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Fix UB in in-place construction #99

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merged 2 commits into from
May 14, 2024
Merged

Fix UB in in-place construction #99

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ffcc3dd
Fix UB
mingxwa May 14, 2024
f244197
Add missing header
mingxwa May 14, 2024
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30 changes: 16 additions & 14 deletions proxy.h
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,7 @@
#ifndef _MSFT_PROXY_
#define _MSFT_PROXY_

#include <cstddef>
#include <bit>
#include <concepts>
#include <initializer_list>
Expand Down Expand Up @@ -174,52 +175,53 @@ R invoke_dispatch(Args&&... args) {
}
}
template <class P, class F, class R, class... Args>
R invocation_dispatcher_ref(const char* self, Args... args)
R invocation_dispatcher_ref(const std::byte* self, Args... args)
noexcept(is_invoker_well_formed<
F, typename ptr_traits<P>::target_type, true, R, Args...>()) {
return invoke_dispatch<F, R>(ptr_traits<P>::dereference(*std::launder(
reinterpret_cast<const P*>(self))), std::forward<Args>(args)...);
}
template <class P, class F, class R, class... Args>
R invocation_dispatcher_ptr(const char* self, Args... args)
R invocation_dispatcher_ptr(const std::byte* self, Args... args)
noexcept(is_invoker_well_formed<F, const P, true, R, Args...>()) {
return invoke_dispatch<F, R>(*std::launder(reinterpret_cast<const P*>(self)),
std::forward<Args>(args)...);
}
template <class F, class R, class... Args>
R invocation_dispatcher_void(const char*, Args... args)
R invocation_dispatcher_void(const std::byte*, Args... args)
noexcept(is_invoker_well_formed<F, void, true, R, Args...>())
{ return invoke_dispatch<F, R>(std::forward<Args>(args)...); }
template <class P>
void copying_dispatcher(char* self, const char* rhs)
void copying_dispatcher(std::byte* self, const std::byte* rhs)
noexcept(has_copyability<P>(constraint_level::nothrow)) {
std::construct_at(reinterpret_cast<P*>(self),
*std::launder(reinterpret_cast<const P*>(rhs)));
}
template <std::size_t Len, std::size_t Align>
void copying_default_dispatcher(char* self, const char* rhs) noexcept {
void copying_default_dispatcher(std::byte* self, const std::byte* rhs)
noexcept {
std::uninitialized_copy_n(
std::assume_aligned<Align>(rhs), Len, std::assume_aligned<Align>(self));
}
template <class P>
void relocation_dispatcher(char* self, const char* rhs)
void relocation_dispatcher(std::byte* self, const std::byte* rhs)
noexcept(has_relocatability<P>(constraint_level::nothrow)) {
P* other = std::launder(reinterpret_cast<P*>(const_cast<char*>(rhs)));
P* other = std::launder(reinterpret_cast<P*>(const_cast<std::byte*>(rhs)));
std::construct_at(reinterpret_cast<P*>(self), std::move(*other));
std::destroy_at(other);
}
template <class P>
void destruction_dispatcher(char* self)
void destruction_dispatcher(std::byte* self)
noexcept(has_destructibility<P>(constraint_level::nothrow))
{ std::destroy_at(std::launder(reinterpret_cast<P*>(self))); }
inline void destruction_default_dispatcher(char*) noexcept {}
inline void destruction_default_dispatcher(std::byte*) noexcept {}

template <bool NE, class R, class... Args>
struct overload_traits_impl : applicable_traits {
template <class D>
struct meta_provider {
template <class P>
static constexpr func_ptr_t<NE, R, const char*, Args...> get() {
static constexpr func_ptr_t<NE, R, const std::byte*, Args...> get() {
if constexpr (invocable_dispatch<
D, typename ptr_traits<P>::target_type, NE, R, Args...>) {
return &invocation_dispatcher_ref<P, typename D::template invoker<
Expand Down Expand Up @@ -314,7 +316,7 @@ struct dispatch_traits<D> : instantiated_t<
template <bool NE>
struct copyability_meta_provider {
template <class P>
static constexpr func_ptr_t<NE, void, char*, const char*> get() {
static constexpr func_ptr_t<NE, void, std::byte*, const std::byte*> get() {
if constexpr (has_copyability<P>(constraint_level::trivial)) {
return &copying_default_dispatcher<sizeof(P), alignof(P)>;
} else {
Expand All @@ -325,7 +327,7 @@ struct copyability_meta_provider {
template <bool NE>
struct relocatability_meta_provider {
template <class P>
static constexpr func_ptr_t<NE, void, char*, const char*> get() {
static constexpr func_ptr_t<NE, void, std::byte*, const std::byte*> get() {
if constexpr (has_relocatability<P>(constraint_level::trivial)) {
return &copying_default_dispatcher<sizeof(P), alignof(P)>;
} else {
Expand All @@ -336,7 +338,7 @@ struct relocatability_meta_provider {
template <bool NE>
struct destructibility_meta_provider {
template <class P>
static constexpr func_ptr_t<NE, void, char*> get() {
static constexpr func_ptr_t<NE, void, std::byte*> get() {
if constexpr (has_destructibility<P>(constraint_level::trivial)) {
return &destruction_default_dispatcher;
} else {
Expand Down Expand Up @@ -685,7 +687,7 @@ class proxy : public details::facade_traits<F>::base {
}

details::meta_ptr<typename Traits::meta> meta_;
alignas(F::constraints.max_align) char ptr_[F::constraints.max_size];
alignas(F::constraints.max_align) std::byte ptr_[F::constraints.max_size];
};

constexpr proxiable_ptr_constraints relocatable_ptr_constraints{
Expand Down
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