Re: Strange behaviour

[David Kastrup]

David Wright <address@hidden> writes:

> On Mon 13 Nov 2017 at 07:13:10 (-0500), Ben wrote:
>> On 11/13/2017 1:58 AM, Don Gingrich wrote:
>> >What I want is to effectively have two voices  in the second bar -- The
>> >first time through fits the d4 r4 r4 e8 e tune and the second uses d4 (
>> >a8) a4 d4 e8 e
>> >
>> >melody = \relative c' {
>> >   \clef treble
>> >   \key d \major
>> >   \time 2/2
>> >   \repeat volta 2 {
>> >     d2 \slurDashed d4 ( d)             |
>> >     d4 ( \grace a8 ) \grace{ a4 d4} r4 r4 e8 e
>> >   }
>> >     \bar "|."
>> >}
>> >
>> >
>> >
>> >It would be good to understand how to insert an occasional bar with an
>> >alternate voice -- much vocal music uses a consistent chord progression
>> >and accompaniment -- but varies the melody to fit the lyric.
>> >
>> >
>> 
>> Hi Don,
>> 
>> < side note >
>> 
>> I just encountered a curious crash when I copied your code into my
>> Frescobaldi / LilyPond setup on Windows 10:
>> (see attached)
>> 
>> I have never seen any message like this ever before, no idea where
>> it came from or what it's talking about but...thought I would share
>> in hopes that it made sense to someone.
>
> For a little more info:
>
> Interpreting music...
> programming error: moving backwards in time
> continuing, cross fingers
> lilypond:
> /home/gub/NewGub/gub/target/linux-x86/src/lilypond-git.sv.gnu.org--lilypond.git-stable-2.20/lily/sequential-iterator.cc:163:
> virtual void Sequential_iterator::next_element(bool): Assertion
> `!grace_fixups_ || grace_fixups_->start_ >= here_mom_' failed.

Well, to quote from the manual:

       Grace sections should only be used within sequential music
    expressions.  Nesting or juxtaposing grace sections is not supported,
    and might produce crashes or other errors.

-- 
David Kastrup