Hi Gerd,
3) The new check did not recognize P-shaped oneways as self-connecting.
This was not a bug in the new check, but a bug in the old check! I agree that by definition, looped ways cannot be dead ends. For the purpose of detecting dead ends, we could ignore non-branching loops formed by a sequence of ways. Actually, it does not matter if the non-branching loops are oneway! If there is no non-looped way connected to both ends of the "foot" of the P, then the foot of the P forms a dead-end oneway. That is, a P-shaped oneway should be treated just like an I-shaped oneway that is obtained by removing the looped part. Maybe you could use this idea to improve dead-end checks? Note that a roundabout does not count as a non-branching loop, unless it is connected to a single oneway flare road only.
Attached is a new version of the patch.
Thanks, I will try it later for today's data. I already ran trunk and the previous patch on the data.
I think this is okay as long as you see the warning for way Y.
Me too, it is OK to be silent about some part of an error scenario, as long as some of the connected ways get flagged. I usually download a region around the problematic spot in order to figure out what the intention is and how it should be fixed. Marko