[libcxx-commits] [libcxx] [libc++] Fix missing 'get_new_handler()' for Windows builds (PR #150182)

[via libcxx-commits]

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@@ -26,11 +24,33 @@
 
 #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;
+}
+} // namespace
+#  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
+}
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siradam7th wrote:

> Why are we implementing this now? AFAICT the point of the previous implementation was that we shared the new handler with MSVC, which this doesn't do anymore IIUC.

their implementation does not define a `get_new_handler()`.

https://github.com/llvm/llvm-project/pull/150182