Don't silently join ways with different tags

[GerdP]

Merkaartor allows to join ways with different tags, the result typically has invalid tags like highway=residential;unclassified or oneway=yes;no I don't see any good reason to do that. I think the program should refuse to join ways with different tags, or maybe open a dialog which asks the user to decide what to do with the different tags. This should also happen when e.g. one way has a tag and the other has not, so that a way with highway=track and surface=asphalt isn't silently combined with a way that only has a highway=track tag.

[Krakonos]

I partially agree. It should be possible to join ways in this was, as I find it useful and it would be terrible if I had to synchronize tags before joining ways. I agree that producing invalid tags is always bad, and I'm planning on implementing rules check before upload, so you can be warned. I might also implement a dialog informing you about mismatched or missing tags, but I can think of more important issues to fix.

[GerdP]

I think a final check is good but too late for this kind of problem. If one joins two ways with different tags (without noticing the effect) and later he is asked to correct the data that can be different. For example one may find 3 parts of a road with name=xyz and he thinks those should be combined. Now if only one of the parts was tagged maxspeed=20 how do you want to find out that this join was not okay ? And how should a user know which part it was?

[Krakonos]

Sure, that's why I was thinking about the merge dialog where you'd be presented with this kind of stuff.