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[libc++] Rewrite std::to_address to avoid relying on element_type 

This is a rough reapplication of the change that fixed std::to_address
to avoid relying on element_type (da456167). It is somewhat different
because the fix to avoid breaking Clang (which caused it to be reverted
in 347f69c55) was a bit more involved.

Differential Revision: https://reviews.llvm.org/D101638
This commit is contained in:
Louis Dionne 2021-05-04 18:51:58 -04:00
parent bb113b9845
commit fe0e86e602
6 changed files with 399 additions and 131 deletions
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70
libcxx/include/__memory/pointer_traits.h
View File

@ -164,64 +164,46 @@ struct __rebind_pointer {
// to_address
template <bool _UsePointerTraits> struct __to_address_helper;
template <> struct __to_address_helper<true> {
template <class _Pointer>
using __return_type = decltype(pointer_traits<_Pointer>::to_address(_VSTD::declval<const _Pointer&>()));
template <class _Pointer>
_LIBCPP_CONSTEXPR
static __return_type<_Pointer>
__do_it(const _Pointer &__p) _NOEXCEPT { return pointer_traits<_Pointer>::to_address(__p); }
};
template <class _Pointer, bool _Dummy = true>
using __choose_to_address = __to_address_helper<_IsValidExpansion<__to_address_helper<_Dummy>::template __return_type, _Pointer>::value>;
template <class _Pointer, class = void>
struct __to_address_helper;
template <class _Tp>
inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
_Tp*
__to_address(_Tp* __p) _NOEXCEPT
{
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
_Tp* __to_address(_Tp* __p) _NOEXCEPT {
static_assert(!is_function<_Tp>::value, "_Tp is a function type");
return __p;
}
template <class _Pointer>
inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
typename __choose_to_address<_Pointer>::template __return_type<_Pointer>
__to_address(const _Pointer& __p) _NOEXCEPT
{
return __choose_to_address<_Pointer>::__do_it(__p);
// enable_if is needed here to avoid instantiating checks for fancy pointers on raw pointers
template <class _Pointer, class = _EnableIf<!is_pointer<_Pointer>::value> >
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
typename decay<decltype(__to_address_helper<_Pointer>::__call(declval<const _Pointer&>()))>::type
__to_address(const _Pointer& __p) _NOEXCEPT {
return __to_address_helper<_Pointer>::__call(__p);
}
template <> struct __to_address_helper<false> {
template <class _Pointer>
using __return_type = typename pointer_traits<_Pointer>::element_type*;
template <class _Pointer>
_LIBCPP_CONSTEXPR
static __return_type<_Pointer>
__do_it(const _Pointer &__p) _NOEXCEPT { return _VSTD::__to_address(__p.operator->()); }
template <class _Pointer, class>
struct __to_address_helper {
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
static decltype(_VSTD::__to_address(declval<const _Pointer&>().operator->()))
__call(const _Pointer&__p) _NOEXCEPT {
return _VSTD::__to_address(__p.operator->());
}
};
template <class _Pointer>
struct __to_address_helper<_Pointer, decltype((void)pointer_traits<_Pointer>::to_address(declval<const _Pointer&>()))> {
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
static decltype(pointer_traits<_Pointer>::to_address(declval<const _Pointer&>()))
__call(const _Pointer&__p) _NOEXCEPT {
return pointer_traits<_Pointer>::to_address(__p);
}
};
#if _LIBCPP_STD_VER > 17
template <class _Tp>
inline _LIBCPP_INLINE_VISIBILITY constexpr
_Tp*
to_address(_Tp* __p) _NOEXCEPT
{
static_assert(!is_function_v<_Tp>, "_Tp is a function type");
return __p;
}
template <class _Pointer>
inline _LIBCPP_INLINE_VISIBILITY constexpr
auto
to_address(const _Pointer& __p) _NOEXCEPT
{
auto to_address(const _Pointer& __p) noexcept {
return _VSTD::__to_address(__p);
}
#endif

2
libcxx/include/iterator
View File

@ -1356,7 +1356,7 @@ public:
_LIBCPP_ASSERT(__get_const_db()->__dereferenceable(this),
"Attempted to dereference a non-dereferenceable iterator");
#endif
return (pointer)_VSTD::addressof(*__i);
return _VSTD::__to_address(__i);
}
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG __wrap_iter& operator++() _NOEXCEPT
{

