Reaction to `_Unwind_RaiseException` not finding a handler in C++

[work-robot]

The exception handling ABI states:

_URC_END_OF_STACK: The unwinder encountered the end of the stack during phase 1, without finding a handler. The unwind runtime will not have modified the stack. The C++ runtime will normally call uncaught_exception() in this case.

But uncaught_exception() is a pure function, it just returns whether stack unwinding is still in progress or not.

__cxa_throw from libstdc++:

#ifdef __USING_SJLJ_EXCEPTIONS__
  _Unwind_SjLj_RaiseException (&header->exc.unwindHeader);
#else
  _Unwind_RaiseException (&header->exc.unwindHeader);
#endif

  // Some sort of unwinding error.  Note that terminate is a handler.
  __cxa_begin_catch (&header->exc.unwindHeader);
  std::terminate ();

It unconditionally calls terminate after marking the exception as caught.

libcxxabi also calls __cxa_begin_catch followed by terminate.

Maybe this should just state terminate instead of uncaught_exception()? Is the call to __cxa_begin_catch mandated?