path: root/dist/clang/patches/220_Support-std-has_unique_object_represesentations.patch

diff --git a/tools/clang/include/clang/AST/ASTContext.h b/tools/clang/include/clang/AST/ASTContext.h
index 703f588c56..d7beffa25e 100644
--- a/tools/clang/include/clang/AST/ASTContext.h
+++ b/tools/clang/include/clang/AST/ASTContext.h
@@ -2072,6 +2072,10 @@ public:
   void CollectInheritedProtocols(const Decl *CDecl,
                           llvm::SmallPtrSet<ObjCProtocolDecl*, 8> &Protocols);
 
+  /// \brief Return true if the specified type has unique object representations
+  /// according to (C++17 [meta.unary.prop]p9)
+  bool hasUniqueObjectRepresentations(QualType Ty) const;
+
   //===--------------------------------------------------------------------===//
   //                            Type Operators
   //===--------------------------------------------------------------------===//
diff --git a/tools/clang/include/clang/Basic/TokenKinds.def b/tools/clang/include/clang/Basic/TokenKinds.def
index be67663a10..90ac33b9ea 100644
--- a/tools/clang/include/clang/Basic/TokenKinds.def
+++ b/tools/clang/include/clang/Basic/TokenKinds.def
@@ -448,6 +448,8 @@ TYPE_TRAIT_1(__is_pod, IsPOD, KEYCXX)
 TYPE_TRAIT_1(__is_polymorphic, IsPolymorphic, KEYCXX)
 TYPE_TRAIT_1(__is_trivial, IsTrivial, KEYCXX)
 TYPE_TRAIT_1(__is_union, IsUnion, KEYCXX)
+TYPE_TRAIT_1(__has_unique_object_representations,
+             HasUniqueObjectRepresentations, KEYCXX)
 
 // Clang-only C++ Type Traits
 TYPE_TRAIT_N(__is_trivially_constructible, IsTriviallyConstructible, KEYCXX)
diff --git a/tools/clang/include/clang/Basic/TypeTraits.h b/tools/clang/include/clang/Basic/TypeTraits.h
index 6aadf795d8..8ecd63f9c3 100644
--- a/tools/clang/include/clang/Basic/TypeTraits.h
+++ b/tools/clang/include/clang/Basic/TypeTraits.h
@@ -70,7 +70,8 @@ namespace clang {
     UTT_IsUnsigned,
     UTT_IsVoid,
     UTT_IsVolatile,
-    UTT_Last = UTT_IsVolatile,
+    UTT_HasUniqueObjectRepresentations,
+    UTT_Last = UTT_HasUniqueObjectRepresentations,
     BTT_IsBaseOf,
     BTT_IsConvertible,
     BTT_IsConvertibleTo,
diff --git a/tools/clang/lib/AST/ASTContext.cpp b/tools/clang/lib/AST/ASTContext.cpp
index c60373c5a9..1ce7d51857 100644
--- a/tools/clang/lib/AST/ASTContext.cpp
+++ b/tools/clang/lib/AST/ASTContext.cpp
@@ -1823,7 +1823,9 @@ TypeInfo ASTContext::getTypeInfoImpl(const Type *T) const {
   }
   case Type::MemberPointer: {
     const MemberPointerType *MPT = cast<MemberPointerType>(T);
-    std::tie(Width, Align) = ABI->getMemberPointerWidthAndAlign(MPT);
+    CXXABI::MemberPointerInfo MPI = ABI->getMemberPointerInfo(MPT);
+    Width = MPI.Width;
+    Align = MPI.Align;
     break;
   }
   case Type::Complex: {
@@ -2107,6 +2109,171 @@ void ASTContext::CollectInheritedProtocols(const Decl *CDecl,
   }
 }
 
