How to construct an exception with context for use in a future returned from __aexit__?

[Ext3h]

The premise is that I'm in an exception, and __aexit__ is currently being called with that exception. My __aexit__ can potentially encounter another error (asynchronously), so I will have to report that via set_exception on the future.

In native Python, I could just do:

class AsyncContext:
    async def __aenter__(self):
        return self
    
    async def __aexit__(self, exc_type, exc_val, exc_tb):
        await something()
        raise RuntimeError("Some other error") from exc_val

(The from exc_val here is explicit - but it would have the same effect implicitly as well!)

In pybind11 I do have raise_from - but unlike the native Python code, I'm interfacing with the future object directly in an async context so I can't immediately raise the exception. Instead I have to construct the exception from value, and pass it by value into the future.

Am I missing something obvious, or does pybind11 lack any C++ interface for the task of construction an exception by value instead of directly raising it?

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And while at it - what about translating native C++ exceptions to Python exceptions by value via the registered exception translators?