Catch more invalid polygon situations

[Marc-marc-marc]

Thanks for the new test to avoid creating a self-crossing invalid polygon.
but I see that a user is still able to make a invalid polygon that make a "forward/backward" with a duplicate node
https://www.openstreetmap.org/way/90262899
duplicate node https://www.openstreetmap.org/node/5356991998
node "external" to the polygon https://www.openstreetmap.org/node/5356991994
it would be great if iD could prevent the user from creating invalid polygons

[bhousel]

It's difficult to see what they did exactly, but there are still plenty of ways to create invalid polygons.

Here's a situation where I dragged a midpoint from one line on an outer way over to a different line on the same multipolygon. It probably shouldn't be allowed.

Also, iD only checks geometry in drag node and drawing modes. You can still select multiple things and just move them or rotate them to cause a self intersection.

[Marc-marc-marc]

Thanks for considering this issue.
I have sent a message to this user to ask how he does exactly.
Did you prefer that I leave the error for some days or a printscreen before fixing it or the history of the object is enough ?

[bhousel]

Did you prefer that I leave the error for some days or a printscreen before fixing it or the history of the object is enough ?

Looks like it was fixed in OSM already, but this is ok since I put some screen captures in the ticket.

[mmd-osm]

Merge is also bypassing self-intersection checks...