+static bool unionHasUniqueObjectRepresentations(const ASTContext &Context,
+                                                const RecordDecl *RD) {
+  assert(RD->isUnion() && "Must be union type");
+  CharUnits UnionSize = Context.getTypeSizeInChars(RD->getTypeForDecl());
+
+  for (const auto *Field : RD->fields()) {
+    if (!Context.hasUniqueObjectRepresentations(Field->getType()))
+      return false;
+    CharUnits FieldSize = Context.getTypeSizeInChars(Field->getType());
+    if (FieldSize != UnionSize)
+      return false;
+  }
+  return !RD->field_empty();
+}
+
+bool isStructEmpty(QualType Ty) {
+  const RecordDecl *RD = Ty->castAs<RecordType>()->getDecl();
+
+  if (!RD->field_empty())
+    return false;
+
+  if (const auto *ClassDecl = dyn_cast<CXXRecordDecl>(RD))
+    return ClassDecl->isEmpty();
+
+  return true;
+}
+
+static llvm::Optional<int64_t>
+structHasUniqueObjectRepresentations(const ASTContext &Context,
+                                     const RecordDecl *RD) {
+  assert(!RD->isUnion() && "Must be struct/class type");
+  const auto &Layout = Context.getASTRecordLayout(RD);
+
+  int64_t CurOffsetInBits = 0;
+  if (const auto *ClassDecl = dyn_cast<CXXRecordDecl>(RD)) {
+    if (ClassDecl->isDynamicClass())
+      return llvm::None;
+
+    SmallVector<std::pair<QualType, int64_t>, 4> Bases;
+    for (const auto Base : ClassDecl->bases()) {
+      // Empty types can be inherited from, and non-empty types can potentially
+      // have tail padding, so just make sure there isn't an error.
+      if (!isStructEmpty(Base.getType())) {
+        llvm::Optional<int64_t> Size = structHasUniqueObjectRepresentations(
+            Context, Base.getType()->getAs<RecordType>()->getDecl());
+        if (!Size)
+          return llvm::None;
+        Bases.emplace_back(Base.getType(), Size.getValue());
+      }
+    }
+
+    std::sort(
+        Bases.begin(), Bases.end(), [&](const std::pair<QualType, int64_t> &L,
+                                        const std::pair<QualType, int64_t> &R) {
+          return Layout.getBaseClassOffset(L.first->getAsCXXRecordDecl()) <
+                 Layout.getBaseClassOffset(R.first->getAsCXXRecordDecl());
+        });
+
+    for (const auto Base : Bases) {
+      int64_t BaseOffset = Context.toBits(
+          Layout.getBaseClassOffset(Base.first->getAsCXXRecordDecl()));
+      int64_t BaseSize = Base.second;
+      if (BaseOffset != CurOffsetInBits)
+        return llvm::None;
+      CurOffsetInBits = BaseOffset + BaseSize;
+    }
+  }
+
+  for (const auto *Field : RD->fields()) {
+    if (!Field->getType()->isReferenceType() &&
+        !Context.hasUniqueObjectRepresentations(Field->getType()))
+      return llvm::None;
+
+    int64_t FieldSizeInBits =
+        Context.toBits(Context.getTypeSizeInChars(Field->getType()));
+    if (Field->isBitField()) {
+      int64_t BitfieldSize = Field->getBitWidthValue(Context);
+
+      if (BitfieldSize > FieldSizeInBits)
+        return llvm::None;
+      FieldSizeInBits = BitfieldSize;
+    }
+
+    int64_t FieldOffsetInBits = Context.getFieldOffset(Field);
+
+    if (FieldOffsetInBits != CurOffsetInBits)
+      return llvm::None;
+
+    CurOffsetInBits = FieldSizeInBits + FieldOffsetInBits;
+  }
+
+  return CurOffsetInBits;
+}
+
+bool ASTContext::hasUniqueObjectRepresentations(QualType Ty) const {
+  // C++17 [meta.unary.prop]:
+  //   The predicate condition for a template specialization
+  //   has_unique_object_representations<T> shall be
+  //   satisfied if and only if:
+  //     (9.1) - T is trivially copyable, and
+  //     (9.2) - any two objects of type T with the same value have the same
+  //     object representation, where two objects
+  //   of array or non-union class type are considered to have the same value
+  //   if their respective sequences of
+  //   direct subobjects have the same values, and two objects of union type
+  //   are considered to have the same
+  //   value if they have the same active member and the corresponding members
+  //   have the same value.
+  //   The set of scalar types for which this condition holds is
+  //   implementation-defined. [ Note: If a type has padding
+  //   bits, the condition does not hold; otherwise, the condition holds true
+  //   for unsigned integral types. -- end note ]
+  assert(!Ty.isNull() && "Null QualType sent to unique object rep check");
+
+  // Arrays are unique only if their element type is unique.
+  if (Ty->isArrayType())
+    return hasUniqueObjectRepresentations(getBaseElementType(Ty));
+
+  // (9.1) - T is trivially copyable...
+  if (!Ty.isTriviallyCopyableType(*this))
+    return false;
+
+  // All integrals and enums are unique.
+  if (Ty->isIntegralOrEnumerationType())
+    return true;
+
+  // All other pointers are unique.
+  if (Ty->isPointerType())
+    return true;
+
+  if (Ty->isMemberPointerType()) {
+    const MemberPointerType *MPT = Ty->getAs<MemberPointerType>();
+    return !ABI->getMemberPointerInfo(MPT).HasPadding;
+  }
+
+  if (Ty->isRecordType()) {
+    const RecordDecl *Record = Ty->getAs<RecordType>()->getDecl();
+
+    if (Record->isInvalidDecl())
+      return false;
+
+    if (Record->isUnion())
+      return unionHasUniqueObjectRepresentations(*this, Record);
+
+    Optional<int64_t> StructSize =
+        structHasUniqueObjectRepresentations(*this, Record);
+
+    return StructSize &&
+           StructSize.getValue() == static_cast<int64_t>(getTypeSize(Ty));
+  }
+
+  // FIXME: More cases to handle here (list by rsmith):
+  // vectors (careful about, eg, vector of 3 foo)
+  // _Complex int and friends
+  // _Atomic T
+  // Obj-C block pointers
+  // Obj-C object pointers
+  // and perhaps OpenCL's various builtin types (pipe, sampler_t, event_t,
+  // clk_event_t, queue_t, reserve_id_t)
+  // There're also Obj-C class types and the Obj-C selector type, but I think it
+  // makes sense for those to return false here.
+
+  return false;
+}
+
 unsigned ASTContext::CountNonClassIvars(const ObjCInterfaceDecl *OI) const {
   unsigned count = 0;  
   // Count ivars declared in class extension.
diff --git a/tools/clang/lib/AST/CXXABI.h b/tools/clang/lib/AST/CXXABI.h
index 924ef00e81..06295b5817 100644
--- a/tools/clang/lib/AST/CXXABI.h
+++ b/tools/clang/lib/AST/CXXABI.h
@@ -31,9 +31,16 @@ class CXXABI {
 public:
   virtual ~CXXABI();
 
