Add a value_type to ArrayRef.

[courbet]

Summary

Not sure this needs a review or not. Erring on the safe side.

[courbet]

Ping.

[RKSimon]

Please ensure you subscribe all patches to the relevant mailing list - clang should auto subscribe to cfe-commits these days but its better to double check.

[courbet]

Oops, thanks.

[dblaikie]

Test case? (maybe just a static_assert with std::is_same type trait or something in the unit test file)

[courbet]

Add unit test.

[courbet]

Thanks.

llvm/trunk/include/llvm/ADT/ArrayRef.h

namespace llvm {
   /// value.
   template<typename T>
   class LLVM_NODISCARD ArrayRef {
   public:
     using iterator = const T *;
     using const_iterator = const T *;
     using size_type = size_t;
     using reverse_iterator = std::reverse_iterator<iterator>;
+    using value_type = typename std::remove_cv<T>::type;
 
   private:
     /// The start of the array, in an external buffer.
     const T *Data = nullptr;
 
     /// The number of elements.
     size_type Length = 0;
 

llvm/trunk/unittests/ADT/ArrayRefTest.cpp

 static_assert(
     std::is_assignable<ArrayRef<int *>, int * &>::value,
     "Assigning from single lvalue element");
 static_assert(
     !std::is_assignable<ArrayRef<int *>, std::initializer_list<int *>>::value,
     "Assigning from an initializer list");
 #endif
 
+// Check Typedefs.
+static_assert(
+    std::is_same<ArrayRef<int>::value_type, int>::value,
+    "erroneous value_type");
+static_assert(
+    std::is_same<ArrayRef<const int>::value_type, int>::value,
+    "erroneous value_type");
+
 namespace {
 
 TEST(ArrayRefTest, AllocatorCopy) {
   BumpPtrAllocator Alloc;
   static const uint16_t Words1[] = { 1, 4, 200, 37 };
   ArrayRef<uint16_t> Array1 = makeArrayRef(Words1, 4);
   static const uint16_t Words2[] = { 11, 4003, 67, 64000, 13 };
   ArrayRef<uint16_t> Array2 = makeArrayRef(Words2, 5);