gecko-dev/mfbt/UniquePtr.h
Jeff Walden 29d704f6d4 Bug 1040830 - Add documentation overview comments for mozilla::MakeUnique. r=jcranmer
--HG--
extra : rebase_source : 22eb26bb8c984a28352db0329da786c419e32dc7
2014-07-18 12:24:47 -04:00

741 lines
25 KiB
C++

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/* Smart pointer managing sole ownership of a resource. */
#ifndef mozilla_UniquePtr_h
#define mozilla_UniquePtr_h
#include "mozilla/Assertions.h"
#include "mozilla/Attributes.h"
#include "mozilla/Compiler.h"
#include "mozilla/Move.h"
#include "mozilla/NullPtr.h"
#include "mozilla/Pair.h"
#include "mozilla/TypeTraits.h"
namespace mozilla {
template<typename T> class DefaultDelete;
template<typename T, class D = DefaultDelete<T>> class UniquePtr;
} // namespace mozilla
namespace mozilla {
/**
* UniquePtr is a smart pointer that wholly owns a resource. Ownership may be
* transferred out of a UniquePtr through explicit action, but otherwise the
* resource is destroyed when the UniquePtr is destroyed.
*
* UniquePtr is similar to C++98's std::auto_ptr, but it improves upon auto_ptr
* in one crucial way: it's impossible to copy a UniquePtr. Copying an auto_ptr
* obviously *can't* copy ownership of its singly-owned resource. So what
* happens if you try to copy one? Bizarrely, ownership is implicitly
* *transferred*, preserving single ownership but breaking code that assumes a
* copy of an object is identical to the original. (This is why auto_ptr is
* prohibited in STL containers.)
*
* UniquePtr solves this problem by being *movable* rather than copyable.
* Instead of passing a |UniquePtr u| directly to the constructor or assignment
* operator, you pass |Move(u)|. In doing so you indicate that you're *moving*
* ownership out of |u|, into the target of the construction/assignment. After
* the transfer completes, |u| contains |nullptr| and may be safely destroyed.
* This preserves single ownership but also allows UniquePtr to be moved by
* algorithms that have been made move-safe. (Note: if |u| is instead a
* temporary expression, don't use |Move()|: just pass the expression, because
* it's already move-ready. For more information see Move.h.)
*
* UniquePtr is also better than std::auto_ptr in that the deletion operation is
* customizable. An optional second template parameter specifies a class that
* (through its operator()(T*)) implements the desired deletion policy. If no
* policy is specified, mozilla::DefaultDelete<T> is used -- which will either
* |delete| or |delete[]| the resource, depending whether the resource is an
* array. Custom deletion policies ideally should be empty classes (no member
* fields, no member fields in base classes, no virtual methods/inheritance),
* because then UniquePtr can be just as efficient as a raw pointer.
*
* Use of UniquePtr proceeds like so:
*
* UniquePtr<int> g1; // initializes to nullptr
* g1.reset(new int); // switch resources using reset()
* g1 = nullptr; // clears g1, deletes the int
*
* UniquePtr<int> g2(new int); // owns that int
* int* p = g2.release(); // g2 leaks its int -- still requires deletion
* delete p; // now freed
*
* struct S { int x; S(int x) : x(x) {} };
* UniquePtr<S> g3, g4(new S(5));
* g3 = Move(g4); // g3 owns the S, g4 cleared
* S* p = g3.get(); // g3 still owns |p|
* assert(g3->x == 5); // operator-> works (if .get() != nullptr)
* assert((*g3).x == 5); // also operator* (again, if not cleared)
* Swap(g3, g4); // g4 now owns the S, g3 cleared
* g3.swap(g4); // g3 now owns the S, g4 cleared
* UniquePtr<S> g5(Move(g3)); // g5 owns the S, g3 cleared
* g5.reset(); // deletes the S, g5 cleared
*
* struct FreePolicy { void operator()(void* p) { free(p); } };
* UniquePtr<int, FreePolicy> g6(static_cast<int*>(malloc(sizeof(int))));
* int* ptr = g6.get();
* g6 = nullptr; // calls free(ptr)
*
* Now, carefully note a few things you *can't* do:
*
* UniquePtr<int> b1;
* b1 = new int; // BAD: can only assign another UniquePtr
* int* ptr = b1; // BAD: no auto-conversion to pointer, use get()
*
* UniquePtr<int> b2(b1); // BAD: can't copy a UniquePtr
* UniquePtr<int> b3 = b1; // BAD: can't copy-assign a UniquePtr
*
* (Note that changing a UniquePtr to store a direct |new| expression is
* permitted, but usually you should use MakeUnique, defined at the end of this
* header.)
