Remove legacy scoped_ptr implementation.

base/memory/scoped_ptr.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Scopers help you manage ownership of a pointer, helping you easily manage a
 // pointer within a scope, and automatically destroying the pointer at the end
 // of a scope.  There are two main classes you will use, which correspond to the
 // operators new/delete and new[]/delete[].
 //
 // Example usage (scoped_ptr<T>):
@@ skipping 72 matching lines @@
 //
 //   scoped_ptr<Foo> foo(new Foo());
 //   scoped_ptr<FooParent> parent(std::move(foo));
 
 #ifndef BASE_MEMORY_SCOPED_PTR_H_
 #define BASE_MEMORY_SCOPED_PTR_H_
 
 // This is an implementation designed to match the anticipated future TR2
 // implementation of the scoped_ptr class.
 
+// TODO(dcheng): Clean up these headers, but there are likely lots of existing
+// IWYU violations.
 #include <stddef.h>
 #include <stdlib.h>
 
 #include <iosfwd>
 #include <memory>
 #include <type_traits>
 #include <utility>
 
 #include "base/compiler_specific.h"
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/move.h"
 #include "build/build_config.h"
 
 namespace base {
 
 // Function object which invokes 'free' on its parameter, which must be
 // a pointer. Can be used to store malloc-allocated pointers in scoped_ptr:
 //
 // scoped_ptr<int, base::FreeDeleter> foo_ptr(
 //     static_cast<int*>(malloc(sizeof(int))));
 struct FreeDeleter {
   inline void operator()(void* ptr) const {
     free(ptr);
   }
 };
 
 }  // namespace base
 
-// Now that scoped_ptr is almost 100% compatible with std::unique_ptr, we're
-// incrementally migrating scoped_ptr to just be a type alias for
-// std::unique_ptr. The eventual goal is to delete scoped_ptr altogether.
-#if defined(OS_LINUX) || defined(OS_WIN) || defined(OS_ANDROID) || \
-    defined(OS_MACOSX)
 template <typename T, typename D = std::default_delete<T>>
 using scoped_ptr = std::unique_ptr<T, D>;
 
 // Versions of libstdc++ 4.8 lack overloads for <, <=, >, and >= when comparing
 // a std::unique_ptr and nullptr_t.
 #if defined(__GLIBCXX__) && __GLIBCXX__ < 20150123
 template <class T, class D>
 bool operator<(const scoped_ptr<T, D>& p, std::nullptr_t) {
   return p.get() < nullptr;
 }
@@ skipping 21 matching lines @@
 }
 
