I don't think the fix for this situation is sprinkling the docs with "is always greater than or equal to 0". I don't really think there is a doubt in someones head about whether or not a size or length function returns negative value no matter if it's unsigned int, qint64 or size_t.
I think the opposite is more reasonable - document cases where it can actually return negative value and what it means, which Qt docs are doing pretty consistently (correct me if I'm wrong).

Hi,

Thanks for your reply.

The problem was the code in snippit I pasted was executed in the Main/UI-Thread, which seems to receive new bytes asynchronously. So my infinite loop was not allowing the Main-Thread to execute the receive-handler and therefore bytesAvailable() always returned 0.
I now call processEvents() within the loop, and things seem to work as expected :)

Thanks & br, Clemens