Comment #11 on issue 2584 by [email protected]: please make partcombine merge slurs
http://code.google.com/p/lilypond/issues/detail?id=2584
The partcombiner does not actually touch the spanner-id as far as I can tell: every slur has the default "" as spanner-id. If the slur-engraver "should know from the spanner-ids that these events refer to a single slur" then the consequence is simply that we effectively keep only one starting slur event for an identical spanner-id. But that means that we can't support multiple ending events with the same id at different points of time, because the first ending event will already cancel the remaining starting event.
Instead of relaxing the warning circumstances to a level where a lot of clearly wrong manual input gets let through and interpreted in interesting ways, it would make more sense to fix the output from the part combiner. This should, for one thing, produce matched parens. For another, it might be necessary to actually generate spanner-id's resolving ambiguities.
