Re: ERROR: In procedure ly:trampoline: ERROR: Wrong type argument in position 3 (expecting Translator): #<freed cell 05CE59A0; GC missed a reference>

[Joseph Srednicki]

Hi David:

Thanks for your message.

Based on your question about the Melody_engraver, I commented out the follow code in the layout block:

%{

  \context {

    \Voice

    \consists "Melody_engraver"

    \override Stem #'neutral-direction = #'()

  }

  %}

I then saved the file, and it compiled with no errors. 

Therefore, it sounds the possible answer to your question is yes.

I am attaching the revised file with the block commented out.

Thanks again for your answer.

Joe  Srednicki

-----Original Message-----
From: David Kastrup <address@hidden>
To: Joseph Srednicki <address@hidden>
Cc: lilypond-user <address@hidden>
Sent: Tue, Jun 4, 2019 6:22 am
Subject: Re: ERROR: In procedure ly:trampoline: ERROR: Wrong type argument in position 3 (expecting Translator): #<freed cell 05CE59A0; GC missed a reference>

Joseph Srednicki <address@hidden> writes:

> Hello:
> I read some messages about this issue in the mail archive, but I have
> not been able to get Lilypond to compile the attached file.
> I know that the attached example is not tiny, but I could not
> reproduce this issue in a tiny example.
> The file compiled without errors until I reached line 266.
> Then I received the following error message:
> ]ERROR: In procedure ly:trampoline:ERROR: Wrong type argument in
> position 3 (expecting Translator): #<freed cell 05CE59A0; GC missed a
> reference>Exited with return code 1.
> My environment is as follows:
> OS Name Microsoft Windows 10 HomeVersion 10.0.17134 Build 1713464
> bitLilypond 2.19.82Frescobaldi 3.0.1
> Thanks to anyone who can suggest how to resolve this issue.
> Joe Srednicki 

Garbage collection issues are notoriously hard to reproduce since their
symptoms occur at a point of time distant from the actual problem and
depend on many circumstances not actually related to the problem.  In
this case, it looks like some grob acknowledger(?) is being called with
an engraver source argument that has already been garbage collected: I
think this would be

lily/include/engraver.hh:    Engraver *e = LY_ASSERT_SMOB (Engraver, source_engraver, 3);

even though I am fuzzy about how the error message would end up
referring the base class "Translator" rather than "Engraver".  So the
main question becomes how a grob manages to get acknowledged while its
source engraver has already been garbage-collected.

I know this is hard to check but do you have the impression that this
problem reliably depends on using the Melody_engraver ?

--
David Kastrup

Vater-unser-in-Himmelreich_2.ly
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