I may be mistaken but, as far as I know the fact that 'arr["x"] is created and set to null' before 'new object of class A is created' is a bug. Right ?

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/* Order of execution (is this a bug ?):
 *   - arr["x"] is created and set to null
 *   - new object of class A is created
 *   - arr["x"] is set to newly created object
 */
 
module program;
 
A[string] arr;
 
class A {
  
  this () {
    // at this point:
    // ("x" in arr)   is true
    // arr["x"]       is set to null
  }
  
}
 
void main () {
  arr["x"] = new A();
}