implement 'set_new_handler' and 'get_new_handler' for Windows

Author: siradam7th

libcxx/include/__new/global_new_delete.h

@@ -32,7 +32,7 @@
 #endif
 
 #if defined(_LIBCPP_ABI_VCRUNTIME)
-#  include <new.h>
+#include <vcruntime_new.h>
 #else
 [[__nodiscard__]] _LIBCPP_OVERRIDABLE_FUNC_VIS void* operator new(std::size_t __sz) _THROW_BAD_ALLOC;
 [[__nodiscard__]] _LIBCPP_OVERRIDABLE_FUNC_VIS void* operator new(std::size_t __sz, const std::nothrow_t&) _NOEXCEPT

libcxx/include/__new/nothrow_t.h

@@ -16,7 +16,7 @@
 #endif
 
 #if defined(_LIBCPP_ABI_VCRUNTIME)
-#  include <new.h>
+#include <vcruntime_new.h>
 #else
 _LIBCPP_BEGIN_UNVERSIONED_NAMESPACE_STD
 struct _LIBCPP_EXPORTED_FROM_ABI nothrow_t {

libcxx/include/__new/placement_new_delete.h

@@ -17,7 +17,7 @@
 #endif
 
 #if defined(_LIBCPP_ABI_VCRUNTIME)
-#  include <new.h>
+#include <vcruntime_new.h>
 #else
 [[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 void*
 operator new(std::size_t, void* __p) _NOEXCEPT {

libcxx/src/new_handler.cpp

@@ -24,13 +24,35 @@
 
 #if defined(_LIBPCPP_DEFINE_NEW_HANDLER)
 
-namespace std { // purposefully not versioned
-
 static constinit std::new_handler __new_handler = nullptr;
 
-new_handler set_new_handler(new_handler handler) noexcept { return __libcpp_atomic_exchange(&__new_handler, handler); }
+#ifdef _LIBCPP_ABI_VCRUNTIME
+// to avoid including <new.h>
+using _new_h = int(__cdecl*)(size_t);
+extern "C" _new_h __cdecl _set_new_handler(_new_h);
+
+namespace {
+    // adapter for _callnewh
+    int __cdecl _new_handler_adapter(size_t) {
+        std::__libcpp_atomic_load(&__new_handler)();
+        return 1;
+    }
+}
+#endif
+
+namespace std { // purposefully not versioned
+
+new_handler set_new_handler(new_handler handler) noexcept {
+#ifdef _LIBCPP_ABI_VCRUNTIME
+    auto old = __libcpp_atomic_exchange(&__new_handler, handler);
+    _set_new_handler(handler ? _new_handler_adapter: nullptr);
+    return old;
+#else
+    return __libcpp_atomic_exchange(&__new_handler, handler); 
+#endif
+}
 
-new_handler get_new_handler() noexcept { return __libcpp_atomic_load(&__new_handler); }
+new_handler get_new_handler() noexcept {return __libcpp_atomic_load(&__new_handler);}
 
 } // namespace std