[LLVMdev] MS VS2010 std implementation: "Cannot assign iterators to two different blocks!"

[Bob Floyd]

When using MS VS2010 there is an issue with std:

 

`SuccIterator` implements a partial assignment operator:

 

inline const _Self &operator=(const _Self &I) {

    assert(Term == I.Term &&"Cannot assign iterators to two different
blocks!");

    idx = I.idx;

    return *this;

    }

 

For copy construction, MS VS2010 std reserves the right, and sometimes
calls,

a method to reverse elements which does so by swap:

 

 template<class _Ty> inline

 void swap(_Ty& _Left, _Ty& _Right)

 {             // exchange values stored at _Left and _Right

   _Ty _Tmp = _Move(_Left);

   _Left = _Move(_Right); <<<<<<<<<<<<< Needs FULL assignment operator!!!!

   _Right = _Move(_Tmp);

 }

 

When `_Ty` is `SuccIterator const` the assert "Cannot assign iterators to
two different blocks!" can fail.

 

Can this be a workaround:

 

inline const _Self &operator=(const _Self &I) {

  new (this) _Self(I);

  return *this;

}

 

The larger question is can both the assert be preserved and swap satisfied?

  

 

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