Re: Updating GNU Guix's package definition for LilyPond

[Jean Abou Samra]

Hi Jahrme,

Le 17/01/2023 à 12:14, Jahrme Risner a écrit :
> Hello all,
>
> I recently moved my primary system onto GNU Guix and have been getting it set 
> up according. While doing that I noticed that the Guix package for LilyPond is 
> still on 2.20.0, seemingly having missed the entire 2.22.0 release cycle,



Given that one of LilyPond's creators now works on Guix, I actually find
this a bit surprising...



> and so I'm now looking at updating Guix's package definition for LilyPond so 
> that users have the latest version. (Incidentally, thank you all for making the 
> recent release happen!)
>
> I have an in-progress package definition (see attached lilypond.scm) for 2.24.0 
> that passed preliminary testing (I was able to process the attached minimal 
> test.ly and produced the attached test.pdf), however it has revealed some 
> complicating issues.
>
> The current issue that I found is that the package definition needed to override the 
> `out` environment variable by passing an empty `out=` variable to make (`#:make-flags 
> #~(list "out=")`) in order to build LilyPond because:
>
> 1) Guix by default sets the environment variable `out` to the store path (see [0] for an 
> explanation about the store if interested) that is being built for, essentially having the 
> following as part of the build environment: `export 
> out="/gnu/store/<hash>-lilypond-2.24.0"`
>
> 2) LilyPond takes the `out` environment variable and, if it exists, makes it part of the 
> `outbase` variable in the make setup (see [1]). This resulted in having files like 
> `out-/gnu/store/<hash>-lilypond-2.24.0/VERSION` where I would have expected a file like 
> `out/VERSION` or `out-web/VERSION`. Interestingly, LilyPond does not seem to be internally 
> consistent about this because the build failure was not just the result of having 
> "weird" outputs, it was that some later steps that were trying to reference these 
> outputs _without_ the store path inserted into the middle which caused the file access to fail.
>
> To summarize, this essentially means that it's not possible to run the equivalent of a 
> minimal `make && make install` when building using Guix's build system because 
> of conflicting assumptions about what `out` should be set to. Initially I wondered 
> whether this was an artifact of Guix sometimes doing things oddly but I couldn't find 
> any other package in Guix's packages that was having to override the `out` environment 
> variable. As such, this seems to suggest that it is actually Lilypond's handling of the 
> `out` environment variable that is unexpected here.
>
> While I'm still working on the final package definition (e.g., still necessary 
> is patching out hard-coded references to `/bin/bash` in some of the Python 
> scripts) I wanted to raise this finding so that I could hear what the LilyPond 
> devel folks think.



`out` is not a standard environment variable. LilyPond's build system
makes extensive use of it, and it seems that Guix happens to have
chosen the same name for something else. It's just an unfortunate name
collision, AFAICS.

In your shoes, I'd just live with "out=".

Best,
Jean

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