[ObjC] Enable using C++ triviality type traits for non-trivial C structs

[ahatanak]

Summary

r326307 and r327870 made changes that allowed C structs to have strong and weak fields in ARC and be non-trivial. This patch make changes that allow using the following type traits for non-trivial C structs:

has_trivial_assign
has_trivial_move_assign
has_trivial_copy
has_trivial_move_constructor
has_trivial_constructor
has_trivial_destructor

[rjmccall]

LGTM.

cfe/trunk/include/clang/Basic/TokenKinds.def

 // MSVC14.0 / VS2015 Type Traits
 TYPE_TRAIT_2(__is_assignable, IsAssignable, KEYCXX)
 
 // GNU and MS Type Traits
 TYPE_TRAIT_1(__has_nothrow_assign, HasNothrowAssign, KEYCXX)
 TYPE_TRAIT_1(__has_nothrow_move_assign, HasNothrowMoveAssign, KEYCXX)
 TYPE_TRAIT_1(__has_nothrow_copy, HasNothrowCopy, KEYCXX)
 TYPE_TRAIT_1(__has_nothrow_constructor, HasNothrowConstructor, KEYCXX)
-TYPE_TRAIT_1(__has_trivial_assign, HasTrivialAssign, KEYCXX)
-TYPE_TRAIT_1(__has_trivial_move_assign, HasTrivialMoveAssign, KEYCXX)
-TYPE_TRAIT_1(__has_trivial_copy, HasTrivialCopy, KEYCXX)
-TYPE_TRAIT_1(__has_trivial_constructor, HasTrivialDefaultConstructor, KEYCXX)
-TYPE_TRAIT_1(__has_trivial_move_constructor, HasTrivialMoveConstructor, KEYCXX)
-TYPE_TRAIT_1(__has_trivial_destructor, HasTrivialDestructor, KEYCXX)
+TYPE_TRAIT_1(__has_trivial_assign, HasTrivialAssign, KEYALL)
+TYPE_TRAIT_1(__has_trivial_move_assign, HasTrivialMoveAssign, KEYALL)
+TYPE_TRAIT_1(__has_trivial_copy, HasTrivialCopy, KEYALL)
+TYPE_TRAIT_1(__has_trivial_constructor, HasTrivialDefaultConstructor, KEYALL)
+TYPE_TRAIT_1(__has_trivial_move_constructor, HasTrivialMoveConstructor, KEYALL)
+TYPE_TRAIT_1(__has_trivial_destructor, HasTrivialDestructor, KEYALL)
 TYPE_TRAIT_1(__has_virtual_destructor, HasVirtualDestructor, KEYCXX)
 TYPE_TRAIT_1(__is_abstract, IsAbstract, KEYCXX)
 TYPE_TRAIT_1(__is_aggregate, IsAggregate, KEYCXX)
 TYPE_TRAIT_2(__is_base_of, IsBaseOf, KEYCXX)
 TYPE_TRAIT_1(__is_class, IsClass, KEYCXX)
 TYPE_TRAIT_2(__is_convertible_to, IsConvertibleTo, KEYCXX)
 TYPE_TRAIT_1(__is_empty, IsEmpty, KEYCXX)
 TYPE_TRAIT_1(__is_enum, IsEnum, KEYCXX)

