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

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

Reviewers: rsmith

Reviewed By: rsmith

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D32984

llvm-svn: 302593

clang/lib/AST/Type.cpp

@@ -2114,18 +2114,15 @@ bool QualType::isTriviallyCopyableType(const ASTContext &Context) const {
   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())

clang/test/CXX/drs/dr20xx.cpp

@@ -0,0 +1,30 @@
+// 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&), "");
+}

clang/test/CXX/drs/dr4xx.cpp

@@ -1202,16 +1202,15 @@ namespace dr495 { // dr495: 3.5
   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];
 }
 

clang/test/SemaCXX/type-traits.cpp

@@ -1256,7 +1256,7 @@ void is_trivially_copyable2()
   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 {

clang/www/cxx_dr_status.html

@@ -3017,7 +3017,7 @@ of class templates</td>
     <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>
@@ -12379,7 +12379,7 @@ and <I>POD class</I></td>
     <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>