*
* A few miscellaneous notes:
*
* UniquePtr, when not instantiated for an array type, can be move-constructed
* and move-assigned, not only from itself but from "derived" UniquePtr<U, E>
* instantiations where U converts to T and E converts to D. If you want to use
* this, you're going to have to specify a deletion policy for both UniquePtr
* instantations, and T pretty much has to have a virtual destructor. In other
* words, this doesn't work:
*
* struct Base { virtual ~Base() {} };
* struct Derived : Base {};
*
* UniquePtr<Base> b1;
* // BAD: DefaultDelete<Base> and DefaultDelete<Derived> don't interconvert
* UniquePtr<Derived> d1(Move(b));
*
* UniquePtr<Base> b2;
* UniquePtr<Derived, DefaultDelete<Base>> d2(Move(b2)); // okay
*
* UniquePtr is specialized for array types. Specializing with an array type
* creates a smart-pointer version of that array -- not a pointer to such an
* array.
*
* UniquePtr<int[]> arr(new int[5]);
* arr[0] = 4;
*
* What else is different? Deletion of course uses |delete[]|. An operator[]
* is provided. Functionality that doesn't make sense for arrays is removed.
* The constructors and mutating methods only accept array pointers (not T*, U*
* that converts to T*, or UniquePtr<U[]> or UniquePtr<U>) or |nullptr|.
*
* It's perfectly okay to return a UniquePtr from a method to assure the related
* resource is properly deleted. You'll need to use |Move()| when returning a
* local UniquePtr. Otherwise you can return |nullptr|, or you can return
* |UniquePtr(ptr)|.
*
* UniquePtr will commonly be a member of a class, with lifetime equivalent to
* that of that class. If you want to expose the related resource, you could
* expose a raw pointer via |get()|, but ownership of a raw pointer is
* inherently unclear. So it's better to expose a |const UniquePtr&| instead.
* This prohibits mutation but still allows use of |get()| when needed (but
* operator-> is preferred). Of course, you can only use this smart pointer as
* long as the enclosing class instance remains live -- no different than if you
* exposed the |get()| raw pointer.
*
* To pass a UniquePtr-managed resource as a pointer, use a |const UniquePtr&|
* argument. To specify an inout parameter (where the method may or may not
* take ownership of the resource, or reset it), or to specify an out parameter
* (where simply returning a |UniquePtr| isn't possible), use a |UniquePtr&|
* argument. To unconditionally transfer ownership of a UniquePtr
* into a method, use a |UniquePtr| argument. To conditionally transfer
* ownership of a resource into a method, should the method want it, use a
* |UniquePtr&&| argument.
*/
template<typename T, class D>
class UniquePtr
{
public:
typedef T* Pointer;
typedef T ElementType;
typedef D DeleterType;
private:
Pair<Pointer, DeleterType> tuple;
Pointer& ptr() { return tuple.first(); }
const Pointer& ptr() const { return tuple.first(); }
DeleterType& del() { return tuple.second(); }
const DeleterType& del() const { return tuple.second(); }
public:
/**
* Construct a UniquePtr containing |nullptr|.
*/
MOZ_CONSTEXPR UniquePtr()
: tuple(static_cast<Pointer>(nullptr), DeleterType())
{
static_assert(!IsPointer<D>::value, "must provide a deleter instance");
static_assert(!IsReference<D>::value, "must provide a deleter instance");
}
/**
* Construct a UniquePtr containing |p|.
