[bug#48434] [PATCH] guile: allow pre-inst-env inject local paths

[Maxime Devos]

Sergei Trofimovich schreef op ma 16-08-2021 om 18:28 [+0100]:
> On Sat, 15 May 2021 10:52:27 +0100
> Sergei Trofimovich <slyfox@gentoo.org> wrote:
> 
> > I observed the problem when tried to run 'guix refresh' from local git 
> > checkout:
> > 
> >     $ strace -f ./pre-inst-env guix refresh -u re2c |& fgrep re2c.scm
> >     ...
> >     [pid 3014757] openat(AT_FDCWD, 
> > "/usr/share/guile/site/3.0/gnu/packages/re2c.scm.qilB0R",
> >         O_RDWR|O_CREAT|O_EXCL, 0600) = -1 EACCES (Permission denied)
> > 
> > Attempt to /usr/share happens because local directory override is ignored:
> > 
> >     $ ./pre-inst-env guile -c '(display (search-path %load-path 
> > "gnu/packages/re2c.scm")) (newline) (display %load-path) (newline)'
> >     /usr/share/guile/site/3.0/gnu/packages/re2c.scm
> >     (/usr/share/guile/3.0 \
> >      /usr/share/guile/site/3.0 \
> >      /usr/share/guile/site \
> >      /usr/share/guile \
> >      /home/slyfox/dev/git/guix \
> >      /home/slyfox/dev/git/guix)

         ^ here's the checkout in the load path

> > 
> > It happens because ./guile ignores GUILE_LOAD_PATH / 
> > GUILE_LOAD_COMPILED_PATH
> > unconditionally.

The local directory isn't ignored, it's at the end (the effect is about the 
same though).

> > The change keeps GUILE_LOAD_PATH / GUILE_LOAD_COMPILED_PATH for 
> > ./pre-inst-env.
> > 
> > * gnu/packages/aux-files/guile-launcher.c (main): don't ignore
> > GUILE_LOAD_PATH / GUILE_LOAD_COMPILED_PATH in GUIX_UNINSTALLED=1 mode.

Could you do something like

#define GUIX_UNINSTALLED 1
#if GUIX_UNINSTALLED
new behaviour
#else
OLD BEHAVIOUR
#endif

and change "Makefile.am" to compile two variants of "guile",
one with "DGUIX_UNINSTALLED=1" which goes into libexec, and another
with "DGUIX_UNINSTALLED=0" named "$CHECKOUT/guile" which isn't installed
anywhere but will be added to PATH by "pre-inst-env", or something like that?

I've a bit of an aversion towards using $..._UNINSTALLED environment variables,
as it leads to difficult situations like ‘what should happen if I 
/gnu/store/.../bin/guix
is run with GUIX_UNINSTALLED set to 1’:

  (a): Reset "GUILE_LOAD{,_COMPILED}_PATH" because we're running directly from 
the store
  (b): Don't reset "GUILE_LOAD_{,_COMPILED}_PATH" because GUIX_UNINSTALLED is 
set to 1.

As a comparison, GUIX_UNINSTALLED, the preprocessor variable, is like a 
‘lexical variable’,
and GUIX_UNINSTALLED, the environment variable, is like a
‘parameter object’/‘dynamically bound variable’ (see, e.g., 6.11.12 Parameters 
in the Guile
manual).  I tend to prefer the former, except for dynamic things like LC_ALL, 
$[...]_PATH
(when used by "guile", "gcc" -- applications typically shouldn't depend on 
$GUILE_LOAD_PATH,
if they do, they need 'wrap-program' or the like’).

Also, "guile-launcher.c" is used by 'quiet-quile" in (guix self).  It should 
probably be
verified that "guix pull" still works well.

Greetings,
Maxime.

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