Implementation Feature Test Macros for P0722R3

Summary:
P1353R0, adopted in San Diego, specified an implementation feature test macro for destroying delete (P0722R3).

The implementation of the feature (https://reviews.llvm.org/rL315662) is not guarded behind a flag, so the macro is not conditional on language version.

Reviewers: rsmith

Reviewed By: rsmith

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D55741

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@350934 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Frontend/InitPreprocessor.cpp

@@ -543,6 +543,7 @@ static void InitializeCPlusPlusFeatureTestMacros(const LangOptions &LangOpts,
   // C++20 features.
   if (LangOpts.Char8)
     Builder.defineMacro("__cpp_char8_t", "201811L");
+  Builder.defineMacro("__cpp_impl_destroying_delete", "201806L");
 
   // TS features.
   if (LangOpts.ConceptsTS)

test/Lexer/cxx-features.cpp

@@ -34,6 +34,10 @@
 #error "wrong value for __cpp_char8_t"
 #endif
 
+#if check(impl_destroying_delete, 201806, 201806, 201806, 201806, 201806)
+#error "wrong value for __cpp_impl_destroying_delete"
+#endif
+
 // --- C++17 features ---
 
 #if check(hex_float, 0, 0, 0, 201603, 201603)

www/cxx_status.html

@@ -1054,9 +1054,9 @@ <h2 id="ts">Technical specifications and standing documents</h2>
     <th>Available in Clang?</th>
  </tr>
     <tr id="sd6">
-      <td rowspan="5">SD-6: SG10 feature test recommendations</td>
-      <td rowspan="5"><a href="http://isocpp.org/std/standing-documents/sd-6-sg10-feature-test-recommendations">SD-6</a></td>
-      <td rowspan="5">N/A</td>
+      <td rowspan="6">SD-6: SG10 feature test recommendations</td>
+      <td rowspan="6"><a href="http://isocpp.org/std/standing-documents/sd-6-sg10-feature-test-recommendations">SD-6</a></td>
+      <td rowspan="6">N/A</td>
       <td class="full" align="center">
         Clang 3.4 (<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3745">N3745</a>)</br>
       </td>
@@ -1081,6 +1081,11 @@ <h2 id="ts">Technical specifications and standing documents</h2>
         Clang 7 (<a href="http://wg21.link/p0096r5">P0096R5</a>)</a>
       </td>
     </tr>
+    <tr>
+      <td class="partial" align="center">
+        WIP (<a href="http://wg21.link/p1353r0">P1353R0</a>)
+      </td>
+    </tr>
     <!-- FIXME: Implement latest recommendations.
     <tr>
       <td class="svn" align="center">