[bug#59843] [PATCH] shell: Enable --target for guix shell (--development)

[bug#59843] [PATCH] shell: Enable --target for guix shell (--development)

[Yarl Baudig]

This enable the use of --target for development inputs, that is:
with `guix shell`, includes the dependencies for cross-building packages
given with --development

* guix/scripts/environment.scm: Enable --target.
* guix/scripts/shell.scm: Enable --target.
* doc/guix.texi: Document it.
---
 doc/guix.texi                |  5 +++++
 guix/scripts/environment.scm | 14 +++++++++++---
 guix/scripts/shell.scm       |  3 +++
 3 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/doc/guix.texi b/doc/guix.texi
index a79b777826..f1da3a4865 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -6176,6 +6176,11 @@ environment.
 @itemx -s @var{system}
 Attempt to build for @var{system}---e.g., @code{i686-linux}.
 
+@item --target=@var{target}
+Attempt to build the environment dependencies (see @option{--development})
+for @var{target}--e.g., @code{aarch64-linux-gnu}. Useful to debug cross-build
+failures (@pxref{Debugging Build Failures}).
+
 @item --container
 @itemx -C
 @cindex container
diff --git a/guix/scripts/environment.scm b/guix/scripts/environment.scm
index 64597f6e9f..b269be828e 100644
--- a/guix/scripts/environment.scm
+++ b/guix/scripts/environment.scm
@@ -127,7 +127,9 @@ (define (show-environment-options-help)
   (display (G_ "
   -v, --verbosity=LEVEL  use the given verbosity LEVEL"))
   (display (G_ "
-      --bootstrap        use bootstrap binaries to build the environment")))
+      --bootstrap        use bootstrap binaries to build the environment"))
+  (display (G_ "
+      --list-targets     list available targets")))
 
 (define (show-help)
   (display (G_ "Usage: guix environment [OPTION]... PACKAGE... [-- COMMAND...]
@@ -144,6 +146,10 @@ (define (show-help)
       --ad-hoc           include all specified packages in the environment instead
                          of only their inputs"))
 
+   (display (G_ "
+      --target=TRIPLET   cross-build inputs for non-adhoc packages for
+ TRIPLET--e.g., \"aarch64-linux-gnu\""))
+
   (show-environment-options-help)
   (newline)
   (show-build-options-help)
@@ -277,7 +283,8 @@ (define %options
 
          (append %transformation-options
                  %standard-build-options
-                 %standard-native-build-options)))
+                 %standard-native-build-options
+                 %standard-cross-build-options)))
 
 (define (pick-all alist key)
   "Return a list of values in ALIST associated with KEY."
@@ -332,7 +339,8 @@ (define (packages->outputs packages mode)
                   (('package 'package (? string? spec))
                    (manifest-entries
                     (package->development-manifest
-                     (transform (specification->package+output spec)))))
+                     (transform (specification->package+output spec))
+                     #:target (assoc-ref opts 'target))))
                   (('expression mode str)
                    ;; Add all the outputs of the package STR evaluates to.
                    (packages->outputs (read/eval str) mode))
diff --git a/guix/scripts/shell.scm b/guix/scripts/shell.scm
index 2fc1dc942a..b2ae12cec2 100644
--- a/guix/scripts/shell.scm
+++ b/guix/scripts/shell.scm
@@ -62,6 +62,9 @@ (define (show-help)
   (display (G_ "
   -f, --file=FILE        add to the environment the package FILE evaluates to"))
 
+   (display (G_ "
+      --target=TRIPLET   cross-build development inputs packages for
+ TRIPLET--e.g., \"aarch64-linux-gnu\""))
   (display (G_ "
   -q                     inhibit loading of 'guix.scm' and 'manifest.scm'"))
   (display (G_ "

base-commit: c3713d53e0bdf1186e08880b9e0ae6dd85f55fc4
-- 
2.38.1

[bug#59843] [PATCH] shell: Enable --target for guix shell (--development)

[Ludovic Courtès]

Hi,

Yarl Baudig <yarl-baudig@mailoo.org> skribis:

> This enable the use of --target for development inputs, that is:
> with `guix shell`, includes the dependencies for cross-building packages
> given with --development
>
> * guix/scripts/environment.scm: Enable --target.
> * guix/scripts/shell.scm: Enable --target.
> * doc/guix.texi: Document it.

