Error in MapCSS Rule?

[GerdP]

While working on #23397 I stumbled over this.
I wonder if the throwerror clause in this test in relation.mapcss could be improved:

/* #15208, #16242 */
relation[type=route][route=mtb    ] > way[bicycle=no],
relation[type=route][route=bicycle] > way[bicycle=no],
relation[type=route][route=mtb    ] > way[bicycle=private],
relation[type=route][route=bicycle] > way[bicycle=private],
relation[type=route][route=mtb    ] > way[bicycle=use_sidepath],
relation[type=route][route=bicycle] > way[bicycle=use_sidepath], 
relation[type=route][route=fitness_trail] > way[foot=no],
relation[type=route][route=hiking       ] > way[foot=no],
relation[type=route][route=running      ] > way[foot=no],
relation[type=route][route=walking      ] > way[foot=no],
relation[type=route][route=fitness_trail] > way[foot=private],
relation[type=route][route=hiking       ] > way[foot=private],
relation[type=route][route=running      ] > way[foot=private],
relation[type=route][route=walking      ] > way[foot=private],
relation[type=route][route=fitness_trail] > way[foot=use_sidepath],
relation[type=route][route=hiking       ] > way[foot=use_sidepath],
relation[type=route][route=running      ] > way[foot=use_sidepath],
relation[type=route][route=walking      ] > way[foot=use_sidepath], 
relation[type=route][route=horse] > way[horse=no],
relation[type=route][route=horse] > way[horse=private],
relation[type=route][route=horse] > way[horse=use_sidepath] { 
  throwWarning: tr("way with {0} is part of a {1} route relation", "{0.tag}", "{0.key}");

If I have a way with bicycle=no in a route=mtb relation it will report
way with bicycle=no is part of a bicycle route relation
I would expect to get a message like
way with bicycle=no is part of a mtb route relation

Another question that I wondered about:
Should this message be produced when a way with bicycle=no + mtb=yes is member of a route=mtb relation?

[skyper]

So we need to change bicycle to mtb for route=mtb and add a new block. Untested:

relation[type=route][route=mtb] > way[mtb!=yes][bicycle=no],
relation[type=route][route=mtb] > way[mtb!=yes][bicycle=private],
relation[type=route][route=mtb] > way[mtb!=yes][bicycle=use_sidepath] {
  throwWarning: tr("way with {0} and without {1} is part of a {2} route relation", "{1.tag}", "mtb=yes", "{0.key}");
}

[GerdP]

Would not work well with mtb=designated. Please concentrate on the first part, this mtb special case is not important.
Is it possible to refer to the route=* tag value in the relation when producing the error?

[skyper]

Replying to GerdP:

Would not work well with mtb=designated.

Ok, [mtb!~/yes|designated/]?

Please concentrate on the first part, this mtb special case is not important.
Is it possible to refer to the route=* tag value in the relation when producing the error?

No, you can only use the keys/tags on the right of the last child/parent selector.

[GerdP]

OK, then the existing rule is a good compromise.