149
libcxx/test/libcxx/utilities/memory/pointer.conversion/to_address.pass.cpp Normal file
View File

@ -0,0 +1,149 @@
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
// <memory>
// template <class T> constexpr T* __to_address(T* p) noexcept;
// template <class Ptr> constexpr auto __to_address(const Ptr& p) noexcept;
#include <memory>
#include <cassert>
#include "test_macros.h"
struct Irrelevant;
struct P1 {
using element_type = Irrelevant;
TEST_CONSTEXPR explicit P1(int *p) : p_(p) { }
TEST_CONSTEXPR int *operator->() const { return p_; }
int *p_;
};
struct P2 {
using element_type = Irrelevant;
TEST_CONSTEXPR explicit P2(int *p) : p_(p) { }
TEST_CONSTEXPR P1 operator->() const { return p_; }
P1 p_;
};
struct P3 {
TEST_CONSTEXPR explicit P3(int *p) : p_(p) { }
int *p_;
};
template<>
struct std::pointer_traits<P3> {
static TEST_CONSTEXPR int *to_address(const P3& p) { return p.p_; }
};
struct P4 {
TEST_CONSTEXPR explicit P4(int *p) : p_(p) { }
int *operator->() const; // should never be called
int *p_;
};
template<>
struct std::pointer_traits<P4> {
static TEST_CONSTEXPR int *to_address(const P4& p) { return p.p_; }
};
struct P5 {
using element_type = Irrelevant;
int const* const& operator->() const;
};
struct P6 {};
template<>
struct std::pointer_traits<P6> {
static int const* const& to_address(const P6&);
};
// Taken from a build breakage caused in Clang
namespace P7 {
template<typename T> struct CanProxy;
template<typename T>
struct CanQual {
CanProxy<T> operator->() const { return CanProxy<T>(); }
};
template<typename T>
struct CanProxy {
const CanProxy<T> *operator->() const { return nullptr; }
};
} // namespace P7
namespace P8 {
template<class T>
struct FancyPtrA {
using element_type = Irrelevant;
T *p_;
TEST_CONSTEXPR FancyPtrA(T *p) : p_(p) {}
T& operator*() const;
TEST_CONSTEXPR T *operator->() const { return p_; }
};
template<class T>
struct FancyPtrB {
T *p_;
TEST_CONSTEXPR FancyPtrB(T *p) : p_(p) {}
T& operator*() const;
};
} // namespace P8
template<class T>
struct std::pointer_traits<P8::FancyPtrB<T> > {
static TEST_CONSTEXPR T *to_address(const P8::FancyPtrB<T>& p) { return p.p_; }
};
struct Incomplete;
template<class T> struct Holder { T t; };
TEST_CONSTEXPR_CXX14 bool test() {
int i = 0;
ASSERT_NOEXCEPT(std::__to_address(&i));
assert(std::__to_address(&i) == &i);
P1 p1(&i);
ASSERT_NOEXCEPT(std::__to_address(p1));
assert(std::__to_address(p1) == &i);
P2 p2(&i);
ASSERT_NOEXCEPT(std::__to_address(p2));
assert(std::__to_address(p2) == &i);
P3 p3(&i);
ASSERT_NOEXCEPT(std::__to_address(p3));
assert(std::__to_address(p3) == &i);
P4 p4(&i);
ASSERT_NOEXCEPT(std::__to_address(p4));
assert(std::__to_address(p4) == &i);
ASSERT_SAME_TYPE(decltype(std::__to_address(std::declval<int const*>())), int const*);
ASSERT_SAME_TYPE(decltype(std::__to_address(std::declval<P5>())), int const*);
ASSERT_SAME_TYPE(decltype(std::__to_address(std::declval<P6>())), int const*);
P7::CanQual<int>* p7 = nullptr;
assert(std::__to_address(p7) == nullptr);
ASSERT_SAME_TYPE(decltype(std::__to_address(p7)), P7::CanQual<int>*);
Holder<Incomplete> *p8_nil = nullptr; // for C++03 compatibility
P8::FancyPtrA<Holder<Incomplete> > p8a = p8_nil;
assert(std::__to_address(p8a) == p8_nil);
ASSERT_SAME_TYPE(decltype(std::__to_address(p8a)), decltype(p8_nil));
P8::FancyPtrB<Holder<Incomplete> > p8b = p8_nil;
assert(std::__to_address(p8b) == p8_nil);
ASSERT_SAME_TYPE(decltype(std::__to_address(p8b)), decltype(p8_nil));
return true;
}
int main(int, char**) {
test();
#if TEST_STD_VER >= 14
static_assert(test(), "");
#endif
return 0;
}

