[libc++] Complete overhaul of constexpr support in std::array
This commit adds missing support for constexpr in std::array under all
standard modes up to and including C++20. It also transforms the <array>
tests to check for constexpr-friendliness under the right standard modes.
Fixes https://llvm.org/PR40124
Fixes rdar://57522096
Supersedes https://reviews.llvm.org/D60666
Differential Revision: https://reviews.llvm.org/D80452
Cr-Mirrored-From: https://chromium.googlesource.com/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: 77b9abfc8e89ca627e4f9a1cc206bea131db6db1
diff --git a/include/array b/include/array
index 7ffa825..215d4e8 100644
--- a/include/array
+++ b/include/array
@@ -32,24 +32,24 @@
typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
// No explicit construct/copy/destroy for aggregate type
- void fill(const T& u);
- void swap(array& a) noexcept(is_nothrow_swappable_v<T>);
+ void fill(const T& u); // constexpr in C++20
+ void swap(array& a) noexcept(is_nothrow_swappable_v<T>); // constexpr in C++20
// iterators:
- iterator begin() noexcept;
- const_iterator begin() const noexcept;
- iterator end() noexcept;
- const_iterator end() const noexcept;
+ iterator begin() noexcept; // constexpr in C++17
+ const_iterator begin() const noexcept; // constexpr in C++17
+ iterator end() noexcept; // constexpr in C++17
+ const_iterator end() const noexcept; // constexpr in C++17
- reverse_iterator rbegin() noexcept;
- const_reverse_iterator rbegin() const noexcept;
- reverse_iterator rend() noexcept;
- const_reverse_iterator rend() const noexcept;
+ reverse_iterator rbegin() noexcept; // constexpr in C++17
+ const_reverse_iterator rbegin() const noexcept; // constexpr in C++17
+ reverse_iterator rend() noexcept; // constexpr in C++17
+ const_reverse_iterator rend() const noexcept; // constexpr in C++17
- const_iterator cbegin() const noexcept;
- const_iterator cend() const noexcept;
- const_reverse_iterator crbegin() const noexcept;
- const_reverse_iterator crend() const noexcept;
+ const_iterator cbegin() const noexcept; // constexpr in C++17
+ const_iterator cend() const noexcept; // constexpr in C++17
+ const_reverse_iterator crbegin() const noexcept; // constexpr in C++17
+ const_reverse_iterator crend() const noexcept; // constexpr in C++17
// capacity:
constexpr size_type size() const noexcept;
@@ -57,46 +57,51 @@
constexpr bool empty() const noexcept;
// element access:
- reference operator[](size_type n);
- const_reference operator[](size_type n) const; // constexpr in C++14
- const_reference at(size_type n) const; // constexpr in C++14
- reference at(size_type n);
+ reference operator[](size_type n); // constexpr in C++17
+ const_reference operator[](size_type n) const; // constexpr in C++14
+ reference at(size_type n); // constexpr in C++17
+ const_reference at(size_type n) const; // constexpr in C++14
- reference front();
- const_reference front() const; // constexpr in C++14
- reference back();
- const_reference back() const; // constexpr in C++14
+ reference front(); // constexpr in C++17
+ const_reference front() const; // constexpr in C++14
+ reference back(); // constexpr in C++17
+ const_reference back() const; // constexpr in C++14
- T* data() noexcept;
- const T* data() const noexcept;
+ T* data() noexcept; // constexpr in C++17
+ const T* data() const noexcept; // constexpr in C++17
};
- template <class T, class... U>
- array(T, U...) -> array<T, 1 + sizeof...(U)>;
+template <class T, class... U>
+ array(T, U...) -> array<T, 1 + sizeof...(U)>; // C++17
template <class T, size_t N>
- bool operator==(const array<T,N>& x, const array<T,N>& y);
+ bool operator==(const array<T,N>& x, const array<T,N>& y); // constexpr in C++20
template <class T, size_t N>
- bool operator!=(const array<T,N>& x, const array<T,N>& y);
