// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.

#pragma once

#include "../Common.h"
#include "../Asserts.h"
#include "ArrayView.h"

#include <algorithm>
#include <cstdlib>
#include <cstring>
#include <initializer_list>
#include <iterator>
#include <limits>
#include <memory>
#include <new>
#include <type_traits>
#include <utility>

namespace Death { namespace Containers {
//###==##====#=====--==~--~=~- --- -- -  -  -   -

	// Forward declarations for the Death::Containers namespace
	template<typename IteratorT> class iterator_range;

	/// This is all the stuff common to all SmallVectors.
	///
	/// The template parameter specifies the type which should be used to hold the
	/// Size and Capacity of the SmallVector, so it can be adjusted.
	/// Using 32-bit size is desirable to shrink the size of the SmallVector.
	/// Using 64-bit size is desirable for cases like SmallVector<char>, where a
	/// 32 bit size would limit the vector to ~4GB. SmallVectors are used for
	/// buffering bitcode output - which can exceed 4GB.
	template<class Size_T> class SmallVectorBase
	{
	protected:
		void* BeginX;
		Size_T Size = 0, Capacity;

		/// The maximum value of the Size_T used.
		static constexpr std::size_t SizeTypeMax() {
			return std::numeric_limits<Size_T>::max();
		}

		SmallVectorBase() = delete;
		SmallVectorBase(void* FirstEl, std::size_t TotalCapacity)
			: BeginX(FirstEl), Capacity((Size_T)TotalCapacity) {}

		/// This is a helper for \a grow() that's out of line to reduce code
		/// duplication.  This function will report a fatal error if it can't grow at
		/// least to \p MinSize.
		void* mallocForGrow(void* FirstEl, std::size_t MinSize, std::size_t TSize, std::size_t& NewCapacity);

		/// This is an implementation of the grow() method which only works
		/// on POD-like data types and is out of line to reduce code duplication.
		/// This function will report a fatal error if it cannot increase capacity.
		void grow_pod(void* FirstEl, std::size_t MinSize, std::size_t TSize);

		/// If vector was first created with capacity 0, getFirstEl() points to the
		/// memory right after, an area unallocated. If a subsequent allocation,
		/// that grows the vector, happens to return the same pointer as getFirstEl(),
		/// get a new allocation, otherwise isSmall() will falsely return that no
		/// allocation was done (true) and the memory will not be freed in the
		/// destructor. If a VSize is given (vector size), also copy that many
		/// elements to the new allocation - used if realloca fails to increase
		/// space, and happens to allocate precisely at BeginX.
		/// This is unlikely to be called often, but resolves a memory leak when the
		/// situation does occur.
		void* replaceAllocation(void* NewElts, std::size_t TSize, std::size_t NewCapacity, std::size_t VSize = 0);

	public:
		std::size_t size() const {
			return Size;
		}
		std::size_t capacity() const {
			return Capacity;
		}

		[[nodiscard]] bool empty() const {
			return !Size;
		}

	protected:
		/// Set the array size to \p N, which the current array must have enough
		/// capacity for.
		///
		/// This does not construct or destroy any elements in the vector.
		void set_size(std::size_t N) {
			DEATH_DEBUG_ASSERT(N <= capacity());
			Size = (Size_T)N;
		}
	};

	template<class T>
	using SmallVectorSizeType = typename std::conditional<sizeof(T) < 4 && sizeof(void*) >= 8, std::uint64_t, std::uint32_t>::type;

	/// Figure out the offset of the first element.
	template<class T, typename = void> struct SmallVectorAlignmentAndSize {
		alignas(SmallVectorBase<SmallVectorSizeType<T>>) char Base[sizeof(
			SmallVectorBase<SmallVectorSizeType<T>>)];
		alignas(T) char FirstEl[sizeof(T)];
	};

	/// This is the part of SmallVectorTemplateBase which does not depend on whether
	/// the type T is a POD. The extra dummy template argument is used by ArrayRef
	/// to avoid unnecessarily requiring T to be complete.
	template<typename T, typename = void>
	class SmallVectorTemplateCommon : public SmallVectorBase<SmallVectorSizeType<T>>
	{
		using Base = SmallVectorBase<SmallVectorSizeType<T>>;

	protected:
		/// Find the address of the first element.  For this pointer math to be valid
		/// with small-size of 0 for T with lots of alignment, it's important that
		/// SmallVectorStorage is properly-aligned even for small-size of 0.
		void* getFirstEl() const {
			return const_cast<void*>(reinterpret_cast<const void*>(
				reinterpret_cast<const char*>(this) +
				offsetof(SmallVectorAlignmentAndSize<T>, FirstEl)));
		}
		// Space after 'FirstEl' is clobbered, do not add any instance vars after it.

		SmallVectorTemplateCommon(std::size_t Size) : Base(getFirstEl(), Size) {}

		void grow_pod(std::size_t MinSize, std::size_t TSize) {
			Base::grow_pod(getFirstEl(), MinSize, TSize);
		}

		/// Return true if this is a smallvector which has not had dynamic
		/// memory allocated for it.
		bool isSmall() const {
			return this->BeginX == getFirstEl();
		}

		/// Put this vector in a state of being small.
		void resetToSmall() {
			this->BeginX = getFirstEl();
			this->Size = this->Capacity = 0; // FIXME: Setting Capacity to 0 is suspect.
		}

		/// Return true if V is an internal reference to the given range.
		bool isReferenceToRange(const void* V, const void* First, const void* Last) const {
			// Use std::less to avoid UB.
			std::less<> LessThan;
			return !LessThan(V, First) && LessThan(V, Last);
		}

		/// Return true if V is an internal reference to this vector.
		bool isReferenceToStorage(const void* V) const {
			return isReferenceToRange(V, this->begin(), this->end());
		}

		/// Return true if First and Last form a valid (possibly empty) range in this
		/// vector's storage.
		bool isRangeInStorage(const void* First, const void* Last) const {
			// Use std::less to avoid UB.
			std::less<> LessThan;
			return !LessThan(First, this->begin()) && !LessThan(Last, First) &&
				!LessThan(this->end(), Last);
		}

		/// Return true unless Elt will be invalidated by resizing the vector to
		/// NewSize.
		bool isSafeToReferenceAfterResize(const void* Elt, std::size_t NewSize) {
			// Past the end.
			if (!isReferenceToStorage(Elt))
				return true;