*/
explicit UniquePtr(Pointer p)
: tuple(p, DeleterType())
{
static_assert(!IsPointer<D>::value, "must provide a deleter instance");
static_assert(!IsReference<D>::value, "must provide a deleter instance");
}
UniquePtr(Pointer p,
typename Conditional<IsReference<D>::value,
D,
const D&>::Type d1)
: tuple(p, d1)
{}
// If you encounter an error with MSVC10 about RemoveReference below, along
// the lines that "more than one partial specialization matches the template
// argument list": don't use UniquePtr<T, reference to function>! Ideally
// you should make deletion use the same function every time, using a
// deleter policy:
//
// // BAD, won't compile with MSVC10, deleter doesn't need to be a
// // variable at all
// typedef void (&FreeSignature)(void*);
// UniquePtr<int, FreeSignature> ptr((int*) malloc(sizeof(int)), free);
//
// // GOOD, compiles with MSVC10, deletion behavior statically known and
// // optimizable
// struct DeleteByFreeing
// {
// void operator()(void* ptr) { free(ptr); }
// };
//
// If deletion really, truly, must be a variable: you might be able to work
// around this with a deleter class that contains the function reference.
// But this workaround is untried and untested, because variable deletion
// behavior really isn't something you should use.
UniquePtr(Pointer p,
typename RemoveReference<D>::Type&& d2)
: tuple(p, Move(d2))
{
static_assert(!IsReference<D>::value,
"rvalue deleter can't be stored by reference");
}
UniquePtr(UniquePtr&& other)
: tuple(other.release(), Forward<DeleterType>(other.getDeleter()))
{}
template<typename N>
UniquePtr(N,
typename EnableIf<IsNullPointer<N>::value, int>::Type dummy = 0)
: tuple(static_cast<Pointer>(nullptr), DeleterType())
{
static_assert(!IsPointer<D>::value, "must provide a deleter instance");
static_assert(!IsReference<D>::value, "must provide a deleter instance");
}
template<typename U, class E>
UniquePtr(UniquePtr<U, E>&& other,
typename EnableIf<IsConvertible<typename UniquePtr<U, E>::Pointer,
Pointer>::value &&
!IsArray<U>::value &&
(IsReference<D>::value
? IsSame<D, E>::value
: IsConvertible<E, D>::value),
int>::Type dummy = 0)
: tuple(other.release(), Forward<E>(other.getDeleter()))
{
}
~UniquePtr() {
reset(nullptr);
}
UniquePtr& operator=(UniquePtr&& other) {
reset(other.release());
getDeleter() = Forward<DeleterType>(other.getDeleter());
return *this;
}
template<typename U, typename E>
UniquePtr& operator=(UniquePtr<U, E>&& other)
{
static_assert(IsConvertible<typename UniquePtr<U, E>::Pointer, Pointer>::value,
"incompatible UniquePtr pointees");
static_assert(!IsArray<U>::value,
"can't assign from UniquePtr holding an array");
reset(other.release());
getDeleter() = Forward<E>(other.getDeleter());
return *this;
}
UniquePtr& operator=(NullptrT n) {
MOZ_ASSERT(n == nullptr);
reset(nullptr);
return *this;
}
T& operator*() const { return *get(); }
Pointer operator->() const {
MOZ_ASSERT(get(), "dereferencing a UniquePtr containing nullptr");
return get();
}
Pointer get() const { return ptr(); }
DeleterType& getDeleter() { return del(); }
const DeleterType& getDeleter() const { return del(); }
private:
typedef void (UniquePtr::* ConvertibleToBool)(double, char);
void nonNull(double, char) {}
public:
operator ConvertibleToBool() const {
return get() != nullptr ? &UniquePtr::nonNull : nullptr;
}
Pointer release() {
Pointer p = ptr();
ptr() = nullptr;
return p;
}
void reset(Pointer p = Pointer()) {
Pointer old = ptr();
ptr() = p;
if (old != nullptr) {
getDeleter()(old);
}
}
void swap(UniquePtr& other) {
tuple.swap(other.tuple);
}
private:
UniquePtr(const UniquePtr& other) MOZ_DELETE; // construct using Move()!
void operator=(const UniquePtr& other) MOZ_DELETE; // assign using Move()!
};
// In case you didn't read the comment by the main definition (you should!): the
// UniquePtr<T[]> specialization exists to manage array pointers. It deletes
// such pointers using delete[], it will reject construction and modification
// attempts using U* or U[]. Otherwise it works like the normal UniquePtr.
template<typename T, class D>
class UniquePtr<T[], D>
{
public:
typedef T* Pointer;
typedef T ElementType;
typedef D DeleterType;
private:
Pair<Pointer, DeleterType> tuple;
public:
/**
* Construct a UniquePtr containing nullptr.
