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<__msvc_threads_core.hpp>: Use aligned byte arrays as aligned buffers #5811

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Merged
merged 2 commits into from
Oct 29, 2025
Merged

<__msvc_threads_core.hpp>: Use aligned byte arrays as aligned buffers #5811

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2c6cedf
Use aligned byte arrays as aligned buffers
frederick-vs-ja Oct 26, 2025
48f86d2
Perma-workaround VSO-2616030.
StephanTLavavej Oct 28, 2025
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6 changes: 3 additions & 3 deletions stl/inc/__msvc_threads_core.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -7,7 +7,7 @@
#define __MSVC_THREADS_CORE_HPP
#include <yvals_core.h>
#if _STL_COMPILER_PREPROCESSOR
#include <type_traits>
#include <cstddef>

#pragma pack(push, _CRT_PACKING)
#pragma warning(push, _STL_WARNING_LEVEL)
Expand Down Expand Up @@ -43,7 +43,7 @@ struct _Mtx_internal_imp_t {
int _Type{};
union {
_Stl_critical_section _Critical_section{};
_STD _Aligned_storage_t<_Critical_section_size, alignof(void*)> _Cs_storage;
alignas(void*) unsigned char _Cs_storage[_Critical_section_size];
};
long _Thread_id{};
int _Count{};
Expand All @@ -68,7 +68,7 @@ struct _Cnd_internal_imp_t {

union {
_Stl_condition_variable _Stl_cv{};
_STD _Aligned_storage_t<_Cnd_internal_imp_size, alignof(void*)> _Cv_storage;
alignas(void*) unsigned char _Cv_storage[_Cnd_internal_imp_size];
};
};
#pragma warning(pop)
Expand Down
22 changes: 11 additions & 11 deletions tests/std/tests/P0660R10_jthread_and_cv_any/test.cpp
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Expand Up @@ -147,30 +147,30 @@ int main() {
assert(jthread::hardware_concurrency() == thread::hardware_concurrency());

{ // first wait_until overload; without the cancellation this would deadlock
jthread worker([](stop_token token) {
mutex m;
condition_variable_any cv;
mutex m;
condition_variable_any cv;
jthread worker([&](stop_token token) {
unique_lock lck{m};
assert(cv.wait(lck, move(token), [] { return false; }) == false);
});
}

static constexpr auto forever = chrono::steady_clock::duration::max();
static constexpr auto infinity = chrono::steady_clock::time_point::max();
constexpr auto forever = chrono::steady_clock::duration::max();
constexpr auto infinity = chrono::steady_clock::time_point::max();

{ // ditto without the cancellation this would deadlock
jthread worker([](stop_token token) {
mutex m;
condition_variable_any cv;
mutex m;
condition_variable_any cv;
jthread worker([&](stop_token token) {
unique_lock lck{m};
assert(cv.wait_until(lck, move(token), infinity, [] { return false; }) == false);
});
}

{ // ditto without the cancellation this would deadlock
jthread worker([](stop_token token) {
mutex m;
condition_variable_any cv;
mutex m;
condition_variable_any cv;
jthread worker([&](stop_token token) {
unique_lock lck{m};
assert(cv.wait_for(lck, move(token), forever, [] { return false; }) == false);
});
Expand Down