[libcxx-commits] [libcxx] [libc++][ranges] Implement LWG4053 and LWG4054 (PR #88612)

[A. Jiang via libcxx-commits]

================
@@ -24,4 +24,7 @@ static_assert(std::same_as<decltype(std::ranges::repeat_view(std::declval<Empty&
 static_assert(std::same_as<decltype(std::ranges::repeat_view(10, 1)), std::ranges::repeat_view<int, int>>);
 static_assert(std::same_as<decltype(std::ranges::repeat_view(10, 1U)), std::ranges::repeat_view<int, unsigned>>);
 static_assert(std::same_as<decltype(std::ranges::repeat_view(10, 1UL)), std::ranges::repeat_view<int, unsigned long>>);
+
+// LWG4053 and LWG4054 "Repeating a repeat_view should repeat the view"
+static_assert(std::same_as<decltype(std::views::repeat(std::views::repeat(1))), std::ranges::repeat_view<std::ranges::repeat_view<int>>>);
----------------
frederick-vs-ja wrote:

IIUC this line is not testing CTAD.

```suggestion
using RPV = std::ranges::repeat_view<const char*>;
static_assert(std::same_as<decltype(std::ranges::repeat_view("foo", std::unreachable_sentinel)), RPV>);  // OK
static_assert(std::same_as<decltype(std::ranges::repeat_view(+"foo", std::unreachable_sentinel)), RPV>); // OK
static_assert(std::same_as<decltype(std::ranges::repeat_view("foo")), RPV>);                             // OK since LWG4053
static_assert(std::same_as<decltype(std::ranges::repeat_view(+"foo")), RPV>);                            // OK
```

https://github.com/llvm/llvm-project/pull/88612