ADT: Remove references in has_rbegin for reverse()

As a follow-up to r278991, add some tests that check that
decltype(reverse(R).begin()) == decltype(R.rbegin()), and get them
passing by adding std::remove_reference to has_rbegin.

I'm using static_assert instead of EXPECT_TRUE (and updated the other
has_rbegin check from r278991 in the same way) since I figure that's
more helpful.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@279084 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 62 insertions, 4 deletions

diff --git a/unittests/ADT/RangeAdapterTest.cpp b/unittests/ADT/RangeAdapterTest.cpp
index 2b12fe47173..d1a357190fc 100644
--- a/unittests/ADT/RangeAdapterTest.cpp
+++ b/unittests/ADT/RangeAdapterTest.cpp
@@ -75,6 +75,50 @@ public:
   const_reverse_iterator rend() const { return Vec.rend(); }
 };
 
+/// Check that types with custom iterators work.
+class CustomIteratorVector {
+  mutable std::vector<int> V;
+
+public:
+  CustomIteratorVector(std::initializer_list<int> list) : V(list) {}
+
+  typedef std::vector<int>::iterator iterator;
+  class reverse_iterator {
+    std::vector<int>::iterator I;
+
+  public:
+    reverse_iterator() = default;
+    reverse_iterator(const reverse_iterator &) = default;
+    reverse_iterator &operator=(const reverse_iterator &) = default;
+
+    explicit reverse_iterator(std::vector<int>::iterator I) : I(I) {}
+
+    reverse_iterator &operator++() {
+      --I;
+      return *this;
+    }
+    reverse_iterator &operator--() {
+      ++I;
+      return *this;
+    }
+    int &operator*() const { return *std::prev(I); }
+    int *operator->() const { return &*std::prev(I); }
+    friend bool operator==(const reverse_iterator &L,
+                           const reverse_iterator &R) {
+      return L.I == R.I;
+    }
+    friend bool operator!=(const reverse_iterator &L,
+                           const reverse_iterator &R) {
+      return !(L == R);
+    }
+  };
+
+  iterator begin() const { return V.begin(); }
+  iterator end()  const { return V.end(); }
+  reverse_iterator rbegin() const { return reverse_iterator(V.end()); }
+  reverse_iterator rend() const { return reverse_iterator(V.begin()); }
+};
+
 template <typename R> void TestRev(const R &r) {
   int counter = 3;
   for (int i : r)
@@ -98,9 +142,10 @@ TYPED_TEST(RangeAdapterLValueTest, TrivialOperation) {
 
 template <typename T> struct RangeAdapterRValueTest : testing::Test {};
 
-typedef ::testing::Types<std::vector<int>, std::list<int>, ReverseOnlyVector,
-                         BidirectionalVector,
-                         BidirectionalVectorConsts> RangeAdapterRValueTestTypes;
+typedef ::testing::Types<std::vector<int>, std::list<int>, CustomIteratorVector,
+                         ReverseOnlyVector, BidirectionalVector,
+                         BidirectionalVectorConsts>
+    RangeAdapterRValueTestTypes;
 TYPED_TEST_CASE(RangeAdapterRValueTest, RangeAdapterRValueTestTypes);
 
 TYPED_TEST(RangeAdapterRValueTest, TrivialOperation) {
@@ -108,7 +153,20 @@ TYPED_TEST(RangeAdapterRValueTest, TrivialOperation) {
 }
 
 TYPED_TEST(RangeAdapterRValueTest, HasRbegin) {
-  EXPECT_TRUE(has_rbegin<TypeParam>::value);
+  static_assert(has_rbegin<TypeParam>::value, "rbegin() should be defined");
+}
+
+TYPED_TEST(RangeAdapterRValueTest, RangeType) {
+  static_assert(
+      std::is_same<
+          decltype(reverse(*static_cast<TypeParam *>(nullptr)).begin()),
+          decltype(static_cast<TypeParam *>(nullptr)->rbegin())>::value,
+      "reverse().begin() should have the same type as rbegin()");
+  static_assert(
+      std::is_same<
+          decltype(reverse(*static_cast<const TypeParam *>(nullptr)).begin()),
+          decltype(static_cast<const TypeParam *>(nullptr)->rbegin())>::value,
+      "reverse().begin() should have the same type as rbegin() [const]");
 }
 
 } // anonymous namespace