[PATCH] __debug::list use C++11 direct initialization

[Jonathan Wakely]

On 16/10/18 07:06 +0200, François Dumont wrote:
>On 10/15/2018 12:07 PM, Jonathan Wakely wrote:
>>On 09/10/18 07:11 +0200, François Dumont wrote:
>>>Here is the communication for my yesterday's patch which I thought 
>>>svn had failed to commit (I had to interrupt it).
>>>
>>>Similarly to what I've done for associative containers here is a 
>>>cleanup of the std::__debug::list implementation leveraging more 
>>>on C++11 direct initialization.
>>>
>>>I also made sure we use consistent comparison between 
>>>iterator/const_iterator in erase and emplace methods.
>>>
>>>2018-10-08  François Dumont <fdumont@gcc.gnu.org>
>>>
>>>Â Â Â  * include/debug/list (list<>::cbegin()): Use C++11 direct
>>>Â Â Â  initialization.
>>>Â Â Â  (list<>::cend()): Likewise.
>>>Â Â Â  (list<>::emplace<>(const_iterator, _Args&&...)): Likewise.
>>>Â Â Â  (list<>::insert(const_iterator, initializer_list<>)): Likewise.
>>>Â Â Â  (list<>::insert(const_iterator, size_type, const _Tp&)): Likewise.
>>>Â Â Â  (list<>::erase(const_iterator, const_iterator)): Ensure consistent
>>>Â Â Â  iterator comparisons.
>>>Â Â Â  (list<>::splice(const_iterator, list&&, const_iterator,
>>>Â Â Â  const_iterator)): Likewise.
>>>
>>>Tested under Linux x86_64 Debug mode and committed.
>>>
>>>François
>>>
>>
>>>diff --git a/libstdc++-v3/include/debug/list 
>>>b/libstdc++-v3/include/debug/list
>>>index 8add1d596e0..879e1177497 100644
>>>--- a/libstdc++-v3/include/debug/list
>>>+++ b/libstdc++-v3/include/debug/list
>>>@@ -244,11 +244,11 @@ namespace __debug
>>>#if __cplusplus >= 201103L
>>>Â Â Â Â Â  const_iterator
>>>Â Â Â Â Â  cbegin() const noexcept
>>>-Â Â Â Â Â  { return const_iterator(_Base::begin(), this); }
>>>+Â Â Â Â Â  { return { _Base::begin(), this }; }
>>>
>>>Â Â Â Â Â  const_iterator
>>>Â Â Â Â Â  cend() const noexcept
>>>-Â Â Â Â Â  { return const_iterator(_Base::end(), this); }
>>>+Â Â Â Â Â  { return { _Base::end(), this }; }
>>
>>For functions like emplace (which are C++11-only) and for forward_list
>>(also C++11-only) using this syntax makes it clearer.
>>
>>But for these functions it just makes cbegin() and cend() look
>>different to the C++98 begin() and end() functions, for no obvious
>>benefit.
>>
>>Simply using { return end(); } would have been another option.
>>
>Personnaly I hesitated in writting:
>
>{ return { _Base::cbegin(), this }; }
>
>cause I prefer when you see clearly that Debug implem forward calls to 
>the Normal implem.
>
>I thought that using C++11 direct init was more likely to have gcc 
>elide the copy constructor so I used it everywhere possible.

It should make no difference to elision at all.