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

[Jonathan Wakely]

On 17/10/18 17:03 +0100, 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
>>@@ -521,15 +521,17 @@ namespace __debug
>>	// _GLIBCXX_RESOLVE_LIB_DEFECTS
>>	// 151. can't currently clear() empty container
>>	__glibcxx_check_erase_range(__first, __last);
>>-	for (_Base_const_iterator __victim = __first.base();
>>+	for (__decltype(__first.base()) __victim = __first.base();
>
>This change causes the regression.
>
>I think the problem is that the decltype is a reference, so every time
>the loop does ++__victim it changes the iterator stored in __first.


This would work:

        typedef typename __decltype(__first)::iterator_type _Base_iter;
	for (_Base_iter __victim = __first.base();
	     __victim != __last.base(); ++__victim)


Or simply:

#if __cplusplus >= 201103L
        typedef _Base_const_iterator _Base_iter;
#else
        typedef _Base_iterator _Base_iter;
#endif
	for (_Base_iter __victim = __first.base();
	     __victim != __last.base(); ++__victim)


Or just restore the original code which worked fine!