How to use Multiway_Trees

[Mart van de Wege <mvdwege@gmail.com>]

I was interested in using Ada.Containers.Multiway_Trees in another
project, so I wrote some Proof of Concept code to see if I understood
correctly how to use it.

However, even the most simple use case, the following code, raises a
Program_Error:

raised PROGRAM_ERROR : Tree_Test.Test_Tree.Replace_Element: Position cursor designates root

with Ada.Text_Io;
with Ada.Containers.Multiway_Trees;
procedure Test_Tree is
   type String_Access is access String;
   package Tr is new Ada.Containers.Multiway_Trees
     ( Element_Type => String_Access );
   use Tr;
   T : Tree := Empty_Tree;
   C : Cursor := Root(T);
begin
   T.Insert_Child(Parent => C,
                  Before => No_Element,
                  New_Item => new String'("Test"));
end Test_Tree;

How do I create a tree if I can't even insert a child under the root
node?

Mart

-- 
"We will need a longer wall when the revolution comes."
    --- AJS, quoting an uncertain source.