-  /// Returns the width and alignment of a member pointer in bits.
-  virtual std::pair<uint64_t, unsigned>
-  getMemberPointerWidthAndAlign(const MemberPointerType *MPT) const = 0;
+  struct MemberPointerInfo {
+    uint64_t Width;
+    unsigned Align;
+    bool HasPadding;
+  };
+
+  /// Returns the width and alignment of a member pointer in bits, as well as
+  /// whether it has padding.
+  virtual MemberPointerInfo
+  getMemberPointerInfo(const MemberPointerType *MPT) const = 0;
 
   /// Returns the default calling convention for C++ methods.
   virtual CallingConv getDefaultMethodCallConv(bool isVariadic) const = 0;
diff --git a/tools/clang/lib/AST/ItaniumCXXABI.cpp b/tools/clang/lib/AST/ItaniumCXXABI.cpp
index 692a455eaf..d6bc16b635 100644
--- a/tools/clang/lib/AST/ItaniumCXXABI.cpp
+++ b/tools/clang/lib/AST/ItaniumCXXABI.cpp
@@ -101,15 +101,17 @@ protected:
 public:
   ItaniumCXXABI(ASTContext &Ctx) : Context(Ctx) { }
 
-  std::pair<uint64_t, unsigned>
-  getMemberPointerWidthAndAlign(const MemberPointerType *MPT) const override {
+  MemberPointerInfo
+  getMemberPointerInfo(const MemberPointerType *MPT) const override {
     const TargetInfo &Target = Context.getTargetInfo();
     TargetInfo::IntType PtrDiff = Target.getPtrDiffType(0);
-    uint64_t Width = Target.getTypeWidth(PtrDiff);
-    unsigned Align = Target.getTypeAlign(PtrDiff);
+    MemberPointerInfo MPI;
+    MPI.Width = Target.getTypeWidth(PtrDiff);
+    MPI.Align = Target.getTypeAlign(PtrDiff);
+    MPI.HasPadding = false;
     if (MPT->isMemberFunctionPointer())
-      Width = 2 * Width;
-    return std::make_pair(Width, Align);
+      MPI.Width *= 2;
+    return MPI;
   }
 