 template <class T, class D>
 bool operator>=(const scoped_ptr<T, D>& p, std::nullptr_t) {
   return !(p < nullptr);
 }
 template <class T, class D>
 bool operator>=(std::nullptr_t, const scoped_ptr<T, D>& p) {
   return !(nullptr < p);
 }
-#endif  // defined(__GLIBCXX__) && __GLIBCX__ < 20150426
-
-#else
-namespace base {
-
-namespace subtle {
-class RefCountedBase;
-class RefCountedThreadSafeBase;
-}  // namespace subtle
-
-namespace internal {
-
-template <typename T> struct IsNotRefCounted {
-  enum {
-    value = !std::is_convertible<T*, base::subtle::RefCountedBase*>::value &&
-        !std::is_convertible<T*, base::subtle::RefCountedThreadSafeBase*>::
-            value
-  };
-};
-
-// Minimal implementation of the core logic of scoped_ptr, suitable for
-// reuse in both scoped_ptr and its specializations.
-template <class T, class D>
-class scoped_ptr_impl {
- public:
-  explicit scoped_ptr_impl(T* p) : data_(p) {}
-
-  // Initializer for deleters that have data parameters.
-  scoped_ptr_impl(T* p, const D& d) : data_(p, d) {}
-
-  // Templated constructor that destructively takes the value from another
-  // scoped_ptr_impl.
-  template <typename U, typename V>
-  scoped_ptr_impl(scoped_ptr_impl<U, V>* other)
-      : data_(other->release(), other->get_deleter()) {
-    // We do not support move-only deleters.  We could modify our move
-    // emulation to have base::subtle::move() and base::subtle::forward()
-    // functions that are imperfect emulations of their C++11 equivalents,
-    // but until there's a requirement, just assume deleters are copyable.
-  }
-
-  template <typename U, typename V>
-  void TakeState(scoped_ptr_impl<U, V>* other) {
-    // See comment in templated constructor above regarding lack of support
-    // for move-only deleters.
-    reset(other->release());
-    get_deleter() = other->get_deleter();
-  }
-
-  ~scoped_ptr_impl() {
-    // Match libc++, which calls reset() in its destructor.
-    // Use nullptr as the new value for three reasons:
-    // 1. libc++ does it.
-    // 2. Avoids infinitely recursing into destructors if two classes are owned
-    //    in a reference cycle (see ScopedPtrTest.ReferenceCycle).
-    // 3. If |this| is accessed in the future, in a use-after-free bug, attempts
-    //    to dereference |this|'s pointer should cause either a failure or a
-    //    segfault closer to the problem. If |this| wasn't reset to nullptr,
-    //    the access would cause the deleted memory to be read or written
-    //    leading to other more subtle issues.
-    reset(nullptr);
-  }
-
-  void reset(T* p) {
-    // Match C++11's definition of unique_ptr::reset(), which requires changing
-    // the pointer before invoking the deleter on the old pointer. This prevents
-    // |this| from being accessed after the deleter is run, which may destroy
-    // |this|.
-    T* old = data_.ptr;
-    data_.ptr = p;
-    if (old != nullptr)
-      static_cast<D&>(data_)(old);
-  }
-
-  T* get() const { return data_.ptr; }
-
-  D& get_deleter() { return data_; }
-  const D& get_deleter() const { return data_; }
-
-  void swap(scoped_ptr_impl& p2) {
-    // Standard swap idiom: 'using std::swap' ensures that std::swap is
-    // present in the overload set, but we call swap unqualified so that
-    // any more-specific overloads can be used, if available.
-    using std::swap;
-    swap(static_cast<D&>(data_), static_cast<D&>(p2.data_));
-    swap(data_.ptr, p2.data_.ptr);
-  }
-
-  T* release() {
-    T* old_ptr = data_.ptr;
-    data_.ptr = nullptr;
-    return old_ptr;
-  }
-
- private:
-  // Needed to allow type-converting constructor.
-  template <typename U, typename V> friend class scoped_ptr_impl;
-
-  // Use the empty base class optimization to allow us to have a D
-  // member, while avoiding any space overhead for it when D is an
-  // empty class.  See e.g. http://www.cantrip.org/emptyopt.html for a good
