[PATCH] 77864 Fix noexcept conditions for map/set default constructors

[François Dumont]

Hi

     I have run all tests with success. Even if it doesn't get rid of 
_GLIBCXX_NOEXCEPT_IF it still limits it to one place.

     So is it ok to commit ?

François


On 12/10/2016 22:36, François Dumont wrote:
> On 10/10/2016 23:01, Tim Song wrote:
>> Trying again...with a few edits.
>>
>>> On Mon, Oct 10, 2016 at 3:24 PM, François Dumont <frs.dumont@gmail.com>
>>> wrote:
>>>
>>> @@ -602,24 +612,32 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>>>           struct _Rb_tree_impl : public _Node_allocator
>>>           {
>>>     _Key_compare _M_key_compare;
>>> -  _Rb_tree_node_base _M_header;
>>> +  _Rb_header_node _M_header;
>>> +#if __cplusplus < 201103L
>>>     size_type _M_node_count; // Keeps track of size of tree.
>>> +#else
>>> +  size_type _M_node_count = 0; // Keeps track of size of tree.
>>> +#endif
>>>
>>> +#if __cplusplus < 201103L
>>>     _Rb_tree_impl()
>>> -  : _Node_allocator(), _M_key_compare(), _M_header(),
>>> -    _M_node_count(0)
>>> -  { _M_initialize(); }
>>> +  : _M_node_count(0)
>>> +  { }
>>> +#else
>>> +  _Rb_tree_impl() = default;
>>> +#endif
>>
>> The default constructor of the associative containers is required to
>> value-initialize the comparator (see their synopses in
>> [map/set/multimap/multiset.overview]).
> I don't have latest Standard version so can't see the exact word but I 
> find quite annoying that the Standard doesn't allow this simple 
> implementation.
>
> I don't know if unodered containers have same kind of requirements for 
> equal or hash functors but if so current implementation doesn't do 
> this value initialization.
>
> So here is another attempt. This time it simply allows to have 
> noexcept condition in one place and closer to where operations are 
> being invoked.
>
> Ok to commit after tests ?
>
> François
>>
>>   _Rb_tree_impl() = default; doesn't do that; it default-initializes the
>>   comparator instead.
>>
>> Tim
>>
>