   CallingConv getDefaultMethodCallConv(bool isVariadic) const override {
diff --git a/tools/clang/lib/AST/MicrosoftCXXABI.cpp b/tools/clang/lib/AST/MicrosoftCXXABI.cpp
index 73324e40f3..b19491f313 100644
--- a/tools/clang/lib/AST/MicrosoftCXXABI.cpp
+++ b/tools/clang/lib/AST/MicrosoftCXXABI.cpp
@@ -76,8 +76,8 @@ class MicrosoftCXXABI : public CXXABI {
 public:
   MicrosoftCXXABI(ASTContext &Ctx) : Context(Ctx) { }
 
-  std::pair<uint64_t, unsigned>
-  getMemberPointerWidthAndAlign(const MemberPointerType *MPT) const override;
+  MemberPointerInfo
+  getMemberPointerInfo(const MemberPointerType *MPT) const override;
 
   CallingConv getDefaultMethodCallConv(bool isVariadic) const override {
     if (!isVariadic &&
@@ -227,7 +227,7 @@ getMSMemberPointerSlots(const MemberPointerType *MPT) {
   return std::make_pair(Ptrs, Ints);
 }
 
-std::pair<uint64_t, unsigned> MicrosoftCXXABI::getMemberPointerWidthAndAlign(
+CXXABI::MemberPointerInfo MicrosoftCXXABI::getMemberPointerInfo(
     const MemberPointerType *MPT) const {
   // The nominal struct is laid out with pointers followed by ints and aligned
   // to a pointer width if any are present and an int width otherwise.
@@ -237,22 +237,25 @@ std::pair<uint64_t, unsigned> MicrosoftCXXABI::getMemberPointerWidthAndAlign(
 
   unsigned Ptrs, Ints;
   std::tie(Ptrs, Ints) = getMSMemberPointerSlots(MPT);
-  uint64_t Width = Ptrs * PtrSize + Ints * IntSize;
-  unsigned Align;
+  MemberPointerInfo MPI;
+  MPI.HasPadding = false;
+  MPI.Width = Ptrs * PtrSize + Ints * IntSize;
 
   // When MSVC does x86_32 record layout, it aligns aggregate member pointers to
   // 8 bytes.  However, __alignof usually returns 4 for data memptrs and 8 for
   // function memptrs.
   if (Ptrs + Ints > 1 && Target.getTriple().isArch32Bit())
-    Align = 64;
+    MPI.Align = 64;
   else if (Ptrs)
-    Align = Target.getPointerAlign(0);
+    MPI.Align = Target.getPointerAlign(0);
   else
-    Align = Target.getIntAlign();
+    MPI.Align = Target.getIntAlign();
 
-  if (Target.getTriple().isArch64Bit())
-    Width = llvm::alignTo(Width, Align);
-  return std::make_pair(Width, Align);
+  if (Target.getTriple().isArch64Bit()) {
+    MPI.Width = llvm::alignTo(MPI.Width, MPI.Align);
+    MPI.HasPadding = MPI.Width != (Ptrs * PtrSize + Ints * IntSize);
+  }
+  return MPI;
 }
 
 CXXABI *clang::CreateMicrosoftCXXABI(ASTContext &Ctx) {
diff --git a/tools/clang/lib/Parse/ParseExpr.cpp b/tools/clang/lib/Parse/ParseExpr.cpp
index 44b87af01a..73aac10c23 100644
--- a/tools/clang/lib/Parse/ParseExpr.cpp
+++ b/tools/clang/lib/Parse/ParseExpr.cpp
@@ -716,6 +716,7 @@ class CastExpressionIdValidator : public CorrectionCandidateCallback {
 ///                   '__is_sealed'                           [MS]
 ///                   '__is_trivial'
 ///                   '__is_union'
+///                   '__has_unique_object_representations'
 ///
 /// [Clang] unary-type-trait:
 ///                   '__is_aggregate'
diff --git a/tools/clang/lib/Sema/SemaExprCXX.cpp b/tools/clang/lib/Sema/SemaExprCXX.cpp
index a9cf3ec799..a7d75ad977 100644
--- a/tools/clang/lib/Sema/SemaExprCXX.cpp
+++ b/tools/clang/lib/Sema/SemaExprCXX.cpp
@@ -4141,6 +4141,7 @@ static bool CheckUnaryTypeTraitTypeCompleteness(Sema &S, TypeTrait UTT,
   case UTT_IsDestructible:
   case UTT_IsNothrowDestructible:
   case UTT_IsTriviallyDestructible:
+  case UTT_HasUniqueObjectRepresentations:
     if (ArgTy->isIncompleteArrayType() || ArgTy->isVoidType())
       return true;
 