+ bool operator!=(const array<T,N>& x, const array<T,N>& y); // constexpr in C++20
template <class T, size_t N>
- bool operator<(const array<T,N>& x, const array<T,N>& y);
+ bool operator<(const array<T,N>& x, const array<T,N>& y); // constexpr in C++20
template <class T, size_t N>
- bool operator>(const array<T,N>& x, const array<T,N>& y);
+ bool operator>(const array<T,N>& x, const array<T,N>& y); // constexpr in C++20
template <class T, size_t N>
- bool operator<=(const array<T,N>& x, const array<T,N>& y);
+ bool operator<=(const array<T,N>& x, const array<T,N>& y); // constexpr in C++20
template <class T, size_t N>
- bool operator>=(const array<T,N>& x, const array<T,N>& y);
+ bool operator>=(const array<T,N>& x, const array<T,N>& y); // constexpr in C++20
template <class T, size_t N >
- void swap(array<T,N>& x, array<T,N>& y) noexcept(noexcept(x.swap(y))); // C++17
+ void swap(array<T,N>& x, array<T,N>& y) noexcept(noexcept(x.swap(y))); // constexpr in C++20
+
+template <class T, size_t N>
+ constexpr array<remove_cv_t<T>, N> to_array(T (&a)[N]); // C++20
+template <class T, size_t N>
+ constexpr array<remove_cv_t<T>, N> to_array(T (&&a)[N]); // C++20
template <class T> struct tuple_size;
template <size_t I, class T> struct tuple_element;
template <class T, size_t N> struct tuple_size<array<T, N>>;
template <size_t I, class T, size_t N> struct tuple_element<I, array<T, N>>;
-template <size_t I, class T, size_t N> T& get(array<T, N>&) noexcept; // constexpr in C++14
-template <size_t I, class T, size_t N> const T& get(const array<T, N>&) noexcept; // constexpr in C++14
-template <size_t I, class T, size_t N> T&& get(array<T, N>&&) noexcept; // constexpr in C++14
+template <size_t I, class T, size_t N> T& get(array<T, N>&) noexcept; // constexpr in C++14
+template <size_t I, class T, size_t N> const T& get(const array<T, N>&) noexcept; // constexpr in C++14
+template <size_t I, class T, size_t N> T&& get(array<T, N>&&) noexcept; // constexpr in C++14
template <size_t I, class T, size_t N> const T&& get(const array<T, N>&&) noexcept; // constexpr in C++14
} // std
@@ -143,11 +148,12 @@
_Tp __elems_[_Size];
// No explicit construct/copy/destroy for aggregate type
- _LIBCPP_INLINE_VISIBILITY void fill(const value_type& __u) {
+ _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+ void fill(const value_type& __u) {
_VSTD::fill_n(__elems_, _Size, __u);
}
- _LIBCPP_INLINE_VISIBILITY
+ _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
void swap(array& __a) _NOEXCEPT_(__is_nothrow_swappable<_Tp>::value) {
std::swap_ranges(__elems_, __elems_ + _Size, __a.__elems_);
}
@@ -236,50 +242,71 @@
typedef std::reverse_iterator<iterator> reverse_iterator;
typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
+#ifndef _LIBCPP_CXX03_LANG
+ union __wrapper {
+ _LIBCPP_CONSTEXPR __wrapper() : __b() { }
+ ~__wrapper() = default;
+
+ bool __b;
+ _Tp __t;
+ } __w;
+
+ _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
+ value_type* data() _NOEXCEPT {return &__w.__t;}
+ _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
+ const value_type* data() const _NOEXCEPT {return &__w.__t;}
+#else // C++03
typedef typename conditional<is_const<_Tp>::value, const char,
char>::type _CharType;
struct _ArrayInStructT { _Tp __data_[1]; };
_ALIGNAS_TYPE(_ArrayInStructT) _CharType __elems_[sizeof(_ArrayInStructT)];
+ _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_);}
+#endif
+
// No explicit construct/copy/destroy for aggregate type
- _LIBCPP_INLINE_VISIBILITY void fill(const value_type&) {
+ _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+ void fill(const value_type&) {
static_assert(!is_const<_Tp>::value,
"cannot fill zero-sized array of type 'const T'");
}
- _LIBCPP_INLINE_VISIBILITY
