[Sema] Implement Core 2094: Trivial copy/move constructor for class with volatile member

[EricWF]

Summary

This patch implements http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#2094 which reverts Core 496.

[EricWF]

• Use sup instead of reverted by to match style of other DRs.

[rsmith]

test/CXX/drs/dr4xx.cpp

1205

Write this as "dr496: sup 2094" and then rerun the make_cxx_dr_status script in www/ to regenerate cxx_dr_status.html

1209–1210

2095 -> 2094? Also, why FIXME?

[EricWF]

• Fix incorrect issue number.
• Regenerate issue list.

[rsmith]

Please first check in a change that just regenerates cxx_dr_status without your changes, to separate out the changes due to the new issues list from the changes due to this patch. (You can go ahead and do that with no review.)

[EricWF]

• Remove unrelated issues list changes.

lib/AST/Type.cpp

 
 bool QualType::isTriviallyCopyableType(const ASTContext &Context) const {
   if ((*this)->isArrayType())
     return Context.getBaseElementType(*this).isTriviallyCopyableType(Context);
 
   if (hasNonTrivialObjCLifetime())
     return false;
 
-  // C++11 [basic.types]p9
+  // C++11 [basic.types]p9 - See Core 2094
   //   Scalar types, trivially copyable class types, arrays of such types, and
-  //   non-volatile const-qualified versions of these types are collectively
+  //   cv-qualified versions of these types are collectively
   //   called trivially copyable types.
 
   QualType CanonicalType = getCanonicalType();
   if (CanonicalType->isDependentType())
     return false;
 
-  if (CanonicalType.isVolatileQualified())
-    return false;
-
   // Return false for incomplete types after skipping any incomplete array types
   // which are expressly allowed by the standard and thus our API.
   if (CanonicalType->isIncompleteType())
     return false;
  
   // As an extension, Clang treats vector types as Scalar types.
   if (CanonicalType->isScalarType() || CanonicalType->isVectorType())
     return true;

test/CXX/drs/dr20xx.cpp

+// RUN: %clang_cc1 -std=c++98 -triple x86_64-unknown-unknown %s -verify -fexceptions -fcxx-exceptions -pedantic-errors \
+// RUN:            -Wno-variadic-macros -Wno-c11-extensions
+// RUN: %clang_cc1 -std=c++11 -triple x86_64-unknown-unknown %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++14 -triple x86_64-unknown-unknown %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++1z -triple x86_64-unknown-unknown %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
+
+// expected-no-diagnostics
+
+#if __cplusplus < 201103L
+#define static_assert(...) _Static_assert(__VA_ARGS__)
+#endif
+
+namespace dr2094 { // dr2094: 5.0
+  struct A { int n; };
+  struct B { volatile int n; };
+  static_assert(__is_trivially_copyable(volatile int), "");
+  static_assert(__is_trivially_copyable(const volatile int), "");
+  static_assert(__is_trivially_copyable(const volatile int[]), "");
+  static_assert(__is_trivially_copyable(A), "");
+  static_assert(__is_trivially_copyable(volatile A), "");
+  static_assert(__is_trivially_copyable(const volatile A), "");
+  static_assert(__is_trivially_copyable(const volatile A[]), "");
+  static_assert(__is_trivially_copyable(B), "");
+
+  static_assert(__is_trivially_constructible(A, A const&), "");
+  static_assert(__is_trivially_constructible(B, B const&), "");
+
+  static_assert(__is_trivially_assignable(A, const A&), "");
+  static_assert(__is_trivially_assignable(B, const B&), "");
+}

test/CXX/drs/dr4xx.cpp

   struct S2 {
     template<typename U> operator U();
     operator int() { return T::error; }
   };
   S2<int> s2;
   long n2 = s2;
 }
 
-namespace dr496 { // dr496: no
+namespace dr496 { // dr496: sup dr2094
   struct A { int n; };
   struct B { volatile int n; };
   int check1[ __is_trivially_copyable(const int) ? 1 : -1];
-  int check2[!__is_trivially_copyable(volatile int) ? 1 : -1];
+  // This checks the dr2094 behavior, not dr496
+  int check2[ __is_trivially_copyable(volatile int) ? 1 : -1];
   int check3[ __is_trivially_constructible(A, const A&) ? 1 : -1];
-  // FIXME: This is wrong.
   int check4[ __is_trivially_constructible(B, const B&) ? 1 : -1];
   int check5[ __is_trivially_assignable(A, const A&) ? 1 : -1];
-  // FIXME: This is wrong.
   int check6[ __is_trivially_assignable(B, const B&) ? 1 : -1];
 }
 
 namespace dr497 { // dr497: sup 253
   void before() {
     struct S {
       mutable int i;
     };

test/SemaCXX/type-traits.cpp

   int t25[T(__is_trivially_copyable(AllDeleted))];
 
   int t30[F(__is_trivially_copyable(void))];
   int t31[F(__is_trivially_copyable(SuperNonTrivialStruct))];
   int t32[F(__is_trivially_copyable(NonTCStruct))];
   int t33[F(__is_trivially_copyable(ExtDefaulted))];
 
   int t34[T(__is_trivially_copyable(const int))];
-  int t35[F(__is_trivially_copyable(volatile int))];
+  int t35[T(__is_trivially_copyable(volatile int))];
 }
 
 struct CStruct {
   int one;
   int two;
 };
 
 struct CEmptyStruct {};

www/cxx_dr_status.html

     <td>CD2</td>
     <td>Overload resolution with template and non-template conversion functions</td>
     <td class="full" align="center">Clang 3.5</td>
   </tr>
   <tr id="496">
     <td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#496">496</a></td>
     <td>CD3</td>
     <td>Is a volatile-qualified type really a POD?</td>
-    <td class="none" align="center">No</td>
+    <td class="none" align="center">Superseded by <a href="#dr2094">dr2094</a></td>
   </tr>
   <tr id="497">
     <td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#497">497</a></td>
     <td>CD1</td>
     <td>Missing required initialization in example</td>
     <td class="none" align="center">Superseded by <a href="#253">253</a></td>
   </tr>
   <tr class="open" id="498">

     <td>CD4</td>
     <td>Qualification conversion for pointer-to-member handler matching</td>
     <td class="none" align="center">Unknown</td>
   </tr>
   <tr id="2094">
     <td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#2094">2094</a></td>
     <td>DR</td>
     <td>Trivial copy/move constructor for class with volatile member</td>
-    <td class="none" align="center">Unknown</td>
+    <td class="full" align="center">Clang 5.0</td>
   </tr>
   <tr id="2095">
     <td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#2095">2095</a></td>
     <td>CD4</td>
     <td>Capturing rvalue references to functions by copy</td>
     <td class="none" align="center">Unknown</td>
   </tr>
   <tr id="2096">