[libcxx-commits] [libcxx] [libc++] Add MSVC's implementation of `exception_ptr` for Windows (PR #94977)

Stephan T. Lavavej via libcxx-commits libcxx-commits at lists.llvm.org
Mon Jun 10 06:20:48 PDT 2024


https://github.com/StephanTLavavej created https://github.com/llvm/llvm-project/pull/94977

As requested by @petrhosek (and earlier by @llvm-beanz), Microsoft is happy to contribute our implementation of `exception_ptr` for Windows, under the Apache License v2.0 with LLVM Exception that our STLs share.

I've copied our files to plausible-looking places and updated their line endings and banners, but otherwise have made no attempt to integrate them into libc++. I copied all of our `<exception>` even though you only need `exception_ptr` from it. These are our current sources, corresponding to what's going to ship for production use in VS 2022 17.11.

Petr explained to me that libc++ developers will be able to do the integration work - please feel free to push arbitrary changes to my branch. I expect that significant overhauls will be necessary! (Significant improvements should be possible when you don't have to worry about the ancient evil `/clr:pure` etc.)

Please let me know if you need any more information or code. There's a bit of `shared_ptr` integration, where that machinery grants access to `_Exception_ptr_access` defined in `excptptr.cpp` - if you need the `<memory>` side of things, I can add that. (For the record, libc++ is always welcome to grab sources directly from microsoft/STL under our license, but we're also happy to deliver sources like this.)

The only caveat is that our "VCRuntime" support library is not open-source. If you need sources from VCRuntime, we'll have to figure out whether that's possible. Presumably this shouldn't be necessary, since our open-source microsoft/STL consumes the proprietary VCRuntime "at arm's length" and everything works.

Finally, although I've maintained our STL since 2007 and have worked on almost every part of it, I didn't write `exception_ptr` and its inner workings remain mysterious to me. It was written by a Microsoft dev who left the VC Libraries team in 2013 (and later, the company). If you have questions about what it's doing, I can try to get answers, but sometimes your guess will be as good as ours. :joy_cat: There's a potential performance improvement that could be made, which we're currently unable to do for ABI compatibility, see https://github.com/microsoft/STL/issues/751. I don't see any active bugs in our internal database about `exception_ptr`.

## Commits

* microsoft/STL's `excptptr.cpp`, copied verbatim.
  + From our `main` branch as of 2024-06-10: https://github.com/microsoft/STL/blob/e36ee6c2b9bc6f5b1f70776c18cf5d3a93a69798/stl/src/excptptr.cpp
* microsoft/STL's `<exception>`, copied verbatim as `win32_exception_ptr.h`.
  + From our `main` branch as of 2024-06-10: https://github.com/microsoft/STL/blob/e36ee6c2b9bc6f5b1f70776c18cf5d3a93a69798/stl/inc/exception
* Convert files to LF line endings.
* Add LLVM banners.
* Update `libcxx/CREDITS.TXT` to mention Microsoft.
  + I am intentionally not crediting myself here, I'm just delivering the pizza, I didn't cook it. :pizza:


>From 8b41047c72465c3d9678163a644184239728b888 Mon Sep 17 00:00:00 2001
From: "Stephan T. Lavavej" <stl at microsoft.com>
Date: Mon, 10 Jun 2024 04:39:43 -0700
Subject: [PATCH 1/5] microsoft/STL's `excptptr.cpp`, copied verbatim.

>From our `main` branch as of 2024-06-10:

https://github.com/microsoft/STL/blob/e36ee6c2b9bc6f5b1f70776c18cf5d3a93a69798/stl/src/excptptr.cpp
---
 libcxx/src/support/win32/excptptr.cpp | 533 ++++++++++++++++++++++++++
 1 file changed, 533 insertions(+)
 create mode 100644 libcxx/src/support/win32/excptptr.cpp