*/
MOZ_CONSTEXPR UniquePtr()
: tuple(static_cast<Pointer>(nullptr), DeleterType())
{
static_assert(!IsPointer<D>::value, "must provide a deleter instance");
static_assert(!IsReference<D>::value, "must provide a deleter instance");
}
/**
* Construct a UniquePtr containing |p|.
*/
explicit UniquePtr(Pointer p)
: tuple(p, DeleterType())
{
static_assert(!IsPointer<D>::value, "must provide a deleter instance");
static_assert(!IsReference<D>::value, "must provide a deleter instance");
}
private:
// delete[] knows how to handle *only* an array of a single class type. For
// delete[] to work correctly, it must know the size of each element, the
// fields and base classes of each element requiring destruction, and so on.
// So forbid all overloads which would end up invoking delete[] on a pointer
// of the wrong type.
template<typename U>
UniquePtr(U&& u,
typename EnableIf<IsPointer<U>::value &&
IsConvertible<U, Pointer>::value,
int>::Type dummy = 0)
MOZ_DELETE;
public:
UniquePtr(Pointer p,
typename Conditional<IsReference<D>::value,
D,
const D&>::Type d1)
: tuple(p, d1)
{}
// If you encounter an error with MSVC10 about RemoveReference below, along
// the lines that "more than one partial specialization matches the template
// argument list": don't use UniquePtr<T[], reference to function>! See the
// comment by this constructor in the non-T[] specialization above.
UniquePtr(Pointer p,
typename RemoveReference<D>::Type&& d2)
: tuple(p, Move(d2))
{
static_assert(!IsReference<D>::value,
"rvalue deleter can't be stored by reference");
}
private:
// Forbidden for the same reasons as stated above.
template<typename U, typename V>
UniquePtr(U&& u, V&& v,
typename EnableIf<IsPointer<U>::value &&
IsConvertible<U, Pointer>::value,
int>::Type dummy = 0)
MOZ_DELETE;
public:
UniquePtr(UniquePtr&& other)
: tuple(other.release(), Forward<DeleterType>(other.getDeleter()))
{}
template<typename N>
UniquePtr(N,
typename EnableIf<IsNullPointer<N>::value, int>::Type dummy = 0)
: tuple(static_cast<Pointer>(nullptr), DeleterType())
{
static_assert(!IsPointer<D>::value, "must provide a deleter instance");
static_assert(!IsReference<D>::value, "must provide a deleter instance");
}
~UniquePtr() {
reset(nullptr);
}
UniquePtr& operator=(UniquePtr&& other) {
reset(other.release());
getDeleter() = Forward<DeleterType>(other.getDeleter());
return *this;
}
UniquePtr& operator=(NullptrT) {
reset();
return *this;
}
T& operator[](decltype(sizeof(int)) i) const { return get()[i]; }
Pointer get() const { return tuple.first(); }
DeleterType& getDeleter() { return tuple.second(); }
const DeleterType& getDeleter() const { return tuple.second(); }
private:
typedef void (UniquePtr::* ConvertibleToBool)(double, char);
void nonNull(double, char) {}
public:
operator ConvertibleToBool() const {
return get() != nullptr ? &UniquePtr::nonNull : nullptr;
}
Pointer release() {
Pointer p = tuple.first();
tuple.first() = nullptr;
return p;
}
void reset(Pointer p = Pointer()) {
Pointer old = tuple.first();
tuple.first() = p;
if (old != nullptr) {
tuple.second()(old);
}
}
private:
// Kill off all remaining overloads that aren't true nullptr (the overload
// above should handle that) or emulated nullptr (which acts like int/long
// on gcc 4.4/4.5).
template<typename U>
void reset(U,
typename EnableIf<!IsNullPointer<U>::value &&
!IsSame<U,
Conditional<(sizeof(int) == sizeof(void*)),
int,
long>::Type>::value,
int>::Type dummy = 0)
MOZ_DELETE;
public:
void swap(UniquePtr& other) {
tuple.swap(other.tuple);
}
private:
UniquePtr(const UniquePtr& other) MOZ_DELETE; // construct using Move()!
void operator=(const UniquePtr& other) MOZ_DELETE; // assign using Move()!
