Re: Conditional segmentation faults

[Kevin Barry]

Hi David,

That certainly is strange behaviour. A segmentation fault occurs when
a program tries to access a segment of memory that it isn't allowed
to. It's usually the result of memory bugs in the program. If it's a
bug in emacs, which looks possible, then I am not sure what you will
be able to do. Generally speaking, if a program segfaults then that is
always a bug in that program, but it's often the result of invalid
input, so sometimes you can at least narrow down the behaviour that is
triggering it. You could try starting emacs with the "-q" option so
that it doesn't load your init file. Then try running the shell
command from within emacs to see if it still segfaults (ctrl_C ctrl_L
won't work with no init loaded). If it doesn't that might tell you
something. Also check if you have multiple versions of LilyPond
installed - maybe emacs is running a different one? I'm sorry I can't
be of more help.

Kevin

On Fri, 28 Aug 2020 at 20:04, David Sumbler <david@aeolia.co.uk> wrote:
>
> I am running Ubuntu 18.04, Lilypond 2.21.4, emacs 25.2.2
>
> Ever since I started my current Lilypond project, I have been
> getting occasional segmentation faults when compiling.  Until today I
> thought it was something to do with errors or inconsistencies in my
> Lilypond code, and I have been able to make changes which appeared to
> solve the problem.
>
> However, today I discovered something very odd.
>
> I edit my files in emacs, and I compile the main file by using Ctrl_C
> Ctrl_L in emacs, which issues the command 'lilypond <filename>'.  Since
> earlier today, whenever I do this, the compile fails with a
> segmentation fault.  Sometimes commenting out one or more instruments
> in the score allows the incomplete score to compile, but there seems to
> be no rhyme or reason as to which combinations of instruments allow
> compilation to take place successfully.
>
> As a result, I have spent several hours today trying to work out why
> this crash has started occurring again.
>
> But now I find that if I issue the command 'lilypond <filename>'
> directly from a GNOME terminal, the file compiles faultlessly.  Yet
> even if I issue 'lilypond <filename>' as a shell command within emacs
> (rather than using Ctrl_C Ctrl_L) I again get a segmentation fault
> reported.
>
> I have tried rebooting the computer and then running emacs without
> starting any other programs at the same time, but I still get the same
> result.
>
> As I don't really understand what "segmentation fault" actually
> implies, can anybody suggest why this apparently inconsistent behaviour
> might be occurring?
>
> David
>
>
>