[libcxx] r324185 - Make array<const T, 0> non-CopyAssignable and make swap and fill ill-formed.
Eric Fiselier via cfe-commits
cfe-commits at lists.llvm.org
Sat Feb 3 18:17:02 PST 2018
Author: ericwf
Date: Sat Feb 3 18:17:02 2018
New Revision: 324185
URL: http://llvm.org/viewvc/llvm-project?rev=324185&view=rev
Log:
Make array<const T, 0> non-CopyAssignable and make swap and fill ill-formed.
The standard isn't exactly clear how std::array should handle zero-sized arrays
with const element types. In particular W.R.T. copy assignment, swap, and fill.
This patch takes the position that those operations should be ill-formed,
and makes changes to libc++ to make it so.
This follows up on commit r324182.
Added:
libcxx/trunk/test/std/containers/sequences/array/array.cons/implicit_copy.pass.cpp
libcxx/trunk/test/std/containers/sequences/array/array.fill/fill.fail.cpp
libcxx/trunk/test/std/containers/sequences/array/array.swap/swap.fail.cpp
Modified:
libcxx/trunk/include/array
libcxx/trunk/test/std/containers/sequences/array/array.data/data.pass.cpp
Modified: libcxx/trunk/include/array
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/array?rev=324185&r1=324184&r2=324185&view=diff
==============================================================================
--- libcxx/trunk/include/array (original)
+++ libcxx/trunk/include/array Sat Feb 3 18:17:02 2018
@@ -122,7 +122,8 @@ struct __array_traits {
typedef _Tp _StorageT[_Size];
_LIBCPP_INLINE_VISIBILITY
- static _LIBCPP_CONSTEXPR_AFTER_CXX14 _Tp* __data(_StorageT& __store) {
+ static _LIBCPP_CONSTEXPR_AFTER_CXX14 typename remove_const<_Tp>::type*
+ __data(typename remove_const<_StorageT>::type& __store) {
return __store;
}
@@ -144,12 +145,16 @@ struct __array_traits {
template <class _Tp>
struct __array_traits<_Tp, 0> {
- typedef typename aligned_storage<sizeof(_Tp), alignment_of<_Tp>::value>::type _StorageT;
+ typedef typename aligned_storage<sizeof(_Tp), alignment_of<_Tp>::value>::type
+ _NonConstStorageT;
+ typedef typename conditional<is_const<_Tp>::value, const _NonConstStorageT,
+ _NonConstStorageT>::type _StorageT;
+ typedef typename remove_const<_Tp>::type _NonConstTp;
_LIBCPP_INLINE_VISIBILITY
- static _Tp* __data(_StorageT& __store) {
+ static _NonConstTp* __data(_NonConstStorageT& __store) {
_StorageT *__ptr = std::addressof(__store);
- return reinterpret_cast<_Tp*>(__ptr);
+ return reinterpret_cast<_NonConstTp*>(__ptr);
}
_LIBCPP_INLINE_VISIBILITY
@@ -162,8 +167,7 @@ struct __array_traits<_Tp, 0> {
static void __swap(_StorageT&, _StorageT&) {}
_LIBCPP_INLINE_VISIBILITY
- static void __fill(_StorageT&, _Tp const&) {
- }
+ static void __fill(_StorageT&, _Tp const&) {}
};
template <class _Tp, size_t _Size>
@@ -187,12 +191,19 @@ struct _LIBCPP_TEMPLATE_VIS array
typename _Traits::_StorageT __elems_;
// No explicit construct/copy/destroy for aggregate type
- _LIBCPP_INLINE_VISIBILITY void fill(const value_type& __u)
- {_Traits::__fill(__elems_, __u);}
+ _LIBCPP_INLINE_VISIBILITY void fill(const value_type& __u) {
+ static_assert(_Size != 0 || !is_const<_Tp>::value,
+ "cannot fill zero-sized array of type 'const T'");
+ _Traits::__fill(__elems_, __u);
+ }
_LIBCPP_INLINE_VISIBILITY
- void swap(array& __a) _NOEXCEPT_(_Size == 0 || __is_nothrow_swappable<_Tp>::value)
- { _Traits::__swap(__elems_, __a.__elems_); }
+ void swap(array& __a)
+ _NOEXCEPT_(_Size == 0 || __is_nothrow_swappable<_Tp>::value) {
+ static_assert(_Size != 0 || !is_const<_Tp>::value,
+ "cannot swap zero-sized array of type 'const T'");
+ _Traits::__swap(__elems_, __a.__elems_);
+ }
// iterators:
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
Added: libcxx/trunk/test/std/containers/sequences/array/array.cons/implicit_copy.pass.cpp
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/std/containers/sequences/array/array.cons/implicit_copy.pass.cpp?rev=324185&view=auto
==============================================================================
--- libcxx/trunk/test/std/containers/sequences/array/array.cons/implicit_copy.pass.cpp (added)
+++ libcxx/trunk/test/std/containers/sequences/array/array.cons/implicit_copy.pass.cpp Sat Feb 3 18:17:02 2018
@@ -0,0 +1,93 @@
+//===----------------------------------------------------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <array>
+
+// implicitly generated array constructors / assignment operators
+
+#include <array>
+#include <type_traits>
+#include <cassert>
+#include "test_macros.h"
+
+// std::array is explicitly allowed to be initialized with A a = { init-list };.
+// Disable the missing braces warning for this reason.
+#include "disable_missing_braces_warning.h"
+
+// FIXME: Clang generates copy assignment operators for types with const members
+// in C++03. The generated operator is ill-formed but still present.