			// Return false if Elt will be destroyed by shrinking.
			if (NewSize <= this->size())
				return Elt < this->begin() + NewSize;

			// Return false if we need to grow.
			return NewSize <= this->capacity();
		}

		/// Check whether Elt will be invalidated by resizing the vector to NewSize.
		void assertSafeToReferenceAfterResize(const void* Elt, std::size_t NewSize) {
			DEATH_DEBUG_ASSERT(isSafeToReferenceAfterResize(Elt, NewSize),
				   "Attempting to reference an element of the vector in an operation that invalidates it", );
		}

		/// Check whether Elt will be invalidated by increasing the size of the
		/// vector by N.
		void assertSafeToAdd(const void* Elt, std::size_t N = 1) {
			this->assertSafeToReferenceAfterResize(Elt, this->size() + N);
		}

		/// Check whether any part of the range will be invalidated by clearing.
		void assertSafeToReferenceAfterClear(const T* From, const T* To) {
			if (From == To)
				return;
			this->assertSafeToReferenceAfterResize(From, 0);
			this->assertSafeToReferenceAfterResize(To - 1, 0);
		}
		template<
			class ItTy,
			std::enable_if_t<!std::is_same<std::remove_const_t<ItTy>, T*>::value,
			bool> = false>
			void assertSafeToReferenceAfterClear(ItTy, ItTy) {}

		/// Check whether any part of the range will be invalidated by growing.
		void assertSafeToAddRange(const T* From, const T* To) {
			if (From == To)
				return;
			this->assertSafeToAdd(From, To - From);
			this->assertSafeToAdd(To - 1, To - From);
		}
		template<
			class ItTy,
			std::enable_if_t<!std::is_same<std::remove_const_t<ItTy>, T*>::value,
			bool> = false>
			void assertSafeToAddRange(ItTy, ItTy) {}

		/// Reserve enough space to add one element, and return the updated element
		/// pointer in case it was a reference to the storage.
		template<class U>
		static const T* reserveForParamAndGetAddressImpl(U* This, const T& Elt, std::size_t N) {
			std::size_t NewSize = This->size() + N;
			if (NewSize <= This->capacity())
				return &Elt;

			bool ReferencesStorage = false;
			std::int64_t Index = -1;
			if (!U::TakesParamByValue) {
				if (This->isReferenceToStorage(&Elt)) {
					ReferencesStorage = true;
					Index = &Elt - This->begin();
				}
			}
			This->grow(NewSize);
			return ReferencesStorage ? This->begin() + Index : &Elt;
		}

	public:
		using size_type = std::size_t;
		using difference_type = std::ptrdiff_t;
		using value_type = T;
		using iterator = T*;
		using const_iterator = const T*;

		using const_reverse_iterator = std::reverse_iterator<const_iterator>;
		using reverse_iterator = std::reverse_iterator<iterator>;

		using reference = T&;
		using const_reference = const T&;
		using pointer = T*;
		using const_pointer = const T*;

		using Base::capacity;
		using Base::empty;
		using Base::size;

		// forward iterator creation methods.
		iterator begin() {
			return (iterator)this->BeginX;
		}
		const_iterator begin() const {
			return (const_iterator)this->BeginX;
		}
		iterator end() {
			return begin() + size();
		}
		const_iterator end() const {
			return begin() + size();
		}

		// reverse iterator creation methods.
		reverse_iterator rbegin() {
			return reverse_iterator(end());
		}
		const_reverse_iterator rbegin() const {
			return const_reverse_iterator(end());
		}
		reverse_iterator rend() {
			return reverse_iterator(begin());
		}
		const_reverse_iterator rend() const {
			return const_reverse_iterator(begin());
		}

		size_type size_in_bytes() const {
			return size() * sizeof(T);
		}
		size_type max_size() const {
			return std::min(this->SizeTypeMax(), size_type(-1) / sizeof(T));
		}

		std::size_t capacity_in_bytes() const {
			return capacity() * sizeof(T);
		}

		/// Return a pointer to the vector's buffer, even if empty().
		pointer data() {
			return pointer(begin());
		}
		/// Return a pointer to the vector's buffer, even if empty().
		const_pointer data() const {
			return const_pointer(begin());
		}

		reference operator[](size_type idx) {
			DEATH_DEBUG_ASSERT(idx < size());
			return begin()[idx];
		}
		const_reference operator[](size_type idx) const {
			DEATH_DEBUG_ASSERT(idx < size());
			return begin()[idx];
		}

		reference front() {
			DEATH_DEBUG_ASSERT(!empty());
			return begin()[0];
		}
		const_reference front() const {
			DEATH_DEBUG_ASSERT(!empty());
			return begin()[0];
		}

		reference back() {
			DEATH_DEBUG_ASSERT(!empty());
			return end()[-1];
		}
		const_reference back() const {
			DEATH_DEBUG_ASSERT(!empty());
			return end()[-1];
		}
	};

	/// SmallVectorTemplateBase<TriviallyCopyable = false> - This is where we put
	/// method implementations that are designed to work with non-trivial T's.
	///
	/// We approximate is_trivially_copyable with trivial move/copy construction and
	/// trivial destruction. While the standard doesn't specify that you're allowed
	/// copy these types with memcpy, there is no way for the type to observe this.
	/// This catches the important case of std::pair<POD, POD>, which is not
	/// trivially assignable.
	template<typename T, bool = (std::is_trivially_copy_constructible<T>::value) &&
		(std::is_trivially_move_constructible<T>::value) &&
		std::is_trivially_destructible<T>::value>
	class SmallVectorTemplateBase : public SmallVectorTemplateCommon<T>
	{
		friend class SmallVectorTemplateCommon<T>;

		protected:
			static constexpr bool TakesParamByValue = false;
			using ValueParamT = const T&;

			SmallVectorTemplateBase(std::size_t Size) : SmallVectorTemplateCommon<T>(Size) {}

			static void destroy_range(T* S, T* E) {
				while (S != E) {
					--E;
					E->~T();
				}
			}

			/// Move the range [I, E) into the uninitialized memory starting with "Dest",
			/// constructing elements as needed.
			template<typename It1, typename It2>
			static void uninitialized_move(It1 I, It1 E, It2 Dest) {
				std::uninitialized_move(I, E, Dest);
			}

			/// Copy the range [I, E) onto the uninitialized memory starting with "Dest",
			/// constructing elements as needed.
			template<typename It1, typename It2>
			static void uninitialized_copy(It1 I, It1 E, It2 Dest) {
				std::uninitialized_copy(I, E, Dest);
			}

