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util/Manual: use std::aligned_storage_t

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By using std::launder(), we can re-enable -Wstrict-aliasing.
This commit is contained in:
Max Kellermann 2022-05-31 16:08:11 +02:00 committed by Max Kellermann
parent 826d1b207e
commit 04041f9583
1 changed files with 7 additions and 17 deletions
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24
src/util/Manual.hxx
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@ -31,13 +31,9 @@
#include <cassert>
#include <new>
#include <type_traits>
#include <utility>
#if defined(__GNUC__) || defined(__clang__)
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wstrict-aliasing"
#endif
/**
* Container for an object that gets constructed and destructed
* manually. The object is constructed in-place, and therefore
@ -46,8 +42,9 @@
*/
template<class T>
class Manual {
alignas(T)
char data[sizeof(T)];
using Storage = std::aligned_storage_t<sizeof(T), alignof(T)>;
Storage storage;
#ifndef NDEBUG
bool initialized = false;
@ -77,8 +74,7 @@ public:
void Construct(Args&&... args) {
assert(!initialized);
void *p = data;
new(p) T(std::forward<Args>(args)...);
::new(&storage) T(std::forward<Args>(args)...);
#ifndef NDEBUG
initialized = true;
@ -99,15 +95,13 @@ public:
reference Get() noexcept {
assert(initialized);
void *p = static_cast<void *>(data);
return *static_cast<pointer>(p);
return *std::launder(reinterpret_cast<pointer>(&storage));
}
const_reference Get() const noexcept {
assert(initialized);
const void *p = static_cast<const void *>(data);
return *static_cast<const_pointer>(p);
return *std::launder(reinterpret_cast<const_pointer>(&storage));
}
operator reference() noexcept {
@ -126,7 +120,3 @@ public:
return &Get();
}
};
#if defined(__GNUC__) || defined(__clang__)
#pragma GCC diagnostic pop
#endif