Revert r353927

llvm-svn: 353940

Author: Serge Guelton

llvm/include/llvm/ADT/Optional.h

@@ -29,77 +29,36 @@ namespace llvm {
 class raw_ostream;
 
 namespace optional_detail {
-
 /// Storage for any type.
-//
-template <class T> struct OptionalTrivialStorage {
+template <typename T, bool = is_trivially_copyable<T>::value> struct OptionalStorage {
   AlignedCharArrayUnion<T> storage;
   bool hasVal = false;
-  OptionalTrivialStorage() = default;
-  OptionalTrivialStorage(OptionalTrivialStorage const &) = default;
-  OptionalTrivialStorage(OptionalTrivialStorage &&) = default;
-  OptionalTrivialStorage &operator=(OptionalTrivialStorage const &) = default;
-  OptionalTrivialStorage &operator=(OptionalTrivialStorage &&) = default;
-  ~OptionalTrivialStorage() = default;
-
-  OptionalTrivialStorage(const T &y) : hasVal(true) {
-    new (storage.buffer) T(y);
-  }
-  OptionalTrivialStorage(T &&y) : hasVal(true) {
-    new (storage.buffer) T(std::move(y));
-  }
-
-  OptionalTrivialStorage &operator=(const T &y) {
-    new (storage.buffer) T(y);
-    hasVal = true;
-    return *this;
-  }
-  OptionalTrivialStorage &operator=(T &&y) {
-    new (storage.buffer) T(std::move(y));
-    hasVal = true;
-    return *this;
-  }
-
-  T *getPointer() {
-    assert(hasVal);
-    return reinterpret_cast<T *>(storage.buffer);
-  }
-  const T *getPointer() const {
-    assert(hasVal);
-    return reinterpret_cast<const T *>(storage.buffer);
-  }
-  void reset() { hasVal = false; }
-};
-
-template <typename T> struct OptionalStorage : OptionalTrivialStorage<T> {
 
   OptionalStorage() = default;
 
-  OptionalStorage(const T &y) : OptionalTrivialStorage<T>(y) {}
-  OptionalStorage(T &&y) : OptionalTrivialStorage<T>(std::move(y)) {}
-
-  OptionalStorage(const OptionalStorage &O) : OptionalTrivialStorage<T>() {
-    this->hasVal = O.hasVal;
-    if (this->hasVal)
-      new (this->storage.buffer) T(*O.getPointer());
+  OptionalStorage(const T &y) : hasVal(true) { new (storage.buffer) T(y); }
+  OptionalStorage(const OptionalStorage &O) : hasVal(O.hasVal) {
+    if (hasVal)
+      new (storage.buffer) T(*O.getPointer());
   }
-
-  OptionalStorage(OptionalStorage &&O) : OptionalTrivialStorage<T>() {
-    this->hasVal = O.hasVal;
+  OptionalStorage(T &&y) : hasVal(true) {
+    new (storage.buffer) T(std::forward<T>(y));
+  }
+  OptionalStorage(OptionalStorage &&O) : hasVal(O.hasVal) {
     if (O.hasVal) {
-      new (this->storage.buffer) T(std::move(*O.getPointer()));
+      new (storage.buffer) T(std::move(*O.getPointer()));
     }
   }
 
   OptionalStorage &operator=(T &&y) {
-    if (this->hasVal)
-      *this->getPointer() = std::move(y);
+    if (hasVal)
+      *getPointer() = std::move(y);
     else {
-      OptionalTrivialStorage<T>::operator=(std::move(y));
+      new (storage.buffer) T(std::move(y));
+      hasVal = true;
     }
     return *this;
   }
-
   OptionalStorage &operator=(OptionalStorage &&O) {
     if (!O.hasVal)
       reset();
@@ -115,10 +74,11 @@ template <typename T> struct OptionalStorage : OptionalTrivialStorage<T> {
   // requirements (notably: the existence of a default ctor) when implemented
   // in that way. Careful SFINAE to avoid such pitfalls would be required.
   OptionalStorage &operator=(const T &y) {
-    if (this->hasVal)
-      *this->getPointer() = y;
+    if (hasVal)
+      *getPointer() = y;
     else {
-      OptionalTrivialStorage<T>::operator=(y);
+      new (storage.buffer) T(y);
+      hasVal = true;
     }
     return *this;
   }
@@ -133,19 +93,26 @@ template <typename T> struct OptionalStorage : OptionalTrivialStorage<T> {
   ~OptionalStorage() { reset(); }
 
   void reset() {
-    if (this->hasVal) {
-      (*this->getPointer()).~T();
-      OptionalTrivialStorage<T>::reset();
+    if (hasVal) {
+      (*getPointer()).~T();
+      hasVal = false;
     }
   }
+
+  T *getPointer() {
+    assert(hasVal);
+    return reinterpret_cast<T *>(storage.buffer);
+  }
+  const T *getPointer() const {
+    assert(hasVal);
+    return reinterpret_cast<const T *>(storage.buffer);
+  }
 };
 
 } // namespace optional_detail
 
 template <typename T> class Optional {
-  typename std::conditional<is_trivially_copyable<T>::value,
-                            optional_detail::OptionalTrivialStorage<T>,
-                            optional_detail::OptionalStorage<T>>::type Storage;
+  optional_detail::OptionalStorage<T> Storage;
 
 public:
   using value_type = T;

llvm/unittests/ADT/OptionalTest.cpp

@@ -18,12 +18,6 @@ using namespace llvm;
 
 namespace {
 
-static_assert(llvm::is_trivially_copyable<Optional<int>>::value,
-              "trivially copyable");
-
-static_assert(llvm::is_trivially_copyable<Optional<std::array<int, 3>>>::value,
-              "trivially copyable");
-
 struct NonDefaultConstructible {
   static unsigned CopyConstructions;
   static unsigned Destructions;
@@ -51,10 +45,6 @@ unsigned NonDefaultConstructible::CopyConstructions = 0;
 unsigned NonDefaultConstructible::Destructions = 0;
 unsigned NonDefaultConstructible::CopyAssignments = 0;
 
-static_assert(
-    !llvm::is_trivially_copyable<Optional<NonDefaultConstructible>>::value,
-    "not trivially copyable");
-
 // Test fixture
 class OptionalTest : public testing::Test {
 };
@@ -213,10 +203,6 @@ struct MultiArgConstructor {
 };
 unsigned MultiArgConstructor::Destructions = 0;
 
-static_assert(
-    !llvm::is_trivially_copyable<Optional<MultiArgConstructor>>::value,
-    "not trivially copyable");
-
 TEST_F(OptionalTest, Emplace) {
   MultiArgConstructor::ResetCounts();
   Optional<MultiArgConstructor> A;
@@ -264,9 +250,6 @@ unsigned MoveOnly::MoveConstructions = 0;
 unsigned MoveOnly::Destructions = 0;
 unsigned MoveOnly::MoveAssignments = 0;
 
-static_assert(!llvm::is_trivially_copyable<Optional<MoveOnly>>::value,
-              "not trivially copyable");
-
 TEST_F(OptionalTest, MoveOnlyNull) {
   MoveOnly::ResetCounts();
   Optional<MoveOnly> O;
@@ -368,9 +351,6 @@ struct Immovable {
 unsigned Immovable::Constructions = 0;
 unsigned Immovable::Destructions = 0;
 
-static_assert(!llvm::is_trivially_copyable<Optional<Immovable>>::value,
-              "not trivially copyable");
-
 TEST_F(OptionalTest, ImmovableEmplace) {
   Optional<Immovable> A;
   Immovable::ResetCounts();