			/// Grow the allocated memory (without initializing new elements), doubling
			/// the size of the allocated memory. Guarantees space for at least one more
			/// element, or MinSize more elements if specified.
			void grow(std::size_t MinSize = 0);

			/// Create a new allocation big enough for \p MinSize and pass back its size
			/// in \p NewCapacity. This is the first section of \a grow().
			T* mallocForGrow(std::size_t MinSize, std::size_t& NewCapacity);

			/// Move existing elements over to the new allocation \p NewElts, the middle
			/// section of \a grow().
			void moveElementsForGrow(T* NewElts);

			/// Transfer ownership of the allocation, finishing up \a grow().
			void takeAllocationForGrow(T* NewElts, std::size_t NewCapacity);

			/// Reserve enough space to add one element, and return the updated element
			/// pointer in case it was a reference to the storage.
			const T* reserveForParamAndGetAddress(const T& Elt, std::size_t N = 1) {
				return this->reserveForParamAndGetAddressImpl(this, Elt, N);
			}

			/// Reserve enough space to add one element, and return the updated element
			/// pointer in case it was a reference to the storage.
			T* reserveForParamAndGetAddress(T& Elt, std::size_t N = 1) {
				return const_cast<T*>(
					this->reserveForParamAndGetAddressImpl(this, Elt, N));
			}

			static T&& forward_value_param(T&& V) {
				return std::move(V);
			}
			static const T& forward_value_param(const T& V) {
				return V;
			}

			void growAndAssign(std::size_t NumElts, const T& Elt) {
				// Grow manually in case Elt is an internal reference.
				std::size_t NewCapacity;
				T* NewElts = mallocForGrow(NumElts, NewCapacity);
				std::uninitialized_fill_n(NewElts, NumElts, Elt);
				this->destroy_range(this->begin(), this->end());
				takeAllocationForGrow(NewElts, NewCapacity);
				this->set_size(NumElts);
			}

			template<typename... ArgTypes> T& growAndEmplaceBack(ArgTypes &&... Args) {
				// Grow manually in case one of Args is an internal reference.
				std::size_t NewCapacity;
				T* NewElts = mallocForGrow(0, NewCapacity);
				::new ((void*)(NewElts + this->size())) T(std::forward<ArgTypes>(Args)...);
				moveElementsForGrow(NewElts);
				takeAllocationForGrow(NewElts, NewCapacity);
				this->set_size(this->size() + 1);
				return this->back();
			}

		public:
			void push_back(const T& Elt) {
				const T* EltPtr = reserveForParamAndGetAddress(Elt);
				::new ((void*)this->end()) T(*EltPtr);
				this->set_size(this->size() + 1);
			}

			void push_back(T&& Elt) {
				T* EltPtr = reserveForParamAndGetAddress(Elt);
				::new ((void*)this->end()) T(::std::move(*EltPtr));
				this->set_size(this->size() + 1);
			}

			void pop_back() {
				this->set_size(this->size() - 1);
				this->end()->~T();
			}
	};

	// Define this out-of-line to dissuade the C++ compiler from inlining it.
	template<typename T, bool TriviallyCopyable>
	void SmallVectorTemplateBase<T, TriviallyCopyable>::grow(std::size_t MinSize) {
		std::size_t NewCapacity;
		T* NewElts = mallocForGrow(MinSize, NewCapacity);
		moveElementsForGrow(NewElts);
		takeAllocationForGrow(NewElts, NewCapacity);
	}

	template<typename T, bool TriviallyCopyable>
	T* SmallVectorTemplateBase<T, TriviallyCopyable>::mallocForGrow(
		std::size_t MinSize, std::size_t& NewCapacity) {
		return static_cast<T*>(
			SmallVectorBase<SmallVectorSizeType<T>>::mallocForGrow(
				this->getFirstEl(), MinSize, sizeof(T), NewCapacity));
	}

	// Define this out-of-line to dissuade the C++ compiler from inlining it.
	template<typename T, bool TriviallyCopyable>
	void SmallVectorTemplateBase<T, TriviallyCopyable>::moveElementsForGrow(
		T* NewElts) {
		// Move the elements over.
		this->uninitialized_move(this->begin(), this->end(), NewElts);

		// Destroy the original elements.
		destroy_range(this->begin(), this->end());
	}

	// Define this out-of-line to dissuade the C++ compiler from inlining it.
	template<typename T, bool TriviallyCopyable>
	void SmallVectorTemplateBase<T, TriviallyCopyable>::takeAllocationForGrow(T* NewElts, std::size_t NewCapacity) {
		// If this wasn't grown from the inline copy, deallocate the old space.
		if (!this->isSmall())
			free(this->begin());

		this->BeginX = NewElts;
		#pragma warning(suppress: 4267)
		this->Capacity = NewCapacity;
	}

	/// SmallVectorTemplateBase<TriviallyCopyable = true> - This is where we put
	/// method implementations that are designed to work with trivially copyable
	/// T's. This allows using memcpy in place of copy/move construction and
	/// skipping destruction.
	template<typename T>
	class SmallVectorTemplateBase<T, true> : public SmallVectorTemplateCommon<T>
	{
		friend class SmallVectorTemplateCommon<T>;

	protected:
		/// True if it's cheap enough to take parameters by value. Doing so avoids
		/// overhead related to mitigations for reference invalidation.
		static constexpr bool TakesParamByValue = sizeof(T) <= 2 * sizeof(void*);

		/// Either const T& or T, depending on whether it's cheap enough to take
		/// parameters by value.
		using ValueParamT = std::conditional_t<TakesParamByValue, T, const T&>;

		SmallVectorTemplateBase(std::size_t Size) : SmallVectorTemplateCommon<T>(Size) {}

		// No need to do a destroy loop for POD's.
		static void destroy_range(T*, T*) {}

		/// Move the range [I, E) onto the uninitialized memory
		/// starting with "Dest", constructing elements into it as needed.
		template<typename It1, typename It2>
		static void uninitialized_move(It1 I, It1 E, It2 Dest) {
			// Just do a copy.
			uninitialized_copy(I, E, Dest);
		}

		/// Copy the range [I, E) onto the uninitialized memory
		/// starting with "Dest", constructing elements into it as needed.
		template<typename It1, typename It2>
		static void uninitialized_copy(It1 I, It1 E, It2 Dest) {
			// Arbitrary iterator types; just use the basic implementation.
			std::uninitialized_copy(I, E, Dest);
		}