diff --git a/libcxx/src/support/win32/excptptr.cpp b/libcxx/src/support/win32/excptptr.cpp
new file mode 100644
index 0000000000000..830cb65a940d5
--- /dev/null
+++ b/libcxx/src/support/win32/excptptr.cpp
@@ -0,0 +1,533 @@
+// Copyright (c) Microsoft Corporation.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+// This implementation communicates with the EH runtime though vcruntime's per-thread-data structure; see
+// _pCurrentException in <trnsctrl.h>.
+//
+// As a result, normal EH runtime services (such as noexcept functions) are safe to use in this file.
+
+#ifndef _VCRT_ALLOW_INTERNALS
+#define _VCRT_ALLOW_INTERNALS
+#endif // !defined(_VCRT_ALLOW_INTERNALS)
+
+#include <Unknwn.h>
+#include <cstdlib> // for abort
+#include <cstring> // for memcpy
+#include <eh.h>
+#include <ehdata.h>
+#include <exception>
+#include <internal_shared.h>
+#include <malloc.h>
+#include <memory>
+#include <new>
+#include <stdexcept>
+#include <trnsctrl.h>
+#include <xcall_once.h>
+
+#include <Windows.h>
+
+// Pre-V4 managed exception code
+#define MANAGED_EXCEPTION_CODE 0XE0434F4D
+
+// V4 and later managed exception code
+#define MANAGED_EXCEPTION_CODE_V4 0XE0434352
+
+extern "C" _CRTIMP2 void* __cdecl __AdjustPointer(void*, const PMD&); // defined in frame.cpp
+
+using namespace std;
+
+namespace {
+#if defined(_M_CEE_PURE)
+    template <class _Ty>
+    _Ty& _Immortalize() { // return a reference to an object that will live forever
+        /* MAGIC */ static _Immortalizer_impl<_Ty> _Static;
+        return reinterpret_cast<_Ty&>(_Static._Storage);
+    }
+#elif !defined(_M_CEE)
+    template <class _Ty>
+    struct _Constexpr_excptptr_immortalize_impl {
+        union {
+            _Ty _Storage;
+        };
+
+        constexpr _Constexpr_excptptr_immortalize_impl() noexcept : _Storage{} {}
+
+        _Constexpr_excptptr_immortalize_impl(const _Constexpr_excptptr_immortalize_impl&)            = delete;
+        _Constexpr_excptptr_immortalize_impl& operator=(const _Constexpr_excptptr_immortalize_impl&) = delete;
+
+        _MSVC_NOOP_DTOR ~_Constexpr_excptptr_immortalize_impl() {
+            // do nothing, allowing _Ty to be used during shutdown
+        }
+    };
+
+    template <class _Ty>
+    _Constexpr_excptptr_immortalize_impl<_Ty> _Immortalize_impl;
+
+    template <class _Ty>
+    [[nodiscard]] _Ty& _Immortalize() noexcept {
+        return _Immortalize_impl<_Ty>._Storage;
+    }
+#else // ^^^ !defined(_M_CEE) / defined(_M_CEE), TRANSITION, VSO-1153256 vvv
+    template <class _Ty>
+    _Ty& _Immortalize() { // return a reference to an object that will live forever
+        static once_flag _Flag;
+        alignas(_Ty) static unsigned char _Storage[sizeof(_Ty)];
+        call_once(_Flag, [&_Storage] { ::new (static_cast<void*>(&_Storage)) _Ty(); });
+        return reinterpret_cast<_Ty&>(_Storage);
+    }
+#endif // ^^^ !defined(_M_CEE_PURE) && defined(_M_CEE), TRANSITION, VSO-1153256 ^^^
+
+    void _PopulateCppExceptionRecord(
+        _EXCEPTION_RECORD& _Record, const void* const _PExcept, ThrowInfo* _PThrow) noexcept {
+        _Record.ExceptionCode           = EH_EXCEPTION_NUMBER;
+        _Record.ExceptionFlags          = EXCEPTION_NONCONTINUABLE;
+        _Record.ExceptionRecord         = nullptr; // no SEH to chain
+        _Record.ExceptionAddress        = nullptr; // Address of exception. Will be overwritten by OS
+        _Record.NumberParameters        = EH_EXCEPTION_PARAMETERS;
+        _Record.ExceptionInformation[0] = EH_MAGIC_NUMBER1; // params.magicNumber
+        _Record.ExceptionInformation[1] = reinterpret_cast<ULONG_PTR>(_PExcept); // params.pExceptionObject
+
+        if (_PThrow && (_PThrow->attributes & TI_IsWinRT)) {
+            // The pointer to the ExceptionInfo structure is stored sizeof(void*) in front of each WinRT Exception Info.
+            const auto _PWei = (*static_cast<WINRTEXCEPTIONINFO** const*>(_PExcept))[-1];
+            _PThrow          = _PWei->throwInfo;
+        }
+
+        _Record.ExceptionInformation[2] = reinterpret_cast<ULONG_PTR>(_PThrow); // params.pThrowInfo
+
+#if _EH_RELATIVE_TYPEINFO
+        void* _ThrowImageBase =
+            _PThrow ? RtlPcToFileHeader(const_cast<void*>(static_cast<const void*>(_PThrow)), &_ThrowImageBase)
+                    : nullptr;
+        _Record.ExceptionInformation[3] = reinterpret_cast<ULONG_PTR>(_ThrowImageBase); // params.pThrowImageBase
+#endif // _EH_RELATIVE_TYPEINFO
+
+        // If the throw info indicates this throw is from a pure region,
+        // set the magic number to the Pure one, so only a pure-region
+        // catch will see it.
+        //
+        // Also use the Pure magic number on 64-bit platforms if we were unable to
+        // determine an image base, since that was the old way to determine
+        // a pure throw, before the TI_IsPure bit was added to the FuncInfo
+        // attributes field.
+        if (_PThrow
+            && ((_PThrow->attributes & TI_IsPure)
+#if _EH_RELATIVE_TYPEINFO
+                || !_ThrowImageBase
+#endif // _EH_RELATIVE_TYPEINFO
+                )) {
+            _Record.ExceptionInformation[0] = EH_PURE_MAGIC_NUMBER1;
+        }
+    }
+
+    void _CopyExceptionRecord(_EXCEPTION_RECORD& _Dest, const _EXCEPTION_RECORD& _Src) noexcept {
+        _Dest.ExceptionCode = _Src.ExceptionCode;
+        // we force EXCEPTION_NONCONTINUABLE because rethrow_exception is [[noreturn]]
+        _Dest.ExceptionFlags   = _Src.ExceptionFlags | EXCEPTION_NONCONTINUABLE;
+        _Dest.ExceptionRecord  = nullptr; // We don't chain SEH exceptions
+        _Dest.ExceptionAddress = nullptr; // Useless field to copy. It will be overwritten by RaiseException()
+        const auto _Parameters = _Src.NumberParameters;
+        _Dest.NumberParameters = _Parameters;
+
+        // copy the number of parameters in use
+        constexpr auto _Max_parameters = static_cast<DWORD>(EXCEPTION_MAXIMUM_PARAMETERS);
+        const auto _In_use             = (_STD min)(_Parameters, _Max_parameters);
+        _CSTD memcpy(_Dest.ExceptionInformation, _Src.ExceptionInformation, _In_use * sizeof(ULONG_PTR));
+        _CSTD memset(&_Dest.ExceptionInformation[_In_use], 0, (_Max_parameters - _In_use) * sizeof(ULONG_PTR));
+    }
+
+    void _CopyExceptionObject(void* _Dest, const void* _Src, const CatchableType* const _PType
+#if _EH_RELATIVE_TYPEINFO
+        ,
+        const uintptr_t _ThrowImageBase
+#endif // _EH_RELATIVE_TYPEINFO
+    ) {
+        // copy an object of type denoted by *_PType from _Src to _Dest; throws whatever the copy ctor of the type
+        // denoted by *_PType throws
+        if ((_PType->properties & CT_IsSimpleType) || _PType->copyFunction == 0) {
+            memcpy(_Dest, _Src, _PType->sizeOrOffset);
+
+            if (_PType->properties & CT_IsWinRTHandle) {
+                const auto _PUnknown = *static_cast<IUnknown* const*>(_Src);
+                if (_PUnknown) {
+                    _PUnknown->AddRef();
+                }
+            }
+            return;
+        }
+
+#if _EH_RELATIVE_TYPEINFO
+        const auto _CopyFunc = reinterpret_cast<void*>(_ThrowImageBase + _PType->copyFunction);
+#else // ^^^ _EH_RELATIVE_TYPEINFO / !_EH_RELATIVE_TYPEINFO vvv
+        const auto _CopyFunc = _PType->copyFunction;
+#endif // ^^^ !_EH_RELATIVE_TYPEINFO ^^^
+
+        const auto _Adjusted = __AdjustPointer(const_cast<void*>(_Src), _PType->thisDisplacement);
+        if (_PType->properties & CT_HasVirtualBase) {
+#ifdef _M_CEE_PURE
+            reinterpret_cast<void(__clrcall*)(void*, void*, int)>(_CopyFunc)(_Dest, _Adjusted, 1);
+#else // ^^^ defined(_M_CEE_PURE) / !defined(_M_CEE_PURE) vvv
+            _CallMemberFunction2(_Dest, _CopyFunc, _Adjusted, 1);
+#endif // ^^^ !defined(_M_CEE_PURE) ^^^
+        } else {
+#ifdef _M_CEE_PURE
+            reinterpret_cast<void(__clrcall*)(void*, void*)>(_CopyFunc)(_Dest, _Adjusted);
+#else // ^^^ defined(_M_CEE_PURE) / !defined(_M_CEE_PURE) vvv
+            _CallMemberFunction1(_Dest, _CopyFunc, _Adjusted);
+#endif // ^^^ !defined(_M_CEE_PURE) ^^^
+        }
+    }
+} // unnamed namespace
+
+// All exception_ptr implementations are out-of-line because <memory> depends on <exception>,
+// which means <exception> cannot include <memory> -- and shared_ptr is defined in <memory>.
+// To workaround this, we created a dummy class exception_ptr, which is structurally identical to shared_ptr.
+
+_STD_BEGIN
+struct _Exception_ptr_access {
+    template <class _Ty, class _Ty2>
+    static void _Set_ptr_rep(_Ptr_base<_Ty>& _This, _Ty2* _Px, _Ref_count_base* _Rx) noexcept {
+        _This._Ptr = _Px;
+        _This._Rep = _Rx;
+    }
+};
+_STD_END
+
+static_assert(sizeof(exception_ptr) == sizeof(shared_ptr<const _EXCEPTION_RECORD>)
+                  && alignof(exception_ptr) == alignof(shared_ptr<const _EXCEPTION_RECORD>),
+    "std::exception_ptr and std::shared_ptr<const _EXCEPTION_RECORD> must have the same layout.");
+
+namespace {
+    template <class _StaticEx>
+    class _ExceptionPtr_static final : public _Ref_count_base {
+        // reference count control block for special "never allocates" exceptions like the bad_alloc or bad_exception
+        // exception_ptrs
+    private:
+        void _Destroy() noexcept override {
+            // intentionally does nothing
+        }
+
+        void _Delete_this() noexcept override {
+            // intentionally does nothing
+        }
+
+    public:
+        // constexpr, TRANSITION P1064
+        explicit _ExceptionPtr_static() noexcept : _Ref_count_base() {
+            _PopulateCppExceptionRecord(_ExRecord, &_Ex, static_cast<ThrowInfo*>(__GetExceptionInfo(_Ex)));
+        }
+
+        static shared_ptr<const _EXCEPTION_RECORD> _Get() noexcept {
+            auto& _Instance = _Immortalize<_ExceptionPtr_static>();
+            shared_ptr<const _EXCEPTION_RECORD> _Ret;
+            _Instance._Incref();
+            _Exception_ptr_access::_Set_ptr_rep(_Ret, &_Instance._ExRecord, &_Instance);
+            return _Ret;
+        }
+
+        _EXCEPTION_RECORD _ExRecord;
+        _StaticEx _Ex;
+    };
+
+    class _ExceptionPtr_normal final : public _Ref_count_base {
+        // reference count control block for exception_ptrs; the exception object is stored at
+        // reinterpret_cast<unsigned char*>(this) + sizeof(_ExceptionPtr_normal)
+    private:
+        void _Destroy() noexcept override {
+            // call the destructor for a stored pure or native C++ exception if necessary
+            const auto& _CppEhRecord = reinterpret_cast<EHExceptionRecord&>(_ExRecord);
+
+            if (!PER_IS_MSVC_PURE_OR_NATIVE_EH(&_CppEhRecord)) {
+                return;
+            }
+
+            const auto _PThrow = _CppEhRecord.params.pThrowInfo;
+            if (!_PThrow) {
+                // No ThrowInfo exists. If this was a C++ exception, something must have corrupted it.
+                _CSTD abort();
+            }
+
+            if (!_CppEhRecord.params.pExceptionObject) {
+                return;
+            }
+
+#if _EH_RELATIVE_TYPEINFO
+            const auto _ThrowImageBase     = reinterpret_cast<uintptr_t>(_CppEhRecord.params.pThrowImageBase);
+            const auto _CatchableTypeArray = reinterpret_cast<const CatchableTypeArray*>(
+                static_cast<uintptr_t>(_PThrow->pCatchableTypeArray) + _ThrowImageBase);
+            const auto _PType = reinterpret_cast<CatchableType*>(
+                static_cast<uintptr_t>(_CatchableTypeArray->arrayOfCatchableTypes[0]) + _ThrowImageBase);
+#else // ^^^ _EH_RELATIVE_TYPEINFO / !_EH_RELATIVE_TYPEINFO vvv
+            const auto _PType = _PThrow->pCatchableTypeArray->arrayOfCatchableTypes[0];
+#endif // ^^^ !_EH_RELATIVE_TYPEINFO ^^^
+
+            if (_PThrow->pmfnUnwind) {
+                // The exception was a user defined type with a nontrivial destructor, call it
+#if defined(_M_CEE_PURE)
+                reinterpret_cast<void(__clrcall*)(void*)>(_PThrow->pmfnUnwind)(_CppEhRecord.params.pExceptionObject);
+#elif _EH_RELATIVE_TYPEINFO
+                _CallMemberFunction0(_CppEhRecord.params.pExceptionObject,
+                    reinterpret_cast<void*>(_PThrow->pmfnUnwind + _ThrowImageBase));
+#else // ^^^ _EH_RELATIVE_TYPEINFO && !defined(_M_CEE_PURE) / !_EH_RELATIVE_TYPEINFO && !defined(_M_CEE_PURE) vvv
+                _CallMemberFunction0(_CppEhRecord.params.pExceptionObject, _PThrow->pmfnUnwind);
+#endif // ^^^ !_EH_RELATIVE_TYPEINFO && !defined(_M_CEE_PURE) ^^^
+            } else if (_PType->properties & CT_IsWinRTHandle) {
+                const auto _PUnknown = *static_cast<IUnknown* const*>(_CppEhRecord.params.pExceptionObject);
+                if (_PUnknown) {
+                    _PUnknown->Release();
+                }
+            }
+        }
+
+        void _Delete_this() noexcept override {
+            free(this);
+        }
+
+    public:
+        explicit _ExceptionPtr_normal(const _EXCEPTION_RECORD& _Record) noexcept : _Ref_count_base() {
+            _CopyExceptionRecord(_ExRecord, _Record);
+        }
+
+        _EXCEPTION_RECORD _ExRecord;
+        void* _Unused_alignment_padding{};
+    };
+
+    // We aren't using alignas because this file might be compiled with _M_CEE_PURE
+    static_assert(sizeof(_ExceptionPtr_normal) % __STDCPP_DEFAULT_NEW_ALIGNMENT__ == 0,
+        "Exception in exception_ptr would be constructed with the wrong alignment");
+
+    void _Assign_seh_exception_ptr_from_record(
+        shared_ptr<const _EXCEPTION_RECORD>& _Dest, const _EXCEPTION_RECORD& _Record, void* const _RxRaw) noexcept {
+        // in the memory _RxRaw, constructs a reference count control block for a SEH exception denoted by _Record
+        // if _RxRaw is nullptr, assigns bad_alloc instead
+        if (!_RxRaw) {
+            _Dest = _ExceptionPtr_static<bad_alloc>::_Get();
+            return;
+        }
+
+        const auto _Rx = ::new (_RxRaw) _ExceptionPtr_normal(_Record);
+        _Exception_ptr_access::_Set_ptr_rep(_Dest, &_Rx->_ExRecord, _Rx);
+    }
+
+    void _Assign_cpp_exception_ptr_from_record(
+        shared_ptr<const _EXCEPTION_RECORD>& _Dest, const EHExceptionRecord& _Record) noexcept {
+        // construct a reference count control block for the C++ exception recorded by _Record, and bind it to _Dest
+        // if allocating memory for the reference count control block fails, sets _Dest to bad_alloc
+        // if copying the exception object referred to _Record throws, constructs a reference count control block for
+        //      that exception instead
+        // if copying the exception object thrown by copying the original exception object throws, sets _Dest to
+        //      bad_exception
+        const auto _PThrow = _Record.params.pThrowInfo;
+#if _EH_RELATIVE_TYPEINFO
+        const auto _ThrowImageBase     = reinterpret_cast<uintptr_t>(_Record.params.pThrowImageBase);
+        const auto _CatchableTypeArray = reinterpret_cast<const CatchableTypeArray*>(
+            static_cast<uintptr_t>(_PThrow->pCatchableTypeArray) + _ThrowImageBase);
+        const auto _PType = reinterpret_cast<CatchableType*>(
+            static_cast<uintptr_t>(_CatchableTypeArray->arrayOfCatchableTypes[0]) + _ThrowImageBase);
+#else // ^^^ _EH_RELATIVE_TYPEINFO / !_EH_RELATIVE_TYPEINFO vvv
+        const auto _PType = _PThrow->pCatchableTypeArray->arrayOfCatchableTypes[0];
+#endif // ^^^ !_EH_RELATIVE_TYPEINFO ^^^
+
+        const auto _ExceptionObjectSize = static_cast<size_t>(_PType->sizeOrOffset);
+        const auto _AllocSize           = sizeof(_ExceptionPtr_normal) + _ExceptionObjectSize;
+        _Analysis_assume_(_AllocSize >= sizeof(_ExceptionPtr_normal));
+        auto _RxRaw = malloc(_AllocSize);
+        if (!_RxRaw) {
+            _Dest = _ExceptionPtr_static<bad_alloc>::_Get();
+            return;
+        }
+
+        try {
+            _CopyExceptionObject(static_cast<_ExceptionPtr_normal*>(_RxRaw) + 1, _Record.params.pExceptionObject, _PType
+#if _EH_RELATIVE_TYPEINFO
+                ,
+                _ThrowImageBase
+#endif // _EH_RELATIVE_TYPEINFO
+            );
+
+            const auto _Rx = ::new (_RxRaw) _ExceptionPtr_normal(reinterpret_cast<const _EXCEPTION_RECORD&>(_Record));
+            reinterpret_cast<EHExceptionRecord&>(_Rx->_ExRecord).params.pExceptionObject =
+                static_cast<_ExceptionPtr_normal*>(_RxRaw) + 1;
+            _Exception_ptr_access::_Set_ptr_rep(_Dest, &_Rx->_ExRecord, _Rx);
+        } catch (...) { // copying the exception object threw an exception
+            const auto& _InnerRecord = *_pCurrentException; // exception thrown by the original exception's copy ctor
+            if (_InnerRecord.ExceptionCode == MANAGED_EXCEPTION_CODE
+                || _InnerRecord.ExceptionCode == MANAGED_EXCEPTION_CODE_V4) {
+                // we don't support managed exceptions and don't want to say there's no active exception, so give up and
+                // say bad_exception
+                free(_RxRaw);
+                _Dest = _ExceptionPtr_static<bad_exception>::_Get();
+                return;
+            }
+
+            if (!PER_IS_MSVC_PURE_OR_NATIVE_EH(&_InnerRecord)) { // catching a non-C++ exception depends on /EHa
+                _Assign_seh_exception_ptr_from_record(
+                    _Dest, reinterpret_cast<const _EXCEPTION_RECORD&>(_InnerRecord), _RxRaw);
+                return;
+            }
+
+            const auto _PInnerThrow = _InnerRecord.params.pThrowInfo;
+#if _EH_RELATIVE_TYPEINFO
+            const auto _InnerThrowImageBase     = reinterpret_cast<uintptr_t>(_InnerRecord.params.pThrowImageBase);
+            const auto _InnerCatchableTypeArray = reinterpret_cast<const CatchableTypeArray*>(
+                static_cast<uintptr_t>(_PInnerThrow->pCatchableTypeArray) + _InnerThrowImageBase);
+            const auto _PInnerType = reinterpret_cast<CatchableType*>(
+                static_cast<uintptr_t>(_InnerCatchableTypeArray->arrayOfCatchableTypes[0]) + _InnerThrowImageBase);
+#else // ^^^ _EH_RELATIVE_TYPEINFO / !_EH_RELATIVE_TYPEINFO vvv
+            const auto _PInnerType = _PInnerThrow->pCatchableTypeArray->arrayOfCatchableTypes[0];
+#endif // ^^^ !_EH_RELATIVE_TYPEINFO ^^^
+
+            const auto _InnerExceptionSize = static_cast<size_t>(_PInnerType->sizeOrOffset);
+            const auto _InnerAllocSize     = sizeof(_ExceptionPtr_normal) + _InnerExceptionSize;
+            if (_InnerAllocSize > _AllocSize) {
+                free(_RxRaw);
+                _RxRaw = malloc(_InnerAllocSize);
+                if (!_RxRaw) {
+                    _Dest = _ExceptionPtr_static<bad_alloc>::_Get();
+                    return;
+                }
+            }
+
+            try {
+                _CopyExceptionObject(
+                    static_cast<_ExceptionPtr_normal*>(_RxRaw) + 1, _InnerRecord.params.pExceptionObject, _PInnerType
+#if _EH_RELATIVE_TYPEINFO
+                    ,
+                    _ThrowImageBase
+#endif // _EH_RELATIVE_TYPEINFO
+                );
+            } catch (...) { // copying the exception emitted while copying the original exception also threw, give up
+                free(_RxRaw);
+                _Dest = _ExceptionPtr_static<bad_exception>::_Get();
+                return;
+            }
+
+            // this next block must be duplicated inside the catch (even though it looks identical to the block in the
+            // try) so that _InnerRecord is held alive; exiting the catch will destroy it
+            const auto _Rx =
+                ::new (_RxRaw) _ExceptionPtr_normal(reinterpret_cast<const _EXCEPTION_RECORD&>(_InnerRecord));
+            reinterpret_cast<EHExceptionRecord&>(_Rx->_ExRecord).params.pExceptionObject =
+                static_cast<_ExceptionPtr_normal*>(_RxRaw) + 1;
+            _Exception_ptr_access::_Set_ptr_rep(_Dest, &_Rx->_ExRecord, _Rx);
+        }
+    }
+} // unnamed namespace
+
+_CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrCreate(_Out_ void* _Ptr) noexcept {
+    ::new (_Ptr) shared_ptr<const _EXCEPTION_RECORD>();
+}
+
+_CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrDestroy(_Inout_ void* _Ptr) noexcept {
+    static_cast<shared_ptr<const _EXCEPTION_RECORD>*>(_Ptr)->~shared_ptr<const _EXCEPTION_RECORD>();
+}
+
+_CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrCopy(_Out_ void* _Dest, _In_ const void* _Src) noexcept {
+    ::new (_Dest) shared_ptr<const _EXCEPTION_RECORD>(*static_cast<const shared_ptr<const _EXCEPTION_RECORD>*>(_Src));
+}
+
+_CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrAssign(_Inout_ void* _Dest, _In_ const void* _Src) noexcept {
+    *static_cast<shared_ptr<const _EXCEPTION_RECORD>*>(_Dest) =
+        *static_cast<const shared_ptr<const _EXCEPTION_RECORD>*>(_Src);
+}
+
+_CRTIMP2_PURE bool __CLRCALL_PURE_OR_CDECL __ExceptionPtrCompare(
+    _In_ const void* _Lhs, _In_ const void* _Rhs) noexcept {
+    return *static_cast<const shared_ptr<const _EXCEPTION_RECORD>*>(_Lhs)
+        == *static_cast<const shared_ptr<const _EXCEPTION_RECORD>*>(_Rhs);
+}
+
+_CRTIMP2_PURE bool __CLRCALL_PURE_OR_CDECL __ExceptionPtrToBool(_In_ const void* _Ptr) noexcept {
+    return static_cast<bool>(*static_cast<const shared_ptr<const _EXCEPTION_RECORD>*>(_Ptr));
+}
+
+_CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrSwap(_Inout_ void* _Lhs, _Inout_ void* _Rhs) noexcept {
+    static_cast<shared_ptr<const _EXCEPTION_RECORD>*>(_Lhs)->swap(
+        *static_cast<shared_ptr<const _EXCEPTION_RECORD>*>(_Rhs));
+}
+
+_CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrCurrentException(void* _Ptr) noexcept {
+    const auto _PRecord = _pCurrentException; // nontrivial FLS cost, pay it once
+    if (!_PRecord || _PRecord->ExceptionCode == MANAGED_EXCEPTION_CODE
+        || _PRecord->ExceptionCode == MANAGED_EXCEPTION_CODE_V4) {
+        return; // no current exception, or we don't support managed exceptions
+    }
+
+    auto& _Dest = *static_cast<shared_ptr<const _EXCEPTION_RECORD>*>(_Ptr);
+    if (PER_IS_MSVC_PURE_OR_NATIVE_EH(_PRecord)) {
+        _Assign_cpp_exception_ptr_from_record(_Dest, *_PRecord);
+    } else {
+        // _Assign_seh_exception_ptr_from_record handles failed malloc
+        _Assign_seh_exception_ptr_from_record(
+            _Dest, reinterpret_cast<_EXCEPTION_RECORD&>(*_PRecord), malloc(sizeof(_ExceptionPtr_normal)));
+    }
+}
+
+[[noreturn]] _CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrRethrow(_In_ const void* _PtrRaw) {
+    const shared_ptr<const _EXCEPTION_RECORD>* _Ptr = static_cast<const shared_ptr<const _EXCEPTION_RECORD>*>(_PtrRaw);
+    // throwing a bad_exception if they give us a nullptr exception_ptr
+    if (!*_Ptr) {
+        throw bad_exception();
+    }
+
+    auto _RecordCopy = **_Ptr;
+    auto& _CppRecord = reinterpret_cast<EHExceptionRecord&>(_RecordCopy);
+    if (PER_IS_MSVC_PURE_OR_NATIVE_EH(&_CppRecord)) {
+        // This is a C++ exception.
+        // We need to build the exception on the stack because the current exception mechanism assumes the exception
+        // object is on the stack and will call the appropriate destructor (if there's a nontrivial one).
+        const auto _PThrow = _CppRecord.params.pThrowInfo;
+        if (!_CppRecord.params.pExceptionObject || !_PThrow || !_PThrow->pCatchableTypeArray) {
+            // Missing or corrupt ThrowInfo. If this was a C++ exception, something must have corrupted it.
+            _CSTD abort();
+        }
+
+#if _EH_RELATIVE_TYPEINFO
+        const auto _ThrowImageBase = reinterpret_cast<uintptr_t>(_CppRecord.params.pThrowImageBase);
+        const auto _CatchableTypeArray =
+            reinterpret_cast<const CatchableTypeArray*>(_ThrowImageBase + _PThrow->pCatchableTypeArray);
+#else // ^^^ _EH_RELATIVE_TYPEINFO / !_EH_RELATIVE_TYPEINFO vvv
+        const auto _CatchableTypeArray = _PThrow->pCatchableTypeArray;
+#endif // ^^^ !_EH_RELATIVE_TYPEINFO ^^^
+
+        if (_CatchableTypeArray->nCatchableTypes <= 0) {
+            // Ditto corrupted.
+            _CSTD abort();
+        }
+
+        // we finally got the type info we want
+#if _EH_RELATIVE_TYPEINFO
+        const auto _PType = reinterpret_cast<CatchableType*>(
+            static_cast<uintptr_t>(_CatchableTypeArray->arrayOfCatchableTypes[0]) + _ThrowImageBase);
+#else // ^^^ _EH_RELATIVE_TYPEINFO / !_EH_RELATIVE_TYPEINFO vvv
+        const auto _PType = _PThrow->pCatchableTypeArray->arrayOfCatchableTypes[0];
+#endif // ^^^ !_EH_RELATIVE_TYPEINFO ^^^
+
+        // Alloc memory on stack for exception object. This might cause a stack overflow SEH exception, or another C++
+        // exception when copying the C++ exception object. In that case, we just let that become the thrown exception.
+
+#pragma warning(suppress : 6255) //  _alloca indicates failure by raising a stack overflow exception
+        void* _PExceptionBuffer = alloca(_PType->sizeOrOffset);
+        _CopyExceptionObject(_PExceptionBuffer, _CppRecord.params.pExceptionObject, _PType
+#if _EH_RELATIVE_TYPEINFO
+            ,
+            _ThrowImageBase
+#endif // _EH_RELATIVE_TYPEINFO
+        );
+
+        _CppRecord.params.pExceptionObject = _PExceptionBuffer;
+    } else {
+        // this is a SEH exception, no special handling is required
+    }
+
+    _Analysis_assume_(_RecordCopy.NumberParameters <= EXCEPTION_MAXIMUM_PARAMETERS);
+    RaiseException(_RecordCopy.ExceptionCode, _RecordCopy.ExceptionFlags, _RecordCopy.NumberParameters,
+        _RecordCopy.ExceptionInformation);
+}
+
+_CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrCopyException(
+    _Inout_ void* _Ptr, _In_ const void* _PExceptRaw, _In_ const void* _PThrowRaw) noexcept {
+    _EXCEPTION_RECORD _Record;
+    _PopulateCppExceptionRecord(_Record, _PExceptRaw, static_cast<ThrowInfo*>(_PThrowRaw));
+    _Assign_cpp_exception_ptr_from_record(
+        *static_cast<shared_ptr<const _EXCEPTION_RECORD>*>(_Ptr), reinterpret_cast<const EHExceptionRecord&>(_Record));
+}

>From a6c26114d89c9a24d90982cf550a91ce97dac0e6 Mon Sep 17 00:00:00 2001
From: "Stephan T. Lavavej" <stl at microsoft.com>
Date: Mon, 10 Jun 2024 05:33:51 -0700
Subject: [PATCH 2/5] microsoft/STL's `<exception>`, copied verbatim as
 `win32_exception_ptr.h`.