@@ -4580,6 +4581,8 @@ static bool EvaluateUnaryTypeTrait(Sema &Self, TypeTrait UTT,
     //   Returns True if and only if T is a complete type at the point of the
     //   function call.
     return !T->isIncompleteType();
+  case UTT_HasUniqueObjectRepresentations:
+    return C.hasUniqueObjectRepresentations(T);
   }
 }
 
diff --git a/tools/clang/test/SemaCXX/has_unique_object_reps_member_ptr.cpp b/tools/clang/test/SemaCXX/has_unique_object_reps_member_ptr.cpp
new file mode 100644
index 0000000000..b8e27f82ff
--- /dev/null
+++ b/tools/clang/test/SemaCXX/has_unique_object_reps_member_ptr.cpp
@@ -0,0 +1,32 @@
+// RUN: %clang_cc1 -triple x86_64-linux-pc -DIS64 -fsyntax-only -verify -std=c++17 %s 
+// RUN: %clang_cc1 -triple x86_64-windows-pc -DIS64 -fsyntax-only -verify -std=c++17 %s
+// RUN: %clang_cc1 -triple i386-linux-pc -fsyntax-only -verify -std=c++17 %s
+// RUN: %clang_cc1 -triple i386-windows-pc -DW32 -fsyntax-only -verify -std=c++17 %s
+// expected-no-diagnostics
+
+struct Base {};
+struct A : virtual Base {
+  virtual void n() {}
+};
+
+auto p = &A::n;
+static_assert(__has_unique_object_representations(decltype(p)));
+
+struct B {
+  decltype(p) x;
+  int b;
+#ifdef IS64
+  // required on 64 bit to fill out the tail padding.
+  int c;
+#endif
+};
+static_assert(__has_unique_object_representations(B));
+
+struct C { // has padding on Win32, but nothing else.
+  decltype(p) x;
+};
+#ifdef W32
+static_assert(!__has_unique_object_representations(C));
+#else
+static_assert(__has_unique_object_representations(C));
+#endif
diff --git a/tools/clang/test/SemaCXX/type-traits.cpp b/tools/clang/test/SemaCXX/type-traits.cpp
index 5879a77dd5..3c2f9c7f0f 100644
--- a/tools/clang/test/SemaCXX/type-traits.cpp
+++ b/tools/clang/test/SemaCXX/type-traits.cpp
@@ -2352,3 +2352,321 @@ void is_trivially_destructible_test() {
   { int arr[F(__is_trivially_destructible(void))]; }
   { int arr[F(__is_trivially_destructible(const volatile void))]; }
 }
+
+// Instantiation of __has_unique_object_representations
+template <typename T>
+struct has_unique_object_representations {
+  static const bool value = __has_unique_object_representations(T);
+};
+
+static_assert(!has_unique_object_representations<void>::value, "void is never unique");
+static_assert(!has_unique_object_representations<const void>::value, "void is never unique");
+static_assert(!has_unique_object_representations<volatile void>::value, "void is never unique");
+static_assert(!has_unique_object_representations<const volatile void>::value, "void is never unique");
+
+static_assert(has_unique_object_representations<int>::value, "integrals are");
+static_assert(has_unique_object_representations<const int>::value, "integrals are");
+static_assert(has_unique_object_representations<volatile int>::value, "integrals are");
+static_assert(has_unique_object_representations<const volatile int>::value, "integrals are");
+
+static_assert(has_unique_object_representations<void *>::value, "as are pointers");
+static_assert(has_unique_object_representations<const void *>::value, "as are pointers");
+static_assert(has_unique_object_representations<volatile void *>::value, "are pointers");
+static_assert(has_unique_object_representations<const volatile void *>::value, "as are pointers");
+
+static_assert(has_unique_object_representations<int *>::value, "as are pointers");
+static_assert(has_unique_object_representations<const int *>::value, "as are pointers");
+static_assert(has_unique_object_representations<volatile int *>::value, "as are pointers");
+static_assert(has_unique_object_representations<const volatile int *>::value, "as are pointers");
+
+class C {};
+using FP = int (*)(int);
+using PMF = int (C::*)(int);
+using PMD = int C::*;
+
+static_assert(has_unique_object_representations<FP>::value, "even function pointers");
+static_assert(has_unique_object_representations<const FP>::value, "even function pointers");
+static_assert(has_unique_object_representations<volatile FP>::value, "even function pointers");
+static_assert(has_unique_object_representations<const volatile FP>::value, "even function pointers");
+
+static_assert(has_unique_object_representations<PMF>::value, "and pointer to members");