		/// Copy the range [I, E) onto the uninitialized memory
		/// starting with "Dest", constructing elements into it as needed.
		template<typename T1, typename T2>
		static void uninitialized_copy(
			T1* I, T1* E, T2* Dest,
			std::enable_if_t<std::is_same<std::remove_const_t<T1>, T2>::value> * = nullptr) {
			// Use memcpy for PODs iterated by pointers (which includes SmallVector
			// iterators): std::uninitialized_copy optimizes to memmove, but we can
			// use memcpy here. Note that I and E are iterators and thus might be
			// invalid for memcpy if they are equal.
			if (I != E)
				memcpy(reinterpret_cast<void*>(Dest), I, (E - I) * sizeof(T));
		}

		/// Double the size of the allocated memory, guaranteeing space for at
		/// least one more element or MinSize if specified.
		void grow(std::size_t MinSize = 0) {
			this->grow_pod(MinSize, sizeof(T));
		}

		/// Reserve enough space to add one element, and return the updated element
		/// pointer in case it was a reference to the storage.
		const T* reserveForParamAndGetAddress(const T& Elt, std::size_t N = 1) {
			return this->reserveForParamAndGetAddressImpl(this, Elt, N);
		}

		/// Reserve enough space to add one element, and return the updated element
		/// pointer in case it was a reference to the storage.
		T* reserveForParamAndGetAddress(T& Elt, std::size_t N = 1) {
			return const_cast<T*>(
				this->reserveForParamAndGetAddressImpl(this, Elt, N));
		}

		/// Copy \p V or return a reference, depending on \a ValueParamT.
		static ValueParamT forward_value_param(ValueParamT V) {
			return V;
		}

		void growAndAssign(std::size_t NumElts, T Elt) {
			// Elt has been copied in case it's an internal reference, side-stepping
			// reference invalidation problems without losing the realloc optimization.
			this->set_size(0);
			this->grow(NumElts);
			std::uninitialized_fill_n(this->begin(), NumElts, Elt);
			this->set_size(NumElts);
		}

		template<typename... ArgTypes> T& growAndEmplaceBack(ArgTypes &&... Args) {
			// Use push_back with a copy in case Args has an internal reference,
			// side-stepping reference invalidation problems without losing the realloc
			// optimization.
			push_back(T(std::forward<ArgTypes>(Args)...));
			return this->back();
		}

	public:
		void push_back(ValueParamT Elt) {
			const T* EltPtr = reserveForParamAndGetAddress(Elt);
			memcpy(reinterpret_cast<void*>(this->end()), EltPtr, sizeof(T));
			this->set_size(this->size() + 1);
		}

		void pop_back() {
			this->set_size(this->size() - 1);
		}
	};

	/// This class consists of common code factored out of the SmallVector class to
	/// reduce code duplication based on the SmallVector 'N' template parameter.
	template<typename T>
	class SmallVectorImpl : public SmallVectorTemplateBase<T>
	{
		using SuperClass = SmallVectorTemplateBase<T>;

	public:
		using iterator = typename SuperClass::iterator;
		using const_iterator = typename SuperClass::const_iterator;
		using reference = typename SuperClass::reference;
		using size_type = typename SuperClass::size_type;

	protected:
		using SmallVectorTemplateBase<T>::TakesParamByValue;
		using ValueParamT = typename SuperClass::ValueParamT;

		// Default ctor - Initialize to empty.
		explicit SmallVectorImpl(unsigned N)
			: SmallVectorTemplateBase<T>(N) {}

		void assignRemote(SmallVectorImpl&& RHS) {
			this->destroy_range(this->begin(), this->end());
			if (!this->isSmall())
				free(this->begin());
			this->BeginX = RHS.BeginX;
			this->Size = RHS.Size;
			this->Capacity = RHS.Capacity;
			RHS.resetToSmall();
		}

	public:
		SmallVectorImpl(const SmallVectorImpl&) = delete;

		~SmallVectorImpl() {
			// Subclass has already destructed this vector's elements.
			// If this wasn't grown from the inline copy, deallocate the old space.
			if (!this->isSmall())
				free(this->begin());
		}

		void clear() {
			this->destroy_range(this->begin(), this->end());
			this->Size = 0;
		}

	private:
		// Make set_size() private to avoid misuse in subclasses.
		using SuperClass::set_size;

		template<bool ForOverwrite> void resizeImpl(size_type N) {
			if (N == this->size())
				return;

			if (N < this->size()) {
				this->truncate(N);
				return;
			}

			this->reserve(N);
			for (auto I = this->end(), E = this->begin() + N; I != E; ++I)
				if (ForOverwrite)
					new (&*I) T;
				else
					new (&*I) T();
			this->set_size(N);
		}

	public:
		void resize(size_type N) {
			resizeImpl<false>(N);
		}

		/// Like resize, but \ref T is POD, the new values won't be initialized.
		void resize_for_overwrite(size_type N) {
			resizeImpl<true>(N);
		}

		/// Like resize, but requires that \p N is less than \a size().
		void truncate(size_type N) {
			DEATH_DEBUG_ASSERT(this->size() >= N, "Cannot increase size with truncate", );
			this->destroy_range(this->begin() + N, this->end());
			this->set_size(N);
		}

		void resize(size_type N, ValueParamT NV) {
			if (N == this->size())
				return;

			if (N < this->size()) {
				this->truncate(N);
				return;
			}

			// N > this->size(). Defer to append.
			this->append(N - this->size(), NV);
		}

		void reserve(size_type N) {
			if (this->capacity() < N)
				this->grow(N);
		}

		void pop_back_n(size_type NumItems) {
			DEATH_DEBUG_ASSERT(this->size() >= NumItems);
			truncate(this->size() - NumItems);
		}

		[[nodiscard]] T pop_back_val() {
			T Result = ::std::move(this->back());
			this->pop_back();
			return Result;
		}

		void swap(SmallVectorImpl& RHS);

		/// Add the specified range to the end of the SmallVector.
		template<typename in_iter,
			typename = std::enable_if_t<std::is_convertible<
			typename std::iterator_traits<in_iter>::iterator_category,
			std::input_iterator_tag>::value>>
			void append(in_iter in_start, in_iter in_end) {
			this->assertSafeToAddRange(in_start, in_end);
			size_type NumInputs = std::distance(in_start, in_end);
			this->reserve(this->size() + NumInputs);
			this->uninitialized_copy(in_start, in_end, this->end());
			this->set_size(this->size() + NumInputs);
		}