>From our `main` branch as of 2024-06-10:

https://github.com/microsoft/STL/blob/e36ee6c2b9bc6f5b1f70776c18cf5d3a93a69798/stl/inc/exception
---
 .../include/__exception/win32_exception_ptr.h | 422 ++++++++++++++++++
 1 file changed, 422 insertions(+)
 create mode 100644 libcxx/include/__exception/win32_exception_ptr.h

diff --git a/libcxx/include/__exception/win32_exception_ptr.h b/libcxx/include/__exception/win32_exception_ptr.h
new file mode 100644
index 0000000000000..95721640b89c4
--- /dev/null
+++ b/libcxx/include/__exception/win32_exception_ptr.h
@@ -0,0 +1,422 @@
+// exception standard header
+
+// Copyright (c) Microsoft Corporation.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+#ifndef _EXCEPTION_
+#define _EXCEPTION_
+#include <yvals.h>
+#if _STL_COMPILER_PREPROCESSOR
+
+#include <cstdlib>
+#include <type_traits>
+
+#pragma pack(push, _CRT_PACKING)
+#pragma warning(push, _STL_WARNING_LEVEL)
+#pragma warning(disable : _STL_DISABLED_WARNINGS)
+_STL_DISABLE_CLANG_WARNINGS
+#pragma push_macro("new")
+#undef new
+
+_STD_BEGIN
+
+#if _HAS_DEPRECATED_UNCAUGHT_EXCEPTION
+_EXPORT_STD extern "C++" _CXX17_DEPRECATE_UNCAUGHT_EXCEPTION _NODISCARD _CRTIMP2_PURE bool __CLRCALL_PURE_OR_CDECL
+    uncaught_exception() noexcept;
+#endif // _HAS_DEPRECATED_UNCAUGHT_EXCEPTION
+_EXPORT_STD extern "C++" _NODISCARD _CRTIMP2_PURE int __CLRCALL_PURE_OR_CDECL uncaught_exceptions() noexcept;
+
+_STD_END
+
+#if _HAS_EXCEPTIONS
+
+#include <malloc.h> // TRANSITION, VSO-2048380: This is unnecessary, but many projects assume it as of 2024-04-29
+#include <vcruntime_exception.h>
+
+_STD_BEGIN
+
+_EXPORT_STD using ::terminate;
+
+#ifndef _M_CEE_PURE
+_EXPORT_STD using ::set_terminate;
+_EXPORT_STD using ::terminate_handler;
+
+_EXPORT_STD _NODISCARD inline terminate_handler __CRTDECL get_terminate() noexcept {
+    // get current terminate handler
+    return _get_terminate();
+}
+#endif // !defined(_M_CEE_PURE)
+
+#if _HAS_UNEXPECTED
+using ::unexpected;
+
+#ifndef _M_CEE_PURE
+using ::set_unexpected;
+using ::unexpected_handler;
+
+_NODISCARD inline unexpected_handler __CRTDECL get_unexpected() noexcept {
+    // get current unexpected handler
+    return _get_unexpected();
+}
+#endif // !defined(_M_CEE_PURE)
+#endif // _HAS_UNEXPECTED
+
+_STD_END
+
+#else // ^^^ _HAS_EXCEPTIONS / !_HAS_EXCEPTIONS vvv
+
+#pragma push_macro("stdext")
+#undef stdext
+
+_STDEXT_BEGIN
+class exception;
+_STDEXT_END
+
+_STD_BEGIN
+
+_EXPORT_STD using _STDEXT exception;
+
+using _Prhand = void(__cdecl*)(const exception&);
+
+extern _CRTIMP2_PURE_IMPORT _Prhand _Raise_handler; // pointer to raise handler
+
+_STD_END
+
+_STDEXT_BEGIN
+class exception { // base of all library exceptions
+public:
+    static _STD _Prhand _Set_raise_handler(_STD _Prhand _Pnew) { // register a handler for _Raise calls
+        const _STD _Prhand _Pold = _STD _Raise_handler;
+        _STD _Raise_handler      = _Pnew;
+        return _Pold;
+    }
+
+    // this constructor is necessary to compile
+    // successfully header new for _HAS_EXCEPTIONS==0 scenario
+    explicit __CLR_OR_THIS_CALL exception(const char* _Message = "unknown", int = 1) noexcept : _Ptr(_Message) {}
+
+    __CLR_OR_THIS_CALL exception(const exception& _Right) noexcept : _Ptr(_Right._Ptr) {}
+
+    exception& __CLR_OR_THIS_CALL operator=(const exception& _Right) noexcept {
+        _Ptr = _Right._Ptr;
+        return *this;
+    }
+
+    virtual __CLR_OR_THIS_CALL ~exception() noexcept {}
+
+    _NODISCARD virtual const char* __CLR_OR_THIS_CALL what() const noexcept { // return pointer to message string
+        return _Ptr ? _Ptr : "unknown exception";
+    }
+
+    [[noreturn]] void __CLR_OR_THIS_CALL _Raise() const { // raise the exception
+        if (_STD _Raise_handler) {
+            (*_STD _Raise_handler)(*this); // call raise handler if present
+        }
+
+        _Doraise(); // call the protected virtual
+        _RAISE(*this); // raise this exception
+    }
+
+protected:
+    virtual void __CLR_OR_THIS_CALL _Doraise() const {} // perform class-specific exception handling
+
+    const char* _Ptr; // the message pointer
+};
+
+class bad_exception : public exception { // base of all bad exceptions
+public:
+    __CLR_OR_THIS_CALL bad_exception(const char* _Message = "bad exception") noexcept : exception(_Message) {}
+
+    __CLR_OR_THIS_CALL ~bad_exception() noexcept override {}
+
+protected:
+    void __CLR_OR_THIS_CALL _Doraise() const override { // raise this exception
+        _RAISE(*this);
+    }
+};
+
+class bad_array_new_length;
+
+class bad_alloc : public exception { // base of all bad allocation exceptions
+public:
+    __CLR_OR_THIS_CALL bad_alloc() noexcept
+        : exception("bad allocation", 1) {} // construct from message string with no memory allocation
+
+    __CLR_OR_THIS_CALL ~bad_alloc() noexcept override {}
+
+private:
+    friend bad_array_new_length;
+
+    __CLR_OR_THIS_CALL bad_alloc(const char* _Message) noexcept
+        : exception(_Message, 1) {} // construct from message string with no memory allocation
+
+protected:
+    void __CLR_OR_THIS_CALL _Doraise() const override { // perform class-specific exception handling
+        _RAISE(*this);
+    }
+};
+
+class bad_array_new_length : public bad_alloc {
+public:
+    bad_array_new_length() noexcept : bad_alloc("bad array new length") {}
+};
+
+_STDEXT_END
+
+_STD_BEGIN
+_EXPORT_STD using terminate_handler = void(__cdecl*)();
+
+_EXPORT_STD inline terminate_handler __CRTDECL set_terminate(terminate_handler) noexcept {
+    // register a terminate handler
+    return nullptr;
+}
+
+_EXPORT_STD [[noreturn]] inline void __CRTDECL terminate() noexcept {
+    // handle exception termination
+    _CSTD abort();
+}
+
+_EXPORT_STD _NODISCARD inline terminate_handler __CRTDECL get_terminate() noexcept {
+    // get current terminate handler
+    return nullptr;
+}
+
+#if _HAS_UNEXPECTED
+using unexpected_handler = void(__cdecl*)();
+
+inline unexpected_handler __CRTDECL set_unexpected(unexpected_handler) noexcept {
+    // register an unexpected handler
+    return nullptr;
+}
+
+inline void __CRTDECL unexpected() {} // handle unexpected exception
+
+_NODISCARD inline unexpected_handler __CRTDECL get_unexpected() noexcept {
+    // get current unexpected handler
+    return nullptr;
+}
+#endif // _HAS_UNEXPECTED
+
+_EXPORT_STD using _STDEXT bad_alloc;
+_EXPORT_STD using _STDEXT bad_array_new_length;
+_EXPORT_STD using _STDEXT bad_exception;
+
+_STD_END
+
+#pragma pop_macro("stdext")
+
+#endif // ^^^ !_HAS_EXCEPTIONS ^^^
+
+extern "C++" _CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrCreate(_Out_ void*) noexcept;
+extern "C++" _CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrDestroy(_Inout_ void*) noexcept;
+extern "C++" _CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrCopy(_Out_ void*, _In_ const void*) noexcept;
+extern "C++" _CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrAssign(_Inout_ void*, _In_ const void*) noexcept;
+extern "C++" _CRTIMP2_PURE bool __CLRCALL_PURE_OR_CDECL __ExceptionPtrCompare(
+    _In_ const void*, _In_ const void*) noexcept;
+extern "C++" _CRTIMP2_PURE bool __CLRCALL_PURE_OR_CDECL __ExceptionPtrToBool(_In_ const void*) noexcept;
+extern "C++" _CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrSwap(_Inout_ void*, _Inout_ void*) noexcept;
+extern "C++" _CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrCurrentException(void*) noexcept;
+extern "C++" [[noreturn]] _CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrRethrow(_In_ const void*);
+extern "C++" _CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrCopyException(
+    _Inout_ void*, _In_ const void*, _In_ const void*) noexcept;
+
+_STD_BEGIN
+
+_EXPORT_STD class exception_ptr {
+public:
+    exception_ptr() noexcept {
+        __ExceptionPtrCreate(this);
+    }
+
+    exception_ptr(nullptr_t) noexcept {
+        __ExceptionPtrCreate(this);
+    }
+
+    ~exception_ptr() noexcept {
+        __ExceptionPtrDestroy(this);
+    }
+
+    exception_ptr(const exception_ptr& _Rhs) noexcept {
+        __ExceptionPtrCopy(this, &_Rhs);
+    }
+
+    exception_ptr& operator=(const exception_ptr& _Rhs) noexcept {
+        __ExceptionPtrAssign(this, &_Rhs);
+        return *this;
+    }
+
+    exception_ptr& operator=(nullptr_t) noexcept {
+        exception_ptr _Ptr;
+        __ExceptionPtrAssign(this, &_Ptr);
+        return *this;
+    }
+
+    explicit operator bool() const noexcept {
+        return __ExceptionPtrToBool(this);
+    }
+
+    static exception_ptr _Copy_exception(_In_ void* _Except, _In_ const void* _Ptr) {
+        exception_ptr _Retval;
+        if (!_Ptr) {
+            // unsupported exceptions
+            return _Retval;
+        }
+        __ExceptionPtrCopyException(&_Retval, _Except, _Ptr);
+        return _Retval;
+    }
+
+    friend void swap(exception_ptr& _Lhs, exception_ptr& _Rhs) noexcept {
+        __ExceptionPtrSwap(&_Lhs, &_Rhs);
+    }
+
+    _NODISCARD_FRIEND bool operator==(const exception_ptr& _Lhs, const exception_ptr& _Rhs) noexcept {
+        return __ExceptionPtrCompare(&_Lhs, &_Rhs);
+    }
+
+    _NODISCARD_FRIEND bool operator==(const exception_ptr& _Lhs, nullptr_t) noexcept {
+        return !_Lhs;
+    }
+
+#if !_HAS_CXX20
+    _NODISCARD_FRIEND bool operator==(nullptr_t, const exception_ptr& _Rhs) noexcept {
+        return !_Rhs;
+    }
+
+    _NODISCARD_FRIEND bool operator!=(const exception_ptr& _Lhs, const exception_ptr& _Rhs) noexcept {
+        return !(_Lhs == _Rhs);
+    }
+
+    _NODISCARD_FRIEND bool operator!=(const exception_ptr& _Lhs, nullptr_t) noexcept {
+        return !(_Lhs == nullptr);
+    }
+
+    _NODISCARD_FRIEND bool operator!=(nullptr_t, const exception_ptr& _Rhs) noexcept {
+        return !(nullptr == _Rhs);
+    }
+#endif // !_HAS_CXX20
+
+private:
+#ifdef __clang__
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wunused-private-field"
+#endif // defined(__clang__)
+    void* _Data1{};
+    void* _Data2{};
+#ifdef __clang__
+#pragma clang diagnostic pop
+#endif // defined(__clang__)
+};
+
+_EXPORT_STD _NODISCARD inline exception_ptr current_exception() noexcept {
+    exception_ptr _Retval;
+    __ExceptionPtrCurrentException(&_Retval);
+    return _Retval;
+}
+
+_EXPORT_STD [[noreturn]] inline void rethrow_exception(_In_ exception_ptr _Ptr) {
+    __ExceptionPtrRethrow(&_Ptr);
+}
+
+template <class _Ex>
+void* __GetExceptionInfo(_Ex);
+
+_EXPORT_STD template <class _Ex>
+_NODISCARD_SMART_PTR_ALLOC exception_ptr make_exception_ptr(_Ex _Except) noexcept {
+    return exception_ptr::_Copy_exception(_STD addressof(_Except), __GetExceptionInfo(_Except));
+}
+
+_EXPORT_STD class nested_exception { // wrap an exception_ptr
+public:
+    nested_exception() noexcept : _Exc(_STD current_exception()) {}
+
+    nested_exception(const nested_exception&) noexcept            = default;
+    nested_exception& operator=(const nested_exception&) noexcept = default;
+    virtual ~nested_exception() noexcept {}
+
+    [[noreturn]] void rethrow_nested() const { // throw wrapped exception_ptr
+        if (_Exc) {
+            _STD rethrow_exception(_Exc);
+        } else {
+            _STD terminate(); // per N4950 [except.nested]/4
+        }
+    }
+
+    _NODISCARD exception_ptr nested_ptr() const noexcept { // return wrapped exception_ptr
+        return _Exc;
+    }
+
+private:
+    exception_ptr _Exc;
+};
+
+template <class _Uty>
+struct _With_nested_v2 : _Uty, nested_exception { // glue user exception to nested_exception
+    template <class _Ty>
+    explicit _With_nested_v2(_Ty&& _Arg)
+        : _Uty(_STD forward<_Ty>(_Arg)), nested_exception() {} // store user exception and current_exception()
+};
+
+_EXPORT_STD template <class _Ty>
+[[noreturn]] void throw_with_nested(_Ty&& _Arg) {
+    // throw user exception, glued to nested_exception if possible
+    using _Uty = decay_t<_Ty>;
+
+    if constexpr (is_class_v<_Uty> && !is_base_of_v<nested_exception, _Uty> && !is_final_v<_Uty>) {
+        // throw user exception glued to nested_exception
+        _THROW(_With_nested_v2<_Uty>(_STD forward<_Ty>(_Arg)));
+    } else {
+        // throw user exception by itself
+        _THROW(_STD forward<_Ty>(_Arg));
+    }
+}
+
+#ifdef _CPPRTTI
+_EXPORT_STD template <class _Ty>
+void rethrow_if_nested(const _Ty& _Arg) {
+    // detect nested_exception inheritance
+    constexpr bool _Can_use_dynamic_cast =
+        is_polymorphic_v<_Ty> && (!is_base_of_v<nested_exception, _Ty> || is_convertible_v<_Ty*, nested_exception*>);
+
+    if constexpr (_Can_use_dynamic_cast) {
+        const auto _Nested = dynamic_cast<const nested_exception*>(_STD addressof(_Arg));
+
+        if (_Nested) {
+            _Nested->rethrow_nested();
+        }
+    }
+}
+#else // ^^^ defined(_CPPRTTI) / !defined(_CPPRTTI) vvv
+_EXPORT_STD template <class _Ty>
+void rethrow_if_nested(const _Ty&) = delete; // requires /GR option
+#endif // ^^^ !defined(_CPPRTTI) ^^^
+
+_EXPORT_STD class bad_variant_access
+    : public exception { // exception for visit of a valueless variant or get<I> on a variant with index() != I
+public:
+    bad_variant_access() noexcept = default;
+
+    _NODISCARD const char* __CLR_OR_THIS_CALL what() const noexcept override {
+        return "bad variant access";
+    }
+
+#if !_HAS_EXCEPTIONS
+protected:
+    void _Doraise() const override { // perform class-specific exception handling
+        _RAISE(*this);
+    }
+#endif // ^^^ !_HAS_EXCEPTIONS ^^^
+};
+
+[[noreturn]] inline void _Throw_bad_variant_access() {
+    _THROW(bad_variant_access{});
+}
+
+_STD_END
+
+#pragma pop_macro("new")
+_STL_RESTORE_CLANG_WARNINGS
+#pragma warning(pop)
+#pragma pack(pop)
+
+#endif // _STL_COMPILER_PREPROCESSOR
+#endif // _EXCEPTION_

>From 95f3871b3189272157cd596271322daa3714b845 Mon Sep 17 00:00:00 2001
From: "Stephan T. Lavavej" <stl at microsoft.com>
Date: Mon, 10 Jun 2024 05:07:16 -0700
Subject: [PATCH 3/5] Convert files to LF line endings.

---
 .../include/__exception/win32_exception_ptr.h |  844 ++++++-------
 libcxx/src/support/win32/excptptr.cpp         | 1066 ++++++++---------
 2 files changed, 955 insertions(+), 955 deletions(-)