-  // discussion of this technique.
-  struct Data : public D {
-    explicit Data(T* ptr_in) : ptr(ptr_in) {}
-    Data(T* ptr_in, const D& other) : D(other), ptr(ptr_in) {}
-    T* ptr;
-  };
-
-  Data data_;
-
-  DISALLOW_COPY_AND_ASSIGN(scoped_ptr_impl);
-};
-
-}  // namespace internal
-
-}  // namespace base
-
-// A scoped_ptr<T> is like a T*, except that the destructor of scoped_ptr<T>
-// automatically deletes the pointer it holds (if any).
-// That is, scoped_ptr<T> owns the T object that it points to.
-// Like a T*, a scoped_ptr<T> may hold either nullptr or a pointer to a T
-// object. Also like T*, scoped_ptr<T> is thread-compatible, and once you
-// dereference it, you get the thread safety guarantees of T.
-//
-// The size of scoped_ptr is small. On most compilers, when using the
-// std::default_delete, sizeof(scoped_ptr<T>) == sizeof(T*). Custom deleters
-// will increase the size proportional to whatever state they need to have. See
-// comments inside scoped_ptr_impl<> for details.
-//
-// Current implementation targets having a strict subset of  C++11's
-// unique_ptr<> features. Known deficiencies include not supporting move-only
-// deleteres, function pointers as deleters, and deleters with reference
-// types.
-template <class T, class D = std::default_delete<T>>
-class scoped_ptr {
-  DISALLOW_COPY_AND_ASSIGN_WITH_MOVE_FOR_BIND(scoped_ptr)
-
-  static_assert(!std::is_array<T>::value,
-                "scoped_ptr doesn't support array with size");
-  static_assert(base::internal::IsNotRefCounted<T>::value,
-                "T is a refcounted type and needs a scoped_refptr");
-
- public:
-  // The element and deleter types.
-  using element_type = T;
-  using deleter_type = D;
-
-  // Constructor.  Defaults to initializing with nullptr.
-  scoped_ptr() : impl_(nullptr) {}
-
-  // Constructor.  Takes ownership of p.
-  explicit scoped_ptr(element_type* p) : impl_(p) {}
-
-  // Constructor.  Allows initialization of a stateful deleter.
-  scoped_ptr(element_type* p, const D& d) : impl_(p, d) {}
-
-  // Constructor.  Allows construction from a nullptr.
-  scoped_ptr(std::nullptr_t) : impl_(nullptr) {}
-
-  // Move constructor.
-  //
-  // IMPLEMENTATION NOTE: Clang requires a move constructor to be defined (and
-  // not just the conversion constructor) in order to warn on pessimizing moves.
-  // The requirements for the move constructor are specified in C++11
-  // 20.7.1.2.1.15-17, which has some subtleties around reference deleters. As
-  // we don't support reference (or move-only) deleters, the post conditions are
-  // trivially true: we always copy construct the deleter from other's deleter.
-  scoped_ptr(scoped_ptr&& other) : impl_(&other.impl_) {}
-
-  // Conversion constructor.  Allows construction from a scoped_ptr rvalue for a
-  // convertible type and deleter.
-  //
-  // IMPLEMENTATION NOTE: C++ 20.7.1.2.1.19 requires this constructor to only
-  // participate in overload resolution if all the following are true:
-  // - U is implicitly convertible to T: this is important for 2 reasons:
-  //     1. So type traits don't incorrectly return true, e.g.
-  //          std::is_convertible<scoped_ptr<Base>, scoped_ptr<Derived>>::value
-  //        should be false.
-  //     2. To make sure code like this compiles:
-  //        void F(scoped_ptr<int>);
-  //        void F(scoped_ptr<Base>);
-  //        // Ambiguous since both conversion constructors match.
-  //        F(scoped_ptr<Derived>());
-  // - U is not an array type: to prevent conversions from scoped_ptr<T[]> to
-  //   scoped_ptr<T>.
-  // - D is a reference type and E is the same type, or D is not a reference
-  //   type and E is implicitly convertible to D: again, we don't support
-  //   reference deleters, so we only worry about the latter requirement.
-  template <typename U,
-            typename E,
-            typename std::enable_if<!std::is_array<U>::value &&
