ladybird/AK/NonnullRefPtr.h
Daniel Bertalan cfadbcd950 AK: Work around Xcode 15 beta mishandling trailing requires clauses
Xcode 15 betas 1-3 lack https://reviews.llvm.org/D135772, which fixes a
bug that causes trailing `requires` clauses to be evaluated twice,
failing the second time. Reported as FB12284201.

This caused compile errors when instantiating types derived from RefPtr:
> error: invalid reference to function 'NonnullRefPtr': constraints not
> satisfied
> note: because substituted constraint expression is ill-formed: value
> of type '<dependent type>' is not contextually convertible to 'bool'.

This commit works around the issue by moving the `requires` clauses
after the template parameter list.

In most cases, trailing `requires` clauses and those specified after the
template parameter list work identically, so this change should not
impact the code's behavior. The only difference is that trailing
requires clauses are evaluated *after* constrained placeholder types
(i.e. `Integral auto i` function parameter).
2023-07-12 15:43:18 +01:00

304 lines
7.1 KiB
C++

/*
* Copyright (c) 2018-2023, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#define NONNULLREFPTR_SCRUB_BYTE 0xe1
#include <AK/Assertions.h>
#include <AK/Format.h>
#include <AK/Traits.h>
#include <AK/Types.h>
namespace AK {
template<typename T>
class RefPtr;
template<typename T>
ALWAYS_INLINE void ref_if_not_null(T* ptr)
{
if (ptr)
ptr->ref();
}
template<typename T>
ALWAYS_INLINE void unref_if_not_null(T* ptr)
{
if (ptr)
ptr->unref();
}
template<typename T>
class [[nodiscard]] NonnullRefPtr {
template<typename U>
friend class RefPtr;
template<typename U>
friend class NonnullRefPtr;
template<typename U>
friend class WeakPtr;
public:
using ElementType = T;
enum AdoptTag { Adopt };
ALWAYS_INLINE NonnullRefPtr(T const& object)
: m_ptr(const_cast<T*>(&object))
{
m_ptr->ref();
}
template<typename U>
requires(IsConvertible<U*, T*>)
ALWAYS_INLINE NonnullRefPtr(U const& object)
: m_ptr(const_cast<T*>(static_cast<T const*>(&object)))
{
m_ptr->ref();
}
ALWAYS_INLINE NonnullRefPtr(AdoptTag, T& object)
: m_ptr(&object)
{
}
ALWAYS_INLINE NonnullRefPtr(NonnullRefPtr&& other)
: m_ptr(&other.leak_ref())
{
}
template<typename U>
requires(IsConvertible<U*, T*>)
ALWAYS_INLINE NonnullRefPtr(NonnullRefPtr<U>&& other)
: m_ptr(static_cast<T*>(&other.leak_ref()))
{
}
ALWAYS_INLINE NonnullRefPtr(NonnullRefPtr const& other)
: m_ptr(const_cast<T*>(other.ptr()))
{
m_ptr->ref();
}
template<typename U>
requires(IsConvertible<U*, T*>)
ALWAYS_INLINE NonnullRefPtr(NonnullRefPtr<U> const& other)
: m_ptr(const_cast<T*>(static_cast<T const*>(other.ptr())))
{
m_ptr->ref();
}
ALWAYS_INLINE ~NonnullRefPtr()
{
auto* ptr = exchange(m_ptr, nullptr);
unref_if_not_null(ptr);
#ifdef SANITIZE_PTRS
m_ptr = reinterpret_cast<T*>(explode_byte(NONNULLREFPTR_SCRUB_BYTE));
#endif
}
template<typename U>
NonnullRefPtr(OwnPtr<U> const&) = delete;
template<typename U>
NonnullRefPtr& operator=(OwnPtr<U> const&) = delete;
template<typename U>
NonnullRefPtr(RefPtr<U> const&) = delete;
template<typename U>
NonnullRefPtr& operator=(RefPtr<U> const&) = delete;
NonnullRefPtr(RefPtr<T> const&) = delete;
NonnullRefPtr& operator=(RefPtr<T> const&) = delete;
NonnullRefPtr& operator=(NonnullRefPtr const& other)
{
NonnullRefPtr tmp { other };
swap(tmp);
return *this;
}
template<typename U>
requires(IsConvertible<U*, T*>)
NonnullRefPtr& operator=(NonnullRefPtr<U> const& other)
{
NonnullRefPtr tmp { other };
swap(tmp);
return *this;
}
ALWAYS_INLINE NonnullRefPtr& operator=(NonnullRefPtr&& other)
{
NonnullRefPtr tmp { move(other) };
swap(tmp);
return *this;
}
template<typename U>
requires(IsConvertible<U*, T*>)
