clang: error: linker command failed with exit code 1 (use -v to see invocation)

This happened to me simply because one function type did not match when 
called recursively. I know there are other types of faults that might cause it.
But this is what happened to me. 

Notice the Delete_Aux(t->left, item) recursive function calling.


TN *Delete_aux(TN *t, int item)
{

    // complete this function
    // write your code here
    TN *temp;
    if (t == NULL)
        return NULL;
    // if item is smaller go to the left node
    if (t->data > item)
    {
        t->left = Delete_Aux(t->left, item); //Should be Delete_aux(t->right, item); Delete_Aux(t->left, item) is shown int type 
        return t;
    }

    else if (t->data < item)
    {
        t->right = Delete_Aux(t->right, item); 
        return t;
    }
    else
    {

        if (t->left == NULL && t->right == NULL)
        {
            free(t);
            return NULL;
        }

        else if (t->left == NULL)
        {
            temp = t->right;
            free(t);
            return temp;
        }
        else if (t->right == NULL)
        {
            temp = t->left;
            free(t);
            return temp;
        }
        else
        {
            // get the smallest node in the right subtree temp = Leftmost(t->right)
            t->data = temp->data;
            t->right = Delete_Aux(t->right, temp->data);
            return t;
        }
    }
}