Re: Conditional segmentation faults

[Paul Scott]

I was also getting occasional seg. faults with 21.1.4.  I would add a little 
more to the code and they would go away.  Since I was able to finish that 
project I didn’t worry about it and it certainly worth the trouble to try too 
create a MWE.  I also use Emacs but I just alt-tab to another shell to compile. 
 (Also alt-tab to look at the results.)

Paul


> On Aug 28, 2020, at 2:39 PM, Kevin Barry <barrykp@gmail.com> wrote:
> 
> 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
>> 
>> 
>> 
>