Add tree heterogeneous lookup in alternative modes

[François Dumont]

On 04/06/2015 14:41, Jonathan Wakely wrote:
> On 03/06/15 21:56 +0200, François Dumont wrote:
>> Hi
>>
>>    Here is a patch to add heterogeneous lookup to alternative modes. 
>
> Excellent.
>
>> To do so I had to expose __is_transparent as __has_is_transparent to 
>> avoid confilct with existing __is_transparent.
>
> That's a better name, thanks.
>
>
>> Should I put it in __detail namespace ?
>
> Could it just be protected instead of at namespace scope?

No, debug containers are inheriting from normal containers, not from 
_Rb_tree.

>
> If it can't be protected it's OK here you put it, it doesn't need to
> be in __detail.
>
> But maybe we should rename the _Kt parameter of __hash_is_transparent
> to _Unused, _Dummy or something like that. It only exists to make the
> specialization dependent on a template argument of the functions that
> use it.
>

I renamed it into _SfinaeType to make the purpose of this type clearer.

>
>>    * include/bits/stl_tree.h (_Rb_tree<>::__is_transparent<>): Move to
>>    outer scope and rename in ...
>
> "rename to ..."
not "rename into..." :-)
>
>>    (std::__hash_is_transparent<>): ... this.
>
> In <bits/stl_set.h> ...
>
>> @@ -429,12 +477,34 @@
>>       std::pair<const_iterator,const_iterator>
>>       equal_range(const key_type& __x) const
>>       {
>> -    std::pair<_Base_iterator, _Base_iterator> __res =
>> +    std::pair<_Base_const_iterator, _Base_const_iterator> __res =
>>     _Base::equal_range(__x);
>>     return std::make_pair(const_iterator(__res.first, this),
>>                   const_iterator(__res.second, this));
>>       }
>
> Huh! Did calls to this function even compile before this fix?

I had a closer look and yes, it was compiling because for set iterator 
and const_iterator are just the same:

       // DR 103. set::iterator is required to be modifiable,
       // but this allows modification of keys.
       typedef typename _Rep_type::const_iterator iterator;
       typedef typename _Rep_type::const_iterator const_iterator;

However I slightly changed some tests to make sure the const version of 
equal_range and some others are used.

If it is still fine I will commit the attached patch tomorrow.

François

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