		/// Append \p NumInputs copies of \p Elt to the end.
		void append(size_type NumInputs, ValueParamT Elt) {
			const T* EltPtr = this->reserveForParamAndGetAddress(Elt, NumInputs);
			std::uninitialized_fill_n(this->end(), NumInputs, *EltPtr);
			this->set_size(this->size() + NumInputs);
		}

		void append(std::initializer_list<T> IL) {
			append(IL.begin(), IL.end());
		}

		void append(const SmallVectorImpl& RHS) {
			append(RHS.begin(), RHS.end());
		}

		void assign(size_type NumElts, ValueParamT Elt) {
			// Note that Elt could be an internal reference.
			if (NumElts > this->capacity()) {
				this->growAndAssign(NumElts, Elt);
				return;
			}

			// Assign over existing elements.
			std::fill_n(this->begin(), std::min(NumElts, this->size()), Elt);
			if (NumElts > this->size())
				std::uninitialized_fill_n(this->end(), NumElts - this->size(), Elt);
			else if (NumElts < this->size())
				this->destroy_range(this->begin() + NumElts, this->end());
			this->set_size(NumElts);
		}

		// FIXME: Consider assigning over existing elements, rather than clearing &
		// re-initializing them - for all assign(...) variants.

		template<typename in_iter,
			typename = std::enable_if_t<std::is_convertible<
			typename std::iterator_traits<in_iter>::iterator_category,
			std::input_iterator_tag>::value>>
			void assign(in_iter in_start, in_iter in_end) {
			this->assertSafeToReferenceAfterClear(in_start, in_end);
			clear();
			append(in_start, in_end);
		}

		void assign(std::initializer_list<T> IL) {
			clear();
			append(IL);
		}

		void assign(const SmallVectorImpl& RHS) {
			assign(RHS.begin(), RHS.end());
		}

		iterator erase(const_iterator CI) {
			// Just cast away constness because this is a non-const member function.
			iterator I = const_cast<iterator>(CI);

			DEATH_DEBUG_ASSERT(this->isReferenceToStorage(CI), "Iterator to erase is out of bounds", I);

			iterator N = I;
			// Shift all elts down one.
			std::move(I + 1, this->end(), I);
			// Drop the last elt.
			this->pop_back();
			return N;
		}

		iterator erase(const_iterator CS, const_iterator CE) {
			// Just cast away constness because this is a non-const member function.
			iterator S = const_cast<iterator>(CS);
			iterator E = const_cast<iterator>(CE);

			DEATH_DEBUG_ASSERT(this->isRangeInStorage(S, E), "Range to erase is out of bounds", S);

			iterator N = S;
			// Shift all elts down.
			iterator I = std::move(E, this->end(), S);
			// Drop the last elts.
			this->destroy_range(I, this->end());
			this->set_size(I - this->begin());
			return N;
		}

		void erase(size_type Index) {
			erase(this->begin() + Index);
		}

		iterator eraseUnordered(const_iterator CI) {
			// Just cast away constness because this is a non-const member function.
			iterator I = const_cast<iterator>(CI);

			DEATH_DEBUG_ASSERT(this->isReferenceToStorage(CI), "Iterator to erase is out of bounds", I);

			iterator IL = this->end() - 1;
			if (I != IL) {
				*I = std::move(*IL);
			}
			// Drop the last elt.
			this->pop_back();
			return I;
		}

		void eraseUnordered(size_type Index) {
			eraseUnordered(this->begin() + Index);
		}

	private:
		template<class ArgType> iterator insert_one_impl(iterator I, ArgType&& Elt) {
			// Callers ensure that ArgType is derived from T.
			static_assert(std::is_same<std::remove_const_t<std::remove_reference_t<ArgType>>, T>::value, "ArgType must be derived from T");

			if (I == this->end()) {  // Important special case for empty vector.
				this->push_back(::std::forward<ArgType>(Elt));
				return this->end() - 1;
			}

			DEATH_DEBUG_ASSERT(this->isReferenceToStorage(I), "Insertion iterator is out of bounds", I);

			// Grow if necessary.
			std::size_t Index = I - this->begin();
			std::remove_reference_t<ArgType>* EltPtr =
				this->reserveForParamAndGetAddress(Elt);
			I = this->begin() + Index;

			::new ((void*)this->end()) T(::std::move(this->back()));
			// Push everything else over.
			std::move_backward(I, this->end() - 1, this->end());
			this->set_size(this->size() + 1);

			// If we just moved the element we're inserting, be sure to update
			// the reference (never happens if TakesParamByValue).
			static_assert(!TakesParamByValue || std::is_same<ArgType, T>::value,
						  "ArgType must be 'T' when taking by value");
			if (!TakesParamByValue && this->isReferenceToRange(EltPtr, I, this->end()))
				++EltPtr;

			*I = ::std::forward<ArgType>(*EltPtr);
			return I;
		}

	public:
		iterator insert(iterator I, T&& Elt) {
			return insert_one_impl(I, this->forward_value_param(std::move(Elt)));
		}

		iterator insert(iterator I, const T& Elt) {
			return insert_one_impl(I, this->forward_value_param(Elt));
		}

		iterator insert(iterator I, size_type NumToInsert, ValueParamT Elt) {
			// Convert iterator to elt# to avoid invalidating iterator when we reserve()
			std::size_t InsertElt = I - this->begin();

			if (I == this->end()) {  // Important special case for empty vector.
				append(NumToInsert, Elt);
				return this->begin() + InsertElt;
			}

			DEATH_DEBUG_ASSERT(this->isReferenceToStorage(I), "Insertion iterator is out of bounds", I);

			// Ensure there is enough space, and get the (maybe updated) address of
			// Elt.
			const T* EltPtr = this->reserveForParamAndGetAddress(Elt, NumToInsert);

			// Uninvalidate the iterator.
			I = this->begin() + InsertElt;

			// If there are more elements between the insertion point and the end of the
			// range than there are being inserted, we can use a simple approach to
			// insertion.  Since we already reserved space, we know that this won't
			// reallocate the vector.
			if (std::size_t(this->end() - I) >= NumToInsert) {
				T* OldEnd = this->end();
				append(std::move_iterator<iterator>(this->end() - NumToInsert),
					   std::move_iterator<iterator>(this->end()));

				// Copy the existing elements that get replaced.
				std::move_backward(I, OldEnd - NumToInsert, OldEnd);

				// If we just moved the element we're inserting, be sure to update
				// the reference (never happens if TakesParamByValue).
				if (!TakesParamByValue && I <= EltPtr && EltPtr < this->end())
					EltPtr += NumToInsert;

				std::fill_n(I, NumToInsert, *EltPtr);
				return I;
			}

			// Otherwise, we're inserting more elements than exist already, and we're
			// not inserting at the end.