diff --git a/libcxx/include/__exception/win32_exception_ptr.h b/libcxx/include/__exception/win32_exception_ptr.h
index 95721640b89c4..efadca1b733d0 100644
--- a/libcxx/include/__exception/win32_exception_ptr.h
+++ b/libcxx/include/__exception/win32_exception_ptr.h
@@ -1,422 +1,422 @@
-// exception standard header
-
-// Copyright (c) Microsoft Corporation.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-
-#ifndef _EXCEPTION_
-#define _EXCEPTION_
-#include <yvals.h>
-#if _STL_COMPILER_PREPROCESSOR
-
-#include <cstdlib>
-#include <type_traits>
-
-#pragma pack(push, _CRT_PACKING)
-#pragma warning(push, _STL_WARNING_LEVEL)
-#pragma warning(disable : _STL_DISABLED_WARNINGS)
-_STL_DISABLE_CLANG_WARNINGS
-#pragma push_macro("new")
-#undef new
-
-_STD_BEGIN
-
-#if _HAS_DEPRECATED_UNCAUGHT_EXCEPTION
-_EXPORT_STD extern "C++" _CXX17_DEPRECATE_UNCAUGHT_EXCEPTION _NODISCARD _CRTIMP2_PURE bool __CLRCALL_PURE_OR_CDECL
-    uncaught_exception() noexcept;
-#endif // _HAS_DEPRECATED_UNCAUGHT_EXCEPTION
-_EXPORT_STD extern "C++" _NODISCARD _CRTIMP2_PURE int __CLRCALL_PURE_OR_CDECL uncaught_exceptions() noexcept;
-
-_STD_END
-
-#if _HAS_EXCEPTIONS
-
-#include <malloc.h> // TRANSITION, VSO-2048380: This is unnecessary, but many projects assume it as of 2024-04-29
-#include <vcruntime_exception.h>
-
-_STD_BEGIN
-
-_EXPORT_STD using ::terminate;
-
-#ifndef _M_CEE_PURE
-_EXPORT_STD using ::set_terminate;
-_EXPORT_STD using ::terminate_handler;
-
-_EXPORT_STD _NODISCARD inline terminate_handler __CRTDECL get_terminate() noexcept {
-    // get current terminate handler
-    return _get_terminate();
-}
-#endif // !defined(_M_CEE_PURE)
-
-#if _HAS_UNEXPECTED
-using ::unexpected;
-
-#ifndef _M_CEE_PURE
-using ::set_unexpected;
-using ::unexpected_handler;
-
-_NODISCARD inline unexpected_handler __CRTDECL get_unexpected() noexcept {
-    // get current unexpected handler
-    return _get_unexpected();
-}
-#endif // !defined(_M_CEE_PURE)
-#endif // _HAS_UNEXPECTED
-
-_STD_END
-
-#else // ^^^ _HAS_EXCEPTIONS / !_HAS_EXCEPTIONS vvv
-
-#pragma push_macro("stdext")
-#undef stdext
-
-_STDEXT_BEGIN
-class exception;
-_STDEXT_END
-
-_STD_BEGIN
-
-_EXPORT_STD using _STDEXT exception;
-
-using _Prhand = void(__cdecl*)(const exception&);
-
-extern _CRTIMP2_PURE_IMPORT _Prhand _Raise_handler; // pointer to raise handler
-
-_STD_END
-
-_STDEXT_BEGIN
-class exception { // base of all library exceptions
-public:
-    static _STD _Prhand _Set_raise_handler(_STD _Prhand _Pnew) { // register a handler for _Raise calls
-        const _STD _Prhand _Pold = _STD _Raise_handler;
-        _STD _Raise_handler      = _Pnew;
-        return _Pold;
-    }
-
-    // this constructor is necessary to compile
-    // successfully header new for _HAS_EXCEPTIONS==0 scenario
-    explicit __CLR_OR_THIS_CALL exception(const char* _Message = "unknown", int = 1) noexcept : _Ptr(_Message) {}
-
-    __CLR_OR_THIS_CALL exception(const exception& _Right) noexcept : _Ptr(_Right._Ptr) {}
-
-    exception& __CLR_OR_THIS_CALL operator=(const exception& _Right) noexcept {
-        _Ptr = _Right._Ptr;
-        return *this;
-    }
-
-    virtual __CLR_OR_THIS_CALL ~exception() noexcept {}
-
-    _NODISCARD virtual const char* __CLR_OR_THIS_CALL what() const noexcept { // return pointer to message string
-        return _Ptr ? _Ptr : "unknown exception";
-    }
-
-    [[noreturn]] void __CLR_OR_THIS_CALL _Raise() const { // raise the exception
-        if (_STD _Raise_handler) {
-            (*_STD _Raise_handler)(*this); // call raise handler if present
-        }
-
-        _Doraise(); // call the protected virtual
-        _RAISE(*this); // raise this exception
-    }
-
-protected:
-    virtual void __CLR_OR_THIS_CALL _Doraise() const {} // perform class-specific exception handling
-
-    const char* _Ptr; // the message pointer
-};
-
-class bad_exception : public exception { // base of all bad exceptions
-public:
-    __CLR_OR_THIS_CALL bad_exception(const char* _Message = "bad exception") noexcept : exception(_Message) {}
-
-    __CLR_OR_THIS_CALL ~bad_exception() noexcept override {}
-
-protected:
-    void __CLR_OR_THIS_CALL _Doraise() const override { // raise this exception
-        _RAISE(*this);
-    }
-};
-
-class bad_array_new_length;
-
-class bad_alloc : public exception { // base of all bad allocation exceptions
-public:
-    __CLR_OR_THIS_CALL bad_alloc() noexcept
-        : exception("bad allocation", 1) {} // construct from message string with no memory allocation
-
-    __CLR_OR_THIS_CALL ~bad_alloc() noexcept override {}
-
-private:
-    friend bad_array_new_length;
-
-    __CLR_OR_THIS_CALL bad_alloc(const char* _Message) noexcept
-        : exception(_Message, 1) {} // construct from message string with no memory allocation
-
-protected:
-    void __CLR_OR_THIS_CALL _Doraise() const override { // perform class-specific exception handling
-        _RAISE(*this);
-    }
-};
-
-class bad_array_new_length : public bad_alloc {
-public:
-    bad_array_new_length() noexcept : bad_alloc("bad array new length") {}
-};
-
-_STDEXT_END
-
-_STD_BEGIN
-_EXPORT_STD using terminate_handler = void(__cdecl*)();
-
-_EXPORT_STD inline terminate_handler __CRTDECL set_terminate(terminate_handler) noexcept {
-    // register a terminate handler
-    return nullptr;
-}
-
-_EXPORT_STD [[noreturn]] inline void __CRTDECL terminate() noexcept {
-    // handle exception termination
-    _CSTD abort();
-}
-
-_EXPORT_STD _NODISCARD inline terminate_handler __CRTDECL get_terminate() noexcept {
-    // get current terminate handler
-    return nullptr;
-}
-
-#if _HAS_UNEXPECTED
-using unexpected_handler = void(__cdecl*)();
-
-inline unexpected_handler __CRTDECL set_unexpected(unexpected_handler) noexcept {
-    // register an unexpected handler
-    return nullptr;
-}
-
-inline void __CRTDECL unexpected() {} // handle unexpected exception
-
-_NODISCARD inline unexpected_handler __CRTDECL get_unexpected() noexcept {
-    // get current unexpected handler
-    return nullptr;
-}
-#endif // _HAS_UNEXPECTED
-
-_EXPORT_STD using _STDEXT bad_alloc;
-_EXPORT_STD using _STDEXT bad_array_new_length;
-_EXPORT_STD using _STDEXT bad_exception;
-
-_STD_END
-
-#pragma pop_macro("stdext")
-
-#endif // ^^^ !_HAS_EXCEPTIONS ^^^
-
-extern "C++" _CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrCreate(_Out_ void*) noexcept;
-extern "C++" _CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrDestroy(_Inout_ void*) noexcept;
-extern "C++" _CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrCopy(_Out_ void*, _In_ const void*) noexcept;
-extern "C++" _CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrAssign(_Inout_ void*, _In_ const void*) noexcept;
-extern "C++" _CRTIMP2_PURE bool __CLRCALL_PURE_OR_CDECL __ExceptionPtrCompare(
-    _In_ const void*, _In_ const void*) noexcept;
-extern "C++" _CRTIMP2_PURE bool __CLRCALL_PURE_OR_CDECL __ExceptionPtrToBool(_In_ const void*) noexcept;
-extern "C++" _CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrSwap(_Inout_ void*, _Inout_ void*) noexcept;
-extern "C++" _CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrCurrentException(void*) noexcept;
-extern "C++" [[noreturn]] _CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrRethrow(_In_ const void*);
-extern "C++" _CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrCopyException(
-    _Inout_ void*, _In_ const void*, _In_ const void*) noexcept;
-
-_STD_BEGIN
-
-_EXPORT_STD class exception_ptr {
-public:
-    exception_ptr() noexcept {
-        __ExceptionPtrCreate(this);
-    }
-
-    exception_ptr(nullptr_t) noexcept {
-        __ExceptionPtrCreate(this);
-    }
-
-    ~exception_ptr() noexcept {
-        __ExceptionPtrDestroy(this);
-    }
-
-    exception_ptr(const exception_ptr& _Rhs) noexcept {
-        __ExceptionPtrCopy(this, &_Rhs);
-    }
-
-    exception_ptr& operator=(const exception_ptr& _Rhs) noexcept {
-        __ExceptionPtrAssign(this, &_Rhs);
-        return *this;
-    }
-
-    exception_ptr& operator=(nullptr_t) noexcept {
-        exception_ptr _Ptr;
-        __ExceptionPtrAssign(this, &_Ptr);
-        return *this;
-    }
-
-    explicit operator bool() const noexcept {
-        return __ExceptionPtrToBool(this);
-    }
-
-    static exception_ptr _Copy_exception(_In_ void* _Except, _In_ const void* _Ptr) {
-        exception_ptr _Retval;
-        if (!_Ptr) {
-            // unsupported exceptions
-            return _Retval;
-        }
-        __ExceptionPtrCopyException(&_Retval, _Except, _Ptr);
-        return _Retval;
-    }
-
-    friend void swap(exception_ptr& _Lhs, exception_ptr& _Rhs) noexcept {
-        __ExceptionPtrSwap(&_Lhs, &_Rhs);
-    }
-
-    _NODISCARD_FRIEND bool operator==(const exception_ptr& _Lhs, const exception_ptr& _Rhs) noexcept {
-        return __ExceptionPtrCompare(&_Lhs, &_Rhs);
-    }
-
-    _NODISCARD_FRIEND bool operator==(const exception_ptr& _Lhs, nullptr_t) noexcept {
-        return !_Lhs;
-    }
-
-#if !_HAS_CXX20
-    _NODISCARD_FRIEND bool operator==(nullptr_t, const exception_ptr& _Rhs) noexcept {
-        return !_Rhs;
-    }
-
-    _NODISCARD_FRIEND bool operator!=(const exception_ptr& _Lhs, const exception_ptr& _Rhs) noexcept {
-        return !(_Lhs == _Rhs);
-    }
-
-    _NODISCARD_FRIEND bool operator!=(const exception_ptr& _Lhs, nullptr_t) noexcept {
-        return !(_Lhs == nullptr);
-    }
-
-    _NODISCARD_FRIEND bool operator!=(nullptr_t, const exception_ptr& _Rhs) noexcept {
-        return !(nullptr == _Rhs);
-    }
-#endif // !_HAS_CXX20
-
-private:
-#ifdef __clang__
-#pragma clang diagnostic push
-#pragma clang diagnostic ignored "-Wunused-private-field"
-#endif // defined(__clang__)
-    void* _Data1{};
-    void* _Data2{};
-#ifdef __clang__
-#pragma clang diagnostic pop
-#endif // defined(__clang__)
-};
-
-_EXPORT_STD _NODISCARD inline exception_ptr current_exception() noexcept {
-    exception_ptr _Retval;
-    __ExceptionPtrCurrentException(&_Retval);
-    return _Retval;
-}
-
-_EXPORT_STD [[noreturn]] inline void rethrow_exception(_In_ exception_ptr _Ptr) {
-    __ExceptionPtrRethrow(&_Ptr);
-}
-
-template <class _Ex>
-void* __GetExceptionInfo(_Ex);
-
-_EXPORT_STD template <class _Ex>
-_NODISCARD_SMART_PTR_ALLOC exception_ptr make_exception_ptr(_Ex _Except) noexcept {
-    return exception_ptr::_Copy_exception(_STD addressof(_Except), __GetExceptionInfo(_Except));
-}
-
-_EXPORT_STD class nested_exception { // wrap an exception_ptr
-public:
-    nested_exception() noexcept : _Exc(_STD current_exception()) {}
-
-    nested_exception(const nested_exception&) noexcept            = default;
-    nested_exception& operator=(const nested_exception&) noexcept = default;
-    virtual ~nested_exception() noexcept {}
-
-    [[noreturn]] void rethrow_nested() const { // throw wrapped exception_ptr
-        if (_Exc) {
-            _STD rethrow_exception(_Exc);
-        } else {
-            _STD terminate(); // per N4950 [except.nested]/4
-        }
-    }
-
-    _NODISCARD exception_ptr nested_ptr() const noexcept { // return wrapped exception_ptr
-        return _Exc;
-    }
-
-private:
-    exception_ptr _Exc;
-};
-
-template <class _Uty>
-struct _With_nested_v2 : _Uty, nested_exception { // glue user exception to nested_exception
-    template <class _Ty>
-    explicit _With_nested_v2(_Ty&& _Arg)
-        : _Uty(_STD forward<_Ty>(_Arg)), nested_exception() {} // store user exception and current_exception()
-};
-
-_EXPORT_STD template <class _Ty>
-[[noreturn]] void throw_with_nested(_Ty&& _Arg) {
-    // throw user exception, glued to nested_exception if possible
-    using _Uty = decay_t<_Ty>;
-
-    if constexpr (is_class_v<_Uty> && !is_base_of_v<nested_exception, _Uty> && !is_final_v<_Uty>) {
-        // throw user exception glued to nested_exception
-        _THROW(_With_nested_v2<_Uty>(_STD forward<_Ty>(_Arg)));
-    } else {
-        // throw user exception by itself
-        _THROW(_STD forward<_Ty>(_Arg));
-    }
-}
-
-#ifdef _CPPRTTI
-_EXPORT_STD template <class _Ty>
-void rethrow_if_nested(const _Ty& _Arg) {
-    // detect nested_exception inheritance
-    constexpr bool _Can_use_dynamic_cast =
-        is_polymorphic_v<_Ty> && (!is_base_of_v<nested_exception, _Ty> || is_convertible_v<_Ty*, nested_exception*>);
-
-    if constexpr (_Can_use_dynamic_cast) {
-        const auto _Nested = dynamic_cast<const nested_exception*>(_STD addressof(_Arg));
-
-        if (_Nested) {
-            _Nested->rethrow_nested();
-        }
-    }
-}
-#else // ^^^ defined(_CPPRTTI) / !defined(_CPPRTTI) vvv
-_EXPORT_STD template <class _Ty>
-void rethrow_if_nested(const _Ty&) = delete; // requires /GR option
-#endif // ^^^ !defined(_CPPRTTI) ^^^
-
-_EXPORT_STD class bad_variant_access
-    : public exception { // exception for visit of a valueless variant or get<I> on a variant with index() != I
-public:
-    bad_variant_access() noexcept = default;
-
-    _NODISCARD const char* __CLR_OR_THIS_CALL what() const noexcept override {
-        return "bad variant access";
-    }
-
-#if !_HAS_EXCEPTIONS
-protected:
-    void _Doraise() const override { // perform class-specific exception handling
-        _RAISE(*this);
-    }
-#endif // ^^^ !_HAS_EXCEPTIONS ^^^
-};
-
-[[noreturn]] inline void _Throw_bad_variant_access() {
-    _THROW(bad_variant_access{});
-}
-
-_STD_END
-
-#pragma pop_macro("new")
-_STL_RESTORE_CLANG_WARNINGS
-#pragma warning(pop)
-#pragma pack(pop)
-
-#endif // _STL_COMPILER_PREPROCESSOR
-#endif // _EXCEPTION_
+// exception standard header
+
+// Copyright (c) Microsoft Corporation.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+#ifndef _EXCEPTION_
+#define _EXCEPTION_
+#include <yvals.h>
+#if _STL_COMPILER_PREPROCESSOR
+
+#include <cstdlib>
+#include <type_traits>
+
+#pragma pack(push, _CRT_PACKING)
+#pragma warning(push, _STL_WARNING_LEVEL)
+#pragma warning(disable : _STL_DISABLED_WARNINGS)
+_STL_DISABLE_CLANG_WARNINGS
+#pragma push_macro("new")
+#undef new
+
+_STD_BEGIN
+
+#if _HAS_DEPRECATED_UNCAUGHT_EXCEPTION
+_EXPORT_STD extern "C++" _CXX17_DEPRECATE_UNCAUGHT_EXCEPTION _NODISCARD _CRTIMP2_PURE bool __CLRCALL_PURE_OR_CDECL
+    uncaught_exception() noexcept;
+#endif // _HAS_DEPRECATED_UNCAUGHT_EXCEPTION
+_EXPORT_STD extern "C++" _NODISCARD _CRTIMP2_PURE int __CLRCALL_PURE_OR_CDECL uncaught_exceptions() noexcept;
+
+_STD_END
+
+#if _HAS_EXCEPTIONS
+
+#include <malloc.h> // TRANSITION, VSO-2048380: This is unnecessary, but many projects assume it as of 2024-04-29
+#include <vcruntime_exception.h>
+
+_STD_BEGIN
+
+_EXPORT_STD using ::terminate;
+
+#ifndef _M_CEE_PURE
+_EXPORT_STD using ::set_terminate;
+_EXPORT_STD using ::terminate_handler;
+
+_EXPORT_STD _NODISCARD inline terminate_handler __CRTDECL get_terminate() noexcept {
+    // get current terminate handler
+    return _get_terminate();
+}
+#endif // !defined(_M_CEE_PURE)
+
+#if _HAS_UNEXPECTED
+using ::unexpected;
+
+#ifndef _M_CEE_PURE
+using ::set_unexpected;
+using ::unexpected_handler;
+
+_NODISCARD inline unexpected_handler __CRTDECL get_unexpected() noexcept {
+    // get current unexpected handler
+    return _get_unexpected();
+}
+#endif // !defined(_M_CEE_PURE)
+#endif // _HAS_UNEXPECTED
+
+_STD_END
+
+#else // ^^^ _HAS_EXCEPTIONS / !_HAS_EXCEPTIONS vvv
+
+#pragma push_macro("stdext")
+#undef stdext
+
+_STDEXT_BEGIN
+class exception;
+_STDEXT_END
+
+_STD_BEGIN
+
+_EXPORT_STD using _STDEXT exception;
+
+using _Prhand = void(__cdecl*)(const exception&);
+
+extern _CRTIMP2_PURE_IMPORT _Prhand _Raise_handler; // pointer to raise handler
+
+_STD_END
+
+_STDEXT_BEGIN
+class exception { // base of all library exceptions
+public:
+    static _STD _Prhand _Set_raise_handler(_STD _Prhand _Pnew) { // register a handler for _Raise calls
+        const _STD _Prhand _Pold = _STD _Raise_handler;
+        _STD _Raise_handler      = _Pnew;
+        return _Pold;
+    }
+
+    // this constructor is necessary to compile
+    // successfully header new for _HAS_EXCEPTIONS==0 scenario
+    explicit __CLR_OR_THIS_CALL exception(const char* _Message = "unknown", int = 1) noexcept : _Ptr(_Message) {}
+
+    __CLR_OR_THIS_CALL exception(const exception& _Right) noexcept : _Ptr(_Right._Ptr) {}
+
+    exception& __CLR_OR_THIS_CALL operator=(const exception& _Right) noexcept {
+        _Ptr = _Right._Ptr;
+        return *this;
+    }
+
+    virtual __CLR_OR_THIS_CALL ~exception() noexcept {}
+
+    _NODISCARD virtual const char* __CLR_OR_THIS_CALL what() const noexcept { // return pointer to message string
+        return _Ptr ? _Ptr : "unknown exception";
+    }
+
+    [[noreturn]] void __CLR_OR_THIS_CALL _Raise() const { // raise the exception
+        if (_STD _Raise_handler) {
+            (*_STD _Raise_handler)(*this); // call raise handler if present
+        }
+
+        _Doraise(); // call the protected virtual
+        _RAISE(*this); // raise this exception
+    }
+
+protected:
+    virtual void __CLR_OR_THIS_CALL _Doraise() const {} // perform class-specific exception handling
+
+    const char* _Ptr; // the message pointer
+};
+
+class bad_exception : public exception { // base of all bad exceptions
+public:
+    __CLR_OR_THIS_CALL bad_exception(const char* _Message = "bad exception") noexcept : exception(_Message) {}
+
+    __CLR_OR_THIS_CALL ~bad_exception() noexcept override {}
+
+protected:
+    void __CLR_OR_THIS_CALL _Doraise() const override { // raise this exception
+        _RAISE(*this);
+    }
+};
+
+class bad_array_new_length;
+
+class bad_alloc : public exception { // base of all bad allocation exceptions
+public:
+    __CLR_OR_THIS_CALL bad_alloc() noexcept
+        : exception("bad allocation", 1) {} // construct from message string with no memory allocation
+
+    __CLR_OR_THIS_CALL ~bad_alloc() noexcept override {}
+
+private:
+    friend bad_array_new_length;
+
+    __CLR_OR_THIS_CALL bad_alloc(const char* _Message) noexcept
+        : exception(_Message, 1) {} // construct from message string with no memory allocation
+
+protected:
+    void __CLR_OR_THIS_CALL _Doraise() const override { // perform class-specific exception handling
+        _RAISE(*this);
+    }
+};
+
+class bad_array_new_length : public bad_alloc {
+public:
+    bad_array_new_length() noexcept : bad_alloc("bad array new length") {}
+};
+
+_STDEXT_END
+
+_STD_BEGIN
+_EXPORT_STD using terminate_handler = void(__cdecl*)();
+
+_EXPORT_STD inline terminate_handler __CRTDECL set_terminate(terminate_handler) noexcept {
+    // register a terminate handler
+    return nullptr;
+}
+
+_EXPORT_STD [[noreturn]] inline void __CRTDECL terminate() noexcept {
+    // handle exception termination
+    _CSTD abort();
+}
+
+_EXPORT_STD _NODISCARD inline terminate_handler __CRTDECL get_terminate() noexcept {
+    // get current terminate handler
+    return nullptr;
+}
+
+#if _HAS_UNEXPECTED
+using unexpected_handler = void(__cdecl*)();
+
+inline unexpected_handler __CRTDECL set_unexpected(unexpected_handler) noexcept {
+    // register an unexpected handler
+    return nullptr;
+}
+
+inline void __CRTDECL unexpected() {} // handle unexpected exception
+
+_NODISCARD inline unexpected_handler __CRTDECL get_unexpected() noexcept {
+    // get current unexpected handler
+    return nullptr;
+}
+#endif // _HAS_UNEXPECTED
+
+_EXPORT_STD using _STDEXT bad_alloc;
+_EXPORT_STD using _STDEXT bad_array_new_length;
+_EXPORT_STD using _STDEXT bad_exception;
+
+_STD_END
+
+#pragma pop_macro("stdext")
+
+#endif // ^^^ !_HAS_EXCEPTIONS ^^^
+
+extern "C++" _CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrCreate(_Out_ void*) noexcept;
+extern "C++" _CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrDestroy(_Inout_ void*) noexcept;
