Ownership semantics

[Matt Elkins via Digitalmars-d-learn]

On Sunday, 31 January 2016 at 20:11:07 UTC, Matt Elkins wrote:
> On Sunday, 31 January 2016 at 20:10:03 UTC, Matt Elkins wrote:
>> On Sunday, 31 January 2016 at 20:07:26 UTC, Steven 
>> Schveighoffer wrote:
>>> What is likely happening is that ptr is already collected, 
>>> and you are invalidly attempting to re-free it.
>>
>> The GC can collect this memory even though there is still an 
>> outstanding root-reachable pointer to it?
>
> Or maybe it isn't root-reachable?

No, it is still present even if root-reachable:

[code]
unittest
{
     import std.algorithm;

     int* x;
     {
         auto map = new UniquePtr!int[1];
         auto uniqueX = UniquePtr!int(5);
         x = uniqueX.get();
         map[0] = move(uniqueX);
     }
}
[/code]

[output]
core.exception.InvalidMemoryOperationError at src\core\exception.d(679): Invalid memory operation
----------------
Program exited with code 1
Made 632560 for this 18FD90
Disposing null for this 18FD70
Disposed null for this 18FD70
Disposing null for this 18FD90
Disposed null for this 18FD90
All unit tests have been run successfully.
Disposing 632560 for this 632550
[/output]