GCC 4.2 Template strange error

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 o开发者_C百科ut how to fix the errors. please help,

Thanks.

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.

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);
}

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.