-                                    std::is_convertible<U*, T*>::value &&
-                                    std::is_convertible<E, D>::value>::type* =
-                nullptr>
-  scoped_ptr(scoped_ptr<U, E>&& other)
-      : impl_(&other.impl_) {}
-
-  // operator=.
-  //
-  // IMPLEMENTATION NOTE: Unlike the move constructor, Clang does not appear to
-  // require a move assignment operator to trigger the pessimizing move warning:
-  // in this case, the warning triggers when moving a temporary. For consistency
-  // with the move constructor, we define it anyway. C++11 20.7.1.2.3.1-3
-  // defines several requirements around this: like the move constructor, the
-  // requirements are simplified by the fact that we don't support move-only or
-  // reference deleters.
-  scoped_ptr& operator=(scoped_ptr&& rhs) {
-    impl_.TakeState(&rhs.impl_);
-    return *this;
-  }
-
-  // operator=.  Allows assignment from a scoped_ptr rvalue for a convertible
-  // type and deleter.
-  //
-  // IMPLEMENTATION NOTE: C++11 unique_ptr<> keeps this operator= distinct from
-  // the normal move assignment operator. C++11 20.7.1.2.3.4-7 contains the
-  // requirement for this operator, but like the conversion constructor, the
-  // requirements are greatly simplified by not supporting move-only or
-  // reference deleters.
-  template <typename U,
-            typename E,
-            typename std::enable_if<!std::is_array<U>::value &&
-                                    std::is_convertible<U*, T*>::value &&
-                                    // Note that this really should be
-                                    // std::is_assignable, but <type_traits>
-                                    // appears to be missing this on some
-                                    // platforms. This is close enough (though
-                                    // it's not the same).
-                                    std::is_convertible<D, E>::value>::type* =
-                nullptr>
-  scoped_ptr& operator=(scoped_ptr<U, E>&& rhs) {
-    impl_.TakeState(&rhs.impl_);
-    return *this;
-  }
-
-  // operator=.  Allows assignment from a nullptr. Deletes the currently owned
-  // object, if any.
-  scoped_ptr& operator=(std::nullptr_t) {
-    reset();
-    return *this;
-  }
-
-  // Reset.  Deletes the currently owned object, if any.
-  // Then takes ownership of a new object, if given.
-  void reset(element_type* p = nullptr) { impl_.reset(p); }
-
-  // Accessors to get the owned object.
-  // operator* and operator-> will DCHECK() if there is no current object.
-  element_type& operator*() const {
-    DCHECK(impl_.get() != nullptr);
-    return *impl_.get();
-  }
-  element_type* operator->() const  {
-    DCHECK(impl_.get() != nullptr);
-    return impl_.get();
-  }
-  element_type* get() const { return impl_.get(); }
-
-  // Access to the deleter.
-  deleter_type& get_deleter() { return impl_.get_deleter(); }
-  const deleter_type& get_deleter() const { return impl_.get_deleter(); }
-
-  // Implement "Safe Bool Idiom"
-  // https://en.wikibooks.org/wiki/More_C%2B%2B_Idioms/Safe_bool
-  //
-  // Allow scoped_ptr<element_type> to be used in boolean expressions such as
-  //   if (scoped_ptr_instance)
-  // But do not become convertible to a real bool (which is dangerous).
-  //   Implementation requires:
-  //     typedef Testable
-  //     operator Testable() const
-  //     operator==
-  //     operator!=
-  //
-  // == and != operators must be declared explicitly or dissallowed, as
-  // otherwise "ptr1 == ptr2" will compile but do the wrong thing (i.e., convert
-  // to Testable and then do the comparison).
-  //
-  // C++11 provides for "explicit operator bool()", however it is currently
-  // banned due to MSVS2013. https://chromium-cpp.appspot.com/#core-blacklist
- private:
-  typedef base::internal::scoped_ptr_impl<element_type, deleter_type>
-      scoped_ptr::*Testable;
- public:
