[PATCH] D34649: Remove addtional parameters in function std::next() and std::prev()

[Jason Liu via Phabricator via cfe-commits]

jasonliu created this revision.

Creating a function pointer with proper parameters pointing to std::next() or std::prev() should work.
This change moves the invented paramater for enable_if over to the return type to resolve this QoI issue.


https://reviews.llvm.org/D34649

Files:
  include/iterator
  test/std/iterators/iterator.primitives/iterator.operations/next.pass.cpp
  test/std/iterators/iterator.primitives/iterator.operations/prev.pass.cpp


Index: test/std/iterators/iterator.primitives/iterator.operations/prev.pass.cpp
===================================================================
--- test/std/iterators/iterator.primitives/iterator.operations/prev.pass.cpp
+++ test/std/iterators/iterator.primitives/iterator.operations/prev.pass.cpp
@@ -22,6 +22,9 @@
 test(It i, typename std::iterator_traits<It>::difference_type n, It x)
 {
     assert(std::prev(i, n) == x);
+
+    It (*prev)(It, typename std::iterator_traits<It>::difference_type) = std::prev;
+    assert(prev(i, n) == x);
 }
 
 template <class It>
Index: test/std/iterators/iterator.primitives/iterator.operations/next.pass.cpp
===================================================================
--- test/std/iterators/iterator.primitives/iterator.operations/next.pass.cpp
+++ test/std/iterators/iterator.primitives/iterator.operations/next.pass.cpp
@@ -24,6 +24,9 @@
 test(It i, typename std::iterator_traits<It>::difference_type n, It x)
 {
     assert(std::next(i, n) == x);
+
+    It (*next)(It, typename std::iterator_traits<It>::difference_type) = std::next;
+    assert(next(i, n) == x);
 }
 
 template <class It>
Index: include/iterator
===================================================================
--- include/iterator
+++ include/iterator
@@ -604,21 +604,27 @@
 
 template <class _InputIter>
 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
-_InputIter
+typename enable_if
+<
+    __is_input_iterator<_InputIter>::value, 
+    _InputIter
+>::type
 next(_InputIter __x,
-     typename iterator_traits<_InputIter>::difference_type __n = 1,
-     typename enable_if<__is_input_iterator<_InputIter>::value>::type* = 0)
+     typename iterator_traits<_InputIter>::difference_type __n = 1)
 {
     _VSTD::advance(__x, __n);
     return __x;
 }
 
 template <class _BidiretionalIter>
 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
-_BidiretionalIter
+typename enable_if
+<
+    __is_bidirectional_iterator<_BidiretionalIter>::value, 
+    _BidiretionalIter
+>::type
 prev(_BidiretionalIter __x,
-     typename iterator_traits<_BidiretionalIter>::difference_type __n = 1,
-     typename enable_if<__is_bidirectional_iterator<_BidiretionalIter>::value>::type* = 0)
+     typename iterator_traits<_BidiretionalIter>::difference_type __n = 1)
 {
     _VSTD::advance(__x, -__n);
     return __x;


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