From 8cef7fd75ac3cbeb8efb767e5ba2dcdb76bf4454 Mon Sep 17 00:00:00 2001
From: Eric Fiselier <eric@efcs.ca>
Date: Tue, 5 Jun 2018 22:32:52 +0000
Subject: Fix PR37694 - std::vector doesn't correctly move construct
 allocators.

C++2a[container.requirements.general]p8 states that when move constructing
a container, the allocator is move constructed. Vector previously copy
constructed these allocators. This patch fixes that bug.

Additionally it cleans up some unnecessary allocator conversions
when copy constructing containers. Libc++ uses
__internal_allocator_traits::select_on_copy_construction to select
the correct allocator during copy construction, but it unnecessarily
converted the resulting allocator to the user specified allocator
type and back. After this patch list and forward_list no longer
do that.

Technically we're supposed to be using allocator_traits<allocator_type>::select_on_copy_construction,
but that should seemingly be addressed as a separate patch, if at all.

llvm-svn: 334053
---
 libcxx/include/vector | 22 ++++++++++++++++------
 1 file changed, 16 insertions(+), 6 deletions(-)

(limited to 'libcxx/include/vector')

diff --git a/libcxx/include/vector b/libcxx/include/vector
index 9e399bdd1f4..74c423ef224 100644
--- a/libcxx/include/vector
+++ b/libcxx/include/vector
@@ -355,6 +355,9 @@ protected:
     __vector_base()
         _NOEXCEPT_(is_nothrow_default_constructible<allocator_type>::value);
     _LIBCPP_INLINE_VISIBILITY __vector_base(const allocator_type& __a);
+#ifndef _LIBCPP_CXX03_LANG
+    _LIBCPP_INLINE_VISIBILITY __vector_base(allocator_type&& __a) _NOEXCEPT;
+#endif
     ~__vector_base();
 
     _LIBCPP_INLINE_VISIBILITY
@@ -438,6 +441,15 @@ __vector_base<_Tp, _Allocator>::__vector_base(const allocator_type& __a)
 {
 }
 
+#ifndef _LIBCPP_CXX03_LANG
+template <class _Tp, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+__vector_base<_Tp, _Allocator>::__vector_base(allocator_type&& __a) _NOEXCEPT
+    : __begin_(nullptr),
+      __end_(nullptr),
+      __end_cap_(nullptr, std::move(__a)) {}
+#endif
+
 template <class _Tp, class _Allocator>
 __vector_base<_Tp, _Allocator>::~__vector_base()
 {
@@ -2863,17 +2875,15 @@ vector<bool, _Allocator>::operator=(const vector& __v)
 #ifndef _LIBCPP_CXX03_LANG
 
 template <class _Allocator>
-inline _LIBCPP_INLINE_VISIBILITY
-vector<bool, _Allocator>::vector(vector&& __v)
+inline _LIBCPP_INLINE_VISIBILITY vector<bool, _Allocator>::vector(vector&& __v)
 #if _LIBCPP_STD_VER > 14
-        _NOEXCEPT
+    _NOEXCEPT
 #else
-        _NOEXCEPT_(is_nothrow_move_constructible<allocator_type>::value)
+    _NOEXCEPT_(is_nothrow_move_constructible<allocator_type>::value)
 #endif
     : __begin_(__v.__begin_),
       __size_(__v.__size_),
-      __cap_alloc_(__v.__cap_alloc_)
-{
+      __cap_alloc_(std::move(__v.__cap_alloc_)) {
     __v.__begin_ = nullptr;
     __v.__size_ = 0;
     __v.__cap() = 0;
-- 
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