[clang] [clang] Add test for CWG 2006 and update status (PR #215259)

[Shengxin Pei via cfe-commits]

https://github.com/TPPPP72 created https://github.com/llvm/llvm-project/pull/215259

Clang already supports CWG 2006. Adding test cases and updating `cxx_dr_status.html` to 3.0.

Assisted by Claude.

>From f5c119e24924c8a08f358f16c7c607d956ed5614 Mon Sep 17 00:00:00 2001
From: Shengxin Pei <TPPPP72 at outlook.com>
Date: Mon, 10 Aug 2026 20:29:25 +0800
Subject: [PATCH] [clang] Add test for CWG 2006 and update status

---
 clang/test/CXX/drs/cwg2006.cpp | 100 +++++++++++++++++++++++++++++++++
 clang/www/cxx_dr_status.html   |   2 +-
 2 files changed, 101 insertions(+), 1 deletion(-)
 create mode 100644 clang/test/CXX/drs/cwg2006.cpp

diff --git a/clang/test/CXX/drs/cwg2006.cpp b/clang/test/CXX/drs/cwg2006.cpp
new file mode 100644
index 0000000000000..c2bcd123db190
--- /dev/null
+++ b/clang/test/CXX/drs/cwg2006.cpp
@@ -0,0 +1,100 @@
+// RUN: %clang_cc1 -std=c++98 %s -fexceptions -fcxx-exceptions -pedantic-errors -verify=expected,cxx98
+// RUN: %clang_cc1 -std=c++11 %s -fexceptions -fcxx-exceptions -pedantic-errors -verify=expected,since-cxx11,cxx11
+// RUN: %clang_cc1 -std=c++14 %s -fexceptions -fcxx-exceptions -pedantic-errors -verify=expected,since-cxx11,since-cxx14
+// RUN: %clang_cc1 -std=c++17 %s -fexceptions -fcxx-exceptions -pedantic-errors -verify=expected,since-cxx11,since-cxx14
+// RUN: %clang_cc1 -std=c++20 %s -fexceptions -fcxx-exceptions -pedantic-errors -verify=expected,since-cxx11,since-cxx14,since-cxx20
+// RUN: %clang_cc1 -std=c++23 %s -fexceptions -fcxx-exceptions -pedantic-errors -verify=expected,since-cxx11,since-cxx14,since-cxx20
+// RUN: %clang_cc1 -std=c++2c %s -fexceptions -fcxx-exceptions -pedantic-errors -verify=expected,since-cxx11,since-cxx14,since-cxx20
+// expected-no-diagnostics
+
+namespace std {
+  class type_info;
+}
+
+namespace cwg2006 { // cwg2006: 3.0
+  void test_object_pointer(const void *cp, volatile void *vp, const volatile void *cvp) {
+    (void)static_cast<const void*>(cp);
+    (void)static_cast<volatile void*>(vp);
+    (void)static_cast<const volatile void*>(cvp);
+
+    int x = 0;
+    const int cx = 0;
+    const void *p1 = &x;
+    const void *p2 = &cx;
+    (void)p1;
+    (void)p2;
+  }
+
+  void test_cast(int x) {
+    (const void)x;
+    (volatile void)x;
+    (const volatile void)x;
+  }
+
+  const void get_const_void()
+#if __cplusplus >= 201103L
+    noexcept
+#endif
+  {}
+
+#if __cplusplus >= 202002L
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wdeprecated-volatile"
+#endif
+
+  volatile void get_volatile_void()
+#if __cplusplus >= 201103L
+    noexcept
+#endif
+  {}
+
+  const volatile void get_cv_void()
+#if __cplusplus >= 201103L
+    noexcept
+#endif
+  {}
+
+#if __cplusplus >= 202002L
+#pragma clang diagnostic pop
+#endif
+
+  void test_return() {
+    return get_const_void();
+  }
+
+  void test_return_volatile() {
+    return get_volatile_void();
+  }
+
+  void test_return_cv() {
+    return get_cv_void();
+  }
+
+  void test_conditional(bool b) {
+    b ? get_const_void() : get_const_void();
+    b ? get_volatile_void() : get_const_void();
+    b ? get_cv_void() : get_const_void();
+  }
+
+  void test_typeid() {
+    (void)typeid(const void);
+    (void)typeid(volatile void);
+    (void)typeid(const volatile void);
+  }
+
+#if __cplusplus >= 201103L
+  template <typename T, typename U>
+  struct is_same { static constexpr bool value = false; };
+
+  template <typename T>
+  struct is_same<T, T> { static constexpr bool value = true; };
+
+  void test_cxx11() {
+    decltype(get_const_void()) *p = nullptr;
+    static_assert(noexcept(get_const_void()), "");
+
+    using CommonType = decltype(true ? get_const_void() : get_volatile_void());
+    static_assert(is_same<CommonType, void>::value, "");
+  }
+#endif
+} // namespace cwg2006
diff --git a/clang/www/cxx_dr_status.html b/clang/www/cxx_dr_status.html
index 4d29e6b4b32f4..7d983650a82b8 100755
--- a/clang/www/cxx_dr_status.html
+++ b/clang/www/cxx_dr_status.html
@@ -13831,7 +13831,7 @@ <h2 id="cxxdr">C++ defect report implementation status</h2>
     <td>[<a href="https://wg21.link/basic.compound">basic.compound</a>]</td>
     <td>CD4</td>
     <td>Cv-qualified <TT>void</TT> types</td>
-    <td class="unknown" align="center">Unknown</td>
+    <td class="full" align="center">Clang 3.0</td>
   </tr>
   <tr id="2007">
     <td><a href="https://cplusplus.github.io/CWG/issues/2007.html">2007</a></td>