

};

i really can't figure out how to fix the errors. please help,

Thanks.

Answer 1

How about this?

template <class T> 
class irrProcessBufferAllocator 
{ 
public: 

    T* allocate(size_t cnt) 
    { 
        return allocProcessBufferOfType<T>(cnt); 
    } 

    void deallocate(T* ptr) 
    { 
        if (ptr) 
        { 
            releaseProcessBuffer(ptr); 
        } 
    } 

    void construct(T* ptr, const T& e) 
    { 
        new ((void*)ptr) T(e);//"error: expected type-specifier before 'e' " and 


        //error: expected `;' before 'e' 
    } 

    void destruct(T* ptr) 
    { 
        ptr->~T();//error: expected class-name before ';' token 
    } 
};

int main(){
    irrProcessBufferAllocator<int> i, j;
    int *p = new int;
    i.construct(p, 2);
    i.destruct(p);
}

Answer 2

This just points out the problem , doesn't fix it. i have specialized the template for all POD types by removing the 'new' and '->~T()' from the construct and destruct functions. The errors still appear in the same spot.

Answer 3

Just to make sure, you are not missing necessary includes: <cstddef> for std::size_t and <new> for placement new?

Otherwise those functions would appear to be correct. If that is the entire allocator, it has other flaws, such as missing required typedefs, address() and max_size() methods, as well as a rebind template.

---

Edit: The only cause for the error could be that you have a function-style macro T defined.

#define T(z) zzz

would make the preprocessor replace all T()'s it encounters, but leave the Ts not followed by brackets.

You could just rename the template argument.