Compare two distinct key values in TagChecker

[naoliv]

I don't know if this really fits into the TagChecker validator, but it would be good if we could use the value of two distinct keys in a comparison.

For example, if the value of "name" == the value of "ref".
As it is now (if I am not wrong), we can only compare one key to some value (but not one key value with another key value)

The logic for this: in Brazil people sometimes wrongly use the same value in name and ref on a highway. I also see cases where unnecessarily the name == old_name == official_name == everyotherkindof_name

Creating a local custom validator with such rules would help a lot.

[Don-vip]

This is not yet possible AFAIK but we should add this possibility in the course of #9414

[simon04]

In 6554/josm:

see #9414 fix #9409 - extend MapCSS condition syntax to allow the comparison of two key values

The syntax is [key1 = *key2] where * is inspired by the C de-reference operator, and = stands for any of =/!=/~=/^=/$=/*=/=~/!~.