+ _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
void swap(array&) _NOEXCEPT {
static_assert(!is_const<_Tp>::value,
"cannot swap zero-sized array of type 'const T'");
}
// iterators:
- _LIBCPP_INLINE_VISIBILITY
+ _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
iterator begin() _NOEXCEPT {return iterator(data());}
- _LIBCPP_INLINE_VISIBILITY
+ _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
const_iterator begin() const _NOEXCEPT {return const_iterator(data());}
- _LIBCPP_INLINE_VISIBILITY
+ _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
iterator end() _NOEXCEPT {return iterator(data());}
- _LIBCPP_INLINE_VISIBILITY
+ _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
const_iterator end() const _NOEXCEPT {return const_iterator(data());}
- _LIBCPP_INLINE_VISIBILITY
+ _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
reverse_iterator rbegin() _NOEXCEPT {return reverse_iterator(end());}
- _LIBCPP_INLINE_VISIBILITY
+ _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
const_reverse_iterator rbegin() const _NOEXCEPT {return const_reverse_iterator(end());}
- _LIBCPP_INLINE_VISIBILITY
+ _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
reverse_iterator rend() _NOEXCEPT {return reverse_iterator(begin());}
- _LIBCPP_INLINE_VISIBILITY
+ _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
const_reverse_iterator rend() const _NOEXCEPT {return const_reverse_iterator(begin());}
- _LIBCPP_INLINE_VISIBILITY
+ _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
const_iterator cbegin() const _NOEXCEPT {return begin();}
- _LIBCPP_INLINE_VISIBILITY
+ _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
const_iterator cend() const _NOEXCEPT {return end();}
- _LIBCPP_INLINE_VISIBILITY
+ _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
const_reverse_iterator crbegin() const _NOEXCEPT {return rbegin();}
- _LIBCPP_INLINE_VISIBILITY
+ _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
const_reverse_iterator crend() const _NOEXCEPT {return rend();}
// capacity:
@@ -291,7 +318,7 @@
_LIBCPP_CONSTEXPR bool empty() const _NOEXCEPT {return true;}
// element access:
- _LIBCPP_INLINE_VISIBILITY
+ _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
reference operator[](size_type) _NOEXCEPT {
_LIBCPP_ASSERT(false, "cannot call array<T, 0>::operator[] on a zero-sized array");
_LIBCPP_UNREACHABLE();
@@ -303,46 +330,41 @@
_LIBCPP_UNREACHABLE();
}
- _LIBCPP_INLINE_VISIBILITY
+ _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
reference at(size_type) {
__throw_out_of_range("array<T, 0>::at");
_LIBCPP_UNREACHABLE();
}
- _LIBCPP_INLINE_VISIBILITY
+ _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
const_reference at(size_type) const {
__throw_out_of_range("array<T, 0>::at");
_LIBCPP_UNREACHABLE();
}
- _LIBCPP_INLINE_VISIBILITY
+ _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
reference front() _NOEXCEPT {
_LIBCPP_ASSERT(false, "cannot call array<T, 0>::front() on a zero-sized array");
_LIBCPP_UNREACHABLE();
}
- _LIBCPP_INLINE_VISIBILITY
+ _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
const_reference front() const _NOEXCEPT {
_LIBCPP_ASSERT(false, "cannot call array<T, 0>::front() on a zero-sized array");
_LIBCPP_UNREACHABLE();
}
- _LIBCPP_INLINE_VISIBILITY
+ _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
reference back() _NOEXCEPT {
_LIBCPP_ASSERT(false, "cannot call array<T, 0>::back() on a zero-sized array");
_LIBCPP_UNREACHABLE();
}
- _LIBCPP_INLINE_VISIBILITY
+ _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
const_reference back() const _NOEXCEPT {
_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_);}
};
@@ -404,7 +426,7 @@
}
template <class _Tp, size_t _Size>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
typename enable_if
<
_Size == 0 ||