Restrict the 1-argument ArrayView constructor to types with .size() and .data()

webrtc/base/array_view_unittest.cc

Index: webrtc/base/array_view_unittest.cc
diff --git a/webrtc/base/array_view_unittest.cc b/webrtc/base/array_view_unittest.cc
index 8bb1bcc4c6ce259a8d1c61c2d3618bc2594f35e5..ac46153bd022015e6946702d128197bf01c91d50 100644
--- a/webrtc/base/array_view_unittest.cc
+++ b/webrtc/base/array_view_unittest.cc
@@ -20,8 +20,45 @@
 namespace rtc {
 
 namespace {
+
+namespace test_has_data_and_size {
+
+template <typename C, typename T>
+using DS = internal::HasDataAndSize<C, T>;
+
+template <typename DR, typename SR>
+struct Test1 {
+  DR data();
+  SR size();
+};
+static_assert(DS<Test1<int*, int>, int>::value, "");
+static_assert(DS<Test1<int*, int>, const int>::value, "");
+static_assert(DS<Test1<const int*, int>, const int>::value, "");
+static_assert(!DS<Test1<const int*, int>, int>::value, "");
+static_assert(!DS<Test1<char*, size_t>, int>::value, "");
+
+struct Test2 {
+  int* data;
+  size_t size;
+};
+static_assert(!DS<Test2, int>::value, "");
+
+struct Test3 {
+  int* data();
+};
+static_assert(!DS<Test3, int>::value, "");
+
+class Test4 {
+  int* data();
+  size_t size();
+};
+static_assert(!DS<Test3, int>::value, "");

[ossu, 2016/09/05 09:32:27]

Surely, this should be DS<Test4, int>::value!

[kwiberg-webrtc, 2016/09/05 09:40:18]

Yes...

[ossu, 2016/09/05 09:50:44]

Ah, so it's supposed to be false because data and size are private? Right. It's
a bit unclear that that's what's going on. I expected it to be true. Maybe just
highlight the intent with a comment. Explicitly putting private: in the class
could also work, but since it's not practically needed, it might look weird as
well.

[kwiberg-webrtc, 2016/09/05 10:11:16]

Added comments.

+
+}  // namespace test_has_data_and_size
+
 template <typename T>
 void Call(ArrayView<T>) {}
+
 }  // namespace
 
 TEST(ArrayViewTest, TestConstructFromPtrAndArray) {