Re: BUG #18070: Assertion failed when processing error from plpy's iterator

On Fri, Sep 15, 2023 at 08:00:00PM +0300, Alexander Lakhin wrote:
> - /* Since we have a format string, we cannot have a SPI detail. */
> - Assert(detail == NULL);
> -
> - /* If there's an exception message, it goes in the detail. */
> - if (xmsg)
> + /*
> + * When we have no detail from the error data, an exception message,
> + * if not empty, goes in the detail.
> + */
> + if (detail == NULL && xmsg != NULL)
> detail = xmsg;

Yeah, I think that you're right here to enforce the use of a DETAIL
message if it exists instead of the xmsg. At least that feels more
natural because we would get the same error when attempting to select
from a composite type.

How about adding a regression test? Say in plpython_error.sql where
we already check a bunch of error patterns?
--
Michael