+// I'm not sure if this is a Clang bug, but we need to work around it for now.
+#if TEST_STD_VER < 11 && defined(__clang__)
+#define TEST_NOT_COPY_ASSIGNABLE(T) ((void)0)
+#else
+#define TEST_NOT_COPY_ASSIGNABLE(T) static_assert(!std::is_copy_assignable<T>::value, "")
+#endif
+
+struct NoDefault {
+ NoDefault(int) {}
+};
+
+int main() {
+ {
+ typedef double T;
+ typedef std::array<T, 3> C;
+ C c = {1.1, 2.2, 3.3};
+ C c2 = c;
+ c2 = c;
+ static_assert(std::is_copy_constructible<C>::value, "");
+ static_assert(std::is_copy_assignable<C>::value, "");
+ }
+ {
+ typedef double T;
+ typedef std::array<const T, 3> C;
+ C c = {1.1, 2.2, 3.3};
+ C c2 = c;
+ ((void)c2);
+ static_assert(std::is_copy_constructible<C>::value, "");
+ TEST_NOT_COPY_ASSIGNABLE(C);
+ }
+ {
+ typedef double T;
+ typedef std::array<T, 0> C;
+ C c = {};
+ C c2 = c;
+ c2 = c;
+ static_assert(std::is_copy_constructible<C>::value, "");
+ static_assert(std::is_copy_assignable<C>::value, "");
+ }
+ {
+ // const arrays of size 0 should disable the implicit copy assignment operator.
+ typedef double T;
+ typedef std::array<const T, 0> C;
+ C c = {};
+ C c2 = c;
+ ((void)c2);
+ static_assert(std::is_copy_constructible<C>::value, "");
+ TEST_NOT_COPY_ASSIGNABLE(C);
+ }
+ {
+ typedef NoDefault T;
+ typedef std::array<T, 0> C;
+ C c = {};
+ C c2 = c;
+ c2 = c;
+ static_assert(std::is_copy_constructible<C>::value, "");
+ static_assert(std::is_copy_assignable<C>::value, "");
+ }
+ {
+ typedef NoDefault T;
+ typedef std::array<const T, 0> C;
+ C c = {};
+ C c2 = c;
+ ((void)c2);
+ static_assert(std::is_copy_constructible<C>::value, "");
+ TEST_NOT_COPY_ASSIGNABLE(C);
+ }
+
+}
Modified: libcxx/trunk/test/std/containers/sequences/array/array.data/data.pass.cpp
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/std/containers/sequences/array/array.data/data.pass.cpp?rev=324185&r1=324184&r2=324185&view=diff
==============================================================================
--- libcxx/trunk/test/std/containers/sequences/array/array.data/data.pass.cpp (original)
+++ libcxx/trunk/test/std/containers/sequences/array/array.data/data.pass.cpp Sat Feb 3 18:17:02 2018
@@ -37,6 +37,14 @@ int main()
(void)p; // to placate scan-build
}
{
+ typedef double T;
+ typedef std::array<const T, 0> C;
+ C c = {};
+ const T* p = c.data();
+ static_assert((std::is_same<decltype(c.data()), const T*>::value), "");
+ (void)p; // to placate scan-build
+ }
+ {
struct NoDefault {
NoDefault(int) {}
};
Added: libcxx/trunk/test/std/containers/sequences/array/array.fill/fill.fail.cpp
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/std/containers/sequences/array/array.fill/fill.fail.cpp?rev=324185&view=auto
==============================================================================
--- libcxx/trunk/test/std/containers/sequences/array/array.fill/fill.fail.cpp (added)
+++ libcxx/trunk/test/std/containers/sequences/array/array.fill/fill.fail.cpp Sat Feb 3 18:17:02 2018
@@ -0,0 +1,29 @@
+//===----------------------------------------------------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <array>
+
+// void fill(const T& u);
+
+#include <array>
+#include <cassert>
+
+// std::array is explicitly allowed to be initialized with A a = { init-list };.
+// Disable the missing braces warning for this reason.
+#include "disable_missing_braces_warning.h"
+
+int main() {
+ {
+ typedef double T;
+ typedef std::array<const T, 0> C;
+ C c = {};
+ // expected-error at array:* {{static_assert failed "cannot fill zero-sized array of type 'const T'"}}
+ c.fill(5.5); // expected-note {{requested here}}
+ }
+}
Added: libcxx/trunk/test/std/containers/sequences/array/array.swap/swap.fail.cpp
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/std/containers/sequences/array/array.swap/swap.fail.cpp?rev=324185&view=auto
==============================================================================
--- libcxx/trunk/test/std/containers/sequences/array/array.swap/swap.fail.cpp (added)
+++ libcxx/trunk/test/std/containers/sequences/array/array.swap/swap.fail.cpp Sat Feb 3 18:17:02 2018
@@ -0,0 +1,30 @@
+//===----------------------------------------------------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <array>
+
+// void swap(array& a);
+
+#include <array>
+#include <cassert>
+
+// std::array is explicitly allowed to be initialized with A a = { init-list };.
+// Disable the missing braces warning for this reason.
+#include "disable_missing_braces_warning.h"
+
+int main() {
+ {
+ typedef double T;
+ typedef std::array<const T, 0> C;
+ C c = {};
+ C c2 = {};
+ // expected-error at array:* {{static_assert failed "cannot swap zero-sized array of type 'const T'"}}
+ c.swap(c2); // expected-note {{requested here}}
+ }
+}
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