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


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>

    * include/debug/list (list<>::cbegin()): Use C++11 direct
    initialization.
    (list<>::cend()): Likewise.
    (list<>::emplace<>(const_iterator, _Args&&...)): Likewise.
    (list<>::insert(const_iterator, initializer_list<>)): Likewise.
    (list<>::insert(const_iterator, size_type, const _Tp&)): Likewise.
    (list<>::erase(const_iterator, const_iterator)): Ensure consistent
    iterator comparisons.
    (list<>::splice(const_iterator, list&&, const_iterator,
    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!


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