NonnullRefPtr& operator=(NonnullRefPtr<U>&& other)
{
NonnullRefPtr tmp { move(other) };
swap(tmp);
return *this;
}
NonnullRefPtr& operator=(T const& object)
{
NonnullRefPtr tmp { object };
swap(tmp);
return *this;
}
[[nodiscard]] ALWAYS_INLINE T& leak_ref()
{
T* ptr = exchange(m_ptr, nullptr);
VERIFY(ptr);
return *ptr;
}
ALWAYS_INLINE RETURNS_NONNULL T* ptr() const
{
return as_nonnull_ptr();
}
ALWAYS_INLINE RETURNS_NONNULL T* operator->() const
{
return as_nonnull_ptr();
}
ALWAYS_INLINE T& operator*() const
{
return *as_nonnull_ptr();
}
ALWAYS_INLINE RETURNS_NONNULL operator T*() const
{
return as_nonnull_ptr();
}
ALWAYS_INLINE operator T&() const
{
return *as_nonnull_ptr();
}
operator bool() const = delete;
bool operator!() const = delete;
void swap(NonnullRefPtr& other)
{
AK::swap(m_ptr, other.m_ptr);
}
template<typename U>
void swap(NonnullRefPtr<U>& other)
requires(IsConvertible<U*, T*>)
{
AK::swap(m_ptr, other.m_ptr);
}
bool operator==(NonnullRefPtr const& other) const { return m_ptr == other.m_ptr; }
template<typename RawPtr>
requires(IsPointer<RawPtr>)
bool operator==(RawPtr other) const
{
return m_ptr == other;
}
private:
NonnullRefPtr() = delete;
ALWAYS_INLINE RETURNS_NONNULL T* as_nonnull_ptr() const
{
VERIFY(m_ptr);
return m_ptr;
}
T* m_ptr { nullptr };
};
template<typename T>
inline NonnullRefPtr<T> adopt_ref(T& object)
{
return NonnullRefPtr<T>(NonnullRefPtr<T>::Adopt, object);
}
// Use like `adopt_nonnull_ref_or_enomem(new (nothrow) T(args...))`.
template<typename T>
inline ErrorOr<NonnullRefPtr<T>> adopt_nonnull_ref_or_enomem(T* object)
{
if (!object)
return Error::from_errno(ENOMEM);
return NonnullRefPtr<T>(NonnullRefPtr<T>::Adopt, *object);
}
template<typename T, class... Args>
requires(IsConstructible<T, Args...>) inline ErrorOr<NonnullRefPtr<T>> try_make_ref_counted(Args&&... args)
{
return adopt_nonnull_ref_or_enomem(new (nothrow) T(forward<Args>(args)...));
}
// FIXME: Remove once P0960R3 is available in Clang.
template<typename T, class... Args>
inline ErrorOr<NonnullRefPtr<T>> try_make_ref_counted(Args&&... args)
{
return adopt_nonnull_ref_or_enomem(new (nothrow) T { forward<Args>(args)... });
}
template<Formattable T>
struct Formatter<NonnullRefPtr<T>> : Formatter<T> {
ErrorOr<void> format(FormatBuilder& builder, NonnullRefPtr<T> const& value)
{
return Formatter<T>::format(builder, *value);
}
};
template<typename T>
requires(!HasFormatter<T>)
struct Formatter<NonnullRefPtr<T>> : Formatter<T const*> {
ErrorOr<void> format(FormatBuilder& builder, NonnullRefPtr<T> const& value)
{
return Formatter<T const*>::format(builder, value.ptr());
}
};
template<typename T, typename U>
requires(IsConvertible<U*, T*>)
inline void swap(NonnullRefPtr<T>& a, NonnullRefPtr<U>& b)
{
a.swap(b);
}
template<typename T, class... Args>
requires(IsConstructible<T, Args...>) inline NonnullRefPtr<T> make_ref_counted(Args&&... args)
{
return NonnullRefPtr<T>(NonnullRefPtr<T>::Adopt, *new T(forward<Args>(args)...));
}
// FIXME: Remove once P0960R3 is available in Clang.
template<typename T, class... Args>
inline NonnullRefPtr<T> make_ref_counted(Args&&... args)
{
return NonnullRefPtr<T>(NonnullRefPtr<T>::Adopt, *new T { forward<Args>(args)... });
}
template<typename T>
struct Traits<NonnullRefPtr<T>> : public GenericTraits<NonnullRefPtr<T>> {
using PeekType = T*;
using ConstPeekType = T const*;
static unsigned hash(NonnullRefPtr<T> const& p) { return ptr_hash(p.ptr()); }
static bool equals(NonnullRefPtr<T> const& a, NonnullRefPtr<T> const& b) { return a.ptr() == b.ptr(); }
};
}
#if USING_AK_GLOBALLY
using AK::adopt_nonnull_ref_or_enomem;
using AK::adopt_ref;
using AK::make_ref_counted;
using AK::NonnullRefPtr;
using AK::try_make_ref_counted;
#endif