Re: Fixing non-reproducibility in some guile packages

[Maxim Cournoyer]

Hi Andy, and thank you for your detailed answer!

Andy Wingo <address@hidden> writes:

> Hi :)
>
> [+guile-devel]
>
> On Mon 13 Feb 2017 07:18, Maxim Cournoyer <address@hidden> writes:
>
>>>>      ;;; note: auto-compilation is enabled, set GUILE_AUTO_COMPILE=0
>>>>      ;;;       or pass the --no-auto-compile argument to disable.
>>>>      ;;; compiling 
>>>> /gnu/store/d3gli8g5bv6yhd3qwk5rfzqpsfvnj4lv-guile-next-2.1.5/bin/guild
>>
>> I've notice this same problem recently while looking at the build-log of
>> our GnuCash package.. It seems to be the problem is caused by the Guile
>> wanting to auto-compile the guild script, and not being able to as it
>> wants to store the compiled version somewhere under $HOME.
>>
>> Could a generally applicable solution be to distribute a pre-compiled
>> guild.go in the store, so that it would use that and never attempt to
>> 'auto-compile' it?  This would effectively fix this problem for good
>> without having to create workaround such as using environment variables
>> or setting HOME to a temp dir.
>
> The compiled .go files that get installed are only for files found in
> the Guile load path.  So like when you load (foo bar), it will look for
> foo/bar.go in the %load-compiled-path (and foo/bar.scm in the
> %load-path).  This lets you compile foo/bar.scm in your build directory
> and have the resulting foo/bar.go in the builddir directly usable from
> the build-time %load-path / %load-compiled-path, and to install you just
> copy into the final %load-path / %load-compiled-path and that works too.
>
> For scripts that are loaded by absolute file name (guild is a prominent
> example) that don't live in the %load-path, this technique isn't
> directly applicable.  The existing %load-compiled-path is effectively a
> function from name-suffix (like "foo/bar.scm") to absolute path of
> compiled .go file.

OK, I see how %load-path and %load-compiled-path currently fail to be
useful in the case of loading a guile script from its absolute
path. Thanks for explaining. 

> function from absolute source file name to absolute path of .go file.
> Perhaps that's doable with an additional path.  Perhaps the fallback
> compilation path (~/.cache/guile/...) could be generalized to include
> something in $prefix also so that packages can install compiled files.

This seem like it would be the simplest solution in the short term, but
maybe not the most elegant. The fallback compilation path seems to refer
to the source file by their exact location though, so it would mean that
if someone was to change the location of the store it would break:

guild
;;; note: auto-compilation is enabled, set GUILE_AUTO_COMPILE=0
;;;       or pass the --no-auto-compile argument to disable.
;;; compiling /gnu/store/jz5pb07j8s9vv07f27p52mmsiap3cwps-profile/bin/guild
;;; compiled
/home/maxim/.cache/guile/ccache/2.0-LE-8-2.0/gnu/store/060piiiz4nmb51jc3wk01bgikajrnfjd-guile-2.0.13/bin/guild.go

> Incidentally probably we should SHA256 the path to prevent so much
> directory traversal...
>
> In some future (is it near or far?), the source -> compiled function
> needs additional inputs: checksums or timestamps of "build inputs" or
> so, so that when for-syntax definitions (like macros) change, users of
> those definitions will recompile.  That is a harder problem though.
>

Interesting problem!

Thanks again,

Maxim

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