			// Move over the elements that we're about to overwrite.
			T* OldEnd = this->end();
			this->set_size(this->size() + NumToInsert);
			std::size_t NumOverwritten = OldEnd - I;
			this->uninitialized_move(I, OldEnd, this->end() - NumOverwritten);

			// If we just moved the element we're inserting, be sure to update
			// the reference (never happens if TakesParamByValue).
			if (!TakesParamByValue && I <= EltPtr && EltPtr < this->end())
				EltPtr += NumToInsert;

			// Replace the overwritten part.
			std::fill_n(I, NumOverwritten, *EltPtr);

			// Insert the non-overwritten middle part.
			std::uninitialized_fill_n(OldEnd, NumToInsert - NumOverwritten, *EltPtr);
			return I;
		}

		template<typename ItTy,
			typename = std::enable_if_t<std::is_convertible<
			typename std::iterator_traits<ItTy>::iterator_category,
			std::input_iterator_tag>::value>>
			iterator insert(iterator I, ItTy From, ItTy To) {
			// Convert iterator to elt# to avoid invalidating iterator when we reserve()
			std::size_t InsertElt = I - this->begin();

			if (I == this->end()) {  // Important special case for empty vector.
				append(From, To);
				return this->begin() + InsertElt;
			}

			DEATH_DEBUG_ASSERT(this->isReferenceToStorage(I), "Insertion iterator is out of bounds", I);

			// Check that the reserve that follows doesn't invalidate the iterators.
			this->assertSafeToAddRange(From, To);

			std::size_t NumToInsert = std::distance(From, To);

			// Ensure there is enough space.
			reserve(this->size() + NumToInsert);

			// Uninvalidate the iterator.
			I = this->begin() + InsertElt;

			// If there are more elements between the insertion point and the end of the
			// range than there are being inserted, we can use a simple approach to
			// insertion.  Since we already reserved space, we know that this won't
			// reallocate the vector.
			if (std::size_t(this->end() - I) >= NumToInsert) {
				T* OldEnd = this->end();
				append(std::move_iterator<iterator>(this->end() - NumToInsert),
					   std::move_iterator<iterator>(this->end()));

				// Copy the existing elements that get replaced.
				std::move_backward(I, OldEnd - NumToInsert, OldEnd);

				std::copy(From, To, I);
				return I;
			}

			// Otherwise, we're inserting more elements than exist already, and we're
			// not inserting at the end.

			// Move over the elements that we're about to overwrite.
			T* OldEnd = this->end();
			this->set_size(this->size() + NumToInsert);
			std::size_t NumOverwritten = OldEnd - I;
			this->uninitialized_move(I, OldEnd, this->end() - NumOverwritten);

			// Replace the overwritten part.
			for (T* J = I; NumOverwritten > 0; --NumOverwritten) {
				*J = *From;
				++J; ++From;
			}

			// Insert the non-overwritten middle part.
			this->uninitialized_copy(From, To, OldEnd);
			return I;
		}

		void insert(iterator I, std::initializer_list<T> IL) {
			insert(I, IL.begin(), IL.end());
		}

		template<typename... ArgTypes> reference emplace_back(ArgTypes &&... Args) {
			if (this->size() >= this->capacity())
				return this->growAndEmplaceBack(std::forward<ArgTypes>(Args)...);

			::new ((void*)this->end()) T(std::forward<ArgTypes>(Args)...);
			this->set_size(this->size() + 1);
			return this->back();
		}

		SmallVectorImpl& operator=(const SmallVectorImpl& RHS);

		SmallVectorImpl& operator=(SmallVectorImpl&& RHS);

		bool operator==(const SmallVectorImpl& RHS) const {
			if (this->size() != RHS.size()) return false;
			return std::equal(this->begin(), this->end(), RHS.begin());
		}
		bool operator!=(const SmallVectorImpl& RHS) const {
			return !(*this == RHS);
		}

		bool operator<(const SmallVectorImpl& RHS) const {
			return std::lexicographical_compare(this->begin(), this->end(),
												RHS.begin(), RHS.end());
		}
		bool operator>(const SmallVectorImpl& RHS) const {
			return RHS < *this;
		}
		bool operator<=(const SmallVectorImpl& RHS) const {
			return !(*this > RHS);
		}
		bool operator>=(const SmallVectorImpl& RHS) const {
			return !(*this < RHS);
		}
	};

	template<typename T>
	void SmallVectorImpl<T>::swap(SmallVectorImpl<T>& RHS) {
		if (this == &RHS) return;

		// We can only avoid copying elements if neither vector is small.
		if (!this->isSmall() && !RHS.isSmall()) {
			std::swap(this->BeginX, RHS.BeginX);
			std::swap(this->Size, RHS.Size);
			std::swap(this->Capacity, RHS.Capacity);
			return;
		}
		this->reserve(RHS.size());
		RHS.reserve(this->size());

		// Swap the shared elements.
		std::size_t NumShared = this->size();
		if (NumShared > RHS.size()) NumShared = RHS.size();
		for (size_type i = 0; i != NumShared; ++i)
			std::swap((*this)[i], RHS[i]);

		// Copy over the extra elts.
		if (this->size() > RHS.size()) {
			std::size_t EltDiff = this->size() - RHS.size();
			this->uninitialized_copy(this->begin() + NumShared, this->end(), RHS.end());
			RHS.set_size(RHS.size() + EltDiff);
			this->destroy_range(this->begin() + NumShared, this->end());
			this->set_size(NumShared);
		} else if (RHS.size() > this->size()) {
			std::size_t EltDiff = RHS.size() - this->size();
			this->uninitialized_copy(RHS.begin() + NumShared, RHS.end(), this->end());
			this->set_size(this->size() + EltDiff);
			this->destroy_range(RHS.begin() + NumShared, RHS.end());
			RHS.set_size(NumShared);
		}
	}

	template<typename T>
	SmallVectorImpl<T>& SmallVectorImpl<T>::operator=(const SmallVectorImpl<T>& RHS) {
		// Avoid self-assignment.
		if (this == &RHS) return *this;