-  operator Testable() const {
-    return impl_.get() ? &scoped_ptr::impl_ : nullptr;
-  }
-
-  // Swap two scoped pointers.
-  void swap(scoped_ptr& p2) {
-    impl_.swap(p2.impl_);
-  }
-
-  // Release a pointer.
-  // The return value is the current pointer held by this object. If this object
-  // holds a nullptr, the return value is nullptr. After this operation, this
-  // object will hold a nullptr, and will not own the object any more.
-  element_type* release() WARN_UNUSED_RESULT {
-    return impl_.release();
-  }
-
- private:
-  // Needed to reach into |impl_| in the constructor.
-  template <typename U, typename V> friend class scoped_ptr;
-  base::internal::scoped_ptr_impl<element_type, deleter_type> impl_;
-
-  // Forbidden for API compatibility with std::unique_ptr.
-  explicit scoped_ptr(int disallow_construction_from_null);
-};
-
-template <class T, class D>
-class scoped_ptr<T[], D> {
-  DISALLOW_COPY_AND_ASSIGN_WITH_MOVE_FOR_BIND(scoped_ptr)
-
- public:
-  // The element and deleter types.
-  using element_type = T;
-  using deleter_type = D;
-
-  // Constructor.  Defaults to initializing with nullptr.
-  scoped_ptr() : impl_(nullptr) {}
-
-  // Constructor. Stores the given array. Note that the argument's type
-  // must exactly match T*. In particular:
-  // - it cannot be a pointer to a type derived from T, because it is
-  //   inherently unsafe in the general case to access an array through a
-  //   pointer whose dynamic type does not match its static type (eg., if
-  //   T and the derived types had different sizes access would be
-  //   incorrectly calculated). Deletion is also always undefined
-  //   (C++98 [expr.delete]p3). If you're doing this, fix your code.
-  // - it cannot be const-qualified differently from T per unique_ptr spec
-  //   (http://cplusplus.github.com/LWG/lwg-active.html#2118). Users wanting
-  //   to work around this may use const_cast<const T*>().
-  explicit scoped_ptr(element_type* array) : impl_(array) {}
-
-  // Constructor.  Allows construction from a nullptr.
-  scoped_ptr(std::nullptr_t) : impl_(nullptr) {}
-
-  // Constructor.  Allows construction from a scoped_ptr rvalue.
-  scoped_ptr(scoped_ptr&& other) : impl_(&other.impl_) {}
-
-  // operator=.  Allows assignment from a scoped_ptr rvalue.
-  scoped_ptr& operator=(scoped_ptr&& rhs) {
-    impl_.TakeState(&rhs.impl_);
-    return *this;
-  }
-
-  // operator=.  Allows assignment from a nullptr. Deletes the currently owned
-  // array, if any.
-  scoped_ptr& operator=(std::nullptr_t) {
-    reset();
-    return *this;
-  }
-
-  // Reset.  Deletes the currently owned array, if any.
-  // Then takes ownership of a new object, if given.
-  void reset(element_type* array = nullptr) { impl_.reset(array); }
-
-  // Accessors to get the owned array.
-  element_type& operator[](size_t i) const {
-    DCHECK(impl_.get() != nullptr);
-    return impl_.get()[i];
-  }
-  element_type* get() const { return impl_.get(); }
-
-  // Access to the deleter.
-  deleter_type& get_deleter() { return impl_.get_deleter(); }
-  const deleter_type& get_deleter() const { return impl_.get_deleter(); }
-
-  // Allow scoped_ptr<element_type> to be used in boolean expressions, but not
-  // implicitly convertible to a real bool (which is dangerous).
- private:
-  typedef base::internal::scoped_ptr_impl<element_type, deleter_type>
-      scoped_ptr::*Testable;
-
- public:
-  operator Testable() const {
-    return impl_.get() ? &scoped_ptr::impl_ : nullptr;
-  }
-
-  // Swap two scoped pointers.
-  void swap(scoped_ptr& p2) {
-    impl_.swap(p2.impl_);
-  }
-
-  // Release a pointer.
-  // The return value is the current pointer held by this object. If this object
-  // holds a nullptr, the return value is nullptr. After this operation, this
-  // object will hold a nullptr, and will not own the object any more.
-  element_type* release() WARN_UNUSED_RESULT {
-    return impl_.release();
-  }
-