+extern "C++" _CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrCopy(_Out_ void*, _In_ const void*) noexcept;
+extern "C++" _CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrAssign(_Inout_ void*, _In_ const void*) noexcept;
+extern "C++" _CRTIMP2_PURE bool __CLRCALL_PURE_OR_CDECL __ExceptionPtrCompare(
+    _In_ const void*, _In_ const void*) noexcept;
+extern "C++" _CRTIMP2_PURE bool __CLRCALL_PURE_OR_CDECL __ExceptionPtrToBool(_In_ const void*) noexcept;
+extern "C++" _CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrSwap(_Inout_ void*, _Inout_ void*) noexcept;
+extern "C++" _CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrCurrentException(void*) noexcept;
+extern "C++" [[noreturn]] _CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrRethrow(_In_ const void*);
+extern "C++" _CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrCopyException(
+    _Inout_ void*, _In_ const void*, _In_ const void*) noexcept;
+
+_STD_BEGIN
+
+_EXPORT_STD class exception_ptr {
+public:
+    exception_ptr() noexcept {
+        __ExceptionPtrCreate(this);
+    }
+
+    exception_ptr(nullptr_t) noexcept {
+        __ExceptionPtrCreate(this);
+    }
+
+    ~exception_ptr() noexcept {
+        __ExceptionPtrDestroy(this);
+    }
+
+    exception_ptr(const exception_ptr& _Rhs) noexcept {
+        __ExceptionPtrCopy(this, &_Rhs);
+    }
+
+    exception_ptr& operator=(const exception_ptr& _Rhs) noexcept {
+        __ExceptionPtrAssign(this, &_Rhs);
+        return *this;
+    }
+
+    exception_ptr& operator=(nullptr_t) noexcept {
+        exception_ptr _Ptr;
+        __ExceptionPtrAssign(this, &_Ptr);
+        return *this;
+    }
+
+    explicit operator bool() const noexcept {
+        return __ExceptionPtrToBool(this);
+    }
+
+    static exception_ptr _Copy_exception(_In_ void* _Except, _In_ const void* _Ptr) {
+        exception_ptr _Retval;
+        if (!_Ptr) {
+            // unsupported exceptions
+            return _Retval;
+        }
+        __ExceptionPtrCopyException(&_Retval, _Except, _Ptr);
+        return _Retval;
+    }
+
+    friend void swap(exception_ptr& _Lhs, exception_ptr& _Rhs) noexcept {
+        __ExceptionPtrSwap(&_Lhs, &_Rhs);
+    }
+
+    _NODISCARD_FRIEND bool operator==(const exception_ptr& _Lhs, const exception_ptr& _Rhs) noexcept {
+        return __ExceptionPtrCompare(&_Lhs, &_Rhs);
+    }
+
+    _NODISCARD_FRIEND bool operator==(const exception_ptr& _Lhs, nullptr_t) noexcept {
+        return !_Lhs;
+    }
+
+#if !_HAS_CXX20
+    _NODISCARD_FRIEND bool operator==(nullptr_t, const exception_ptr& _Rhs) noexcept {
+        return !_Rhs;
+    }
+
+    _NODISCARD_FRIEND bool operator!=(const exception_ptr& _Lhs, const exception_ptr& _Rhs) noexcept {
+        return !(_Lhs == _Rhs);
+    }
+
+    _NODISCARD_FRIEND bool operator!=(const exception_ptr& _Lhs, nullptr_t) noexcept {
+        return !(_Lhs == nullptr);
+    }
+
+    _NODISCARD_FRIEND bool operator!=(nullptr_t, const exception_ptr& _Rhs) noexcept {
+        return !(nullptr == _Rhs);
+    }
+#endif // !_HAS_CXX20
+
+private:
+#ifdef __clang__
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wunused-private-field"
+#endif // defined(__clang__)
+    void* _Data1{};
+    void* _Data2{};
+#ifdef __clang__
+#pragma clang diagnostic pop
+#endif // defined(__clang__)
+};
+
+_EXPORT_STD _NODISCARD inline exception_ptr current_exception() noexcept {
+    exception_ptr _Retval;
+    __ExceptionPtrCurrentException(&_Retval);
+    return _Retval;
+}
+
+_EXPORT_STD [[noreturn]] inline void rethrow_exception(_In_ exception_ptr _Ptr) {
+    __ExceptionPtrRethrow(&_Ptr);
+}
+
+template <class _Ex>
+void* __GetExceptionInfo(_Ex);
+
+_EXPORT_STD template <class _Ex>
+_NODISCARD_SMART_PTR_ALLOC exception_ptr make_exception_ptr(_Ex _Except) noexcept {
+    return exception_ptr::_Copy_exception(_STD addressof(_Except), __GetExceptionInfo(_Except));
+}
+
+_EXPORT_STD class nested_exception { // wrap an exception_ptr
+public:
+    nested_exception() noexcept : _Exc(_STD current_exception()) {}
+
+    nested_exception(const nested_exception&) noexcept            = default;
+    nested_exception& operator=(const nested_exception&) noexcept = default;
+    virtual ~nested_exception() noexcept {}
+
+    [[noreturn]] void rethrow_nested() const { // throw wrapped exception_ptr
+        if (_Exc) {
+            _STD rethrow_exception(_Exc);
+        } else {
+            _STD terminate(); // per N4950 [except.nested]/4
+        }
+    }
+
+    _NODISCARD exception_ptr nested_ptr() const noexcept { // return wrapped exception_ptr
+        return _Exc;
+    }
+
+private:
+    exception_ptr _Exc;
+};
+
+template <class _Uty>
+struct _With_nested_v2 : _Uty, nested_exception { // glue user exception to nested_exception
+    template <class _Ty>
+    explicit _With_nested_v2(_Ty&& _Arg)
+        : _Uty(_STD forward<_Ty>(_Arg)), nested_exception() {} // store user exception and current_exception()
+};
+
+_EXPORT_STD template <class _Ty>
+[[noreturn]] void throw_with_nested(_Ty&& _Arg) {
+    // throw user exception, glued to nested_exception if possible
+    using _Uty = decay_t<_Ty>;
+
+    if constexpr (is_class_v<_Uty> && !is_base_of_v<nested_exception, _Uty> && !is_final_v<_Uty>) {
+        // throw user exception glued to nested_exception
+        _THROW(_With_nested_v2<_Uty>(_STD forward<_Ty>(_Arg)));
+    } else {
+        // throw user exception by itself
+        _THROW(_STD forward<_Ty>(_Arg));
+    }
+}
+
+#ifdef _CPPRTTI
+_EXPORT_STD template <class _Ty>
+void rethrow_if_nested(const _Ty& _Arg) {
+    // detect nested_exception inheritance
+    constexpr bool _Can_use_dynamic_cast =
+        is_polymorphic_v<_Ty> && (!is_base_of_v<nested_exception, _Ty> || is_convertible_v<_Ty*, nested_exception*>);
+
+    if constexpr (_Can_use_dynamic_cast) {
+        const auto _Nested = dynamic_cast<const nested_exception*>(_STD addressof(_Arg));
+
+        if (_Nested) {
+            _Nested->rethrow_nested();
+        }
+    }
+}
+#else // ^^^ defined(_CPPRTTI) / !defined(_CPPRTTI) vvv
+_EXPORT_STD template <class _Ty>
+void rethrow_if_nested(const _Ty&) = delete; // requires /GR option
+#endif // ^^^ !defined(_CPPRTTI) ^^^
+
+_EXPORT_STD class bad_variant_access
+    : public exception { // exception for visit of a valueless variant or get<I> on a variant with index() != I
+public:
+    bad_variant_access() noexcept = default;
+
+    _NODISCARD const char* __CLR_OR_THIS_CALL what() const noexcept override {
+        return "bad variant access";
+    }
+
+#if !_HAS_EXCEPTIONS
+protected:
+    void _Doraise() const override { // perform class-specific exception handling
+        _RAISE(*this);
+    }
+#endif // ^^^ !_HAS_EXCEPTIONS ^^^
+};
+
+[[noreturn]] inline void _Throw_bad_variant_access() {
+    _THROW(bad_variant_access{});
+}
+
+_STD_END
+
+#pragma pop_macro("new")
+_STL_RESTORE_CLANG_WARNINGS
+#pragma warning(pop)
+#pragma pack(pop)
+
+#endif // _STL_COMPILER_PREPROCESSOR
+#endif // _EXCEPTION_
diff --git a/libcxx/src/support/win32/excptptr.cpp b/libcxx/src/support/win32/excptptr.cpp
index 830cb65a940d5..a78d1528b0862 100644
--- a/libcxx/src/support/win32/excptptr.cpp
+++ b/libcxx/src/support/win32/excptptr.cpp
@@ -1,533 +1,533 @@
-// Copyright (c) Microsoft Corporation.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-
-// This implementation communicates with the EH runtime though vcruntime's per-thread-data structure; see
-// _pCurrentException in <trnsctrl.h>.
-//
-// As a result, normal EH runtime services (such as noexcept functions) are safe to use in this file.
-
-#ifndef _VCRT_ALLOW_INTERNALS
-#define _VCRT_ALLOW_INTERNALS
-#endif // !defined(_VCRT_ALLOW_INTERNALS)
-
-#include <Unknwn.h>
-#include <cstdlib> // for abort
-#include <cstring> // for memcpy
-#include <eh.h>
-#include <ehdata.h>
-#include <exception>
-#include <internal_shared.h>
-#include <malloc.h>
-#include <memory>
-#include <new>
-#include <stdexcept>
-#include <trnsctrl.h>
-#include <xcall_once.h>
-
-#include <Windows.h>
-
-// Pre-V4 managed exception code
-#define MANAGED_EXCEPTION_CODE 0XE0434F4D
-
-// V4 and later managed exception code
-#define MANAGED_EXCEPTION_CODE_V4 0XE0434352
-
-extern "C" _CRTIMP2 void* __cdecl __AdjustPointer(void*, const PMD&); // defined in frame.cpp
-
-using namespace std;
-
-namespace {
-#if defined(_M_CEE_PURE)
-    template <class _Ty>
-    _Ty& _Immortalize() { // return a reference to an object that will live forever
-        /* MAGIC */ static _Immortalizer_impl<_Ty> _Static;
-        return reinterpret_cast<_Ty&>(_Static._Storage);
-    }
-#elif !defined(_M_CEE)
-    template <class _Ty>
-    struct _Constexpr_excptptr_immortalize_impl {
-        union {
-            _Ty _Storage;
-        };
-
-        constexpr _Constexpr_excptptr_immortalize_impl() noexcept : _Storage{} {}
-
-        _Constexpr_excptptr_immortalize_impl(const _Constexpr_excptptr_immortalize_impl&)            = delete;
-        _Constexpr_excptptr_immortalize_impl& operator=(const _Constexpr_excptptr_immortalize_impl&) = delete;
-
-        _MSVC_NOOP_DTOR ~_Constexpr_excptptr_immortalize_impl() {
-            // do nothing, allowing _Ty to be used during shutdown
-        }
-    };
-
-    template <class _Ty>
-    _Constexpr_excptptr_immortalize_impl<_Ty> _Immortalize_impl;
-
-    template <class _Ty>
-    [[nodiscard]] _Ty& _Immortalize() noexcept {
-        return _Immortalize_impl<_Ty>._Storage;
-    }
-#else // ^^^ !defined(_M_CEE) / defined(_M_CEE), TRANSITION, VSO-1153256 vvv
-    template <class _Ty>
-    _Ty& _Immortalize() { // return a reference to an object that will live forever
-        static once_flag _Flag;
-        alignas(_Ty) static unsigned char _Storage[sizeof(_Ty)];
-        call_once(_Flag, [&_Storage] { ::new (static_cast<void*>(&_Storage)) _Ty(); });
-        return reinterpret_cast<_Ty&>(_Storage);
-    }
-#endif // ^^^ !defined(_M_CEE_PURE) && defined(_M_CEE), TRANSITION, VSO-1153256 ^^^
-
-    void _PopulateCppExceptionRecord(
-        _EXCEPTION_RECORD& _Record, const void* const _PExcept, ThrowInfo* _PThrow) noexcept {
-        _Record.ExceptionCode           = EH_EXCEPTION_NUMBER;
-        _Record.ExceptionFlags          = EXCEPTION_NONCONTINUABLE;
-        _Record.ExceptionRecord         = nullptr; // no SEH to chain
-        _Record.ExceptionAddress        = nullptr; // Address of exception. Will be overwritten by OS
-        _Record.NumberParameters        = EH_EXCEPTION_PARAMETERS;
-        _Record.ExceptionInformation[0] = EH_MAGIC_NUMBER1; // params.magicNumber
-        _Record.ExceptionInformation[1] = reinterpret_cast<ULONG_PTR>(_PExcept); // params.pExceptionObject
-
-        if (_PThrow && (_PThrow->attributes & TI_IsWinRT)) {
-            // The pointer to the ExceptionInfo structure is stored sizeof(void*) in front of each WinRT Exception Info.
-            const auto _PWei = (*static_cast<WINRTEXCEPTIONINFO** const*>(_PExcept))[-1];
-            _PThrow          = _PWei->throwInfo;
-        }
-
-        _Record.ExceptionInformation[2] = reinterpret_cast<ULONG_PTR>(_PThrow); // params.pThrowInfo
-
-#if _EH_RELATIVE_TYPEINFO
-        void* _ThrowImageBase =
-            _PThrow ? RtlPcToFileHeader(const_cast<void*>(static_cast<const void*>(_PThrow)), &_ThrowImageBase)
-                    : nullptr;
-        _Record.ExceptionInformation[3] = reinterpret_cast<ULONG_PTR>(_ThrowImageBase); // params.pThrowImageBase
-#endif // _EH_RELATIVE_TYPEINFO
-
-        // If the throw info indicates this throw is from a pure region,
-        // set the magic number to the Pure one, so only a pure-region
-        // catch will see it.
-        //
-        // Also use the Pure magic number on 64-bit platforms if we were unable to
-        // determine an image base, since that was the old way to determine
-        // a pure throw, before the TI_IsPure bit was added to the FuncInfo
-        // attributes field.
-        if (_PThrow
-            && ((_PThrow->attributes & TI_IsPure)
-#if _EH_RELATIVE_TYPEINFO
-                || !_ThrowImageBase
-#endif // _EH_RELATIVE_TYPEINFO
-                )) {
-            _Record.ExceptionInformation[0] = EH_PURE_MAGIC_NUMBER1;
-        }
-    }
-
-    void _CopyExceptionRecord(_EXCEPTION_RECORD& _Dest, const _EXCEPTION_RECORD& _Src) noexcept {
-        _Dest.ExceptionCode = _Src.ExceptionCode;
-        // we force EXCEPTION_NONCONTINUABLE because rethrow_exception is [[noreturn]]
-        _Dest.ExceptionFlags   = _Src.ExceptionFlags | EXCEPTION_NONCONTINUABLE;
-        _Dest.ExceptionRecord  = nullptr; // We don't chain SEH exceptions
-        _Dest.ExceptionAddress = nullptr; // Useless field to copy. It will be overwritten by RaiseException()
-        const auto _Parameters = _Src.NumberParameters;
-        _Dest.NumberParameters = _Parameters;
-
-        // copy the number of parameters in use
-        constexpr auto _Max_parameters = static_cast<DWORD>(EXCEPTION_MAXIMUM_PARAMETERS);
-        const auto _In_use             = (_STD min)(_Parameters, _Max_parameters);
-        _CSTD memcpy(_Dest.ExceptionInformation, _Src.ExceptionInformation, _In_use * sizeof(ULONG_PTR));
-        _CSTD memset(&_Dest.ExceptionInformation[_In_use], 0, (_Max_parameters - _In_use) * sizeof(ULONG_PTR));
-    }
-
-    void _CopyExceptionObject(void* _Dest, const void* _Src, const CatchableType* const _PType
-#if _EH_RELATIVE_TYPEINFO
-        ,
-        const uintptr_t _ThrowImageBase
-#endif // _EH_RELATIVE_TYPEINFO
-    ) {
-        // copy an object of type denoted by *_PType from _Src to _Dest; throws whatever the copy ctor of the type
-        // denoted by *_PType throws
-        if ((_PType->properties & CT_IsSimpleType) || _PType->copyFunction == 0) {
-            memcpy(_Dest, _Src, _PType->sizeOrOffset);
-
-            if (_PType->properties & CT_IsWinRTHandle) {
-                const auto _PUnknown = *static_cast<IUnknown* const*>(_Src);
-                if (_PUnknown) {
-                    _PUnknown->AddRef();
-                }
-            }
-            return;
-        }
-
-#if _EH_RELATIVE_TYPEINFO
-        const auto _CopyFunc = reinterpret_cast<void*>(_ThrowImageBase + _PType->copyFunction);
-#else // ^^^ _EH_RELATIVE_TYPEINFO / !_EH_RELATIVE_TYPEINFO vvv
-        const auto _CopyFunc = _PType->copyFunction;
-#endif // ^^^ !_EH_RELATIVE_TYPEINFO ^^^
-
-        const auto _Adjusted = __AdjustPointer(const_cast<void*>(_Src), _PType->thisDisplacement);
-        if (_PType->properties & CT_HasVirtualBase) {
-#ifdef _M_CEE_PURE
-            reinterpret_cast<void(__clrcall*)(void*, void*, int)>(_CopyFunc)(_Dest, _Adjusted, 1);
-#else // ^^^ defined(_M_CEE_PURE) / !defined(_M_CEE_PURE) vvv
-            _CallMemberFunction2(_Dest, _CopyFunc, _Adjusted, 1);
-#endif // ^^^ !defined(_M_CEE_PURE) ^^^
-        } else {
-#ifdef _M_CEE_PURE
-            reinterpret_cast<void(__clrcall*)(void*, void*)>(_CopyFunc)(_Dest, _Adjusted);
-#else // ^^^ defined(_M_CEE_PURE) / !defined(_M_CEE_PURE) vvv
-            _CallMemberFunction1(_Dest, _CopyFunc, _Adjusted);
-#endif // ^^^ !defined(_M_CEE_PURE) ^^^
-        }
-    }
-} // unnamed namespace
-
-// All exception_ptr implementations are out-of-line because <memory> depends on <exception>,
-// which means <exception> cannot include <memory> -- and shared_ptr is defined in <memory>.
-// To workaround this, we created a dummy class exception_ptr, which is structurally identical to shared_ptr.
-
-_STD_BEGIN
-struct _Exception_ptr_access {
-    template <class _Ty, class _Ty2>
-    static void _Set_ptr_rep(_Ptr_base<_Ty>& _This, _Ty2* _Px, _Ref_count_base* _Rx) noexcept {
-        _This._Ptr = _Px;
-        _This._Rep = _Rx;
-    }
-};
-_STD_END
-
-static_assert(sizeof(exception_ptr) == sizeof(shared_ptr<const _EXCEPTION_RECORD>)
-                  && alignof(exception_ptr) == alignof(shared_ptr<const _EXCEPTION_RECORD>),
-    "std::exception_ptr and std::shared_ptr<const _EXCEPTION_RECORD> must have the same layout.");
-
-namespace {
-    template <class _StaticEx>
-    class _ExceptionPtr_static final : public _Ref_count_base {
-        // reference count control block for special "never allocates" exceptions like the bad_alloc or bad_exception
-        // exception_ptrs
-    private:
-        void _Destroy() noexcept override {
-            // intentionally does nothing
-        }
-
-        void _Delete_this() noexcept override {
-            // intentionally does nothing
-        }
-
-    public:
-        // constexpr, TRANSITION P1064
-        explicit _ExceptionPtr_static() noexcept : _Ref_count_base() {
-            _PopulateCppExceptionRecord(_ExRecord, &_Ex, static_cast<ThrowInfo*>(__GetExceptionInfo(_Ex)));
-        }
-
-        static shared_ptr<const _EXCEPTION_RECORD> _Get() noexcept {
-            auto& _Instance = _Immortalize<_ExceptionPtr_static>();
-            shared_ptr<const _EXCEPTION_RECORD> _Ret;
-            _Instance._Incref();
-            _Exception_ptr_access::_Set_ptr_rep(_Ret, &_Instance._ExRecord, &_Instance);
-            return _Ret;
-        }
-
-        _EXCEPTION_RECORD _ExRecord;
-        _StaticEx _Ex;
-    };
-
-    class _ExceptionPtr_normal final : public _Ref_count_base {
-        // reference count control block for exception_ptrs; the exception object is stored at
-        // reinterpret_cast<unsigned char*>(this) + sizeof(_ExceptionPtr_normal)
-    private:
-        void _Destroy() noexcept override {
-            // call the destructor for a stored pure or native C++ exception if necessary
-            const auto& _CppEhRecord = reinterpret_cast<EHExceptionRecord&>(_ExRecord);
-
-            if (!PER_IS_MSVC_PURE_OR_NATIVE_EH(&_CppEhRecord)) {
-                return;
-            }
-
-            const auto _PThrow = _CppEhRecord.params.pThrowInfo;
-            if (!_PThrow) {
-                // No ThrowInfo exists. If this was a C++ exception, something must have corrupted it.
-                _CSTD abort();
-            }
-
-            if (!_CppEhRecord.params.pExceptionObject) {
-                return;
-            }
-
-#if _EH_RELATIVE_TYPEINFO
-            const auto _ThrowImageBase     = reinterpret_cast<uintptr_t>(_CppEhRecord.params.pThrowImageBase);
-            const auto _CatchableTypeArray = reinterpret_cast<const CatchableTypeArray*>(
-                static_cast<uintptr_t>(_PThrow->pCatchableTypeArray) + _ThrowImageBase);
-            const auto _PType = reinterpret_cast<CatchableType*>(
-                static_cast<uintptr_t>(_CatchableTypeArray->arrayOfCatchableTypes[0]) + _ThrowImageBase);
-#else // ^^^ _EH_RELATIVE_TYPEINFO / !_EH_RELATIVE_TYPEINFO vvv
-            const auto _PType = _PThrow->pCatchableTypeArray->arrayOfCatchableTypes[0];
-#endif // ^^^ !_EH_RELATIVE_TYPEINFO ^^^
-
-            if (_PThrow->pmfnUnwind) {
-                // The exception was a user defined type with a nontrivial destructor, call it
-#if defined(_M_CEE_PURE)
-                reinterpret_cast<void(__clrcall*)(void*)>(_PThrow->pmfnUnwind)(_CppEhRecord.params.pExceptionObject);
-#elif _EH_RELATIVE_TYPEINFO
-                _CallMemberFunction0(_CppEhRecord.params.pExceptionObject,
-                    reinterpret_cast<void*>(_PThrow->pmfnUnwind + _ThrowImageBase));
-#else // ^^^ _EH_RELATIVE_TYPEINFO && !defined(_M_CEE_PURE) / !_EH_RELATIVE_TYPEINFO && !defined(_M_CEE_PURE) vvv
-                _CallMemberFunction0(_CppEhRecord.params.pExceptionObject, _PThrow->pmfnUnwind);
-#endif // ^^^ !_EH_RELATIVE_TYPEINFO && !defined(_M_CEE_PURE) ^^^
-            } else if (_PType->properties & CT_IsWinRTHandle) {
