[PATCH] D23217: [ADT] Change iterator_adaptor_base's default template arguments to forward more underlying typedefs

[Tim Shen via llvm-commits]

timshen updated this revision to Diff 67402.
timshen added a comment.

Moved the compile-time test to the outer anonymous namespace.


https://reviews.llvm.org/D23217

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

Index: unittests/Support/IteratorTest.cpp
===================================================================
--- unittests/Support/IteratorTest.cpp
+++ unittests/Support/IteratorTest.cpp
@@ -16,6 +16,24 @@
 
 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;
Index: include/llvm/ADT/iterator.h
===================================================================
--- include/llvm/ADT/iterator.h
+++ include/llvm/ADT/iterator.h
@@ -155,7 +155,14 @@
     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


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