};
/** A default deletion policy using plain old operator delete. */
template<typename T>
class DefaultDelete
{
public:
MOZ_CONSTEXPR DefaultDelete() {}
template<typename U>
DefaultDelete(const DefaultDelete<U>& other,
typename EnableIf<mozilla::IsConvertible<U*, T*>::value,
int>::Type dummy = 0)
{}
void operator()(T* ptr) const {
static_assert(sizeof(T) > 0, "T must be complete");
delete ptr;
}
};
/** A default deletion policy using operator delete[]. */
template<typename T>
class DefaultDelete<T[]>
{
public:
MOZ_CONSTEXPR DefaultDelete() {}
void operator()(T* ptr) const {
static_assert(sizeof(T) > 0, "T must be complete");
delete[] ptr;
}
private:
template<typename U>
void operator()(U* ptr) const MOZ_DELETE;
};
template<typename T, class D>
void
Swap(UniquePtr<T, D>& x, UniquePtr<T, D>& y)
{
x.swap(y);
}
template<typename T, class D, typename U, class E>
bool
operator==(const UniquePtr<T, D>& x, const UniquePtr<U, E>& y)
{
return x.get() == y.get();
}
template<typename T, class D, typename U, class E>
bool
operator!=(const UniquePtr<T, D>& x, const UniquePtr<U, E>& y)
{
return x.get() != y.get();
}
template<typename T, class D>
bool
operator==(const UniquePtr<T, D>& x, NullptrT n)
{
MOZ_ASSERT(n == nullptr);
return !x;
}
template<typename T, class D>
bool
operator==(NullptrT n, const UniquePtr<T, D>& x)
{
MOZ_ASSERT(n == nullptr);
return !x;
}
template<typename T, class D>
bool
operator!=(const UniquePtr<T, D>& x, NullptrT n)
{
MOZ_ASSERT(n == nullptr);
return bool(x);
}
template<typename T, class D>
bool
operator!=(NullptrT n, const UniquePtr<T, D>& x)
{
MOZ_ASSERT(n == nullptr);
return bool(x);
}
// No operator<, operator>, operator<=, operator>= for now because simplicity.
namespace detail {
template<typename T>
struct UniqueSelector
{
typedef UniquePtr<T> SingleObject;
};
template<typename T>
struct UniqueSelector<T[]>
{
typedef UniquePtr<T[]> UnknownBound;
};
template<typename T, decltype(sizeof(int)) N>
struct UniqueSelector<T[N]>
{
typedef UniquePtr<T[N]> KnownBound;
};
} // namespace detail
/**
* MakeUnique is a helper function for allocating new'd objects and arrays,
* returning a UniquePtr containing the resulting pointer. The semantics of
* MakeUnique<Type>(...) are as follows.
*
* If Type is an array T[n]:
* Disallowed, deleted, no overload for you!
* If Type is an array T[]:
* MakeUnique<T[]>(size_t) is the only valid overload. The pointer returned
* is as if by |new T[n]()|, which value-initializes each element. (If T
* isn't a class type, this will zero each element. If T is a class type,
* then roughly speaking, each element will be constructed using its default
* constructor. See C++11 [dcl.init]p7 for the full gory details.)
* If Type is non-array T:
* The arguments passed to MakeUnique<T>(...) are forwarded into a
* |new T(...)| call, initializing the T as would happen if executing
* |T(...)|. (Note: literal nullptr must not be provided as an argument to
* MakeUnique, because nullptr may be emulated. See Move.h for details.)
*
* There are various benefits to using MakeUnique instead of |new| expressions.
*
* First, MakeUnique eliminates use of |new| from code entirely. If objects are
* only created through UniquePtr, then (assuming all explicit release() calls
* are safe, including transitively, and no type-safety casting funniness)
* correctly maintained ownership of the UniquePtr guarantees no leaks are
* possible. (This pays off best if a class is only ever created through a
* factory method on the class, using a private constructor.)
*
* Second, initializing a UniquePtr using a |new| expression requires renaming
* the new'd type, whereas MakeUnique in concert with the |auto| keyword names
* it only once:
*
* UniquePtr<char> ptr1(new char()); // repetitive
* auto ptr2 = MakeUnique<char>(); // shorter
*
* Of course this assumes the reader understands the operation MakeUnique
* performs. In the long run this is probably a reasonable assumption. In the
* short run you'll have to use your judgment about what readers can be expected
* to know, or to quickly look up.
