[llvm] r278157 - [ADT] Change iterator_adaptor_base's default template arguments to forward more underlying typedefs

[Tim Shen via llvm-commits]

Author: timshen
Date: Tue Aug  9 15:23:13 2016
New Revision: 278157

URL: http://llvm.org/viewvc/llvm-project?rev=278157&view=rev
Log:
[ADT] Change iterator_adaptor_base's default template arguments to forward more underlying typedefs

Reviewers: chandlerc

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D23217

Modified:
    llvm/trunk/include/llvm/ADT/iterator.h
    llvm/trunk/unittests/Support/IteratorTest.cpp

Modified: llvm/trunk/include/llvm/ADT/iterator.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/ADT/iterator.h?rev=278157&r1=278156&r2=278157&view=diff
==============================================================================
--- llvm/trunk/include/llvm/ADT/iterator.h (original)
+++ llvm/trunk/include/llvm/ADT/iterator.h Tue Aug  9 15:23:13 2016
@@ -155,7 +155,14 @@ template <
     typename T = typename std::iterator_traits<WrappedIteratorT>::value_type,
     typename DifferenceTypeT =
         typename std::iterator_traits<WrappedIteratorT>::difference_type,
-    typename PointerT = T *, typename ReferenceT = T &,
+    typename PointerT = typename std::conditional<
+        std::is_same<T, typename std::iterator_traits<
+                            WrappedIteratorT>::value_type>::value,
+        typename std::iterator_traits<WrappedIteratorT>::pointer, T *>::type,
+    typename ReferenceT = typename std::conditional<
+        std::is_same<T, typename std::iterator_traits<
+                            WrappedIteratorT>::value_type>::value,
+        typename std::iterator_traits<WrappedIteratorT>::reference, T &>::type,
     // Don't provide these, they are mostly to act as aliases below.
     typename WrappedTraitsT = std::iterator_traits<WrappedIteratorT>>
 class iterator_adaptor_base

Modified: llvm/trunk/unittests/Support/IteratorTest.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/unittests/Support/IteratorTest.cpp?rev=278157&r1=278156&r2=278157&view=diff
==============================================================================
--- llvm/trunk/unittests/Support/IteratorTest.cpp (original)
+++ llvm/trunk/unittests/Support/IteratorTest.cpp Tue Aug  9 15:23:13 2016
@@ -16,6 +16,24 @@ using namespace llvm;
 
 namespace {
 
+template <int> struct Shadow;
+
+struct WeirdIter : std::iterator<std::input_iterator_tag, Shadow<0>, Shadow<1>,
+                                 Shadow<2>, Shadow<3>> {};
+
+struct AdaptedIter : iterator_adaptor_base<AdaptedIter, WeirdIter> {};
+
+// Test that iterator_adaptor_base forwards typedefs, if value_type is
+// unchanged.
+static_assert(std::is_same<typename AdaptedIter::value_type, Shadow<0>>::value,
+              "");
+static_assert(
+    std::is_same<typename AdaptedIter::difference_type, Shadow<1>>::value, "");
+static_assert(std::is_same<typename AdaptedIter::pointer, Shadow<2>>::value,
+              "");
+static_assert(std::is_same<typename AdaptedIter::reference, Shadow<3>>::value,
+              "");
+
 TEST(PointeeIteratorTest, Basic) {
   int arr[4] = { 1, 2, 3, 4 };
   SmallVector<int *, 4> V;