+static_assert(has_unique_object_representations<const PMF>::value, "and pointer to members");
+static_assert(has_unique_object_representations<volatile PMF>::value, "and pointer to members");
+static_assert(has_unique_object_representations<const volatile PMF>::value, "and pointer to members");
+
+static_assert(has_unique_object_representations<PMD>::value, "and pointer to members");
+static_assert(has_unique_object_representations<const PMD>::value, "and pointer to members");
+static_assert(has_unique_object_representations<volatile PMD>::value, "and pointer to members");
+static_assert(has_unique_object_representations<const volatile PMD>::value, "and pointer to members");
+
+static_assert(has_unique_object_representations<bool>::value, "yes, all integral types");
+static_assert(has_unique_object_representations<char>::value, "yes, all integral types");
+static_assert(has_unique_object_representations<signed char>::value, "yes, all integral types");
+static_assert(has_unique_object_representations<unsigned char>::value, "yes, all integral types");
+static_assert(has_unique_object_representations<short>::value, "yes, all integral types");
+static_assert(has_unique_object_representations<unsigned short>::value, "yes, all integral types");
+static_assert(has_unique_object_representations<int>::value, "yes, all integral types");
+static_assert(has_unique_object_representations<unsigned int>::value, "yes, all integral types");
+static_assert(has_unique_object_representations<long>::value, "yes, all integral types");
+static_assert(has_unique_object_representations<unsigned long>::value, "yes, all integral types");
+static_assert(has_unique_object_representations<long long>::value, "yes, all integral types");
+static_assert(has_unique_object_representations<unsigned long long>::value, "yes, all integral types");
+static_assert(has_unique_object_representations<wchar_t>::value, "yes, all integral types");
+static_assert(has_unique_object_representations<char16_t>::value, "yes, all integral types");
+static_assert(has_unique_object_representations<char32_t>::value, "yes, all integral types");
+
+static_assert(!has_unique_object_representations<void>::value, "but not void!");
+static_assert(!has_unique_object_representations<decltype(nullptr)>::value, "or nullptr_t");
+static_assert(!has_unique_object_representations<float>::value, "definitely not Floating Point");
+static_assert(!has_unique_object_representations<double>::value, "definitely not Floating Point");
+static_assert(!has_unique_object_representations<long double>::value, "definitely not Floating Point");
+
+struct NoPadding {
+  int a;
+  int b;
+};
+
+static_assert(has_unique_object_representations<NoPadding>::value, "types without padding are");
+
+struct InheritsFromNoPadding : NoPadding {
+  int c;
+  int d;
+};
+
+static_assert(has_unique_object_representations<InheritsFromNoPadding>::value, "types without padding are");
+
+struct VirtuallyInheritsFromNoPadding : virtual NoPadding {
+  int c;
+  int d;
+};
+
+static_assert(!has_unique_object_representations<VirtuallyInheritsFromNoPadding>::value, "No virtual inheritence");
+
+struct Padding {
+  char a;
+  int b;
+};
+
+//static_assert(!has_unique_object_representations<Padding>::value, "but not with padding");
+
+struct InheritsFromPadding : Padding {
+  int c;
+  int d;
+};
+
+static_assert(!has_unique_object_representations<InheritsFromPadding>::value, "or its subclasses");
+
+struct TailPadding {
+  int a;
+  char b;
+};
+
+static_assert(!has_unique_object_representations<TailPadding>::value, "even at the end");
+
+struct TinyStruct {
+  char a;
+};
+
+static_assert(has_unique_object_representations<TinyStruct>::value, "Should be no padding");
+
+struct InheritsFromTinyStruct : TinyStruct {
+  int b;
+};
+
+static_assert(!has_unique_object_representations<InheritsFromTinyStruct>::value, "Inherit causes padding");
+
+union NoPaddingUnion {
+  int a;
+  unsigned int b;
+};
+
+static_assert(has_unique_object_representations<NoPaddingUnion>::value, "unions follow the same rules as structs");
+
+union PaddingUnion {
+  int a;
+  long long b;
+};
+
+static_assert(!has_unique_object_representations<PaddingUnion>::value, "unions follow the same rules as structs");
