Hello guys,
Im using D llvm for my personal project, and i run into a strange behavior. My code is:

struct Node {
   string name;
   ...
   Node[] children;

   Node* search(in string nodeName) {
      if(name==nodeName)
         return &this;
      foreach(child;children) {
         auto r=child.search(nodeName);
         if(r)
            return r;
      }
      return null;
   }
}

Usually first i build the tree from Node-s. Then i seach the tree for nodes. It is pritty simple.
But today i run into a problem. The returned Node* from search function points to invalid data. Search code:

Node* result=root.search("whatever node name");
if(result) {
   writeln(result.name);
}

And this code crashes. The result.name.ptr points to some unknown data. But the result pointer has the same value as in the search function. This gives me headakes.
Complete code:

struct Node {
   string name;
   ...
   Node[] children;

   Node* search(in string nodeName) {
      if(name==nodeName) {
         writeln("returned node: ",&this," name: ",name); //0xABCDEF01 nodename
         return &this;
      }
      foreach(child;children) {
         auto r=child.search(nodeName);
         if(r)
            return r;
      }
      return null;
   }
}

Node* result=root.search("whatever node name");
writeln(result); //0xABCDEF01 //same pointer as before
writeln(result.name); //crashes result.name.ptr is random pointer, as anything else in the struct has random value

1. If i do a second search (for the same name), the result is the same pointer value, so data is there, and it isnt moved by anything.
2. If i search again (for the same name): the writeln() in the search function prints the correct name, so the memory of the struct is not been overwrited
3. If i search again (still for the same name) the result.name.ptr is incorrect  but the same as the first search value.
4. I use unly 1 thread. And Thread.getThis() is the same everywhere.

I dont know what the issue is here. Am i missing something?

Ty: collerblade

I forget 1 thing!

5. If i rewrite the struct to class. (And i return Node instead of Node* ofc). The code works perfectly!!!

On Monday, 18 January 2016 at 09:43:13 UTC, collerblade wrote:
....
>
> struct Node {
>    string name;
>    ...
>    Node[] children;
>
>    Node* search(in string nodeName) {
>       if(name==nodeName) {
>          writeln("returned node: ",&this," name: ",name); //0xABCDEF01 nodename
>          return &this;
>       }
>       foreach(child;children) {

The problem is here. In D the structs have value semantics, i.e. child is a stack allocated copy of the element in children and consequently an address on stack is returned.
foreach (ref child, children) should solve your problem.

>          auto r=child.search(nodeName);
>          if(r)
>             return r;
>       }
>       return null;
>    }
> }
>

PS: this is a typical post for the learn forum

You are right. I miss that part.
Ty: collerblade