[clang] [clang-tools-extra] [libcxx] [llvm] [libc++][ranges] P2542R8: Implement `views::concat` (PR #120920)

[A. Jiang via llvm-commits]

================
@@ -0,0 +1,70 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20, c++23
----------------
frederick-vs-ja wrote:

```suggestion
// REQUIRES: std-at-least-c++26
```

Ditto for all repetitions.

https://github.com/llvm/llvm-project/pull/120920