-                const auto _PUnknown = *static_cast<IUnknown* const*>(_CppEhRecord.params.pExceptionObject);
-                if (_PUnknown) {
-                    _PUnknown->Release();
-                }
-            }
-        }
-
-        void _Delete_this() noexcept override {
-            free(this);
-        }
-
-    public:
-        explicit _ExceptionPtr_normal(const _EXCEPTION_RECORD& _Record) noexcept : _Ref_count_base() {
-            _CopyExceptionRecord(_ExRecord, _Record);
-        }
-
-        _EXCEPTION_RECORD _ExRecord;
-        void* _Unused_alignment_padding{};
-    };
-
-    // We aren't using alignas because this file might be compiled with _M_CEE_PURE
-    static_assert(sizeof(_ExceptionPtr_normal) % __STDCPP_DEFAULT_NEW_ALIGNMENT__ == 0,
-        "Exception in exception_ptr would be constructed with the wrong alignment");
-
-    void _Assign_seh_exception_ptr_from_record(
-        shared_ptr<const _EXCEPTION_RECORD>& _Dest, const _EXCEPTION_RECORD& _Record, void* const _RxRaw) noexcept {
-        // in the memory _RxRaw, constructs a reference count control block for a SEH exception denoted by _Record
-        // if _RxRaw is nullptr, assigns bad_alloc instead
-        if (!_RxRaw) {
-            _Dest = _ExceptionPtr_static<bad_alloc>::_Get();
-            return;
-        }
-
-        const auto _Rx = ::new (_RxRaw) _ExceptionPtr_normal(_Record);
-        _Exception_ptr_access::_Set_ptr_rep(_Dest, &_Rx->_ExRecord, _Rx);
-    }
-
-    void _Assign_cpp_exception_ptr_from_record(
-        shared_ptr<const _EXCEPTION_RECORD>& _Dest, const EHExceptionRecord& _Record) noexcept {
-        // construct a reference count control block for the C++ exception recorded by _Record, and bind it to _Dest
-        // if allocating memory for the reference count control block fails, sets _Dest to bad_alloc
-        // if copying the exception object referred to _Record throws, constructs a reference count control block for
-        //      that exception instead
-        // if copying the exception object thrown by copying the original exception object throws, sets _Dest to
-        //      bad_exception
-        const auto _PThrow = _Record.params.pThrowInfo;
-#if _EH_RELATIVE_TYPEINFO
-        const auto _ThrowImageBase     = reinterpret_cast<uintptr_t>(_Record.params.pThrowImageBase);
-        const auto _CatchableTypeArray = reinterpret_cast<const CatchableTypeArray*>(
-            static_cast<uintptr_t>(_PThrow->pCatchableTypeArray) + _ThrowImageBase);
-        const auto _PType = reinterpret_cast<CatchableType*>(
-            static_cast<uintptr_t>(_CatchableTypeArray->arrayOfCatchableTypes[0]) + _ThrowImageBase);
-#else // ^^^ _EH_RELATIVE_TYPEINFO / !_EH_RELATIVE_TYPEINFO vvv
-        const auto _PType = _PThrow->pCatchableTypeArray->arrayOfCatchableTypes[0];
-#endif // ^^^ !_EH_RELATIVE_TYPEINFO ^^^
-
-        const auto _ExceptionObjectSize = static_cast<size_t>(_PType->sizeOrOffset);
-        const auto _AllocSize           = sizeof(_ExceptionPtr_normal) + _ExceptionObjectSize;
-        _Analysis_assume_(_AllocSize >= sizeof(_ExceptionPtr_normal));
-        auto _RxRaw = malloc(_AllocSize);
-        if (!_RxRaw) {
-            _Dest = _ExceptionPtr_static<bad_alloc>::_Get();
-            return;
-        }
-
-        try {
-            _CopyExceptionObject(static_cast<_ExceptionPtr_normal*>(_RxRaw) + 1, _Record.params.pExceptionObject, _PType
-#if _EH_RELATIVE_TYPEINFO
-                ,
-                _ThrowImageBase
-#endif // _EH_RELATIVE_TYPEINFO
-            );
-
-            const auto _Rx = ::new (_RxRaw) _ExceptionPtr_normal(reinterpret_cast<const _EXCEPTION_RECORD&>(_Record));
-            reinterpret_cast<EHExceptionRecord&>(_Rx->_ExRecord).params.pExceptionObject =
-                static_cast<_ExceptionPtr_normal*>(_RxRaw) + 1;
-            _Exception_ptr_access::_Set_ptr_rep(_Dest, &_Rx->_ExRecord, _Rx);
-        } catch (...) { // copying the exception object threw an exception
-            const auto& _InnerRecord = *_pCurrentException; // exception thrown by the original exception's copy ctor
-            if (_InnerRecord.ExceptionCode == MANAGED_EXCEPTION_CODE
-                || _InnerRecord.ExceptionCode == MANAGED_EXCEPTION_CODE_V4) {
-                // we don't support managed exceptions and don't want to say there's no active exception, so give up and
-                // say bad_exception
-                free(_RxRaw);
-                _Dest = _ExceptionPtr_static<bad_exception>::_Get();
-                return;
-            }
-
-            if (!PER_IS_MSVC_PURE_OR_NATIVE_EH(&_InnerRecord)) { // catching a non-C++ exception depends on /EHa
-                _Assign_seh_exception_ptr_from_record(
-                    _Dest, reinterpret_cast<const _EXCEPTION_RECORD&>(_InnerRecord), _RxRaw);
-                return;
-            }
-
-            const auto _PInnerThrow = _InnerRecord.params.pThrowInfo;
-#if _EH_RELATIVE_TYPEINFO
-            const auto _InnerThrowImageBase     = reinterpret_cast<uintptr_t>(_InnerRecord.params.pThrowImageBase);
-            const auto _InnerCatchableTypeArray = reinterpret_cast<const CatchableTypeArray*>(
-                static_cast<uintptr_t>(_PInnerThrow->pCatchableTypeArray) + _InnerThrowImageBase);
-            const auto _PInnerType = reinterpret_cast<CatchableType*>(
-                static_cast<uintptr_t>(_InnerCatchableTypeArray->arrayOfCatchableTypes[0]) + _InnerThrowImageBase);
-#else // ^^^ _EH_RELATIVE_TYPEINFO / !_EH_RELATIVE_TYPEINFO vvv
-            const auto _PInnerType = _PInnerThrow->pCatchableTypeArray->arrayOfCatchableTypes[0];
-#endif // ^^^ !_EH_RELATIVE_TYPEINFO ^^^
-
-            const auto _InnerExceptionSize = static_cast<size_t>(_PInnerType->sizeOrOffset);
-            const auto _InnerAllocSize     = sizeof(_ExceptionPtr_normal) + _InnerExceptionSize;
-            if (_InnerAllocSize > _AllocSize) {
-                free(_RxRaw);
-                _RxRaw = malloc(_InnerAllocSize);
-                if (!_RxRaw) {
-                    _Dest = _ExceptionPtr_static<bad_alloc>::_Get();
-                    return;
-                }
-            }
-
-            try {
-                _CopyExceptionObject(
-                    static_cast<_ExceptionPtr_normal*>(_RxRaw) + 1, _InnerRecord.params.pExceptionObject, _PInnerType
-#if _EH_RELATIVE_TYPEINFO
-                    ,
-                    _ThrowImageBase
-#endif // _EH_RELATIVE_TYPEINFO
-                );
-            } catch (...) { // copying the exception emitted while copying the original exception also threw, give up
-                free(_RxRaw);
-                _Dest = _ExceptionPtr_static<bad_exception>::_Get();
-                return;
-            }
-
-            // this next block must be duplicated inside the catch (even though it looks identical to the block in the
-            // try) so that _InnerRecord is held alive; exiting the catch will destroy it
-            const auto _Rx =
-                ::new (_RxRaw) _ExceptionPtr_normal(reinterpret_cast<const _EXCEPTION_RECORD&>(_InnerRecord));
-            reinterpret_cast<EHExceptionRecord&>(_Rx->_ExRecord).params.pExceptionObject =
-                static_cast<_ExceptionPtr_normal*>(_RxRaw) + 1;
-            _Exception_ptr_access::_Set_ptr_rep(_Dest, &_Rx->_ExRecord, _Rx);
-        }
-    }
-} // unnamed namespace
-
-_CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrCreate(_Out_ void* _Ptr) noexcept {
-    ::new (_Ptr) shared_ptr<const _EXCEPTION_RECORD>();
-}
-
-_CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrDestroy(_Inout_ void* _Ptr) noexcept {
-    static_cast<shared_ptr<const _EXCEPTION_RECORD>*>(_Ptr)->~shared_ptr<const _EXCEPTION_RECORD>();
-}
-
-_CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrCopy(_Out_ void* _Dest, _In_ const void* _Src) noexcept {
-    ::new (_Dest) shared_ptr<const _EXCEPTION_RECORD>(*static_cast<const shared_ptr<const _EXCEPTION_RECORD>*>(_Src));
-}
-
-_CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrAssign(_Inout_ void* _Dest, _In_ const void* _Src) noexcept {
-    *static_cast<shared_ptr<const _EXCEPTION_RECORD>*>(_Dest) =
-        *static_cast<const shared_ptr<const _EXCEPTION_RECORD>*>(_Src);
-}
-
-_CRTIMP2_PURE bool __CLRCALL_PURE_OR_CDECL __ExceptionPtrCompare(
-    _In_ const void* _Lhs, _In_ const void* _Rhs) noexcept {
-    return *static_cast<const shared_ptr<const _EXCEPTION_RECORD>*>(_Lhs)
-        == *static_cast<const shared_ptr<const _EXCEPTION_RECORD>*>(_Rhs);
-}
-
-_CRTIMP2_PURE bool __CLRCALL_PURE_OR_CDECL __ExceptionPtrToBool(_In_ const void* _Ptr) noexcept {
-    return static_cast<bool>(*static_cast<const shared_ptr<const _EXCEPTION_RECORD>*>(_Ptr));
-}
-
-_CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrSwap(_Inout_ void* _Lhs, _Inout_ void* _Rhs) noexcept {
-    static_cast<shared_ptr<const _EXCEPTION_RECORD>*>(_Lhs)->swap(
-        *static_cast<shared_ptr<const _EXCEPTION_RECORD>*>(_Rhs));
-}
-
-_CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrCurrentException(void* _Ptr) noexcept {
-    const auto _PRecord = _pCurrentException; // nontrivial FLS cost, pay it once
-    if (!_PRecord || _PRecord->ExceptionCode == MANAGED_EXCEPTION_CODE
-        || _PRecord->ExceptionCode == MANAGED_EXCEPTION_CODE_V4) {
-        return; // no current exception, or we don't support managed exceptions
-    }
-
-    auto& _Dest = *static_cast<shared_ptr<const _EXCEPTION_RECORD>*>(_Ptr);
-    if (PER_IS_MSVC_PURE_OR_NATIVE_EH(_PRecord)) {
-        _Assign_cpp_exception_ptr_from_record(_Dest, *_PRecord);
-    } else {
-        // _Assign_seh_exception_ptr_from_record handles failed malloc
-        _Assign_seh_exception_ptr_from_record(
-            _Dest, reinterpret_cast<_EXCEPTION_RECORD&>(*_PRecord), malloc(sizeof(_ExceptionPtr_normal)));
-    }
-}
-
-[[noreturn]] _CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrRethrow(_In_ const void* _PtrRaw) {
-    const shared_ptr<const _EXCEPTION_RECORD>* _Ptr = static_cast<const shared_ptr<const _EXCEPTION_RECORD>*>(_PtrRaw);
-    // throwing a bad_exception if they give us a nullptr exception_ptr
-    if (!*_Ptr) {
-        throw bad_exception();
-    }
-
-    auto _RecordCopy = **_Ptr;
-    auto& _CppRecord = reinterpret_cast<EHExceptionRecord&>(_RecordCopy);
-    if (PER_IS_MSVC_PURE_OR_NATIVE_EH(&_CppRecord)) {
-        // This is a C++ exception.
-        // We need to build the exception on the stack because the current exception mechanism assumes the exception
-        // object is on the stack and will call the appropriate destructor (if there's a nontrivial one).
-        const auto _PThrow = _CppRecord.params.pThrowInfo;
-        if (!_CppRecord.params.pExceptionObject || !_PThrow || !_PThrow->pCatchableTypeArray) {
-            // Missing or corrupt ThrowInfo. If this was a C++ exception, something must have corrupted it.
-            _CSTD abort();
-        }
-
-#if _EH_RELATIVE_TYPEINFO
-        const auto _ThrowImageBase = reinterpret_cast<uintptr_t>(_CppRecord.params.pThrowImageBase);
-        const auto _CatchableTypeArray =
-            reinterpret_cast<const CatchableTypeArray*>(_ThrowImageBase + _PThrow->pCatchableTypeArray);
-#else // ^^^ _EH_RELATIVE_TYPEINFO / !_EH_RELATIVE_TYPEINFO vvv
-        const auto _CatchableTypeArray = _PThrow->pCatchableTypeArray;
-#endif // ^^^ !_EH_RELATIVE_TYPEINFO ^^^
-
-        if (_CatchableTypeArray->nCatchableTypes <= 0) {
-            // Ditto corrupted.
-            _CSTD abort();
-        }
-
-        // we finally got the type info we want
-#if _EH_RELATIVE_TYPEINFO
-        const auto _PType = reinterpret_cast<CatchableType*>(
-            static_cast<uintptr_t>(_CatchableTypeArray->arrayOfCatchableTypes[0]) + _ThrowImageBase);
-#else // ^^^ _EH_RELATIVE_TYPEINFO / !_EH_RELATIVE_TYPEINFO vvv
-        const auto _PType = _PThrow->pCatchableTypeArray->arrayOfCatchableTypes[0];
-#endif // ^^^ !_EH_RELATIVE_TYPEINFO ^^^
-
-        // Alloc memory on stack for exception object. This might cause a stack overflow SEH exception, or another C++
-        // exception when copying the C++ exception object. In that case, we just let that become the thrown exception.
-
-#pragma warning(suppress : 6255) //  _alloca indicates failure by raising a stack overflow exception
-        void* _PExceptionBuffer = alloca(_PType->sizeOrOffset);
-        _CopyExceptionObject(_PExceptionBuffer, _CppRecord.params.pExceptionObject, _PType
-#if _EH_RELATIVE_TYPEINFO
-            ,
-            _ThrowImageBase
-#endif // _EH_RELATIVE_TYPEINFO
-        );
-
-        _CppRecord.params.pExceptionObject = _PExceptionBuffer;
-    } else {
-        // this is a SEH exception, no special handling is required
-    }
-
-    _Analysis_assume_(_RecordCopy.NumberParameters <= EXCEPTION_MAXIMUM_PARAMETERS);
-    RaiseException(_RecordCopy.ExceptionCode, _RecordCopy.ExceptionFlags, _RecordCopy.NumberParameters,
-        _RecordCopy.ExceptionInformation);
-}
-
-_CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrCopyException(
-    _Inout_ void* _Ptr, _In_ const void* _PExceptRaw, _In_ const void* _PThrowRaw) noexcept {
-    _EXCEPTION_RECORD _Record;
-    _PopulateCppExceptionRecord(_Record, _PExceptRaw, static_cast<ThrowInfo*>(_PThrowRaw));
-    _Assign_cpp_exception_ptr_from_record(
-        *static_cast<shared_ptr<const _EXCEPTION_RECORD>*>(_Ptr), reinterpret_cast<const EHExceptionRecord&>(_Record));
-}
+// Copyright (c) Microsoft Corporation.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+// This implementation communicates with the EH runtime though vcruntime's per-thread-data structure; see
+// _pCurrentException in <trnsctrl.h>.
+//
+// As a result, normal EH runtime services (such as noexcept functions) are safe to use in this file.
+
+#ifndef _VCRT_ALLOW_INTERNALS
+#define _VCRT_ALLOW_INTERNALS
+#endif // !defined(_VCRT_ALLOW_INTERNALS)
+
+#include <Unknwn.h>
+#include <cstdlib> // for abort
+#include <cstring> // for memcpy
+#include <eh.h>
+#include <ehdata.h>
+#include <exception>
+#include <internal_shared.h>
+#include <malloc.h>
+#include <memory>
+#include <new>
+#include <stdexcept>
+#include <trnsctrl.h>
+#include <xcall_once.h>
+
+#include <Windows.h>
+
+// Pre-V4 managed exception code
+#define MANAGED_EXCEPTION_CODE 0XE0434F4D
+
+// V4 and later managed exception code
+#define MANAGED_EXCEPTION_CODE_V4 0XE0434352
+
+extern "C" _CRTIMP2 void* __cdecl __AdjustPointer(void*, const PMD&); // defined in frame.cpp
+
+using namespace std;
+
+namespace {
+#if defined(_M_CEE_PURE)
+    template <class _Ty>
+    _Ty& _Immortalize() { // return a reference to an object that will live forever
+        /* MAGIC */ static _Immortalizer_impl<_Ty> _Static;
+        return reinterpret_cast<_Ty&>(_Static._Storage);
+    }
+#elif !defined(_M_CEE)
+    template <class _Ty>
+    struct _Constexpr_excptptr_immortalize_impl {
+        union {
+            _Ty _Storage;
+        };
+
+        constexpr _Constexpr_excptptr_immortalize_impl() noexcept : _Storage{} {}
+
+        _Constexpr_excptptr_immortalize_impl(const _Constexpr_excptptr_immortalize_impl&)            = delete;
+        _Constexpr_excptptr_immortalize_impl& operator=(const _Constexpr_excptptr_immortalize_impl&) = delete;
+
+        _MSVC_NOOP_DTOR ~_Constexpr_excptptr_immortalize_impl() {
+            // do nothing, allowing _Ty to be used during shutdown
+        }
+    };
+
+    template <class _Ty>
+    _Constexpr_excptptr_immortalize_impl<_Ty> _Immortalize_impl;
+
+    template <class _Ty>
+    [[nodiscard]] _Ty& _Immortalize() noexcept {
+        return _Immortalize_impl<_Ty>._Storage;
+    }
+#else // ^^^ !defined(_M_CEE) / defined(_M_CEE), TRANSITION, VSO-1153256 vvv
+    template <class _Ty>
+    _Ty& _Immortalize() { // return a reference to an object that will live forever
+        static once_flag _Flag;
+        alignas(_Ty) static unsigned char _Storage[sizeof(_Ty)];
+        call_once(_Flag, [&_Storage] { ::new (static_cast<void*>(&_Storage)) _Ty(); });
+        return reinterpret_cast<_Ty&>(_Storage);
+    }
+#endif // ^^^ !defined(_M_CEE_PURE) && defined(_M_CEE), TRANSITION, VSO-1153256 ^^^
+
+    void _PopulateCppExceptionRecord(
+        _EXCEPTION_RECORD& _Record, const void* const _PExcept, ThrowInfo* _PThrow) noexcept {
+        _Record.ExceptionCode           = EH_EXCEPTION_NUMBER;
+        _Record.ExceptionFlags          = EXCEPTION_NONCONTINUABLE;
+        _Record.ExceptionRecord         = nullptr; // no SEH to chain
+        _Record.ExceptionAddress        = nullptr; // Address of exception. Will be overwritten by OS
+        _Record.NumberParameters        = EH_EXCEPTION_PARAMETERS;
+        _Record.ExceptionInformation[0] = EH_MAGIC_NUMBER1; // params.magicNumber
+        _Record.ExceptionInformation[1] = reinterpret_cast<ULONG_PTR>(_PExcept); // params.pExceptionObject
+
+        if (_PThrow && (_PThrow->attributes & TI_IsWinRT)) {
+            // The pointer to the ExceptionInfo structure is stored sizeof(void*) in front of each WinRT Exception Info.
+            const auto _PWei = (*static_cast<WINRTEXCEPTIONINFO** const*>(_PExcept))[-1];
+            _PThrow          = _PWei->throwInfo;
+        }
+
+        _Record.ExceptionInformation[2] = reinterpret_cast<ULONG_PTR>(_PThrow); // params.pThrowInfo
+
+#if _EH_RELATIVE_TYPEINFO
+        void* _ThrowImageBase =
+            _PThrow ? RtlPcToFileHeader(const_cast<void*>(static_cast<const void*>(_PThrow)), &_ThrowImageBase)
+                    : nullptr;
+        _Record.ExceptionInformation[3] = reinterpret_cast<ULONG_PTR>(_ThrowImageBase); // params.pThrowImageBase
+#endif // _EH_RELATIVE_TYPEINFO
+
+        // If the throw info indicates this throw is from a pure region,
+        // set the magic number to the Pure one, so only a pure-region
+        // catch will see it.
+        //
+        // Also use the Pure magic number on 64-bit platforms if we were unable to
+        // determine an image base, since that was the old way to determine
+        // a pure throw, before the TI_IsPure bit was added to the FuncInfo
+        // attributes field.
+        if (_PThrow
+            && ((_PThrow->attributes & TI_IsPure)
+#if _EH_RELATIVE_TYPEINFO
+                || !_ThrowImageBase
+#endif // _EH_RELATIVE_TYPEINFO
+                )) {
+            _Record.ExceptionInformation[0] = EH_PURE_MAGIC_NUMBER1;
+        }
+    }
+
+    void _CopyExceptionRecord(_EXCEPTION_RECORD& _Dest, const _EXCEPTION_RECORD& _Src) noexcept {
+        _Dest.ExceptionCode = _Src.ExceptionCode;
+        // we force EXCEPTION_NONCONTINUABLE because rethrow_exception is [[noreturn]]
+        _Dest.ExceptionFlags   = _Src.ExceptionFlags | EXCEPTION_NONCONTINUABLE;
+        _Dest.ExceptionRecord  = nullptr; // We don't chain SEH exceptions
+        _Dest.ExceptionAddress = nullptr; // Useless field to copy. It will be overwritten by RaiseException()
+        const auto _Parameters = _Src.NumberParameters;
+        _Dest.NumberParameters = _Parameters;
+
+        // copy the number of parameters in use
+        constexpr auto _Max_parameters = static_cast<DWORD>(EXCEPTION_MAXIMUM_PARAMETERS);
+        const auto _In_use             = (_STD min)(_Parameters, _Max_parameters);
+        _CSTD memcpy(_Dest.ExceptionInformation, _Src.ExceptionInformation, _In_use * sizeof(ULONG_PTR));
+        _CSTD memset(&_Dest.ExceptionInformation[_In_use], 0, (_Max_parameters - _In_use) * sizeof(ULONG_PTR));
+    }
+
+    void _CopyExceptionObject(void* _Dest, const void* _Src, const CatchableType* const _PType
+#if _EH_RELATIVE_TYPEINFO
+        ,
