Reverting an old optimization that conflicts with the new allocator model, and causes some test casees to compile that shouldn't.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@122830 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/vector b/include/vector
index 9b9f2e8..7c0fc70 100644
--- a/include/vector
+++ b/include/vector
@@ -624,14 +624,8 @@
     void allocate(size_type __n);
     void deallocate();
     _LIBCPP_INLINE_VISIBILITY size_type __recommend(size_type __new_size) const;
-    _LIBCPP_INLINE_VISIBILITY void __construct_at_end(size_type __n);
-        void __construct_at_end(size_type __n, false_type);
-    _LIBCPP_INLINE_VISIBILITY void __construct_at_end(size_type __n, true_type);
-    _LIBCPP_INLINE_VISIBILITY
+    void __construct_at_end(size_type __n);
     void __construct_at_end(size_type __n, const_reference __x);
-    void __construct_at_end(size_type __n, const_reference __x, false_type);
-    _LIBCPP_INLINE_VISIBILITY
-        void __construct_at_end(size_type __n, const_reference __x, true_type);
     template <class _ForwardIterator>
         typename enable_if
         <
@@ -741,17 +735,9 @@
 //  Precondition:  size() + __n <= capacity()
 //  Postcondition:  size() == size() + __n
 template <class _Tp, class _Allocator>
-_LIBCPP_INLINE_VISIBILITY inline
 void
 vector<_Tp, _Allocator>::__construct_at_end(size_type __n)
 {
-    __construct_at_end(__n, __is_zero_default_constructible<value_type>());
-}
-
-template <class _Tp, class _Allocator>
-void
-vector<_Tp, _Allocator>::__construct_at_end(size_type __n, false_type)
-{
     allocator_type& __a = this->__alloc();
     do
     {
@@ -761,15 +747,6 @@
     } while (__n > 0);
 }
 
-template <class _Tp, class _Allocator>
-_LIBCPP_INLINE_VISIBILITY inline
-void
-vector<_Tp, _Allocator>::__construct_at_end(size_type __n, true_type)
-{
-    _STD::memset(this->__end_, 0, __n*sizeof(value_type));
-    this->__end_ += __n;
-}
-
 //  Copy constructs __n objects starting at __end_ from __x
 //  throws if construction throws
 //  Precondition:  __n > 0
@@ -781,14 +758,6 @@
 void
 vector<_Tp, _Allocator>::__construct_at_end(size_type __n, const_reference __x)
 {
-    __construct_at_end(__n, __x, integral_constant<bool, is_trivially_copy_constructible<value_type>::value &&
-                                                         is_trivially_copy_assignable<value_type>::value>());
-}
-
-template <class _Tp, class _Allocator>
-void
-vector<_Tp, _Allocator>::__construct_at_end(size_type __n, const_reference __x, false_type)
-{
     allocator_type& __a = this->__alloc();
     do
     {
@@ -799,15 +768,6 @@
 }
 
 template <class _Tp, class _Allocator>
-_LIBCPP_INLINE_VISIBILITY inline
-void
-vector<_Tp, _Allocator>::__construct_at_end(size_type __n, const_reference __x, true_type)
-{
-    _STD::fill_n(this->__end_, __n, __x);
-    this->__end_ += __n;
-}
-
-template <class _Tp, class _Allocator>
 template <class _ForwardIterator>
 typename enable_if
 <
@@ -2765,10 +2725,6 @@
 };
 
 template <class _Tp, class _Allocator>
-struct __is_zero_default_constructible<vector<_Tp, _Allocator> >
-    : public integral_constant<bool, __is_zero_default_constructible<_Allocator>::value> {};
-
-template <class _Tp, class _Allocator>
 _LIBCPP_INLINE_VISIBILITY inline
 bool
 operator==(const vector<_Tp, _Allocator>& __x, const vector<_Tp, _Allocator>& __y)