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Fix C++23 compilation errors in leveldb #47

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Merged
merged 2 commits into from
Mar 7, 2025
Merged

Fix C++23 compilation errors in leveldb #47

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82c3104
Fix C++23 compilation errors in leveldb
a-googler Jan 8, 2025
183e79a
Fix speculatively some "placement new" issues in leveldb
a-googler Jan 21, 2025
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11 changes: 7 additions & 4 deletions util/env_posix.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -854,9 +854,13 @@ class SingletonEnv {
#endif // !defined(NDEBUG)
static_assert(sizeof(env_storage_) >= sizeof(EnvType),
"env_storage_ will not fit the Env");
static_assert(alignof(decltype(env_storage_)) >= alignof(EnvType),
static_assert(std::is_standard_layout_v<SingletonEnv<EnvType>>);
static_assert(
offsetof(SingletonEnv<EnvType>, env_storage_) % alignof(EnvType) == 0,
"env_storage_ does not meet the Env's alignment needs");
static_assert(alignof(SingletonEnv<EnvType>) % alignof(EnvType) == 0,
"env_storage_ does not meet the Env's alignment needs");
new (&env_storage_) EnvType();
new (env_storage_) EnvType();
}
~SingletonEnv() = default;

Expand All @@ -872,8 +876,7 @@ class SingletonEnv {
}

private:
typename std::aligned_storage<sizeof(EnvType), alignof(EnvType)>::type
env_storage_;
alignas(EnvType) char env_storage_[sizeof(EnvType)];
#if !defined(NDEBUG)
static std::atomic<bool> env_initialized_;
#endif // !defined(NDEBUG)
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11 changes: 7 additions & 4 deletions util/env_windows.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -802,9 +802,13 @@ class SingletonEnv {
#endif // !defined(NDEBUG)
static_assert(sizeof(env_storage_) >= sizeof(EnvType),
"env_storage_ will not fit the Env");
static_assert(alignof(decltype(env_storage_)) >= alignof(EnvType),
static_assert(std::is_standard_layout_v<SingletonEnv<EnvType>>);
static_assert(
offsetof(SingletonEnv<EnvType>, env_storage_) % alignof(EnvType) == 0,
"env_storage_ does not meet the Env's alignment needs");
static_assert(alignof(SingletonEnv<EnvType>) % alignof(EnvType) == 0,
"env_storage_ does not meet the Env's alignment needs");
new (&env_storage_) EnvType();
new (env_storage_) EnvType();
}
~SingletonEnv() = default;

Expand All @@ -820,8 +824,7 @@ class SingletonEnv {
}

private:
typename std::aligned_storage<sizeof(EnvType), alignof(EnvType)>::type
env_storage_;
alignas(EnvType) char env_storage_[sizeof(EnvType)];
#if !defined(NDEBUG)
static std::atomic<bool> env_initialized_;
#endif // !defined(NDEBUG)
Expand Down
12 changes: 8 additions & 4 deletions util/no_destructor.h
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,7 @@
#ifndef STORAGE_LEVELDB_UTIL_NO_DESTRUCTOR_H_
#define STORAGE_LEVELDB_UTIL_NO_DESTRUCTOR_H_

#include <cstddef>
#include <type_traits>
#include <utility>

Expand All @@ -20,10 +21,14 @@ class NoDestructor {
explicit NoDestructor(ConstructorArgTypes&&... constructor_args) {
static_assert(sizeof(instance_storage_) >= sizeof(InstanceType),
"instance_storage_ is not large enough to hold the instance");
static_assert(std::is_standard_layout_v<NoDestructor<InstanceType>>);
static_assert(
alignof(decltype(instance_storage_)) >= alignof(InstanceType),
offsetof(NoDestructor, instance_storage_) % alignof(InstanceType) == 0,
"instance_storage_ does not meet the instance's alignment requirement");
new (&instance_storage_)
static_assert(
alignof(NoDestructor<InstanceType>) % alignof(InstanceType) == 0,
"instance_storage_ does not meet the instance's alignment requirement");
new (instance_storage_)
InstanceType(std::forward<ConstructorArgTypes>(constructor_args)...);
}

Expand All @@ -37,8 +42,7 @@ class NoDestructor {
}

private:
typename std::aligned_storage<sizeof(InstanceType),
alignof(InstanceType)>::type instance_storage_;
alignas(InstanceType) char instance_storage_[sizeof(InstanceType)];
};

} // namespace leveldb
Expand Down