Re: should xlog_outdesc modify its argument?

On 09/28/2016 02:35 AM, Mark Dilger wrote:
> The function
>
>   static void xlog_outdesc(StringInfo buf, XLogReaderState *record);
>
> in src/backend/access/transam/xlog.c is called by XLogInsertRecord,
> and after returning a string describing an XLogRecord, it clears the
> state data in its XLogReaderState argument.  That mixes the read-only
> semantics of "give me a string that describes this argument" and the
> read-write semantics of "clear out the value in this argument".

I don't see where the "clears the state data" is happening. Can you 
elaborate?

- Heikki