[libc++] Fix PR35491 - std::array of zero-size doesn't work with non-default constructible types.
Summary:
This patch fixes llvm.org/PR35491 and LWG2157 (https://cplusplus.github.io/LWG/issue2157)
The fix attempts to maintain ABI compatibility by replacing the array with a instance of `aligned_storage`.
Reviewers: mclow.lists, EricWF
Reviewed By: EricWF
Subscribers: lichray, cfe-commits
Differential Revision: https://reviews.llvm.org/D41223
llvm-svn: 324526
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: 59cdf90ac8bea16abbb9d637c5124e69d2c75c09
diff --git a/include/array b/include/array
index 4eb2fe6..706e573 100644
--- a/include/array
+++ b/include/array
@@ -108,6 +108,8 @@
#include <iterator>
#include <algorithm>
#include <stdexcept>
+#include <cstdlib> // for _LIBCPP_UNREACHABLE
+#include <__debug>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#pragma GCC system_header
@@ -117,6 +119,7 @@
_LIBCPP_BEGIN_NAMESPACE_STD
+
template <class _Tp, size_t _Size>
struct _LIBCPP_TEMPLATE_VIS array
{
@@ -134,31 +137,27 @@
typedef std::reverse_iterator<iterator> reverse_iterator;
typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
- value_type __elems_[_Size > 0 ? _Size : 1];
+ _Tp __elems_[_Size];
// No explicit construct/copy/destroy for aggregate type
- _LIBCPP_INLINE_VISIBILITY void fill(const value_type& __u)
- {_VSTD::fill_n(__elems_, _Size, __u);}
- _LIBCPP_INLINE_VISIBILITY
- void swap(array& __a) _NOEXCEPT_(_Size == 0 || __is_nothrow_swappable<_Tp>::value)
- { __swap_dispatch((std::integral_constant<bool, _Size == 0>()), __a); }
+ _LIBCPP_INLINE_VISIBILITY void fill(const value_type& __u) {
+ _VSTD::fill_n(__elems_, _Size, __u);
+ }
_LIBCPP_INLINE_VISIBILITY
- void __swap_dispatch(std::true_type, array&) {}
-
- _LIBCPP_INLINE_VISIBILITY
- void __swap_dispatch(std::false_type, array& __a)
- { _VSTD::swap_ranges(__elems_, __elems_ + _Size, __a.__elems_);}
+ void swap(array& __a) _NOEXCEPT_(__is_nothrow_swappable<_Tp>::value) {
+ std::swap_ranges(__elems_, __elems_ + _Size, __a.__elems_);
+ }
// iterators:
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
- iterator begin() _NOEXCEPT {return iterator(__elems_);}
+ iterator begin() _NOEXCEPT {return iterator(data());}
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
- const_iterator begin() const _NOEXCEPT {return const_iterator(__elems_);}
+ const_iterator begin() const _NOEXCEPT {return const_iterator(data());}
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
- iterator end() _NOEXCEPT {return iterator(__elems_ + _Size);}
+ iterator end() _NOEXCEPT {return iterator(data() + _Size);}
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
- const_iterator end() const _NOEXCEPT {return const_iterator(__elems_ + _Size);}
+ const_iterator end() const _NOEXCEPT {return const_iterator(data() + _Size);}
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
reverse_iterator rbegin() _NOEXCEPT {return reverse_iterator(end());}
@@ -184,7 +183,7 @@
_LIBCPP_INLINE_VISIBILITY
_LIBCPP_CONSTEXPR size_type max_size() const _NOEXCEPT {return _Size;}
_LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY
- _LIBCPP_CONSTEXPR bool empty() const _NOEXCEPT {return _Size == 0;}
+ _LIBCPP_CONSTEXPR bool empty() const _NOEXCEPT {return false; }
// element access:
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
@@ -197,8 +196,8 @@
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14 reference front() {return __elems_[0];}
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 const_reference front() const {return __elems_[0];}
- _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14 reference back() {return __elems_[_Size > 0 ? _Size-1 : 0];}
- _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 const_reference back() const {return __elems_[_Size > 0 ? _Size-1 : 0];}
+ _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14 reference back() {return __elems_[_Size - 1];}
+ _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 const_reference back() const {return __elems_[_Size - 1];}
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
value_type* data() _NOEXCEPT {return __elems_;}
@@ -206,6 +205,7 @@
const value_type* data() const _NOEXCEPT {return __elems_;}
};
+
template <class _Tp, size_t _Size>
_LIBCPP_CONSTEXPR_AFTER_CXX14
typename array<_Tp, _Size>::reference
@@ -227,12 +227,138 @@
return __elems_[__n];
}
+template <class _Tp>
+struct _LIBCPP_TEMPLATE_VIS array<_Tp, 0>
+{
+ // types:
+ typedef array __self;
+ typedef _Tp value_type;
+ typedef value_type& reference;
+ typedef const value_type& const_reference;
+ typedef value_type* iterator;
