[C++20] Claim full support for consteval again

After resolving several outstanding issues now is the time to mark it as
fully supported.

Fixes https://github.com/llvm/llvm-project/issues/57094

Reviewed By: aaron.ballman, cor3ntin, #clang-language-wg

Differential Revision: https://reviews.llvm.org/D147717

clang/docs/ReleaseNotes.rst

@@ -111,6 +111,7 @@ C++20 Feature Support
   SFINAE.
 - Clang now supports `requires cplusplus20` for module maps.
 - Implemented missing parts of `P2002R1: Consistent comparison operators <https://wg21.link/P2002R1>`_
+- Clang now defines `__cpp_consteval` macro.
 
 C++23 Feature Support
 ^^^^^^^^^^^^^^^^^^^^^

clang/lib/Frontend/InitPreprocessor.cpp

@@ -683,7 +683,7 @@ static void InitializeCPlusPlusFeatureTestMacros(const LangOptions &LangOpts,
     // Refer to the discussion of this at https://reviews.llvm.org/D128619.
     Builder.defineMacro("__cpp_concepts", "201907L");
     Builder.defineMacro("__cpp_conditional_explicit", "201806L");
-    // Builder.defineMacro("__cpp_consteval", "202211L");
+    Builder.defineMacro("__cpp_consteval", "202211L");
     Builder.defineMacro("__cpp_constexpr_dynamic_alloc", "201907L");
     Builder.defineMacro("__cpp_constinit", "201907L");
     Builder.defineMacro("__cpp_impl_coroutine", "201902L");

clang/test/Lexer/cxx-features.cpp

@@ -78,8 +78,7 @@
 #error "wrong value for __cpp_conditional_explicit"
 #endif
 
-#if check(consteval, 0, 0, 0, 0, 0, 0)
-// FIXME: 201811 in C++20
+#if check(consteval, 0, 0, 0, 0, 202211, 202211)
 #error "wrong value for __cpp_consteval"
 #endif
 

clang/www/cxx_status.html

@@ -643,14 +643,7 @@ C++23, informally referred to as C++26.</p>
     <tr>
       <td rowspan=2>Immediate functions (<tt>consteval</tt>)</td>
       <td><a href="https://wg21.link/p1073r3">P1073R3</a></td>
-      <td class="partial" align="center">
-        <details><summary>Clang 15 (Partial)</summary>
-          Clang still incorrectly defers some consteval executions to runtime,
-          resulting in CodeGen crashes. Additionally, Clang does not properly
-          handle default arguments in consteval functions under all
-          circumstances.
-        </details>
-      </td>
+      <td class="full" align="center">Clang 17</td>
     </tr>
       <tr> <!-- from Prague -->
         <td><a href="https://wg21.link/p1937r2">P1937R2</a></td>