+
+struct NotTriviallyCopyable {
+  int x;
+  NotTriviallyCopyable(const NotTriviallyCopyable &) {}
+};
+
+static_assert(!has_unique_object_representations<NotTriviallyCopyable>::value, "must be trivially copyable");
+
+struct HasNonUniqueMember {
+  float x;
+};
+
+static_assert(!has_unique_object_representations<HasNonUniqueMember>::value, "all members must be unique");
+
+enum ExampleEnum { xExample,
+                   yExample };
+enum LLEnum : long long { xLongExample,
+                          yLongExample };
+
+static_assert(has_unique_object_representations<ExampleEnum>::value, "Enums are integrals, so unique!");
+static_assert(has_unique_object_representations<LLEnum>::value, "Enums are integrals, so unique!");
+
+enum class ExampleEnumClass { xExample,
+                              yExample };
+enum class LLEnumClass : long long { xLongExample,
+                                     yLongExample };
+
+static_assert(has_unique_object_representations<ExampleEnumClass>::value, "Enums are integrals, so unique!");
+static_assert(has_unique_object_representations<LLEnumClass>::value, "Enums are integrals, so unique!");
+
+// because references aren't trivially copyable.
+static_assert(!has_unique_object_representations<int &>::value, "No references!");
+static_assert(!has_unique_object_representations<const int &>::value, "No references!");
+static_assert(!has_unique_object_representations<volatile int &>::value, "No references!");
+static_assert(!has_unique_object_representations<const volatile int &>::value, "No references!");
+static_assert(!has_unique_object_representations<Empty>::value, "No empty types!");
+static_assert(!has_unique_object_representations<EmptyUnion>::value, "No empty types!");
+
+class Compressed : Empty {
+  int x;
+};
+
+static_assert(has_unique_object_representations<Compressed>::value, "But inheriting from one is ok");
+
+class EmptyInheritor : Compressed {};
+
+static_assert(has_unique_object_representations<EmptyInheritor>::value, "As long as the base has items, empty is ok");
+
+class Dynamic {
+  virtual void A();
+  int i;
+};
+
+static_assert(!has_unique_object_representations<Dynamic>::value, "Dynamic types are not valid");
+
+class InheritsDynamic : Dynamic {
+  int j;
+};
+
+static_assert(!has_unique_object_representations<InheritsDynamic>::value, "Dynamic types are not valid");
+
+static_assert(has_unique_object_representations<int[42]>::value, "Arrays are fine, as long as their value type is");
+static_assert(has_unique_object_representations<int[]>::value, "Arrays are fine, as long as their value type is");
+static_assert(has_unique_object_representations<int[][42]>::value, "Arrays are fine, as long as their value type is");
+static_assert(!has_unique_object_representations<double[42]>::value, "So no array of doubles!");
+static_assert(!has_unique_object_representations<double[]>::value, "So no array of doubles!");
+static_assert(!has_unique_object_representations<double[][42]>::value, "So no array of doubles!");
+
+struct __attribute__((aligned(16))) WeirdAlignment {
+  int i;
+};
+union __attribute__((aligned(16))) WeirdAlignmentUnion {
+  int i;
+};
+static_assert(!has_unique_object_representations<WeirdAlignment>::value, "Alignment causes padding");
+static_assert(!has_unique_object_representations<WeirdAlignmentUnion>::value, "Alignment causes padding");
+static_assert(!has_unique_object_representations<WeirdAlignment[42]>::value, "Also no arrays that have padding");
+
+static_assert(!has_unique_object_representations<int(int)>::value, "Functions are not unique");
+static_assert(!has_unique_object_representations<int(int) const>::value, "Functions are not unique");
+static_assert(!has_unique_object_representations<int(int) volatile>::value, "Functions are not unique");
+static_assert(!has_unique_object_representations<int(int) const volatile>::value, "Functions are not unique");
+static_assert(!has_unique_object_representations<int(int) &>::value, "Functions are not unique");
+static_assert(!has_unique_object_representations<int(int) const &>::value, "Functions are not unique");
+static_assert(!has_unique_object_representations<int(int) volatile &>::value, "Functions are not unique");
