Re: [boost] [asio] Invalidated iterator bug in hash_map

From: Christopher Kohlhoff (chris_at_[hidden])
Date: 2006-04-04 06:45:29

Hi Felipe,

--- Felipe Magno de Almeida <felipe.m.almeida_at_[hidden]> wrote:

> the file hash_map.hpp has a bug, caught by STLPort checked-STL.
> The clear member-function is:
> 
>   // Remove all entries from the map.
>   void clear()
>   {
>     // Initialise all buckets to empty.
>     for (size_t i = 0; i < num_buckets; ++i)
>       buckets_[i].first = buckets_[i].last = values_.end();
> 
>     // Clear the values.
>     values_.clear();
>   }
> 
> But the clear member function of values_invalidates all iterators.
> So, the values recorded in the buckets are all invalidated. Which is
> caught in a later call to insert.
> 
> I've swapped the clear call above the for and everything is fine
> here.

No problem, I'll change it as soon as sourceforge cvs is working again.
However, I do wonder if it's STLPort's checked iterator support that
has the bug. 23.2.2.3/3 specifies the effects of clear(), and says:

 Invalidates only the iterators and references to the erased elements.

To me this means that the iterator returned by end() is not invalidated
by the call to clear(), since that iterator does not correspond to any
element that can be erased. Perhaps there is another part of the
standard that says otherwise?

Cheers,
Chris