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Fix size and alignment of array<T, 0>. 

An array T[1] isn't necessarily the same say when it's
a member of a struct. This patch addresses that problem and corrects
the tests to deal with it.

llvm-svn: 324545
This commit is contained in:
Eric Fiselier 2018-02-07 23:50:25 +00:00
parent 06ac8cfbd1
commit 1a78ae3c89
3 changed files with 22 additions and 4 deletions
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1
libcxx/include/__config
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@ -582,6 +582,7 @@ namespace std {
#define __alignof__ __alignof
#define _LIBCPP_NORETURN __declspec(noreturn)
#define _ALIGNAS(x) __declspec(align(x))
#define _ALIGNAS_TYPE(x) alignas(x)
#define _LIBCPP_HAS_NO_VARIADICS
#define _LIBCPP_BEGIN_NAMESPACE_STD namespace std {

5
libcxx/include/array
View File

@ -244,10 +244,11 @@ struct _LIBCPP_TEMPLATE_VIS array<_Tp, 0>
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])];
struct _ArrayInStructT { _Tp __data_[1]; };
_ALIGNAS_TYPE(_ArrayInStructT) _CharType __elems_[sizeof(_ArrayInStructT)];
// No explicit construct/copy/destroy for aggregate type
_LIBCPP_INLINE_VISIBILITY void fill(const value_type&) {

20
libcxx/test/std/containers/sequences/array/size_and_alignment.pass.cpp
View File

@ -21,12 +21,26 @@
#include "test_macros.h"
template <class T, size_t Size>
struct MyArray {
T elems[Size];
};
template <class T, size_t Size>
void test() {
typedef T CArrayT[Size == 0 ? 1 : Size];
typedef std::array<T, Size> ArrayT;
static_assert(sizeof(CArrayT) == sizeof(ArrayT), "");
static_assert(TEST_ALIGNOF(CArrayT) == TEST_ALIGNOF(ArrayT), "");
typedef MyArray<T, Size == 0 ? 1 : Size> MyArrayT;
static_assert(sizeof(ArrayT) == sizeof(CArrayT), "");
static_assert(sizeof(ArrayT) == sizeof(MyArrayT), "");
static_assert(TEST_ALIGNOF(ArrayT) == TEST_ALIGNOF(MyArrayT), "");
#if defined(_LIBCPP_VERSION)
ArrayT a;
((void)a);
static_assert(sizeof(ArrayT) == sizeof(a.__elems_), "");
static_assert(TEST_ALIGNOF(ArrayT) == __alignof__(a.__elems_), "");
#endif
}
template <class T>
@ -44,6 +58,8 @@ struct TEST_ALIGNAS(TEST_ALIGNOF(std::max_align_t) * 2) TestType2 {
char data[1000];
};
//static_assert(sizeof(void*) == 4, "");
int main() {
test_type<char>();
test_type<int>();