- private:
-  // Force element_type to be a complete type.
-  enum { type_must_be_complete = sizeof(element_type) };
-
-  // Actually hold the data.
-  base::internal::scoped_ptr_impl<element_type, deleter_type> impl_;
-
-  // Disable initialization from any type other than element_type*, by
-  // providing a constructor that matches such an initialization, but is
-  // private and has no definition. This is disabled because it is not safe to
-  // call delete[] on an array whose static type does not match its dynamic
-  // type.
-  template <typename U> explicit scoped_ptr(U* array);
-  explicit scoped_ptr(int disallow_construction_from_null);
-
-  // Disable reset() from any type other than element_type*, for the same
-  // reasons as the constructor above.
-  template <typename U> void reset(U* array);
-  void reset(int disallow_reset_from_null);
-};
-
-// Free functions
-template <class T, class D>
-void swap(scoped_ptr<T, D>& p1, scoped_ptr<T, D>& p2) {
-  p1.swap(p2);
-}
-
-template <class T1, class D1, class T2, class D2>
-bool operator==(const scoped_ptr<T1, D1>& p1, const scoped_ptr<T2, D2>& p2) {
-  return p1.get() == p2.get();
-}
-template <class T, class D>
-bool operator==(const scoped_ptr<T, D>& p, std::nullptr_t) {
-  return p.get() == nullptr;
-}
-template <class T, class D>
-bool operator==(std::nullptr_t, const scoped_ptr<T, D>& p) {
-  return p.get() == nullptr;
-}
-
-template <class T1, class D1, class T2, class D2>
-bool operator!=(const scoped_ptr<T1, D1>& p1, const scoped_ptr<T2, D2>& p2) {
-  return !(p1 == p2);
-}
-template <class T, class D>
-bool operator!=(const scoped_ptr<T, D>& p, std::nullptr_t) {
-  return !(p == nullptr);
-}
-template <class T, class D>
-bool operator!=(std::nullptr_t, const scoped_ptr<T, D>& p) {
-  return !(p == nullptr);
-}
-
-template <class T1, class D1, class T2, class D2>
-bool operator<(const scoped_ptr<T1, D1>& p1, const scoped_ptr<T2, D2>& p2) {
-  return p1.get() < p2.get();
-}
-template <class T, class D>
-bool operator<(const scoped_ptr<T, D>& p, std::nullptr_t) {
-  return p.get() < nullptr;
-}
-template <class T, class D>
-bool operator<(std::nullptr_t, const scoped_ptr<T, D>& p) {
-  return nullptr < p.get();
-}
-
-template <class T1, class D1, class T2, class D2>
-bool operator>(const scoped_ptr<T1, D1>& p1, const scoped_ptr<T2, D2>& p2) {
-  return p2 < p1;
-}
-template <class T, class D>
-bool operator>(const scoped_ptr<T, D>& p, std::nullptr_t) {
-  return nullptr < p;
-}
-template <class T, class D>
-bool operator>(std::nullptr_t, const scoped_ptr<T, D>& p) {
-  return p < nullptr;
-}
-
-template <class T1, class D1, class T2, class D2>
-bool operator<=(const scoped_ptr<T1, D1>& p1, const scoped_ptr<T2, D2>& p2) {
-  return !(p1 > p2);
-}
-template <class T, class D>
-bool operator<=(const scoped_ptr<T, D>& p, std::nullptr_t) {
-  return !(p > nullptr);
-}
-template <class T, class D>
-bool operator<=(std::nullptr_t, const scoped_ptr<T, D>& p) {
-  return !(nullptr > p);
-}
-
-template <class T1, class D1, class T2, class D2>
-bool operator>=(const scoped_ptr<T1, D1>& p1, const scoped_ptr<T2, D2>& p2) {
-  return !(p1 < p2);
-}
-template <class T, class D>
-bool operator>=(const scoped_ptr<T, D>& p, std::nullptr_t) {
-  return !(p < nullptr);
-}
-template <class T, class D>
-bool operator>=(std::nullptr_t, const scoped_ptr<T, D>& p) {
-  return !(nullptr < p);
-}
-
-template <typename T>
-std::ostream& operator<<(std::ostream& out, const scoped_ptr<T>& p) {
-  return out << p.get();
-}
-#endif  // defined(OS_LINUX)
+#endif  // defined(__GLIBCXX__) && __GLIBCXX__ < 20150123
 
 // A function to convert T* into scoped_ptr<T>
 // Doing e.g. make_scoped_ptr(new FooBarBaz<type>(arg)) is a shorter notation
 // for scoped_ptr<FooBarBaz<type> >(new FooBarBaz<type>(arg))
 template <typename T>
 scoped_ptr<T> make_scoped_ptr(T* ptr) {
   return scoped_ptr<T>(ptr);
 }
 
 #endif  // BASE_MEMORY_SCOPED_PTR_H_