56
libcxx/test/libcxx/utilities/memory/pointer.conversion/to_address_std_iterators.pass.cpp Normal file
View File

@ -0,0 +1,56 @@
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
// <memory>
// template <class T> constexpr T* __to_address(T* p) noexcept;
// template <class Ptr> constexpr auto __to_address(const Ptr& p) noexcept;
#include <memory>
#include <array>
#include <cassert>
#include <span>
#include <string>
#include <string_view>
#include <valarray>
#include <vector>
#include "test_macros.h"
template<class C>
void test_container_iterators(C c)
{
const C& cc = c;
assert(std::__to_address(c.begin()) == c.data());
assert(std::__to_address(c.end()) == c.data() + c.size());
assert(std::__to_address(cc.begin()) == cc.data());
assert(std::__to_address(cc.end()) == cc.data() + cc.size());
}
void test_valarray_iterators()
{
std::valarray<int> v(100);
int *p = std::__to_address(std::begin(v));
int *q = std::__to_address(std::end(v));
assert(q - p == 100);
}
int main(int, char**) {
test_container_iterators(std::array<int, 3>());
test_container_iterators(std::vector<int>(3));
test_container_iterators(std::string("abc"));
#if TEST_STD_VER >= 17
test_container_iterators(std::string_view("abc"));
#endif
#if TEST_STD_VER >= 20
test_container_iterators(std::span<const char>("abc"));
#endif
test_valarray_iterators();
return 0;
}

157
libcxx/test/std/utilities/memory/pointer.conversion/to_address.pass.cpp
View File

