Thomas Morley <thomasmorle...@gmail.com> writes:
> To get more space between NoteColumn and DotColumn the following used
> to work with 2.18.2
>
> foo =
> \override Score.DotColumn.before-line-breaking =
> #(lambda (dot-column)
> (ly:grob-set-property! dot-column 'positioning-done
> (lambda (grob)
> (ly:dot-column::calc-positioning-done grob)
> (ly:grob-translate-axis! grob 15 X))))
>
>
> {
> \foo
> <gis' a' c''>4.
> }
Stock 2.18.2 from Ubuntu:
-*- mode: compilation; default-directory: "/tmp/" -*-
Compilation started at Thu May 12 15:02:35
/usr/bin/lilypond crash.ly
GNU LilyPond 2.18.2
Processing `crash.ly'
Parsing...
crash.ly:1: warning: no \version statement found, please add
\version "2.18.2"
for future compatibility
Interpreting music...
Preprocessing graphical objects...lilypond: grob-property.cc:248:
scm_unused_struct* Grob::try_callback_on_alist(scm_unused_struct**, SCM, SCM):
Assertion `value == ((SCM) ((((4)) << 8) + scm_tc8_flag)) || value == marker'
failed.
Compilation aborted (core dumped) at Thu May 12 15:03:04
Wow, they compiled with options enabling assertions. In principle
that's good, but I fear it might have been done using
--disable-optimising.
> With a build from latest master I get:
>
> lilypond: /home/hermann/lilypond-git/lily/grob-property.cc:242:
> scm_unused_struct* Grob::try_callback_on_alist(scm_unused_struct**,
> SCM, SCM): Assertion `scm_is_null (value) || scm_is_eq (value,
> marker)' failed.
> Aborted (core dumped)
Ok, I might focus on the wrong things here... But do you notice that
the 2.18.2 assertion message at the top is much less readable because of
being macro-expanded?
That means that you are compiling with a rather current libc version.
One that has already has my fix for this assertion message expansion
issue.
> A bug?
It's not new, anyway.
> How to do it different?
Good question. Wait. When the call returned by a callback passed to
try_callback_on_alist is *unspecified*, then the assertion checks that
the original value is unset (or blocked by the current call).
Otherwise, it _caches_ the callback value.
The condition is rather obscure. But the point appears to be that a
callback should _never_ return *unspecified* since that messes with the
caching.
So probably your callback is missing a final #t.
The assertion has been added with
commit 635bff94c5a920d5866be4ff16751d771a35b7da
Author: Han-Wen Nienhuys <han...@xs4all.nl>
Date: Thu Jan 4 21:39:34 2007 +0100
allow callbacks on object values too. Init via meta field.
However, the value checked by the assertion is fetched via
internal_get_property rather than get_property_data (as it is now) in
that commit. This has been changed in
commit a7646e7a00e1fe86e4f52123049f20fd28b48739
Author: Han-Wen Nienhuys <han...@xs4all.nl>
Date: Fri Jan 26 01:34:03 2007 +0100
check for calculation-in-progress marker in get_property().
The problem we have after this commit is that get_property_data will
return a procedure if the original entry was a callback (which it will
be most of the time) and thus the assertion triggers.
I am surprised we are not seeing this more often. So at any rate, that
assertion seems to be rather flaky. We only reach it when a callback
returns *unspecified*, though.
I'm not sure what the expected behavior should be.
--
David Kastrup
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