import std, core.lifetime;

struct Node {
    Node* pNext;
    void func() { "Node::func %s".writeln( pNext); }
}
void func( Node* p ) { "::func %s(%s)".writeln( p, p == null ? p : p.next); }

void main()
{
    Node n;
    auto pn = &n; //cast( Node* )0;
    pn.func(); // prints: Node::func
    // WTF?
    // why called Node::func for Node* when ::func is right choice for it?
}

problem:
member func has invariant that this is not null (programmer thinks so).
global func hasn't the one and programmer should check for it before doing something.

when pn is null u've got AccessViolation/Signal_11 with no stacktrace.

workaround:
avoid overloaded UFCS for pointers

On Thursday, 6 April 2023 at 14:26:01 UTC, a11e99z wrote:

I understand what you mean. When you try to access the last node of a linked list, you will get the segmentation fault if you are using a built-in viewer (toString). For example:

struct Node
{
  int item;
  Node * back;

  string toString()
  {
    import std.format : format;

    return format("Node::%s (back)-> %s", item,
                                     back.item);
  }
}

void main()
{
  import std.stdio : writeln;

  auto node1 = Node(41);
  auto node1Ptr = &node1;

  //printNode(node1Ptr);/* NOT COMPILE!
  node1.writeln;//* Main::41 (back)-> null */

  auto node2 = Node(42);
  node2.back = node1Ptr;

  printNode(&node2); // Main::42 (back)-> 41
  node2.writeln;     // Node::42 (back)-> 41
}

void printNode(Node * p)
{
  import std.stdio : writefln;

  if(p.back is null)
  {
    writefln("Main::%s (back)-> null", p.item);
  } else {
    writefln("Main::%s (back)-> %s", p.item,
                                p.back.item);
  }
}

If you don't remove the comment line (just remove the // sign: toggle-comment) the above code will not compile. Because it is not connect to any node.

@SDB