@ -17,87 +17,93 @@
#include <cassert>
#include "test_macros.h"
class P1
{
public:
using element_type = int;
struct Irrelevant;
constexpr explicit P1(int* p)
: p_(p) { }
constexpr int* operator->() const noexcept
{ return p_; }
private:
int* p_;
struct P1 {
using element_type = Irrelevant;
constexpr explicit P1(int *p) : p_(p) { }
constexpr int *operator->() const { return p_; }
int *p_;
};
class P2
{
public:
using element_type = int;
constexpr explicit P2(int* p)
: p_(p) { }
constexpr P1 operator->() const noexcept
{ return p_; }
private:
struct P2 {
using element_type = Irrelevant;
constexpr explicit P2(int *p) : p_(p) { }
constexpr P1 operator->() const { return p_; }
P1 p_;
};
class P3
{
public:
constexpr explicit P3(int* p)
: p_(p) { }
constexpr int* get() const noexcept
{ return p_; }
private:
int* p_;
struct P3 {
constexpr explicit P3(int *p) : p_(p) { }
int *p_;
};
namespace std
{
template<>
struct pointer_traits<::P3>
{
static constexpr int* to_address(const ::P3& p) noexcept
{ return p.get(); }
};
}
class P4
{
public:
constexpr explicit P4(int* p)
: p_(p) { }
constexpr int* operator->() const noexcept
{ return nullptr; }
constexpr int* get() const noexcept
{ return p_; }
private:
int* p_;
struct std::pointer_traits<P3> {
static constexpr int *to_address(const P3& p) { return p.p_; }
};
struct P4 {
constexpr explicit P4(int *p) : p_(p) { }
int *operator->() const; // should never be called
int *p_;
};
namespace std
{
template<>
struct pointer_traits<::P4>
{
constexpr static int* to_address(const ::P4& p) noexcept
{ return p.get(); }
struct std::pointer_traits<P4> {
static constexpr int *to_address(const P4& p) { return p.p_; }
};
}
int n = 0;
static_assert(std::to_address(&n) == &n);
struct P5 {
using element_type = Irrelevant;
int const* const& operator->() const;
};
struct P6 {};
template<>
struct std::pointer_traits<P6> {
static int const* const& to_address(const P6&);
};
// Taken from a build breakage caused in Clang
namespace P7 {
template<typename T> struct CanProxy;
template<typename T>
struct CanQual {
CanProxy<T> operator->() const { return CanProxy<T>(); }
};
template<typename T>
struct CanProxy {
const CanProxy<T> *operator->() const { return nullptr; }
};
} // namespace P7
namespace P8 {
template<class T>
struct FancyPtrA {
using element_type = Irrelevant;
T *p_;
TEST_CONSTEXPR FancyPtrA(T *p) : p_(p) {}
T& operator*() const;
TEST_CONSTEXPR T *operator->() const { return p_; }
};
template<class T>
struct FancyPtrB {
T *p_;
TEST_CONSTEXPR FancyPtrB(T *p) : p_(p) {}
T& operator*() const;
};
} // namespace P8
template<class T>
struct std::pointer_traits<P8::FancyPtrB<T> > {
static TEST_CONSTEXPR T *to_address(const P8::FancyPtrB<T>& p) { return p.p_; }
};
struct Incomplete;
template<class T> struct Holder { T t; };
constexpr bool test() {
int i = 0;
@ -116,6 +122,23 @@ constexpr bool test() {
ASSERT_NOEXCEPT(std::to_address(p4));
assert(std::to_address(p4) == &i);
ASSERT_SAME_TYPE(decltype(std::to_address(std::declval<int const*>())), int const*);
ASSERT_SAME_TYPE(decltype(std::to_address(std::declval<P5>())), int const*);
ASSERT_SAME_TYPE(decltype(std::to_address(std::declval<P6>())), int const*);
P7::CanQual<int>* p7 = nullptr;
assert(std::to_address(p7) == nullptr);
ASSERT_SAME_TYPE(decltype(std::to_address(p7)), P7::CanQual<int>*);
Holder<Incomplete> *p8_nil = nullptr; // for C++03 compatibility
P8::FancyPtrA<Holder<Incomplete> > p8a = p8_nil;
assert(std::to_address(p8a) == p8_nil);
ASSERT_SAME_TYPE(decltype(std::to_address(p8a)), decltype(p8_nil));
P8::FancyPtrB<Holder<Incomplete> > p8b = p8_nil;
assert(std::to_address(p8b) == p8_nil);
ASSERT_SAME_TYPE(decltype(std::to_address(p8b)), decltype(p8_nil));
return true;
}

58
libcxx/test/std/utilities/memory/pointer.conversion/to_address_std_iterators.pass.cpp Normal file
View File

@ -0,0 +1,58 @@
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
// <memory>
// UNSUPPORTED: c++03, c++11, c++14, c++17
// TODO: We should enable this test in Debug mode once we fix __wrap_iter
// to be a proper contiguous_iterator.
// UNSUPPORTED: LIBCXX-DEBUG-FIXME
// template <class T> constexpr T* to_address(T* p) noexcept;
// template <class Ptr> constexpr auto to_address(const Ptr& p) noexcept;
#include <memory>
#include <array>
#include <cassert>
#include <span>
#include <string>
#include <string_view>
#include <valarray>
#include <vector>
#include "test_macros.h"
template<class C>
void test_container_iterators(C c)
{
const C& cc = c;
assert(std::to_address(c.begin()) == c.data());
assert(std::to_address(c.end()) == c.data() + c.size());
assert(std::to_address(cc.begin()) == cc.data());
assert(std::to_address(cc.end()) == cc.data() + cc.size());
}
void test_valarray_iterators()
{
std::valarray<int> v(100);
int *p = std::to_address(std::begin(v));
int *q = std::to_address(std::end(v));
assert(q - p == 100);
}
int main(int, char**) {
test_container_iterators(std::array<int, 3>());
test_container_iterators(std::vector<int>(3));
test_container_iterators(std::string("abc"));
test_container_iterators(std::string_view("abc"));
test_container_iterators(std::span<const char>("abc"));
test_valarray_iterators();
return 0;
}