Peter Collingbourne: If a pointer is passed as the third argument of the (iterator,

iterator, allocator) constructor with the intention of it being
implicitly converted to the allocator type, it is possible for overload
resolution to favour the (iterator, iterator, enable_if) constructor.
Eliminate this possibility by moving the enable_if to one of the
existing arguments and removing the third argument.

llvm-svn: 191145

2 files changed, 26 insertions, 10 deletions

diff --git a/libcxx/include/vector b/libcxx/include/vector
index 258a950dc7d..619faaa5f63 100644
--- a/libcxx/include/vector
+++ b/libcxx/include/vector
@@ -524,12 +524,13 @@ public:
     vector(size_type __n, const_reference __x);
     vector(size_type __n, const_reference __x, const allocator_type& __a);
     template <class _InputIterator>
-        vector(_InputIterator __first, _InputIterator __last,
+        vector(_InputIterator __first,
                typename enable_if<__is_input_iterator  <_InputIterator>::value &&
                                  !__is_forward_iterator<_InputIterator>::value &&
                                  is_constructible<
                                     value_type,
-                                    typename iterator_traits<_InputIterator>::reference>::value>::type* = 0);
+                                    typename iterator_traits<_InputIterator>::reference>::value,
+                                 _InputIterator>::type __last);
     template <class _InputIterator>
         vector(_InputIterator __first, _InputIterator __last, const allocator_type& __a,
                typename enable_if<__is_input_iterator  <_InputIterator>::value &&
@@ -538,11 +539,12 @@ public:
                                     value_type,
                                     typename iterator_traits<_InputIterator>::reference>::value>::type* = 0);
     template <class _ForwardIterator>
-        vector(_ForwardIterator __first, _ForwardIterator __last,
+        vector(_ForwardIterator __first,
                typename enable_if<__is_forward_iterator<_ForwardIterator>::value &&
                                  is_constructible<
                                     value_type,
-                                    typename iterator_traits<_ForwardIterator>::reference>::value>::type* = 0);
+                                    typename iterator_traits<_ForwardIterator>::reference>::value,
+                                 _ForwardIterator>::type __last);
     template <class _ForwardIterator>
         vector(_ForwardIterator __first, _ForwardIterator __last, const allocator_type& __a,
                typename enable_if<__is_forward_iterator<_ForwardIterator>::value &&
@@ -1072,12 +1074,13 @@ vector<_Tp, _Allocator>::vector(size_type __n, const_reference __x, const alloca
 
 template <class _Tp, class _Allocator>
 template <class _InputIterator>
-vector<_Tp, _Allocator>::vector(_InputIterator __first, _InputIterator __last,
+vector<_Tp, _Allocator>::vector(_InputIterator __first,
        typename enable_if<__is_input_iterator  <_InputIterator>::value &&
                          !__is_forward_iterator<_InputIterator>::value &&
                          is_constructible<
                             value_type,
-                            typename iterator_traits<_InputIterator>::reference>::value>::type*)
+                            typename iterator_traits<_InputIterator>::reference>::value,
+                          _InputIterator>::type __last)
 {
 #if _LIBCPP_DEBUG_LEVEL >= 2
     __get_db()->__insert_c(this);
@@ -1105,11 +1108,12 @@ vector<_Tp, _Allocator>::vector(_InputIterator __first, _InputIterator __last, c
 
 template <class _Tp, class _Allocator>
 template <class _ForwardIterator>
-vector<_Tp, _Allocator>::vector(_ForwardIterator __first, _ForwardIterator __last,
+vector<_Tp, _Allocator>::vector(_ForwardIterator __first,
                                 typename enable_if<__is_forward_iterator<_ForwardIterator>::value &&
                                 is_constructible<
                                    value_type,
-                                   typename iterator_traits<_ForwardIterator>::reference>::value>::type*)
+                                   typename iterator_traits<_ForwardIterator>::reference>::value,
+                                                   _ForwardIterator>::type __last)
 {
 #if _LIBCPP_DEBUG_LEVEL >= 2
     __get_db()->__insert_c(this);
diff --git a/libcxx/test/containers/sequences/vector/vector.cons/construct_iter_iter_alloc.pass.cpp b/libcxx/test/containers/sequences/vector/vector.cons/construct_iter_iter_alloc.pass.cpp
index e386297cf7a..afc8ea5d3d2 100644
--- a/libcxx/test/containers/sequences/vector/vector.cons/construct_iter_iter_alloc.pass.cpp
+++ b/libcxx/test/containers/sequences/vector/vector.cons/construct_iter_iter_alloc.pass.cpp
@@ -19,9 +19,9 @@
 #include "../../../stack_allocator.h"
 #include "../../../min_allocator.h"
 
-template <class C, class Iterator>
+template <class C, class Iterator, class A>
 void
-test(Iterator first, Iterator last, const typename C::allocator_type& a)
+test(Iterator first, Iterator last, const A& a)
 {
     C c(first, last, a);
     assert(c.__invariants());
@@ -30,6 +30,17 @@ test(Iterator first, Iterator last, const typename C::allocator_type& a)
         assert(*i == *first);
 }
 
+#if __cplusplus >= 201103L
+
+template <class T>
+struct implicit_conv_allocator : min_allocator<T>
+{
+    implicit_conv_allocator(void* p) {}
+    implicit_conv_allocator(const implicit_conv_allocator&) = default;
+};
+
+#endif
+
 int main()
 {
     {
@@ -52,6 +63,7 @@ int main()
     test<std::vector<int, min_allocator<int>> >(bidirectional_iterator<const int*>(a), bidirectional_iterator<const int*>(an), alloc);
     test<std::vector<int, min_allocator<int>> >(random_access_iterator<const int*>(a), random_access_iterator<const int*>(an), alloc);
     test<std::vector<int, min_allocator<int>> >(a, an, alloc);
+    test<std::vector<int, implicit_conv_allocator<int>> >(a, an, nullptr);
     }
 #endif
 }