		// If we already have sufficient space, assign the common elements, then
		// destroy any excess.
		std::size_t RHSSize = RHS.size();
		std::size_t CurSize = this->size();
		if (CurSize >= RHSSize) {
			// Assign common elements.
			iterator NewEnd;
			if (RHSSize)
				NewEnd = std::copy(RHS.begin(), RHS.begin() + RHSSize, this->begin());
			else
				NewEnd = this->begin();

			// Destroy excess elements.
			this->destroy_range(NewEnd, this->end());

			// Trim.
			this->set_size(RHSSize);
			return *this;
		}

		// If we have to grow to have enough elements, destroy the current elements.
		// This allows us to avoid copying them during the grow.
		// FIXME: don't do this if they're efficiently moveable.
		if (this->capacity() < RHSSize) {
			// Destroy current elements.
			this->clear();
			CurSize = 0;
			this->grow(RHSSize);
		} else if (CurSize) {
			// Otherwise, use assignment for the already-constructed elements.
			std::copy(RHS.begin(), RHS.begin() + CurSize, this->begin());
		}

		// Copy construct the new elements in place.
		this->uninitialized_copy(RHS.begin() + CurSize, RHS.end(),
								 this->begin() + CurSize);

		// Set end.
		this->set_size(RHSSize);
		return *this;
	}

	template<typename T>
	SmallVectorImpl<T>& SmallVectorImpl<T>::operator=(SmallVectorImpl<T>&& RHS) {
		// Avoid self-assignment.
		if (this == &RHS) return *this;

		// If the RHS isn't small, clear this vector and then steal its buffer.
		if (!RHS.isSmall()) {
			this->assignRemote(std::move(RHS));
			return *this;
		}

		// If we already have sufficient space, assign the common elements, then
		// destroy any excess.
		std::size_t RHSSize = RHS.size();
		std::size_t CurSize = this->size();
		if (CurSize >= RHSSize) {
			// Assign common elements.
			iterator NewEnd = this->begin();
			if (RHSSize)
				NewEnd = std::move(RHS.begin(), RHS.end(), NewEnd);

			// Destroy excess elements and trim the bounds.
			this->destroy_range(NewEnd, this->end());
			this->set_size(RHSSize);

			// Clear the RHS.
			RHS.clear();

			return *this;
		}

		// If we have to grow to have enough elements, destroy the current elements.
		// This allows us to avoid copying them during the grow.
		// FIXME: this may not actually make any sense if we can efficiently move
		// elements.
		if (this->capacity() < RHSSize) {
			// Destroy current elements.
			this->clear();
			CurSize = 0;
			this->grow(RHSSize);
		} else if (CurSize) {
			// Otherwise, use assignment for the already-constructed elements.
			std::move(RHS.begin(), RHS.begin() + CurSize, this->begin());
		}

		// Move-construct the new elements in place.
		this->uninitialized_move(RHS.begin() + CurSize, RHS.end(),
								 this->begin() + CurSize);

		// Set end.
		this->set_size(RHSSize);

		RHS.clear();
		return *this;
	}

	/// Storage for the SmallVector elements.  This is specialized for the N=0 case
	/// to avoid allocating unnecessary storage.
	template<typename T, unsigned N>
	struct SmallVectorStorage {
		alignas(T) char InlineElts[N * sizeof(T)];
	};

	/// We need the storage to be properly aligned even for small-size of 0 so that
	/// the pointer math in \a SmallVectorTemplateCommon::getFirstEl() is
	/// well-defined.
	template<typename T> struct alignas(T) SmallVectorStorage<T, 0> {};

	/// Forward declaration of SmallVector so that
	/// calculateSmallVectorDefaultInlinedElements can reference
	/// `sizeof(SmallVector<T, 0>)`.
	template<typename T, unsigned N> class SmallVector;

	/// Helper class for calculating the default number of inline elements for
	/// `SmallVector<T>`.
	///
	/// This should be migrated to a constexpr function when our minimum
	/// compiler support is enough for multi-statement constexpr functions.
	template<typename T> struct CalculateSmallVectorDefaultInlinedElements {
		// Parameter controlling the default number of inlined elements
		// for `SmallVector<T>`.
		//
		// The default number of inlined elements ensures that
		// 1. There is at least one inlined element.
		// 2. `sizeof(SmallVector<T>) <= kPreferredSmallVectorSizeof` unless
		// it contradicts 1.
		static constexpr std::size_t kPreferredSmallVectorSizeof = 64;

		// static_assert that sizeof(T) is not "too big".
		//
		// Because our policy guarantees at least one inlined element, it is possible
		// for an arbitrarily large inlined element to allocate an arbitrarily large
		// amount of inline storage. We generally consider it an antipattern for a
		// SmallVector to allocate an excessive amount of inline storage, so we want
		// to call attention to these cases and make sure that users are making an
		// intentional decision if they request a lot of inline storage.
		//
		// We want this assertion to trigger in pathological cases, but otherwise
		// not be too easy to hit. To accomplish that, the cutoff is actually somewhat
		// larger than kPreferredSmallVectorSizeof (otherwise,
		// `SmallVector<SmallVector<T>>` would be one easy way to trip it, and that
		// pattern seems useful in practice).
		//
		// One wrinkle is that this assertion is in theory non-portable, since
		// sizeof(T) is in general platform-dependent. However, we don't expect this
		// to be much of an issue, because most LLVM development happens on 64-bit
		// hosts, and therefore sizeof(T) is expected to *decrease* when compiled for
		// 32-bit hosts, dodging the issue. The reverse situation, where development
		// happens on a 32-bit host and then fails due to sizeof(T) *increasing* on a
		// 64-bit host, is expected to be very rare.
		static_assert(
			sizeof(T) <= 256,
			"You are trying to use a default number of inlined elements for "
			"`SmallVector<T>` but `sizeof(T)` is really big! Please use an "
			"explicit number of inlined elements with `SmallVector<T, N>` to make "
			"sure you really want that much inline storage.");

		// Discount the size of the header itself when calculating the maximum inline bytes.
		static constexpr std::size_t PreferredInlineBytes =
			kPreferredSmallVectorSizeof - sizeof(SmallVector<T, 0>);
		static constexpr std::size_t NumElementsThatFit = PreferredInlineBytes / sizeof(T);
		static constexpr std::size_t value =
			NumElementsThatFit == 0 ? 1 : NumElementsThatFit;
	};