+        const uintptr_t _ThrowImageBase
+#endif // _EH_RELATIVE_TYPEINFO
+    ) {
+        // copy an object of type denoted by *_PType from _Src to _Dest; throws whatever the copy ctor of the type
+        // denoted by *_PType throws
+        if ((_PType->properties & CT_IsSimpleType) || _PType->copyFunction == 0) {
+            memcpy(_Dest, _Src, _PType->sizeOrOffset);
+
+            if (_PType->properties & CT_IsWinRTHandle) {
+                const auto _PUnknown = *static_cast<IUnknown* const*>(_Src);
+                if (_PUnknown) {
+                    _PUnknown->AddRef();
+                }
+            }
+            return;
+        }
+
+#if _EH_RELATIVE_TYPEINFO
+        const auto _CopyFunc = reinterpret_cast<void*>(_ThrowImageBase + _PType->copyFunction);
+#else // ^^^ _EH_RELATIVE_TYPEINFO / !_EH_RELATIVE_TYPEINFO vvv
+        const auto _CopyFunc = _PType->copyFunction;
+#endif // ^^^ !_EH_RELATIVE_TYPEINFO ^^^
+
+        const auto _Adjusted = __AdjustPointer(const_cast<void*>(_Src), _PType->thisDisplacement);
+        if (_PType->properties & CT_HasVirtualBase) {
+#ifdef _M_CEE_PURE
+            reinterpret_cast<void(__clrcall*)(void*, void*, int)>(_CopyFunc)(_Dest, _Adjusted, 1);
+#else // ^^^ defined(_M_CEE_PURE) / !defined(_M_CEE_PURE) vvv
+            _CallMemberFunction2(_Dest, _CopyFunc, _Adjusted, 1);
+#endif // ^^^ !defined(_M_CEE_PURE) ^^^
+        } else {
+#ifdef _M_CEE_PURE
+            reinterpret_cast<void(__clrcall*)(void*, void*)>(_CopyFunc)(_Dest, _Adjusted);
+#else // ^^^ defined(_M_CEE_PURE) / !defined(_M_CEE_PURE) vvv
+            _CallMemberFunction1(_Dest, _CopyFunc, _Adjusted);
+#endif // ^^^ !defined(_M_CEE_PURE) ^^^
+        }
+    }
+} // unnamed namespace
+
+// All exception_ptr implementations are out-of-line because <memory> depends on <exception>,
+// which means <exception> cannot include <memory> -- and shared_ptr is defined in <memory>.
+// To workaround this, we created a dummy class exception_ptr, which is structurally identical to shared_ptr.
+
+_STD_BEGIN
+struct _Exception_ptr_access {
+    template <class _Ty, class _Ty2>
+    static void _Set_ptr_rep(_Ptr_base<_Ty>& _This, _Ty2* _Px, _Ref_count_base* _Rx) noexcept {
+        _This._Ptr = _Px;
+        _This._Rep = _Rx;
+    }
+};
+_STD_END
+
+static_assert(sizeof(exception_ptr) == sizeof(shared_ptr<const _EXCEPTION_RECORD>)
+                  && alignof(exception_ptr) == alignof(shared_ptr<const _EXCEPTION_RECORD>),
+    "std::exception_ptr and std::shared_ptr<const _EXCEPTION_RECORD> must have the same layout.");
+
+namespace {
+    template <class _StaticEx>
+    class _ExceptionPtr_static final : public _Ref_count_base {
+        // reference count control block for special "never allocates" exceptions like the bad_alloc or bad_exception
+        // exception_ptrs
+    private:
+        void _Destroy() noexcept override {
+            // intentionally does nothing
+        }
+
+        void _Delete_this() noexcept override {
+            // intentionally does nothing
+        }
+
+    public:
+        // constexpr, TRANSITION P1064
+        explicit _ExceptionPtr_static() noexcept : _Ref_count_base() {
+            _PopulateCppExceptionRecord(_ExRecord, &_Ex, static_cast<ThrowInfo*>(__GetExceptionInfo(_Ex)));
+        }
+
+        static shared_ptr<const _EXCEPTION_RECORD> _Get() noexcept {
+            auto& _Instance = _Immortalize<_ExceptionPtr_static>();
+            shared_ptr<const _EXCEPTION_RECORD> _Ret;
+            _Instance._Incref();
+            _Exception_ptr_access::_Set_ptr_rep(_Ret, &_Instance._ExRecord, &_Instance);
+            return _Ret;
+        }
+
+        _EXCEPTION_RECORD _ExRecord;
+        _StaticEx _Ex;
+    };
+
+    class _ExceptionPtr_normal final : public _Ref_count_base {
+        // reference count control block for exception_ptrs; the exception object is stored at
+        // reinterpret_cast<unsigned char*>(this) + sizeof(_ExceptionPtr_normal)
+    private:
+        void _Destroy() noexcept override {
+            // call the destructor for a stored pure or native C++ exception if necessary
+            const auto& _CppEhRecord = reinterpret_cast<EHExceptionRecord&>(_ExRecord);
+
+            if (!PER_IS_MSVC_PURE_OR_NATIVE_EH(&_CppEhRecord)) {
+                return;
+            }
+
+            const auto _PThrow = _CppEhRecord.params.pThrowInfo;
+            if (!_PThrow) {
+                // No ThrowInfo exists. If this was a C++ exception, something must have corrupted it.
+                _CSTD abort();
+            }
+
+            if (!_CppEhRecord.params.pExceptionObject) {
+                return;
+            }
+
+#if _EH_RELATIVE_TYPEINFO
+            const auto _ThrowImageBase     = reinterpret_cast<uintptr_t>(_CppEhRecord.params.pThrowImageBase);
+            const auto _CatchableTypeArray = reinterpret_cast<const CatchableTypeArray*>(
+                static_cast<uintptr_t>(_PThrow->pCatchableTypeArray) + _ThrowImageBase);
+            const auto _PType = reinterpret_cast<CatchableType*>(
+                static_cast<uintptr_t>(_CatchableTypeArray->arrayOfCatchableTypes[0]) + _ThrowImageBase);
+#else // ^^^ _EH_RELATIVE_TYPEINFO / !_EH_RELATIVE_TYPEINFO vvv
+            const auto _PType = _PThrow->pCatchableTypeArray->arrayOfCatchableTypes[0];
+#endif // ^^^ !_EH_RELATIVE_TYPEINFO ^^^
+
+            if (_PThrow->pmfnUnwind) {
+                // The exception was a user defined type with a nontrivial destructor, call it
+#if defined(_M_CEE_PURE)
+                reinterpret_cast<void(__clrcall*)(void*)>(_PThrow->pmfnUnwind)(_CppEhRecord.params.pExceptionObject);
+#elif _EH_RELATIVE_TYPEINFO
+                _CallMemberFunction0(_CppEhRecord.params.pExceptionObject,
+                    reinterpret_cast<void*>(_PThrow->pmfnUnwind + _ThrowImageBase));
+#else // ^^^ _EH_RELATIVE_TYPEINFO && !defined(_M_CEE_PURE) / !_EH_RELATIVE_TYPEINFO && !defined(_M_CEE_PURE) vvv
+                _CallMemberFunction0(_CppEhRecord.params.pExceptionObject, _PThrow->pmfnUnwind);
+#endif // ^^^ !_EH_RELATIVE_TYPEINFO && !defined(_M_CEE_PURE) ^^^
+            } else if (_PType->properties & CT_IsWinRTHandle) {
+                const auto _PUnknown = *static_cast<IUnknown* const*>(_CppEhRecord.params.pExceptionObject);
+                if (_PUnknown) {
+                    _PUnknown->Release();
+                }
+            }
+        }
+
+        void _Delete_this() noexcept override {
+            free(this);
+        }
+
+    public:
+        explicit _ExceptionPtr_normal(const _EXCEPTION_RECORD& _Record) noexcept : _Ref_count_base() {
+            _CopyExceptionRecord(_ExRecord, _Record);
+        }
+
+        _EXCEPTION_RECORD _ExRecord;
+        void* _Unused_alignment_padding{};
+    };
+
+    // We aren't using alignas because this file might be compiled with _M_CEE_PURE
+    static_assert(sizeof(_ExceptionPtr_normal) % __STDCPP_DEFAULT_NEW_ALIGNMENT__ == 0,
+        "Exception in exception_ptr would be constructed with the wrong alignment");
+
+    void _Assign_seh_exception_ptr_from_record(
+        shared_ptr<const _EXCEPTION_RECORD>& _Dest, const _EXCEPTION_RECORD& _Record, void* const _RxRaw) noexcept {
+        // in the memory _RxRaw, constructs a reference count control block for a SEH exception denoted by _Record
+        // if _RxRaw is nullptr, assigns bad_alloc instead
+        if (!_RxRaw) {
+            _Dest = _ExceptionPtr_static<bad_alloc>::_Get();
+            return;
+        }
+
+        const auto _Rx = ::new (_RxRaw) _ExceptionPtr_normal(_Record);
+        _Exception_ptr_access::_Set_ptr_rep(_Dest, &_Rx->_ExRecord, _Rx);
+    }
+
+    void _Assign_cpp_exception_ptr_from_record(
+        shared_ptr<const _EXCEPTION_RECORD>& _Dest, const EHExceptionRecord& _Record) noexcept {
+        // construct a reference count control block for the C++ exception recorded by _Record, and bind it to _Dest
+        // if allocating memory for the reference count control block fails, sets _Dest to bad_alloc
+        // if copying the exception object referred to _Record throws, constructs a reference count control block for
+        //      that exception instead
+        // if copying the exception object thrown by copying the original exception object throws, sets _Dest to
+        //      bad_exception
+        const auto _PThrow = _Record.params.pThrowInfo;
+#if _EH_RELATIVE_TYPEINFO
+        const auto _ThrowImageBase     = reinterpret_cast<uintptr_t>(_Record.params.pThrowImageBase);
+        const auto _CatchableTypeArray = reinterpret_cast<const CatchableTypeArray*>(
+            static_cast<uintptr_t>(_PThrow->pCatchableTypeArray) + _ThrowImageBase);
+        const auto _PType = reinterpret_cast<CatchableType*>(
+            static_cast<uintptr_t>(_CatchableTypeArray->arrayOfCatchableTypes[0]) + _ThrowImageBase);
+#else // ^^^ _EH_RELATIVE_TYPEINFO / !_EH_RELATIVE_TYPEINFO vvv
+        const auto _PType = _PThrow->pCatchableTypeArray->arrayOfCatchableTypes[0];
+#endif // ^^^ !_EH_RELATIVE_TYPEINFO ^^^
+
+        const auto _ExceptionObjectSize = static_cast<size_t>(_PType->sizeOrOffset);
+        const auto _AllocSize           = sizeof(_ExceptionPtr_normal) + _ExceptionObjectSize;
+        _Analysis_assume_(_AllocSize >= sizeof(_ExceptionPtr_normal));
+        auto _RxRaw = malloc(_AllocSize);
+        if (!_RxRaw) {
+            _Dest = _ExceptionPtr_static<bad_alloc>::_Get();
+            return;
+        }
+
+        try {
+            _CopyExceptionObject(static_cast<_ExceptionPtr_normal*>(_RxRaw) + 1, _Record.params.pExceptionObject, _PType
+#if _EH_RELATIVE_TYPEINFO
+                ,
+                _ThrowImageBase
+#endif // _EH_RELATIVE_TYPEINFO
+            );
+
+            const auto _Rx = ::new (_RxRaw) _ExceptionPtr_normal(reinterpret_cast<const _EXCEPTION_RECORD&>(_Record));
+            reinterpret_cast<EHExceptionRecord&>(_Rx->_ExRecord).params.pExceptionObject =
+                static_cast<_ExceptionPtr_normal*>(_RxRaw) + 1;
+            _Exception_ptr_access::_Set_ptr_rep(_Dest, &_Rx->_ExRecord, _Rx);
+        } catch (...) { // copying the exception object threw an exception
+            const auto& _InnerRecord = *_pCurrentException; // exception thrown by the original exception's copy ctor
+            if (_InnerRecord.ExceptionCode == MANAGED_EXCEPTION_CODE
+                || _InnerRecord.ExceptionCode == MANAGED_EXCEPTION_CODE_V4) {
+                // we don't support managed exceptions and don't want to say there's no active exception, so give up and
+                // say bad_exception
+                free(_RxRaw);
+                _Dest = _ExceptionPtr_static<bad_exception>::_Get();
+                return;
+            }
+
+            if (!PER_IS_MSVC_PURE_OR_NATIVE_EH(&_InnerRecord)) { // catching a non-C++ exception depends on /EHa
+                _Assign_seh_exception_ptr_from_record(
+                    _Dest, reinterpret_cast<const _EXCEPTION_RECORD&>(_InnerRecord), _RxRaw);
+                return;
+            }
+
+            const auto _PInnerThrow = _InnerRecord.params.pThrowInfo;
+#if _EH_RELATIVE_TYPEINFO
+            const auto _InnerThrowImageBase     = reinterpret_cast<uintptr_t>(_InnerRecord.params.pThrowImageBase);
+            const auto _InnerCatchableTypeArray = reinterpret_cast<const CatchableTypeArray*>(
+                static_cast<uintptr_t>(_PInnerThrow->pCatchableTypeArray) + _InnerThrowImageBase);
+            const auto _PInnerType = reinterpret_cast<CatchableType*>(
+                static_cast<uintptr_t>(_InnerCatchableTypeArray->arrayOfCatchableTypes[0]) + _InnerThrowImageBase);
+#else // ^^^ _EH_RELATIVE_TYPEINFO / !_EH_RELATIVE_TYPEINFO vvv
+            const auto _PInnerType = _PInnerThrow->pCatchableTypeArray->arrayOfCatchableTypes[0];
+#endif // ^^^ !_EH_RELATIVE_TYPEINFO ^^^
+
+            const auto _InnerExceptionSize = static_cast<size_t>(_PInnerType->sizeOrOffset);
+            const auto _InnerAllocSize     = sizeof(_ExceptionPtr_normal) + _InnerExceptionSize;
+            if (_InnerAllocSize > _AllocSize) {
+                free(_RxRaw);
+                _RxRaw = malloc(_InnerAllocSize);
+                if (!_RxRaw) {
+                    _Dest = _ExceptionPtr_static<bad_alloc>::_Get();
+                    return;
+                }
+            }
+
+            try {
+                _CopyExceptionObject(
+                    static_cast<_ExceptionPtr_normal*>(_RxRaw) + 1, _InnerRecord.params.pExceptionObject, _PInnerType
+#if _EH_RELATIVE_TYPEINFO
+                    ,
+                    _ThrowImageBase
+#endif // _EH_RELATIVE_TYPEINFO
+                );
+            } catch (...) { // copying the exception emitted while copying the original exception also threw, give up
+                free(_RxRaw);
+                _Dest = _ExceptionPtr_static<bad_exception>::_Get();
+                return;
+            }
+
+            // this next block must be duplicated inside the catch (even though it looks identical to the block in the
+            // try) so that _InnerRecord is held alive; exiting the catch will destroy it
+            const auto _Rx =
+                ::new (_RxRaw) _ExceptionPtr_normal(reinterpret_cast<const _EXCEPTION_RECORD&>(_InnerRecord));
+            reinterpret_cast<EHExceptionRecord&>(_Rx->_ExRecord).params.pExceptionObject =
+                static_cast<_ExceptionPtr_normal*>(_RxRaw) + 1;
+            _Exception_ptr_access::_Set_ptr_rep(_Dest, &_Rx->_ExRecord, _Rx);
+        }
+    }
+} // unnamed namespace
+
+_CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrCreate(_Out_ void* _Ptr) noexcept {
+    ::new (_Ptr) shared_ptr<const _EXCEPTION_RECORD>();
+}
+
+_CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrDestroy(_Inout_ void* _Ptr) noexcept {
+    static_cast<shared_ptr<const _EXCEPTION_RECORD>*>(_Ptr)->~shared_ptr<const _EXCEPTION_RECORD>();
+}
+
+_CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrCopy(_Out_ void* _Dest, _In_ const void* _Src) noexcept {
+    ::new (_Dest) shared_ptr<const _EXCEPTION_RECORD>(*static_cast<const shared_ptr<const _EXCEPTION_RECORD>*>(_Src));
+}
+
+_CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrAssign(_Inout_ void* _Dest, _In_ const void* _Src) noexcept {
+    *static_cast<shared_ptr<const _EXCEPTION_RECORD>*>(_Dest) =
+        *static_cast<const shared_ptr<const _EXCEPTION_RECORD>*>(_Src);
+}
+
+_CRTIMP2_PURE bool __CLRCALL_PURE_OR_CDECL __ExceptionPtrCompare(
+    _In_ const void* _Lhs, _In_ const void* _Rhs) noexcept {
+    return *static_cast<const shared_ptr<const _EXCEPTION_RECORD>*>(_Lhs)
+        == *static_cast<const shared_ptr<const _EXCEPTION_RECORD>*>(_Rhs);
+}
+
+_CRTIMP2_PURE bool __CLRCALL_PURE_OR_CDECL __ExceptionPtrToBool(_In_ const void* _Ptr) noexcept {
+    return static_cast<bool>(*static_cast<const shared_ptr<const _EXCEPTION_RECORD>*>(_Ptr));
+}
+
+_CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrSwap(_Inout_ void* _Lhs, _Inout_ void* _Rhs) noexcept {
+    static_cast<shared_ptr<const _EXCEPTION_RECORD>*>(_Lhs)->swap(
+        *static_cast<shared_ptr<const _EXCEPTION_RECORD>*>(_Rhs));
+}
+
+_CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrCurrentException(void* _Ptr) noexcept {
+    const auto _PRecord = _pCurrentException; // nontrivial FLS cost, pay it once
+    if (!_PRecord || _PRecord->ExceptionCode == MANAGED_EXCEPTION_CODE
+        || _PRecord->ExceptionCode == MANAGED_EXCEPTION_CODE_V4) {
+        return; // no current exception, or we don't support managed exceptions
+    }
+
+    auto& _Dest = *static_cast<shared_ptr<const _EXCEPTION_RECORD>*>(_Ptr);
+    if (PER_IS_MSVC_PURE_OR_NATIVE_EH(_PRecord)) {
+        _Assign_cpp_exception_ptr_from_record(_Dest, *_PRecord);
+    } else {
+        // _Assign_seh_exception_ptr_from_record handles failed malloc
+        _Assign_seh_exception_ptr_from_record(
+            _Dest, reinterpret_cast<_EXCEPTION_RECORD&>(*_PRecord), malloc(sizeof(_ExceptionPtr_normal)));
+    }
+}
+
+[[noreturn]] _CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrRethrow(_In_ const void* _PtrRaw) {
+    const shared_ptr<const _EXCEPTION_RECORD>* _Ptr = static_cast<const shared_ptr<const _EXCEPTION_RECORD>*>(_PtrRaw);
+    // throwing a bad_exception if they give us a nullptr exception_ptr
+    if (!*_Ptr) {
+        throw bad_exception();
+    }
+
+    auto _RecordCopy = **_Ptr;
+    auto& _CppRecord = reinterpret_cast<EHExceptionRecord&>(_RecordCopy);
+    if (PER_IS_MSVC_PURE_OR_NATIVE_EH(&_CppRecord)) {
+        // This is a C++ exception.
+        // We need to build the exception on the stack because the current exception mechanism assumes the exception
+        // object is on the stack and will call the appropriate destructor (if there's a nontrivial one).
+        const auto _PThrow = _CppRecord.params.pThrowInfo;
+        if (!_CppRecord.params.pExceptionObject || !_PThrow || !_PThrow->pCatchableTypeArray) {
+            // Missing or corrupt ThrowInfo. If this was a C++ exception, something must have corrupted it.
+            _CSTD abort();
+        }
+
+#if _EH_RELATIVE_TYPEINFO
+        const auto _ThrowImageBase = reinterpret_cast<uintptr_t>(_CppRecord.params.pThrowImageBase);
+        const auto _CatchableTypeArray =
+            reinterpret_cast<const CatchableTypeArray*>(_ThrowImageBase + _PThrow->pCatchableTypeArray);
+#else // ^^^ _EH_RELATIVE_TYPEINFO / !_EH_RELATIVE_TYPEINFO vvv
+        const auto _CatchableTypeArray = _PThrow->pCatchableTypeArray;
+#endif // ^^^ !_EH_RELATIVE_TYPEINFO ^^^
+
+        if (_CatchableTypeArray->nCatchableTypes <= 0) {
+            // Ditto corrupted.
+            _CSTD abort();
+        }
+
+        // we finally got the type info we want
+#if _EH_RELATIVE_TYPEINFO
+        const auto _PType = reinterpret_cast<CatchableType*>(
+            static_cast<uintptr_t>(_CatchableTypeArray->arrayOfCatchableTypes[0]) + _ThrowImageBase);
+#else // ^^^ _EH_RELATIVE_TYPEINFO / !_EH_RELATIVE_TYPEINFO vvv
+        const auto _PType = _PThrow->pCatchableTypeArray->arrayOfCatchableTypes[0];
+#endif // ^^^ !_EH_RELATIVE_TYPEINFO ^^^
+
+        // Alloc memory on stack for exception object. This might cause a stack overflow SEH exception, or another C++
+        // exception when copying the C++ exception object. In that case, we just let that become the thrown exception.
+
+#pragma warning(suppress : 6255) //  _alloca indicates failure by raising a stack overflow exception
+        void* _PExceptionBuffer = alloca(_PType->sizeOrOffset);
+        _CopyExceptionObject(_PExceptionBuffer, _CppRecord.params.pExceptionObject, _PType
+#if _EH_RELATIVE_TYPEINFO
+            ,
+            _ThrowImageBase
+#endif // _EH_RELATIVE_TYPEINFO
+        );
+
+        _CppRecord.params.pExceptionObject = _PExceptionBuffer;
+    } else {
+        // this is a SEH exception, no special handling is required
+    }
+
+    _Analysis_assume_(_RecordCopy.NumberParameters <= EXCEPTION_MAXIMUM_PARAMETERS);
+    RaiseException(_RecordCopy.ExceptionCode, _RecordCopy.ExceptionFlags, _RecordCopy.NumberParameters,
+        _RecordCopy.ExceptionInformation);
+}
+
+_CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrCopyException(
+    _Inout_ void* _Ptr, _In_ const void* _PExceptRaw, _In_ const void* _PThrowRaw) noexcept {
+    _EXCEPTION_RECORD _Record;
+    _PopulateCppExceptionRecord(_Record, _PExceptRaw, static_cast<ThrowInfo*>(_PThrowRaw));
+    _Assign_cpp_exception_ptr_from_record(
+        *static_cast<shared_ptr<const _EXCEPTION_RECORD>*>(_Ptr), reinterpret_cast<const EHExceptionRecord&>(_Record));
+}

