Re: Wrong type in part-combiner.scm

[Dan Eble]

> On Oct 5, 2020, at 19:16, Dan Eble <dan@faithful.be> wrote:
> 
> On Oct 5, 2020, at 18:58, Dan Eble <dan@faithful.be> wrote:
>> 
>> After some investigation, I'd like to ask the other contributors some 
>> questions because I don't see very strong reasons to go one way or the other.
>> 
>> A. Should context-specific music with no music inside it create the context 
>> or not?  Right now, it doesn't.  I'm slightly in favor of changing it 
>> because it would allow reverting David's recent fix and one of my earlier 
>> ones and it seems that it might raise fewer questions; however, changing 
>> this would have some consequences (item B and perhaps others).
>> 
>> B. Which conditions should trigger the "no music found in score" warning?  
>> Are the cases in input/regression/no-music.ly working as desired?  Would it 
>> be a bad change if \new Voice {} were considered music?  If that were a 
>> problem, maybe we could broaden the test to warn about music with no 
>> duration (grace or main).
>> 
>> Your thoughts?
> 
> New discovery in master:
> 
>  \new Voice {}       %% warning
>  { \new Voice {} }   %% no warning
> 
> This gives me something to feel more strongly about: an inconsistency.  I'll 
> see where it leads.  (You're still welcome to provide feedback.)

Here's where it led:

    https://gitlab.com/lilypond/lilypond/-/merge_requests/438

For partCombine, quotation, etc., the changes restore the previous behavior of 
creating contexts even for empty music.

For score-level processing, the changes treat any zero-duration music as 
non-music.
— 
Dan