*
* Third, a call to MakeUnique can be assigned directly to a UniquePtr. In
* contrast you can't assign a pointer into a UniquePtr without using the
* cumbersome reset().
*
* UniquePtr<char> p;
* p = new char; // ERROR
* p.reset(new char); // works, but fugly
* p = MakeUnique<char>(); // preferred
*
* (And third, although not relevant to Mozilla: MakeUnique is exception-safe.
* An exception thrown after |new T| succeeds will leak that memory, unless the
* pointer is assigned to an object that will manage its ownership. UniquePtr
* ably serves this function.)
*/
// We don't have variadic template support everywhere, so just hard-code arities
// 0-5 for now. If you need more arguments, feel free to add the extra
// overloads (and deletions for the T = E[N] case).
//
// Beware! Due to lack of true nullptr support in gcc 4.4 and 4.5, passing
// literal nullptr to MakeUnique will not work on some platforms. See Move.h
// for more details.
template<typename T>
typename detail::UniqueSelector<T>::SingleObject
MakeUnique()
{
return UniquePtr<T>(new T());
}
template<typename T, typename A1>
typename detail::UniqueSelector<T>::SingleObject
MakeUnique(A1&& a1)
{
return UniquePtr<T>(new T(Forward<A1>(a1)));
}
template<typename T, typename A1, typename A2>
typename detail::UniqueSelector<T>::SingleObject
MakeUnique(A1&& a1, A2&& a2)
{
return UniquePtr<T>(new T(Forward<A1>(a1), Forward<A2>(a2)));
}
template<typename T, typename A1, typename A2, typename A3>
typename detail::UniqueSelector<T>::SingleObject
MakeUnique(A1&& a1, A2&& a2, A3&& a3)
{
return UniquePtr<T>(new T(Forward<A1>(a1), Forward<A2>(a2), Forward<A3>(a3)));
}
template<typename T, typename A1, typename A2, typename A3, typename A4>
typename detail::UniqueSelector<T>::SingleObject
MakeUnique(A1&& a1, A2&& a2, A3&& a3, A4&& a4)
{
return UniquePtr<T>(new T(Forward<A1>(a1), Forward<A2>(a2), Forward<A3>(a3),
Forward<A4>(a4)));
}
template<typename T, typename A1, typename A2, typename A3, typename A4, typename A5>
typename detail::UniqueSelector<T>::SingleObject
MakeUnique(A1&& a1, A2&& a2, A3&& a3, A4&& a4, A5&& a5)
{
return UniquePtr<T>(new T(Forward<A1>(a1), Forward<A2>(a2), Forward<A3>(a3), Forward<A4>(a4), Forward<A5>(a5)));
}
template<typename T>
typename detail::UniqueSelector<T>::UnknownBound
MakeUnique(decltype(sizeof(int)) n)
{
typedef typename RemoveExtent<T>::Type ArrayType;
return UniquePtr<T>(new ArrayType[n]());
}
template<typename T>
typename detail::UniqueSelector<T>::KnownBound
MakeUnique() MOZ_DELETE;
template<typename T, typename A1>
typename detail::UniqueSelector<T>::KnownBound
MakeUnique(A1&& a1) MOZ_DELETE;
template<typename T, typename A1, typename A2>
typename detail::UniqueSelector<T>::KnownBound
MakeUnique(A1&& a1, A2&& a2) MOZ_DELETE;
template<typename T, typename A1, typename A2, typename A3>
typename detail::UniqueSelector<T>::KnownBound
MakeUnique(A1&& a1, A2&& a2, A3&& a3) MOZ_DELETE;
template<typename T, typename A1, typename A2, typename A3, typename A4>
typename detail::UniqueSelector<T>::KnownBound
MakeUnique(A1&& a1, A2&& a2, A3&& a3, A4&& a4) MOZ_DELETE;
template<typename T, typename A1, typename A2, typename A3, typename A4, typename A5>
typename detail::UniqueSelector<T>::KnownBound
MakeUnique(A1&& a1, A2&& a2, A3&& a3, A4&& a4, A5&& a5) MOZ_DELETE;
} // namespace mozilla
#endif /* mozilla_UniquePtr_h */