[libcxx-commits] [libcxx] [llvm] [libc++] Implement P1885R12: `<text_encoding>` (PR #141312)

[A. Jiang via libcxx-commits]

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@@ -0,0 +1,73 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++26
+
+// <text_encoding>
+
+// text_encoding::text_encoding(std::text_encoding::id) noexcept
+
+#include <algorithm>
+#include <cassert>
+#include <concepts>
+#include <ranges>
+#include <text_encoding>
+#include <type_traits>
+
+#include "../test_text_encoding.h"
+
+using id = std::text_encoding::id;
+
+constexpr bool test() {
+  {
+    // 2. Constructing an object with a valid id must set mib() and the name to the corresponding value.
+    for (auto pair : unique_encoding_data) {
+      std::same_as<std::text_encoding> decltype(auto) te = std::text_encoding(id(pair.mib));
+
+      assert(te.mib() == id(pair.mib));
+      assert(pair.name == te.name());
+      assert(std::ranges::contains(te.aliases(), pair.name));
+    }
+  }
+
+  {
+    // 3. Constructing an object using id::unknown or id::other must set mib() to id::unknown or id::other, respectively, and the name to an empty string.
+    {
+      std::text_encoding te = std::text_encoding(id::other);
+
+      assert(te.mib() == id::other);
+      assert(std::string_view("") == te.name());
+      assert(std::ranges::empty(te.aliases()));
+    }
+
+    {
+      std::text_encoding te = std::text_encoding(id::unknown);
+
+      assert(te.mib() == id::unknown);
+      assert(std::string_view("") == te.name());
+      assert(std::ranges::empty(te.aliases()));
+    }
+  }
+
+  return true;
+}
+
+int main(int, char**) {
+  {
+    // 1. text_encoding(id) must be nothrow
+    static_assert(std::is_nothrow_constructible<std::text_encoding, std::text_encoding::id>::value,
+                  "Must be nothrow constructible with id");
+  }
+
+  {
+    test();
+    static_assert(test());
+  }
----------------
frederick-vs-ja wrote:

```suggestion
  // text_encoding(id) must be nothrow
  static_assert(std::is_nothrow_constructible_v<std::text_encoding, std::text_encoding::id>,
                "Must be nothrow constructible with id");

  test();
  static_assert(test());
```

https://github.com/llvm/llvm-project/pull/141312