cfe/trunk/lib/Sema/SemaExprCXX.cpp

case UTT_IsUnsigned:
     //
     // Note that these builtins do not behave as documented in g++: if a class
     // has both a trivial and a non-trivial special member of a particular kind,
     // they return false! For now, we emulate this behavior.
     // FIXME: This appears to be a g++ bug: more complex cases reveal that it
     // does not correctly compute triviality in the presence of multiple special
     // members of the same kind. Revisit this once the g++ bug is fixed.
   case UTT_HasTrivialDefaultConstructor:
+    if (T.isNonTrivialToPrimitiveDefaultInitialize())
+      return false;
     // http://gcc.gnu.org/onlinedocs/gcc/Type-Traits.html:
     //   If __is_pod (type) is true then the trait is true, else if type is
     //   a cv class or union type (or array thereof) with a trivial default
     //   constructor ([class.ctor]) then the trait is true, else it is false.
     if (T.isPODType(C))
       return true;
     if (CXXRecordDecl *RD = C.getBaseElementType(T)->getAsCXXRecordDecl())
       return RD->hasTrivialDefaultConstructor() &&
              !RD->hasNonTrivialDefaultConstructor();
     return false;
   case UTT_HasTrivialMoveConstructor:
+    if (T.isNonTrivialToPrimitiveDestructiveMove())
+      return false;
     //  This trait is implemented by MSVC 2012 and needed to parse the
     //  standard library headers. Specifically this is used as the logic
     //  behind std::is_trivially_move_constructible (20.9.4.3).
     if (T.isPODType(C))
       return true;
     if (CXXRecordDecl *RD = C.getBaseElementType(T)->getAsCXXRecordDecl())
       return RD->hasTrivialMoveConstructor() && !RD->hasNonTrivialMoveConstructor();
     return false;
   case UTT_HasTrivialCopy:
+    if (T.isNonTrivialToPrimitiveCopy())
+      return false;
     // http://gcc.gnu.org/onlinedocs/gcc/Type-Traits.html:
     //   If __is_pod (type) is true or type is a reference type then
     //   the trait is true, else if type is a cv class or union type
     //   with a trivial copy constructor ([class.copy]) then the trait
     //   is true, else it is false.
     if (T.isPODType(C) || T->isReferenceType())
       return true;
     if (CXXRecordDecl *RD = T->getAsCXXRecordDecl())
       return RD->hasTrivialCopyConstructor() &&
              !RD->hasNonTrivialCopyConstructor();
     return false;
   case UTT_HasTrivialMoveAssign:
+    if (T.isNonTrivialToPrimitiveDestructiveMove())
+      return false;
     //  This trait is implemented by MSVC 2012 and needed to parse the
     //  standard library headers. Specifically it is used as the logic
     //  behind std::is_trivially_move_assignable (20.9.4.3)
     if (T.isPODType(C))
       return true;
     if (CXXRecordDecl *RD = C.getBaseElementType(T)->getAsCXXRecordDecl())
       return RD->hasTrivialMoveAssignment() && !RD->hasNonTrivialMoveAssignment();
     return false;
   case UTT_HasTrivialAssign:
+    if (T.isNonTrivialToPrimitiveCopy())
+      return false;
     // http://gcc.gnu.org/onlinedocs/gcc/Type-Traits.html:
     //   If type is const qualified or is a reference type then the
     //   trait is false. Otherwise if __is_pod (type) is true then the
     //   trait is true, else if type is a cv class or union type with
     //   a trivial copy assignment ([class.copy]) then the trait is
     //   true, else it is false.
     // Note: the const and reference restrictions are interesting,
     // given that const and reference members don't prevent a class
if (auto *RD = C.getBaseElementType(T)->getAsCXXRecordDecl()) {
         CPT = Self.ResolveExceptionSpec(KeyLoc, CPT);
         if (!CPT || !CPT->isNothrow(C))
           return false;
       }
     }
     return true;
 
   case UTT_HasTrivialDestructor:
+    if (T.isDestructedType() == QualType::DK_nontrivial_c_struct)
+      return false;
     // http://gcc.gnu.org/onlinedocs/gcc/Type-Traits.html
     //   If __is_pod (type) is true or type is a reference type
     //   then the trait is true, else if type is a cv class or union
     //   type (or array thereof) with a trivial destructor
     //   ([class.dtor]) then the trait is true, else it is
     //   false.
     if (T.isPODType(C) || T->isReferenceType())
       return true;

cfe/trunk/test/SemaObjC/non-trivial-struct-traits.m

+// RUN: %clang_cc1 -fsyntax-only -fobjc-arc -verify %s
+
+// expected-no-diagnostics
+
+struct Trivial {
+  int x;
+};
+
+struct NonTrivial {
+  id x;
+};
+
+int trivial_assign[__has_trivial_assign(struct Trivial) ? 1 : -1];
+int trivial_move_assign[__has_trivial_move_assign(struct Trivial) ? 1 : -1];
+int trivial_copy_constructor[__has_trivial_copy(struct Trivial) ? 1 : -1];
+int trivial_move_constructor[__has_trivial_move_constructor(struct Trivial) ? 1 : -1];
+int trivial_constructor[__has_trivial_constructor(struct Trivial) ? 1 : -1];
+int trivial_destructor[__has_trivial_destructor(struct Trivial) ? 1 : -1];
+
+int non_trivial_assign[__has_trivial_assign(struct NonTrivial) ? -1 : 1];
+int non_trivial_move_assign[__has_trivial_move_assign(struct NonTrivial) ? -1 : 1];
+int non_trivial_copy_constructor[__has_trivial_copy(struct NonTrivial) ? -1 : 1];
+int non_trivial_move_constructor[__has_trivial_move_constructor(struct NonTrivial) ? -1 : 1];
+int non_trivial_constructor[__has_trivial_constructor(struct NonTrivial) ? -1 : 1];
+int non_trivial_destructor[__has_trivial_destructor(struct NonTrivial) ? -1 : 1];