>From 1e535c2abbb993b1723ab1e13b6720a57ddd0f2f Mon Sep 17 00:00:00 2001
From: "Stephan T. Lavavej" <stl at microsoft.com>
Date: Mon, 10 Jun 2024 05:07:55 -0700
Subject: [PATCH 4/5] Add LLVM banners.

---
 libcxx/include/__exception/win32_exception_ptr.h | 8 ++++++++
 libcxx/src/support/win32/excptptr.cpp            | 8 ++++++++
 2 files changed, 16 insertions(+)

diff --git a/libcxx/include/__exception/win32_exception_ptr.h b/libcxx/include/__exception/win32_exception_ptr.h
index efadca1b733d0..ec92762751822 100644
--- a/libcxx/include/__exception/win32_exception_ptr.h
+++ b/libcxx/include/__exception/win32_exception_ptr.h
@@ -1,3 +1,11 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
 // exception standard header
 
 // Copyright (c) Microsoft Corporation.
diff --git a/libcxx/src/support/win32/excptptr.cpp b/libcxx/src/support/win32/excptptr.cpp
index a78d1528b0862..a73c33cb1c7d7 100644
--- a/libcxx/src/support/win32/excptptr.cpp
+++ b/libcxx/src/support/win32/excptptr.cpp
@@ -1,3 +1,11 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
 // Copyright (c) Microsoft Corporation.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 

>From 08801a4877bbf426cc3b6026540eeb09475ea463 Mon Sep 17 00:00:00 2001
From: "Stephan T. Lavavej" <stl at microsoft.com>
Date: Mon, 10 Jun 2024 04:58:42 -0700
Subject: [PATCH 5/5] Update `libcxx/CREDITS.TXT` to mention Microsoft.

I am intentionally not crediting myself here,
I'm just delivering the pizza, I didn't cook it.
---
 libcxx/CREDITS.TXT | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libcxx/CREDITS.TXT b/libcxx/CREDITS.TXT
index aa3c8cf1a8c6e..6ed18072de9a5 100644
--- a/libcxx/CREDITS.TXT
+++ b/libcxx/CREDITS.TXT
@@ -98,7 +98,7 @@ E: lebrungrandt at ornl.gov
 D: Implementation of mdspan.
 
 N: Microsoft Corporation
-D: Contributed floating-point to_chars.
+D: Contributed floating-point to_chars and an implementation of exception_ptr for Windows.
 
 N: Bruce Mitchener, Jr.
 E: bruce.mitchener at gmail.com



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