	/// This is a 'vector' (really, a variable-sized array), optimized
	/// for the case when the array is small.  It contains some number of elements
	/// in-place, which allows it to avoid heap allocation when the actual number of
	/// elements is below that threshold.  This allows normal "small" cases to be
	/// fast without losing generality for large inputs.
	///
	/// \note
	/// In the absence of a well-motivated choice for the number of inlined
	/// elements \p N, it is recommended to use \c SmallVector<T> (that is,
	/// omitting the \p N). This will choose a default number of inlined elements
	/// reasonable for allocation on the stack (for example, trying to keep \c
	/// sizeof(SmallVector<T>) around 64 bytes).
	///
	/// \warning This does not attempt to be exception safe.
	///
	/// \see https://llvm.org/docs/ProgrammersManual.html#llvm-adt-smallvector-h
	template<typename T,
		unsigned N = CalculateSmallVectorDefaultInlinedElements<T>::value>
	class SmallVector : public SmallVectorImpl<T>, SmallVectorStorage<T, N>
	{
	public:
		SmallVector() : SmallVectorImpl<T>(N) {}

		~SmallVector() {
			// Destroy the constructed elements in the vector.
			this->destroy_range(this->begin(), this->end());
		}

		explicit SmallVector(std::size_t Size)
			: SmallVectorImpl<T>(N) {
			this->resize(Size);
		}

		SmallVector(std::size_t Size, const T& Value)
			: SmallVectorImpl<T>(N) {
			this->assign(Size, Value);
		}

		template <typename ItTy,
			typename = std::enable_if_t<std::is_convertible<
			typename std::iterator_traits<ItTy>::iterator_category,
			std::input_iterator_tag>::value>>
			SmallVector(ItTy S, ItTy E) : SmallVectorImpl<T>(N) {
			this->append(S, E);
		}

		template <typename RangeTy>
		explicit SmallVector(const iterator_range<RangeTy>& R)
			: SmallVectorImpl<T>(N) {
			this->append(R.begin(), R.end());
		}

		SmallVector(std::initializer_list<T> IL) : SmallVectorImpl<T>(N) {
			this->assign(IL);
		}

		SmallVector(const SmallVector& RHS) : SmallVectorImpl<T>(N) {
			if (!RHS.empty())
				SmallVectorImpl<T>::operator=(RHS);
		}

		SmallVector& operator=(const SmallVector& RHS) {
			SmallVectorImpl<T>::operator=(RHS);
			return *this;
		}

		SmallVector(SmallVector&& RHS) : SmallVectorImpl<T>(N) {
			if (!RHS.empty())
				SmallVectorImpl<T>::operator=(::std::move(RHS));
		}

		SmallVector(SmallVectorImpl<T>&& RHS) : SmallVectorImpl<T>(N) {
			if (!RHS.empty())
				SmallVectorImpl<T>::operator=(::std::move(RHS));
		}

		SmallVector& operator=(SmallVector&& RHS) {
			if (N) {
				SmallVectorImpl<T>::operator=(::std::move(RHS));
				return *this;
			}
			// SmallVectorImpl<T>::operator= does not leverage N==0. Optimize the
			// case.
			if (this == &RHS)
				return *this;
			if (RHS.empty()) {
				this->destroy_range(this->begin(), this->end());
				this->Size = 0;
			} else {
				this->assignRemote(std::move(RHS));
			}
			return *this;
		}

		SmallVector& operator=(SmallVectorImpl<T>&& RHS) {
			SmallVectorImpl<T>::operator=(::std::move(RHS));
			return *this;
		}

		SmallVector& operator=(std::initializer_list<T> IL) {
			this->assign(IL);
			return *this;
		}
	};

	template<typename T, unsigned N>
	inline std::size_t capacity_in_bytes(const SmallVector<T, N>& X) {
		return X.capacity_in_bytes();
	}

	template<typename RangeType>
	using ValueTypeFromRangeType = std::remove_const_t<std::remove_reference_t<decltype(*std::begin(std::declval<RangeType &>()))>>;

	/// Given a range of type R, iterate the entire range and return a
	/// SmallVector with elements of the vector.  This is useful, for example,
	/// when you want to iterate a range and then sort the results.
	template<unsigned Size, typename R>
	SmallVector<ValueTypeFromRangeType<R>, Size> to_vector(R&& Range) {
		return { std::begin(Range), std::end(Range) };
	}
	template<typename R>
	SmallVector<ValueTypeFromRangeType<R>,
		CalculateSmallVectorDefaultInlinedElements<
		ValueTypeFromRangeType<R>>::value>
		to_vector(R&& Range) {
		return { std::begin(Range), std::end(Range) };
	}

	// Explicit instantiations
	extern template class SmallVectorBase<std::uint32_t>;
#if SIZE_MAX > UINT32_MAX
	extern template class SmallVectorBase<std::uint64_t>;
#endif

	namespace Implementation
	{
		template<class T, unsigned N> struct ArrayViewConverter<T, SmallVector<T, N>> {
			static ArrayView<T> from(SmallVector<T, N>& other) {
				return { other.data(), other.size() };
			}
			static ArrayView<T> from(SmallVector<T, N>&& other) {
				return { other.data(), other.size() };
			}
		};
		template<class T, unsigned N> struct ArrayViewConverter<const T, SmallVector<T, N>> {
			static ArrayView<const T> from(const SmallVector<T, N>& other) {
				return { other.data(), other.size() };
			}
		};
		template<class T, unsigned N> struct ErasedArrayViewConverter<SmallVector<T, N>> : ArrayViewConverter<T, SmallVector<T, N>> {};
		template<class T, unsigned N> struct ErasedArrayViewConverter<const SmallVector<T, N>> : ArrayViewConverter<const T, SmallVector<T, N>> {};
	}

}}

namespace std
{
	/// Implement std::swap in terms of SmallVector swap.
	template<typename T>
	inline void swap(Death::Containers::SmallVectorImpl<T>& lhs, Death::Containers::SmallVectorImpl<T>& rhs) {
		lhs.swap(rhs);
	}

	/// Implement std::swap in terms of SmallVector swap.
	template<typename T, unsigned N>
	inline void swap(Death::Containers::SmallVector<T, N>& lhs, Death::Containers::SmallVector<T, N>& rhs) {
		lhs.swap(rhs);
	}
}