Addressed comments

Author: Zingam

libcxx/test/std/containers/views/views.span/span.cons/initializer_list.pass.cpp

@@ -5,12 +5,14 @@
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
+
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 
 // <span>
 
 // constexpr explicit(extent != dynamic_extent) span(std::initializer_list<value_type> il); // Since C++26
 
+#include <any>
 #include <cassert>
 #include <cstddef>
 #include <initializer_list>
@@ -89,9 +91,48 @@ constexpr bool test() {
   return true;
 }
 
+// Test P2447R4 "Annex C examples"
+
+constexpr int three(std::span<void* const> sp) { return sp.size(); }
+
+constexpr int four(std::span<const std::any> sp) { return sp.size(); }
+
+bool test_P2447R4_annex_c_examples() {
+  // 1. Overload resolution is affected
+  // --> tested in "initializer_list.verify.cpp"
+
+  // 2. The `initializer_list` ctor has high precedence
+  // --> tested in "initializer_list.verify.cpp"
+
+  // 3. Implicit two-argument construction with a highly convertible value_type
+#if TEST_STD_VER >= 26
+  {
+    void* a[10];
+    assert(three({a, 0}) == 2);
+  }
+  {
+    std::any a[10];
+    assert(four({a, a + 10}) == 2);
+  }
+#else
+  {
+    void* a[10];
+    assert(three({a, 0}) == 0);
+  }
+  {
+    std::any a[10];
+    assert(four({a, a + 10}) == 10);
+  }
+#endif
+
+  return true;
+}
+
 int main(int, char**) {
-  test();
+  assert(test());
   static_assert(test());
 
+  assert(test_P2447R4_annex_c_examples());
+
   return 0;
 }

libcxx/test/std/containers/views/views.span/span.cons/initializer_list.verify.cpp

@@ -0,0 +1,48 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// <span>
+
+// constexpr explicit(extent != dynamic_extent) span(std::initializer_list<value_type> il); // Since C++26
+
+#include <span>
+#include <utility>
+
+#include "test_macros.h"
+
+// Test P2447R4 "Annex C examples"
+
+void one(std::pair<int, int>);
+void one(std::span<const int>);
+
+void two(std::span<const int, 2>);
+
+void test_P2447R4_annex_c_examples() {
+  // 1. Overload resolution is affected
+#if TEST_STD_VER >= 26
+  // expected-error@+1 {{call to 'one' is ambiguous}}
+  one({1, 2});
+#else
+  // expected-no-diagnostics
+  one({1, 2});
+#endif
+
+// 2. The `initializer_list` ctor has high precedence
+#if TEST_STD_VER >= 26
+  // expected-error@+1 {{chosen constructor is explicit in copy-initialization}}
+  two({{1, 2}});
+#else
+  // expected-no-diagnostics
+  two({{1, 2}});
+#endif
+
+  // 3. Implicit two-argument construction with a highly convertible value_type
+  // --> tested in "initializer_list.pass.cpp"
+}