+ typedef const value_type* const_iterator;
+ typedef value_type* pointer;
+ typedef const value_type* const_pointer;
+ typedef size_t size_type;
+ typedef ptrdiff_t difference_type;
+ typedef std::reverse_iterator<iterator> reverse_iterator;
+ typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
+
+
+ typedef typename conditional<is_const<_Tp>::value, const char,
+ char>::type _CharType;
+ _ALIGNAS(alignment_of<_Tp[1]>::value) _CharType __elems_[sizeof(_Tp[1])];
+
+ // No explicit construct/copy/destroy for aggregate type
+ _LIBCPP_INLINE_VISIBILITY void fill(const value_type&) {
+ static_assert(!is_const<_Tp>::value,
+ "cannot fill zero-sized array of type 'const T'");
+ }
+
+ _LIBCPP_INLINE_VISIBILITY
+ void swap(array&) _NOEXCEPT {
+ static_assert(!is_const<_Tp>::value,
+ "cannot swap zero-sized array of type 'const T'");
+ }
+
+ // iterators:
+ _LIBCPP_INLINE_VISIBILITY
+ iterator begin() _NOEXCEPT {return iterator(data());}
+ _LIBCPP_INLINE_VISIBILITY
+ const_iterator begin() const _NOEXCEPT {return const_iterator(data());}
+ _LIBCPP_INLINE_VISIBILITY
+ iterator end() _NOEXCEPT {return iterator(data());}
+ _LIBCPP_INLINE_VISIBILITY
+ const_iterator end() const _NOEXCEPT {return const_iterator(data());}
+
+ _LIBCPP_INLINE_VISIBILITY
+ reverse_iterator rbegin() _NOEXCEPT {return reverse_iterator(end());}
+ _LIBCPP_INLINE_VISIBILITY
+ const_reverse_iterator rbegin() const _NOEXCEPT {return const_reverse_iterator(end());}
+ _LIBCPP_INLINE_VISIBILITY
+ reverse_iterator rend() _NOEXCEPT {return reverse_iterator(begin());}
+ _LIBCPP_INLINE_VISIBILITY
+ const_reverse_iterator rend() const _NOEXCEPT {return const_reverse_iterator(begin());}
+
+ _LIBCPP_INLINE_VISIBILITY
+ const_iterator cbegin() const _NOEXCEPT {return begin();}
+ _LIBCPP_INLINE_VISIBILITY
+ const_iterator cend() const _NOEXCEPT {return end();}
+ _LIBCPP_INLINE_VISIBILITY
+ const_reverse_iterator crbegin() const _NOEXCEPT {return rbegin();}
+ _LIBCPP_INLINE_VISIBILITY
+ const_reverse_iterator crend() const _NOEXCEPT {return rend();}
+
+ // capacity:
+ _LIBCPP_INLINE_VISIBILITY
+ _LIBCPP_CONSTEXPR size_type size() const _NOEXCEPT {return 0; }
+ _LIBCPP_INLINE_VISIBILITY
+ _LIBCPP_CONSTEXPR size_type max_size() const _NOEXCEPT {return 0;}
+ _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY
+ _LIBCPP_CONSTEXPR bool empty() const _NOEXCEPT {return true;}
+
+ // element access:
+ _LIBCPP_INLINE_VISIBILITY
+ reference operator[](size_type) {
+ _LIBCPP_ASSERT(false, "cannot call array<T, 0>::operator[] on a zero-sized array");
+ _LIBCPP_UNREACHABLE();
+ }
+
+ _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+ const_reference operator[](size_type) const {
+ _LIBCPP_ASSERT(false, "cannot call array<T, 0>::operator[] on a zero-sized array");
+ _LIBCPP_UNREACHABLE();
+ }
+
+ _LIBCPP_INLINE_VISIBILITY
+ reference at(size_type) {
+ __throw_out_of_range("array<T, 0>::at");
+ _LIBCPP_UNREACHABLE();
+ }
+
+ _LIBCPP_INLINE_VISIBILITY
+ const_reference at(size_type) const {
+ __throw_out_of_range("array<T, 0>::at");
+ _LIBCPP_UNREACHABLE();
+ }
+
+ _LIBCPP_INLINE_VISIBILITY
+ reference front() {
+ _LIBCPP_ASSERT(false, "cannot call array<T, 0>::front() on a zero-sized array");
+ _LIBCPP_UNREACHABLE();
+ }
+
+ _LIBCPP_INLINE_VISIBILITY
+ const_reference front() const {
+ _LIBCPP_ASSERT(false, "cannot call array<T, 0>::front() on a zero-sized array");
+ _LIBCPP_UNREACHABLE();
+ }
+
+ _LIBCPP_INLINE_VISIBILITY
+ reference back() {
+ _LIBCPP_ASSERT(false, "cannot call array<T, 0>::back() on a zero-sized array");
+ _LIBCPP_UNREACHABLE();
+ }
+
+ _LIBCPP_INLINE_VISIBILITY
+ const_reference back() const {
+ _LIBCPP_ASSERT(false, "cannot call array<T, 0>::back() on a zero-sized array");
+ _LIBCPP_UNREACHABLE();
+ }
+
+ _LIBCPP_INLINE_VISIBILITY
+ value_type* data() _NOEXCEPT {return reinterpret_cast<value_type*>(__elems_);}
+ _LIBCPP_INLINE_VISIBILITY
+ const value_type* data() const _NOEXCEPT {return reinterpret_cast<const value_type*>(__elems_);}
+};
+
+
template <class _Tp, size_t _Size>
inline _LIBCPP_INLINE_VISIBILITY
bool
operator==(const array<_Tp, _Size>& __x, const array<_Tp, _Size>& __y)
{
- return _VSTD::equal(__x.__elems_, __x.__elems_ + _Size, __y.__elems_);
+ return _VSTD::equal(__x.begin(), __x.end(), __y.begin());
}
template <class _Tp, size_t _Size>
@@ -248,7 +374,8 @@
bool
operator<(const array<_Tp, _Size>& __x, const array<_Tp, _Size>& __y)
{
- return _VSTD::lexicographical_compare(__x.__elems_, __x.__elems_ + _Size, __y.__elems_, __y.__elems_ + _Size);
+ return _VSTD::lexicographical_compare(__x.begin(), __x.end(),
+ __y.begin(), __y.end());
}
template <class _Tp, size_t _Size>