+static_assert(!has_unique_object_representations<int(int) const volatile &>::value, "Functions are not unique");
+static_assert(!has_unique_object_representations<int(int) &&>::value, "Functions are not unique");
+static_assert(!has_unique_object_representations<int(int) const &&>::value, "Functions are not unique");
+static_assert(!has_unique_object_representations<int(int) volatile &&>::value, "Functions are not unique");
+static_assert(!has_unique_object_representations<int(int) const volatile &&>::value, "Functions are not unique");
+
+static_assert(!has_unique_object_representations<int(int, ...)>::value, "Functions are not unique");
+static_assert(!has_unique_object_representations<int(int, ...) const>::value, "Functions are not unique");
+static_assert(!has_unique_object_representations<int(int, ...) volatile>::value, "Functions are not unique");
+static_assert(!has_unique_object_representations<int(int, ...) const volatile>::value, "Functions are not unique");
+static_assert(!has_unique_object_representations<int(int, ...) &>::value, "Functions are not unique");
+static_assert(!has_unique_object_representations<int(int, ...) const &>::value, "Functions are not unique");
+static_assert(!has_unique_object_representations<int(int, ...) volatile &>::value, "Functions are not unique");
+static_assert(!has_unique_object_representations<int(int, ...) const volatile &>::value, "Functions are not unique");
+static_assert(!has_unique_object_representations<int(int, ...) &&>::value, "Functions are not unique");
+static_assert(!has_unique_object_representations<int(int, ...) const &&>::value, "Functions are not unique");
+static_assert(!has_unique_object_representations<int(int, ...) volatile &&>::value, "Functions are not unique");
+static_assert(!has_unique_object_representations<int(int, ...) const volatile &&>::value, "Functions are not unique");
+
+void foo(){
+  static auto lambda = []() {};
+  static_assert(!has_unique_object_representations<decltype(lambda)>::value, "Lambdas follow struct rules");
+  int i;
+  static auto lambda2 = [i]() {};
+  static_assert(has_unique_object_representations<decltype(lambda2)>::value, "Lambdas follow struct rules");
+}
+
+struct PaddedBitfield {
+  char c : 6;
+  char d : 1;
+};
+
+struct UnPaddedBitfield {
+  char c : 6;
+  char d : 2;
+};
+
+struct AlignedPaddedBitfield {
+  char c : 6;
+  __attribute__((aligned(1)))
+  char d : 2;
+};
+
+static_assert(!has_unique_object_representations<PaddedBitfield>::value, "Bitfield padding");
+static_assert(has_unique_object_representations<UnPaddedBitfield>::value, "Bitfield padding");
+static_assert(!has_unique_object_representations<AlignedPaddedBitfield>::value, "Bitfield padding");
+
+struct BoolBitfield {
+  bool b : 8;
+};
+
+static_assert(has_unique_object_representations<BoolBitfield>::value, "Bitfield bool");
+
+struct BoolBitfield2 {
+  bool b : 16;
+};
+
+static_assert(!has_unique_object_representations<BoolBitfield2>::value, "Bitfield bool");
+
+struct GreaterSizeBitfield {
+  //expected-warning@+1 {{width of bit-field 'n'}}
+  int n : 1024;
+};
+
+static_assert(sizeof(GreaterSizeBitfield) == 128, "Bitfield Size");
+static_assert(!has_unique_object_representations<GreaterSizeBitfield>::value, "Bitfield padding");
+
+struct StructWithRef {
+  int &I;
+};
+
+static_assert(has_unique_object_representations<StructWithRef>::value, "References are still unique");
+
+struct NotUniqueBecauseTailPadding {
+  int &r;
+  char a;
+};
+struct CanBeUniqueIfNoPadding : NotUniqueBecauseTailPadding {
+  char b[7];
+};
+
+static_assert(!has_unique_object_representations<NotUniqueBecauseTailPadding>::value, 
+              "non trivial");
+// Can be unique on Itanium, since the is child class' data is 'folded' into the
+// parent's tail padding.
+static_assert(sizeof(CanBeUniqueIfNoPadding) != 16 ||
+              has_unique_object_representations<CanBeUniqueIfNoPadding>::value,
+              "inherit from std layout");
+
+namespace ErrorType {
+  struct S; //expected-note{{forward declaration of 'ErrorType::S'}}
+
+  struct T {
+        S t; //expected-error{{field has incomplete type 'ErrorType::S'}}
+  };
+  bool b = __has_unique_object_representations(T);
+};
-- 
2.14.1