This change won’t give something useful per se, because the environment
will contain a mixture of “host” and “build” inputs.

To make it work, we need two profiles: one for “build” inputs, and one
for “host/target” inputs.  Search path environment variables must be
evaluated in a way that accounts for these two profiles.  For example,
target libraries will appear on CROSS_C_INCLUDE_PATH but not on
C_INCLUDE_PATH.

Does that make sense?

IOW, it’s a trickier endeavor that one could hope for.  :-)

Thanks,
Ludo’.

[bug#59843] [PATCH] shell: Enable --target for guix shell (--development)

[yarl baudig]

> 
> This change won’t give something useful per se, because the environment
> will contain a mixture of “host” and “build” inputs.
> 
> To make it work, we need two profiles: one for “build” inputs, and one
> for “host/target” inputs.  Search path environment variables must be
> evaluated in a way that accounts for these two profiles.  For example,
> target libraries will appear on CROSS_C_INCLUDE_PATH but not on
> C_INCLUDE_PATH.
> 
> Does that make sense?
> 
> IOW, it’s a trickier endeavor that one could hope for.  :-)
> 
> Thanks,
> Ludo’.
> 

Obviously, you know a lot more about this than I do. However (please correct me, I probably did not completely understand your point) I think it is useful and works for the goal I mentioned in the part of the patch concerning the manual. It can help debugging failing (cross-)builds because you source "environment-variables" and that's the reason why I sent this patch. I tried it with texinfo (because the cross-compilation fails and I want to fix it) and it seem to work (i.e. you have access to paths in CROSS_C_INCLUDE_PATH, for example). Maybe I missed something and you saw that "debugging cross-builds" is my intent. Please do tell.

I take avantage of having reached you to mention https://issues.guix.gnu.org/59839 I was working on this in parallel and I may have made things confusing because (in 59839) that's --system I am talking about (see the last version, number 3, of the patch please)... Thank you a lot.

[bug#59843] [PATCH] shell: Enable --target for guix shell (--development)

[yarl baudig]

I responded too fast. You are right, something is wrong. Not every path is accessible. I will try to understand when I'll have some time.

---- Message d'origine ----
> De : Ludovic Courtès <ludo@gnu.org>
> À : Yarl Baudig <yarl-baudig@mailoo.org>
> Sujet : Re: bug#59843: [PATCH] shell: Enable --target for guix shell (--development)
> Date : 14/12/2022 11:59:31 Europe/Paris
> Copie à : 59843@debbugs.gnu.org
> 
> Hi,
> 
> Yarl Baudig <yarl-baudig@mailoo.org> skribis:
> 
> > This enable the use of --target for development inputs, that is:
> > with `guix shell`, includes the dependencies for cross-building packages
> > given with --development
> >
> > * guix/scripts/environment.scm: Enable --target.
> > * guix/scripts/shell.scm: Enable --target.
> > * doc/guix.texi: Document it.
> 
> This change won’t give something useful per se, because the environment
> will contain a mixture of “host” and “build” inputs.
> 
> To make it work, we need two profiles: one for “build” inputs, and one
> for “host/target” inputs.  Search path environment variables must be
> evaluated in a way that accounts for these two profiles.  For example,
> target libraries will appear on CROSS_C_INCLUDE_PATH but not on
> C_INCLUDE_PATH.
> 
> Does that make sense?
> 
> IOW, it’s a trickier endeavor that one could hope for.  :-)
> 
> Thanks,
> Ludo’.
>

bug#59843: [PATCH] shell: Enable --target for guix shell (--development)

[Ludovic Courtès]

Hi,

"yarl baudig" <yarl-baudig@mailoo.org> skribis:

> I responded too fast. You are right, something is wrong. Not every path is accessible. I will try to understand when I'll have some time.

Alright!  I’m closing this bug for now, but do get in touch on IRC or
guix-devel if you’d like to discuss it.

Thanks,
Ludo’.